Requirements to safetyvalves
High reliability.
Ensuring work stability.
Trouble-free and timely opening of the valve in case of excess operating pressure in the system.
Providing the valve with the required throughput.
Carrying out timely closure with the required degree of tightness in the event of a drop in pressure in the system and maintaining the established degree of tightness when the pressure increases.
Safety valves with spring loading must be manufactured with nominal diameters of inlet and outlet pipes (DNinput/DNoutput) 25/40; 40/65; 50/80; 80/100; 100/150; 150/200; 200/300 and nominal pressure of the inlet pipe PN 1.6 MPa, PN 2.5 MPa.
At pump stations, the most widely used is a special spring safety valve of the SPPK type, shown in Figure 6.15.
The technological parameters of the valve are controlled by a ring screwed onto the nozzle. The ring has a narrow flat belt on top. When screwing, the ring approaches the end plane of the plate. By adjusting the gap between the planes of the ring belt and the end of the plate, it is possible to regulate the pressure of full opening of the valve and the pressure of its closing within a wide range, i.e. the amount of blowing.
Installationsafety valves
Installation safety valves on vessels and apparatus operating under excess pressure is carried out in accordance with current regulatory and technical materials and safety rules. The number, design, installation location of valves, the need to install control valves and the direction of discharge are determined by the project.
In any case of installation of the valve, free access must be provided for its maintenance, installation and dismantling.
When replacing a valve, the flow coefficient of the newly installed one should not be lower than that of the one being replaced.
Safety valves must be installed in a vertical position in the highest part of the vessel in such a way that, in the event of opening, vapors and gases are removed from the vessel first.
On horizontal cylindrical devices, the safety valve is installed along the length of the upper position of the generatrix, on vertical devices - on the upper bottoms or in places of greatest accumulation of gases.
If these design requirements cannot be met, then the safety valve can be installed on a pipeline or a special outlet in the immediate vicinity of the vessel, provided that there is no shut-off device between the valve and the vessel.
Figure 2
1 – body; 2 – nozzle; 3 – spool; 4 – rod; 5 – spring; 6 – screw
On column-type devices with a large number of trays (more than 40), if there is a possibility of a sharp increase in their resistance due to a violation of the technological regime, which can lead to a significant difference between the pressure in the bottom and upper parts of the device, it is recommended to install a safety valve in the bottom part of the device in the steam zone cube phases.
The diameter of the fitting for the safety valve must be no less than the diameter of the valve inlet pipe.
When determining the cross-section of connecting pipelines longer than 1 m, it is necessary to take into account the value of their resistance.
The diameter of the valve outlet pipe must be no less than the diameter of the valve outlet fitting.
When combining outlet pipes from several valves installed on one device, the cross-section of the collector must be no less than the sum of the cross-sections of the outlet pipes from these valves.
In the case of combining the outlet pipes of valves installed on several devices, the diameter of the common manifold is calculated based on the maximum possible simultaneous discharge of the valves, determined by the project.
The riser diverting the discharge from the safety valve into the atmosphere must be protected from precipitation and at the lowest point have a drainage hole with a diameter of 20 - 50 mm for draining liquid.
The direction of discharge and the height of the outlet riser are determined by the design and safety rules.
The combined collector, which serves for discharges from safety valves into the atmosphere, must be laid with a slope and at the lowest point have a drain with a diameter of 50 - 80 mm with a discharge into a drainage tank. “Bags” are not allowed on such pipelines.
Sampling of the working medium from branch pipes and sections of connecting pipelines from the vessel to the valve on which safety valves are installed is not allowed.
The installation of any shut-off devices, as well as fire fuses, between the apparatus and the safety valve is not permitted.
Heating, cooling, separation and neutralization devices can be installed after the valve. The total reset resistance should not be more than specified in paragraph
The resistance of the valve discharge pipeline should not be higher than 0.5 kgf/cm2, taking into account the installation of a separator, heating-cooling devices, neutralization, etc.
At an operating pressure of less than 1 kgf/cm2, the resistance of the relief system should not be higher than 0.2 kgf/cm2.
On devices of continuously operating processes equipped with safety valves, the duration of the inter-inspection period is less than the inter-repair period of the installation or workshop, backup safety valves with switching devices can be installed.
If the safety valve is removed for inspection from containers for storing liquefied gas, or flammable liquid with a boiling point of up to 45 ° C, under pressure, a pre-prepared valve must be installed in its place. It is prohibited to install a valve or plug in place of a removed valve.
Adjustment
Adjustment of safety valves to the opening pressure - set pressure (pop) is carried out on a special stand.
The set pressure is determined based on the operating pressure in the vessel, apparatus or pipeline.
Operating pressure is the maximum excess pressure at which the operation of a vessel, apparatus or pipeline is permitted. At operating pressure (P p), the safety valve is closed and provides the tightness class specified in the relevant documentation for the safety valve (GOST, TU).
The set pressure of the safety valve when discharging from it into a closed system with back pressure must be taken into account taking into account the pressure in this system and the design of the safety valve.
The value of the set pressure, the frequency of inspection and testing, the installation location, the direction of discharge from the safety valves are indicated in the list of set pressures. The statement is compiled for each installation (shop) by the head and mechanic (senior mechanic) of the installation (shop), agreed with the technical supervision service, the chief mechanic and approved by the chief engineer of the enterprise.
Each valve body must have a nameplate securely affixed to it. of stainless steel or aluminum, on which is stamped:
a) location of installation - workshop number, code name of the installation or its number, designation of the device according to the technological diagram;
b) set pressure - P mouth;
c) operating pressure in the apparatus - P r.
Frequency of audit and inspection.
On vessels, apparatus and pipelines of oil refining and petrochemical plants, inspection and testing of safety valves is carried out on a special stand with the valve removed. In this case, the frequency of inspection and revision is established based on operating conditions, corrosiveness of the environment, operating experience and should be no less than through:
a) for continuously operating technological production:
24 months - on vessels and devices of the ELOU, vessels and devices working with media that do not cause corrosion of valve parts, in the absence of the possibility of freezing, sticking and polymerization (clogging) of the valves in working condition;
12 months - on vessels and devices operating with media that cause a corrosion rate of the valve parts material of up to 0.2 mm/year, in the absence of the possibility of freezing, sticking and polymerization (clogging) of the valves in working condition;
6 months - on vessels and devices working with media that cause a corrosion rate of the material of the valve parts of more than 0.2 mm/year;
4 months - on vessels and apparatus operating under conditions of possible coking of the medium, formation of solid sediment inside the valve, freezing or sticking of the valve;
b) 4 months - for intermediate and commercial liquefied storage tanks petroleum gases, as well as flammable liquids with a boiling point of up to 45 ° C;
c) for periodically operating industries:
6 months - provided that the possibility of freezing, sticking or clogging of the valve is excluded working environment;
4 months - on vessels and devices with media in which coking of the media, formation of solid sediment inside the valve, freezing or sticking of the valve is possible.
The need and timing of checking valves in working condition are determined by the chief engineer of the enterprise.
The rate of corrosion of valve parts is determined based on the operating experience of the valves, the results of examining their technical condition during an audit or testing samples of similar steel under operating conditions.
Checks and revisions of safety valves are carried out according to a schedule drawn up in accordance with clause 2.3.1. annually for each workshop (installation), agreed with the technical supervision service, the chief mechanic and approved by the chief engineer.
The chief engineer of the enterprise is given the right, under his responsibility, in certain technically justified cases, to increase the periodic inspection of safety valves, but not more than 30% of the established schedule.
Each case of deviation from the audit schedule is documented in an act, which is approved by the chief engineer of the plant.
Valves received from the manufacturer or from reserve storage must be adjusted on a bench to the set pressure immediately before installation on vessels and apparatus. After the expiration of the preservation period specified in the passport, the valve must be subjected to inspection with complete disassembly.
Transportation and storage
Safety valves are transported to the installation or repair site in a vertical position on wooden stands.
When transporting valves, dropping them from the platform of any type of transport or installation site, careless tilting, or installing valves on the ground without pads is strictly prohibited.
Safety valves received from the manufacturer, as well as used ones, are stored in a vertical position, packaged on pads in a dry, closed room. The spring must be weakened, the inlet and outlet fittings must be closed with wooden plugs.
Responsibility for operation, storage and repair.
Responsible for installation of the valve after inspection on the corresponding devices, safety of seals, timely inspection of the valve, correct maintenance and safety technical documentation, as well as the storage of valves in a technological workshop is the head of the installation (shop).
Responsible for storing valves received for inspection, quality inspection and repair, as well as the use of appropriate materials during repairs, is the foreman (head) of the repair shop section.
The person responsible for accepting safety valves from repair is the installation (workshop) mechanic or the mechanical engineer of the technical supervision department.
The installation (shop) mechanic is responsible for transporting safety valves to the installation site. The person responsible for the installation is the installer (foreman, head of the repair area).
Inspection and repair of safety valves
Revision. An inspection of safety valves includes disassembling the valve, cleaning and troubleshooting parts, testing the body for strength, testing the valve connections for tightness, checking the tightness of the valve, testing the spring, and adjusting the set pressure.
Inspection of safety valves is carried out in a specialized repair shop (site) on special stands.
Safety valves removed for inspection must be steamed and washed.
For valves that have undergone inspection and repair, a report is drawn up, which is signed by the repair shop (site) foreman, the work contractor, the mechanic of the facility where the valves are installed, or the mechanical engineer of the technical supervision department.
Disassembly
The valve is disassembled in the following sequence (Fig. 5.1. Appendix 1):
remove cap 1, mounted on studs above the adjusting screw;
release the spring from tension, to do this, loosen the lock nut of the adjusting screw 2 and turn it to the upper position;
loosen evenly, and then remove the nuts from the studs 4 holding the cover 3. Remove the cover. Before removing the cover, mark the flanges of the cover and body or cover, separator and body if the valve is made with a separator;
remove the spring with support washers 6 and carefully place it in a safe place. It is strictly forbidden to throw the spring, hit it, etc.;
remove spool 7 from the valve body together with the rod and partition, carefully place it in a safe place to avoid damage to the sealing surface of the spool and deflection of the rod.
If there is a separator in the valve, first remove the separator from the body, freeing it from its attachment to the body;
release the locking screws 8 of the adjusting bushings 9 and 10;
loosen the guide sleeve 11 and remove it from the body together with the adjusting sleeve 9. If the guide sleeve sits tightly in the housing socket, you should tap the valve body with a hammer near the guide sleeve to facilitate its release from the body;
remove the adjusting sleeve 10 and valve nozzle 12. If the sealing surface of the nozzle is slightly damaged, it is recommended to restore the nozzle without unscrewing the latter from its seat in the body.
Assembly
Valve assembly begins after cleaning, inspection and restoration of all its parts. The assembly sequence is as follows (Fig. 5.1. Appendix 1):
install nozzle 12 into valve body 5, check with kerosene for the tightness of the connection between the nozzle and the body; install the adjusting sleeve 10 of the nozzle;
install guide bushing 11 with gasket and upper adjusting bushing into the valve body. The hole for draining the medium in the guide bushing must be turned towards the discharge pipe of the valve;
install spool 7, connected to the rod, into the guide sleeve;
install partition 13 and separator;
place the spring together with support washers 6 on the rod;
Place the gasket on the adjacent surface of the body and lower the cover onto the body, being careful not to damage the stem. Then center the cover along the protrusion of the guide sleeve and secure it evenly to the studs. Checking the correct installation of the cover is determined by a uniform gap around the circumference between the cover flange and the body.
Before adjusting the spring, you need to make sure that the rod does not jam in the guides. In cases where the spring is freely located in the cover, the rod should rotate freely by hand.
If the spring has a height slightly greater than the height of the cover and is clamped by it after installation, the check is also carried out by turning the rod around the axis. The uniform force obtained when the rod rotates around its axis will indicate the correct assembly of the valve;
Create a pre-tension of the spring using adjusting screw 2 and finally work it out on the stand;
Place cap 1 and tighten the valve nuts.
Figure 2 - Installation diagram of adjusting bushings.
1 - guide sleeve; 2 - spool; 3 - nozzle; 4 - lower adjusting sleeve; 5 - upper adjusting sleeve.
To operate the valve on gas, the adjusting bushings are installed as follows:
the lower adjusting sleeve 4 must be installed in the uppermost position with a gap between the end of the sleeve and the valve spool within 0.2 ¸ 0.3 mm;
the upper adjusting sleeve 5 is pre-installed flush with the outer edge of spool 2; the final installation is made in the uppermost position, at which a sharp bang occurs during adjustment on the stand.
When the valve operates on liquid, the lower adjusting sleeve is installed in the lowest position, the upper adjusting sleeve is installed in the same way as indicated above.
Air and nitrogen are used as a control medium for valves operating on vapor-gas products; for valves operating on liquid media - water, air, nitrogen.
The control medium must be clean, free of mechanical impurities. The presence of solid particles in the test medium can cause damage to the sealing surfaces.
The valves are adjusted to the set pressure using the adjusting screw by tightening or loosening it. After each spring adjustment, it is necessary to secure the adjusting screw with a locknut.
Pressure during adjustment is measured using a pressure gauge of accuracy class 1 (GOST 8625-69).
The valve is considered adjusted if, at a given pressure and using air as a control medium, it opens and closes with a clean, sharp pop.
When adjusting the valve on liquids, it opens without popping.
Tests
The valve seal is checked for tightness at operating pressure.
After adjustment, the tightness of the valve and the connection of the nozzle with the body is checked as follows: water is poured into the valve from the discharge flange, the level of which should cover the sealing surfaces of the valve. The required air pressure is created under the valve. The absence of bubbles within 2 minutes indicates that the valve is completely sealed. If bubbles appear, check the tightness of the connection between the nozzle and the body.
To determine the tightness of the connection between the nozzle and the body, the water level should be lowered so that the valve is above the water level. The absence of bubbles on the surface of the water for 2 minutes indicates that the connection is completely sealed.
If the valve does not have a seal in the valve or in the connection between the nozzle and the body, it is rejected and sent for additional inspection and repair.
The valve's detachable connections are tested for tightness during each inspection by supplying air to the discharge pipe.
Valves of the PPK and SPPK types are tested at a pressure of 1.5 R at the flange of the discharge pipe with a holding period of 5 minutes, followed by a decrease in pressure to R y and washing of the detachable connections. Valves with a diaphragm - pressure 2 kgf/cm 2, valves with a bellows - pressure 4 kgf/cm 2.
Hydraulic testing of the inlet part of the valves (inlet pipe and nozzle) is carried out with a pressure of 1.5 R at the inlet flange with holding for 5 minutes, followed by a decrease in pressure to R y and inspection.
The frequency of hydrotesting is established by the technical supervision service of the enterprise depending on operating conditions, the results of the audit and should be at least once every 8 years.
The test results of the valves are recorded in the inspection and repair report and the operational passport.
Valves that have undergone inspection and repair are sealed with a special seal kept by the repairman. The locking screws of the adjusting bushings, detachable body-cover and cover-cap connections are subject to mandatory sealing.
Malfunctions and methods for eliminating them
Media leakage is the passage of media through the valve plug at a pressure lower than the set pressure. The causes of media leakage may be:
retention of foreign substances (scale, processed products, etc.) on the sealing surfaces is eliminated by purging the valve;
Damage to the sealing surfaces can be restored by lapping or grooving, followed by lapping and checking for leaks. By grinding in, minor damage to the sealing surfaces of the nozzle and spool is eliminated.
Restoration of sealing surfaces with a damage depth of 0.1 mm or more must be carried out by mechanical processing in order to restore the geometry and remove defective areas, followed by grinding. The repair dimensions of the sealing surfaces of the spools and nozzles are shown in Fig. 3.2. The dotted line indicates the configuration of the sealing surface after repair; the numbers indicate the permissible values to which the sealing surfaces can be processed during repair;
misalignment of valve parts due to excessive load - check the inlet and outlet lines, remove the load. Re-tighten the studs;
spring deformation - replace the spring;
opening pressure is too low - adjust the valve again;
poor-quality assembly after repair - eliminate assembly defects.
Pulsation is the rapid and frequent opening and closing of a valve. This may happen for the following reasons:
the valve capacity is excessively large - it is necessary to replace the valve with a valve of a smaller diameter or limit the lifting height of the spool;
a narrowed cross-section of the supply pipe or pipe of the device, which causes the valve to “starve” and thereby causes pulsation - install supply pipes with a cross-sectional area no less than the inlet cross-sectional area of the valve.
Vibration . Narrowed flow pipes with a small radius of curvature create high back pressure at the flow pipe and can cause valve vibration. Elimination of this drawback is achieved by installing exhaust pipes with a passage no less than the nominal passage of the valve discharge pipe and with a minimum number of bends and turns.
Scoring of moving parts can occur when the valve is assembled or installed incorrectly due to distortions and the appearance of lateral forces on the moving parts (spool, rod). Seizures must be removed by mechanical treatment, and the causes that cause them must be eliminated by qualified assembly.
The valve does not open at the specified set pressure:
the spring is not adjusted correctly - the spring needs to be adjusted to the specified pressure;
The spring stiffness is high - install a lower stiffness spring;
increased friction in the spool guides - eliminate distortions, check the gaps between the spool and the guide.
RUSSIAN JOINT STOCK COMPANY OF ENERGY AND ELECTRIFICATION "UES OF RUSSIA"
DEPARTMENT OF DEVELOPMENT STRATEGY AND SCIENTIFIC AND TECHNICAL POLICY
INSTRUCTIONS FOR ORGANIZING OPERATION, PROCEDURE AND TIMELINES FOR CHECKING SAFETY DEVICES OF BOILERS OF THERMAL POWER PLANTS
RD 153-34.1-26.304-98
Enters into force from 01.10.99.
Developed Open joint-stock company "Company for setting up, improving technology and operating power plants and networks of ORGRES"
Executor V.B. KAKUZIN
Agreed with Gosgortekhnadzor of Russia 12/25/97
Approved Department of Development Strategy and Scientific and Technical Policy of RAO "UES of Russia" 01/22/98
First Deputy Chief D.L. BERSENEV
1. GENERAL PROVISIONS
1.1. This Instruction applies to safety devices installed on thermal power plant boilers.
1.2. The instructions contain basic installation requirements safety devices and determines the procedure for their regulation, operation and maintenance.
Appendix 1 sets out the basic requirements for boiler safety devices, contained in the rules of the Gosgortekhnadzor of Russia and GOST 24570-81, are given specifications and design solutions for boiler safety devices, calculation recommendations bandwidth safety valves.
The purpose of the Instruction is to help improve the safety of operation of thermal power plant boilers.
1.3. When developing the Instructions, the guidelines of the Gosgortekhnadzor of Russia, , , , , and data on operating experience of safety devices of thermal power plant boilers were used.
1.4. With the publication of this Instruction, the "Instructions for organizing the operation, procedure and timing of testing pulse safety devices of boilers with operating steam pressure from 1.4 to 4.0 MPa (inclusive): RD 34.26.304-91" and "Instructions for organizing operation, procedure and timing of inspection of impulse safety devices of boilers with steam pressure above 4.0 MPa: RD 34.26.301 -91".
1.5. The following abbreviations are adopted in the Instructions;
PU- safety device:
PC- direct acting safety valve;
RGPC- direct-acting lever-load safety valve;
PPK- direct acting spring safety valve;
IPU- impulse safety device;
Civil Procedure Code- main safety valve;
IR- pulse valve;
CHZEM- JSC "Chekhov Power Engineering Plant";
TKZ- PA "Krasny Kotelshchik"
1.6. The methodology for calculating the throughput capacity of boiler safety valves, forms of technical documentation for safety devices, basic terms and definitions, designs and technical characteristics of safety valves are given in Appendices 2-5.
2. BASIC REQUIREMENTS FOR PROTECTING BOILERS FROM INCREASING PRESSURE ABOVE THE ALLOWABLE VALUES
2.1. Each steam boiler must be equipped with at least two safety devices.
2.2. The following may be used as safety devices on boilers with pressures up to 4 MPa (40 kgf/cm2) inclusive:
direct-acting lever-weight safety valves;
Direct acting spring safety valves.
2.3. Steam boilers with steam pressure over 4.0 MPa (40 kgf/cm2) must be equipped only with pulse-safety devices with an electromagnetic drive.
2.4. The passage diameter (conditional) of direct-acting lever-weight and spring valves and pulse valves IPU must be at least 20 mm.
2.5. The nominal diameter of the tubes connecting the pulse valve to the IPU GPK must be at least 15 mm.
2.6. Safety devices must be installed:
a) in steam boilers With natural circulation without a superheater - on the upper drum or steam steamer;
b) in once-through steam boilers, as well as in boilers with forced circulation- on the outlet manifolds or outlet steam pipeline;
c) in hot water boilers- on the output collectors or drum;
d) in intermediate superheaters, all safety devices are on the steam inlet side;
e) in water-switched economizers - at least one safety device at the water outlet and water inlet.
2.7. If the boiler has a non-switchable superheater, part of the safety valves with a capacity of at least 50% of the total capacity of all valves must be installed on the outlet manifold of the superheater.
2.8. On steam boilers with an operating pressure of more than 4.0 MPa (40 kgf/cm2), pulse safety valves (indirect action) must be installed on the outlet manifold of a non-switchable superheater or on the steam line to the main shut-off valve, while in drum boilers for 50% of the valves Based on the total throughput, steam selection for pulses should be made from the boiler drum.
If there is an odd number of identical valves, it is allowed to select steam for pulses from the drum for no less than 1/3 and no more than 1/2 of the valves installed on the boiler.
On block installations, if valves are placed on the steam pipeline directly next to the turbines, it is allowed to use superheated steam for impulses of all valves, while for 50% of the valves an additional electrical impulse must be supplied from a contact pressure gauge connected to the boiler drum.
If there is an odd number of identical valves, it is allowed to supply an additional electrical impulse from a contact pressure gauge connected to the boiler drum for no less than 1/3 and no more than 1/2 of the valves.
2.9. In power units with intermediate superheating of steam after the cylinder high pressure turbines (HPC), safety valves must be installed with a throughput capacity of at least the maximum amount of steam entering the intermediate superheater. If there is a shut-off valve behind the HPC, additional safety valves must be installed. These valves must be calculated taking into account both the total capacity of the pipelines connecting the reheater system with higher pressure sources that are not protected by their safety valves at the entrance to the reheat system, and possible steam leaks that may occur if the high pressure steam and steam pipes are damaged. gas-steam heat exchangers steam temperature regulation.
2.10. The total capacity of the safety devices installed on the boiler must be at least the hourly steam output of the boiler.
Calculation of the throughput capacity of boiler safety devices according to GOST 24570-81 is given in Appendix 1.
2.11. Safety devices must protect boilers, superheaters and economizers from increasing their pressure by more than 10%. Exceeding the steam pressure when the safety valves are fully open by more than 10% of the calculated value can only be allowed if this is provided for in the strength calculations of the boiler, superheater, or economizer.
2.12. The design pressure of safety devices installed on cold reheat pipelines should be taken as the lowest design pressure for low-temperature elements of the reheat system.
2.13. Sampling of the medium from the branch pipe or pipeline connecting the safety device to the protected element is not allowed.
2.14. The installation of shut-off devices on the steam supply line to the safety valves and between the main and pulse valves is not allowed.
2.15. To control the operation of the IPU, it is recommended to use an electrical circuit developed by the Teploelektroproekt Institute (Fig. 1), which provides for pressing the plate to the seat at normal pressure in the boiler due to the constant flow of current around the winding of the closing electromagnet.
For IPU installed on boilers with a nominal excess pressure of 13.7 MPa (140 kgf/cm 2) and below, by decision of the chief engineer of the thermal power plant, operation of the IPU is allowed without constant current flowing around the winding of the closing electromagnet. In this case, the control circuit must ensure that the IR is closed using an electromagnet and turned off 20 s after the IR is closed.
The IR solenoid control circuit must be connected to a backup DC source.
In all cases, only return keys should be used in the control scheme.
2.16. Devices should be installed in the connecting pipes and supply pipelines to prevent sudden changes in wall temperature (thermal shocks) when the valve is activated.
2.17. The internal diameter of the supply pipe must be no less than the maximum internal diameter of the supply pipe of the safety valve. The pressure drop in the supply pipeline to direct-acting safety valves should not exceed 3% of the valve opening pressure. In the supply lines of safety valves controlled by auxiliary devices, the pressure drop should not exceed 15%.
2.18. Steam from safety valves must be vented to a safe location. The internal diameter of the outlet pipe must be no less than the largest internal diameter of the outlet pipe of the safety valve.
2.19. The installation of a noise suppression device on the outlet pipeline should not cause a reduction in the capacity of the safety devices below the value required by safety conditions. When the outlet pipeline is equipped with a noise-attenuating device, a fitting for installing a pressure gauge must be provided immediately behind the valve.
2.20. The total resistance of the outlet pipelines, including the noise suppression device, must be calculated so that when the flow rate of the medium through it is equal to the maximum throughput of the safety device, the back pressure in the valve outlet pipe does not exceed 25% of the response pressure.
2.21. The outlet pipelines of safety devices must be protected from freezing and equipped with drains to drain condensate that accumulates in them. Installation of shut-off devices on drains is not permitted.
2.22. The riser (a vertical pipeline through which the medium is discharged into the atmosphere) must be securely fastened. In this case, the static and dynamic loads that arise when the main valve operates must be taken into account.
2.23. Temperature expansion compensation must be ensured in the safety valve pipelines. The fastening of the body and pipeline of safety valves must be designed taking into account static loads and dynamic forces that arise when the safety valves operate.
Rice. 1. Electrical diagram IPU
Note - The diagram is made for one pair of IPCs
3. INSTRUCTIONS FOR INSTALLATION OF SAFETY DEVICES
3.1. Valve storage rules
3.1.1. Safety devices must be stored in places that prevent moisture and dirt from entering the internal cavities of the valves, corrosion and mechanical damage to parts.
3.1.2. Pulse valves with an electromagnetic drive must be stored in dry, enclosed areas free of dust and vapors that could cause destruction of the electromagnet windings.
3.1.3. The valves have a shelf life of no more than two years from the date of shipment from the manufacturer. If longer storage is required, the products must be re-preserved.
3.1.4. Loading, transporting and unloading of valves must be carried out in compliance with precautions to ensure they are not broken or damaged.
3.1.5. Subject to the above transportation and storage rules, the presence of plugs and the absence of external damage, the valves can be installed on workplace without revision.
3.1.6. If transportation and storage rules are not observed, the valves should be inspected before installation. The issue of compliance of the storage conditions of the valves with the requirements of the normative and technical documentation should be decided by a commission of representatives of the operational and repair departments of the thermal power plant and the installation organization.
3.1.7. When inspecting valves, you should check:
condition of the sealing surfaces of the valve.
After inspection, the sealing surfaces must be clean R a = 0.32;
condition of gaskets;
condition of the seal packing of the servomotor piston.
If necessary, install new packing from pre-compressed rings. Based on the CHZEM tests, a combined seal consisting of a set of rings can be recommended for installation in the GPC servo drive chamber: two packages of rings made of graphite and metal foil and several rings made of thermally expanded graphite. (The seal is manufactured and supplied by JSC Unikhimtek, 167607, Moscow, Michurinsky Prospekt, 31, building 5);
the condition of the piston working jacket in contact with the stuffing box; traces of possible corrosion damage to the shirt must be eliminated;
condition of the threads of fasteners (no nicks, burrs, chipping of threads);
condition and elasticity of springs,
After assembly, you should check the ease of movement of the moving parts and the compliance of the valve stroke with the requirements of the drawing.
3.2. Placement and installation
3.2.1. Impulse safety devices must be installed in enclosed spaces.
The valves may be operated under the following conditions: limit parameters environment:
when using valves intended for delivery to countries with temperate climate: temperature - +40°C and relative humidity - up to 80% at a temperature of 20°C;
when using valves intended for delivery to countries with tropical climates; temperature - +40°C;
relative humidity - 80% at temperatures up to 27°C.
3.2.2. The products included in the IPU kit must be installed in places that allow for their maintenance and repair, as well as assembly and disassembly on site without cutting out from the pipeline.
3.2.3. Installation of valves and connecting pipelines must be carried out according to working drawings developed by the design organization.
3.2.4. The main safety valve is welded to the fitting of the manifold or steam line with the stem strictly vertically upward. Deviation of the rod axis from the vertical is allowed no more than 0.2 mm per 100 mm of valve height. When welding a valve into a pipeline, it is necessary to prevent burr, splashes, and scale from entering their cavity and pipelines. After welding, the welds are subject to heat treatment in accordance with the requirements of the current instructions for the installation of pipeline equipment.
3.2.5. The main safety valves are attached with the paws available in the design of the products to a support, which must absorb the reactive forces that arise when the IPU is triggered. The exhaust pipes of the valves must also be securely fastened. In this case, any additional stress must be eliminated in the connection between the exhaust and the connecting flanges of the exhaust pipes. Constant drainage must be organized from the lowest point.
3.2.6. Pulse valves for fresh steam and reheat steam produced by LMZ, mounted on a special frame, must be installed on sites that are convenient for maintenance and protected from dust and moisture.
3.2.7. The pulse valve must be installed on the frame so that its stem is strictly vertical in two mutually perpendicular planes. The IR lever with a load and an electromagnet core suspended on it should not have distortions in the vertical and horizontal planes. To avoid jamming when opening the IR, the lower electromagnet must be located relative to the IR so that the centers of the holes in the core and lever are on the same vertical; the electromagnets must be located on the frame so that the axes of the cores are strictly vertical and located in a plane passing through the axes of the rod and the IR lever.
3.2.8. To ensure a tight fit of the IR plate on the saddle, the bar on which the clamp of the upper electromagnet rests must be welded so that the gap between the lower plane of the lever and the clamp is at least 5 mm.
3.2.9. When selecting pulses on an IR and an electric contact pressure gauge (ECM) from the same element on which the GPC is installed, the pulse sampling points must be at such a distance from the GPC that when it is triggered, the disturbance of the steam flow does not affect the operation of the IR and ECM (at least 2 m). The length of the impulse lines between the impulse and main valves should not exceed 15 m.
3.2.10. Electric contact pressure gauges must be installed at the boiler service level. Acceptable Maximum temperature The ambient temperature in the ECM installation area should not exceed 60°C. The shut-off valve on the medium supply line to the ECM must be open and sealed during operation.
4. PREPARATION OF VALVES FOR OPERATION
4.1. The compliance of the installed valves with the requirements of the design documentation and section is checked. 3.
4.2. The tightness of the valve fasteners, the condition and quality of fit of the supporting surfaces of the prism of lever-weight valves are checked: the lever and the prism must mate across the entire width of the lever.
4.3. The compliance of the actual stroke value of the hydraulic pump with the instructions of the technical documentation is checked (see Appendix 5).
4.4. In the case of a reheat steam generator, moving the adjusting nut along the stem ensures a gap between its lower end and the upper end of the support disk, equal to the valve stroke.
4.5. For the reheat steam generator set produced by ChZEM, the screw of the throttle valve built into the cover is turned out by 0.7-1.0 turns,
4.6. The condition of the electromagnet cores is checked. They must be cleaned of old grease, rust, dust, washed with gasoline, ground and rubbed with dry graphite. The rod at the junction with the core and the core itself should not be distorted. The movement of the cores must be free.
4.7. The position of the damper screw of the electromagnets is checked. This screw should be screwed in so that it protrudes above the end of the electromagnet housing by approximately 1.5-2.0 mm. If the screw is completely screwed in, then when the armature rises, a vacuum is created under it, and with the electrical circuit de-energized, it is almost impossible to adjust the valve to operate at a given pressure. Over-tightening the screw will cause the core to move violently as it retracts, causing the sealing surfaces of the impulse valves to break.
5. ADJUSTING SAFETY DEVICES TO ACTIVATE AT A SET PRESSURE
5.1. Adjustment of safety devices to operate at a given pressure is carried out:
after installation of the boiler is completed;
after a major overhaul, if safety valves or their major renovation(complete disassembly, grooving of sealing surfaces, replacement of chassis parts, etc.), and for PPK - in case of replacing a spring.
5.2. To adjust the valves, a pressure gauge with an accuracy class of 1.0, tested in the laboratory using a standard pressure gauge, must be installed in close proximity to them.
5.3. Safety valves are regulated at the valve installation site by raising the pressure in the boiler to the response pressure.
Adjustment of spring safety valves can be done on a steam bench with operating parameters, followed by a control check on the boiler.
5.4. The actuation of the valves during adjustment is determined by:
for IPU - at the moment of activation of the GPC, accompanied by impact and loud noise;
for direct-acting full-lift valves - by a sharp pop observed when the spool reaches the top position.
For all types of safety devices, operation is controlled by the beginning of the pressure drop on the pressure gauge.
5.5. Before adjusting the safety devices, you must:
5.5.1. Ensure that all installation, repair and commissioning work on the systems in which the steam pressure necessary for regulation will be created, on the safety devices themselves and on their exhaust pipes.
5.5.2. Check the reliability of disconnecting systems in which pressure will increase from adjacent systems.
5.5.3. Remove all bystanders from the valve adjustment area.
5.5.4. Provide good lighting PU installation workplaces, service platforms and adjacent passages.
5.5.5. Establish two-way communication between valve adjustment points and the control panel.
5.5.6. Conduct instruction for shift and adjustment personnel involved in valve adjustment work.
Staff should be well aware design features subject to PU regulation and the requirements of the instructions for their operation.
5.6. Adjustment of direct-acting lever-load valves is carried out in the following sequence;
5.6.1. The weights on the valve levers are moved to their extreme position.
5.6.2. In the protected object (drum, superheater), a pressure is established that is 10% higher than the calculated (permitted) one.
5.6.3. The weight on one of the valves is slowly moved towards the body until the valve is activated.
5.6.4. After closing the valve, the position of the weight is fixed with a locking screw.
5.6.5. The pressure in the protected object rises again and the pressure value at which the valve operates is checked. If it differs from that set in paragraph 5.6.2, the position of the weight on the lever is adjusted and the correct operation of the valve is re-checked.
5.6.6. After the adjustment is completed, the position of the weight on the lever is finally fixed with a locking screw. To prevent uncontrolled movement of the load, the screw is sealed.
5.6.7. An additional weight is installed on the lever of the adjusted valve and the remaining valves are adjusted in the same sequence.
5.6.8. After completing the adjustment of all valves in the protected object, the operating pressure is established. Additional weights are removed from the levers. A record is made in the Maintenance and Operation Log of safety devices about the readiness of the valves for operation.
5.7. Adjustment of direct acting spring safety valves:
5.7.1. The protective cap is removed and the tension height of the spring h 1 is checked (Table 6).
5.7.2. The pressure value in the protected object is set in accordance with clause 5.6.2.
5.7.3. By turning the adjusting sleeve counterclockwise, the compression of the spring is reduced to the position at which the valve will operate.
5.7.4. The pressure in the boiler rises again and the pressure value at which the valve operates is checked. If it differs from that set according to clause 5.6.2, then the spring compression is adjusted and the valve is re-checked for operation. At the same time, the pressure at which the valve closes is monitored. The difference between the actuation pressure and the closing pressure should be no more than 0.3 MPa (3.0 kgf/cm2). If this value is greater or less, then the position of the upper adjusting sleeve must be adjusted.
For this:
For TKZ valves, unscrew the locking screw located above the cover and turn the damper bushing counterclockwise to reduce the drop or clockwise to increase the drop;
For the PPK and SPPK valves of the Blagoveshchensk Valve Plant, the pressure difference between the actuation and closing pressures can be adjusted by changing the position of the upper adjusting sleeve, which is accessed through a hole closed with a plug on the side surface of the body.
5.7.5. The height of the spring in the adjusted position is recorded in the Journal of Repair and Operation of Safety Devices and it is compressed to the value h 1 to be able to adjust the remaining valves. After completing the adjustment of all valves, the spring height recorded in the log in the adjusted position is set on each valve. To prevent unauthorized changes in the spring tension, a protective cap is installed on the valve, covering the adjusting sleeve and the end of the lever. The bolts securing the protective cap are sealed.
5.7.6. After the adjustment is completed, a record is made in the Maintenance and Operation Log of safety devices indicating that the valves are ready for operation.
5.8. Pulse safety devices with IR, equipped with an electromagnetic drive, are regulated to operate both from electromagnets and when the electromagnets are de-energized.
5.9. To ensure that the IPU is triggered by electromagnets, the ECM is configured:
5.9.1. The ECM readings are compared with the readings of a standard pressure gauge with a class of 1.0%.
5.9.2. The ECM is adjusted to turn on the opening electromagnet;
MPa,
where h is the correction for water column pressure
MPa,
here r is the density of water, kg/m3;
DN is the difference between the marks of the place where the impulse line is connected to the protected object and the place where the ECM is installed, m.
5.9.3. The ECM is adjusted to turn on the closing electromagnet:
MPa.
5.9.4. The limits of IR operation are marked on the ECM scale.
5.10. Adjusting the IR to operate at a given pressure with de-energized electromagnets is carried out in the same sequence as adjusting direct-acting lever-load valves:
5.10.1. The weights on the IR levers are moved to their extreme position.
5.10.2. The pressure in the boiler drum rises to the IPU response set point ( R av = 1.1 R b); on one of the IR loads connected to the boiler drum, the load moves towards the lever to a position at which the IPU is triggered. In this position, the load is fixed to the lever with a screw. After this, the pressure in the drum rises again and it is checked at what pressure the IPU is triggered. If necessary, the position of the load on the lever is adjusted. After adjustment, the weights on the lever are secured with a screw and sealed.
If more than one IR is connected to the boiler drum, an additional weight is installed on the lever of the adjusted valve to allow adjustment of the remaining IR connected to the drum.
5.10.3. A pressure equal to the response pressure of the IPU behind the boiler ( R av = 1.1 R R). In the manner prescribed in clause 5.10.2, it is regulated for the operation of the IPU, in which the steam on the IR is taken from the boiler.
5.10.4. After the adjustment is completed, the pressure behind the boiler is reduced to nominal and additional weights are removed from the IR levers.
5.11. Voltage is supplied to the electrical control circuits of the IPU. The valve control keys are set to the "Automatic" position.
5.12. The steam pressure behind the boiler is increased to the value at which the IPU should operate, and the opening of the gas pumps of all IPUs, the impulse to open which is taken behind the boiler, is checked locally.
When adjusting the IPU to drum boilers IPU control keys, triggered by a pulse behind the boiler, are set to the “Closed” position and the pressure in the drum rises to the IPU response set point. The operation of the GPK IPU, operating on an impulse from the drum, is checked locally.
5.13. Pulse-safety devices for reheat steam, which do not have shut-off elements behind them, are configured to operate after installation during the boiler firing for steam density. The procedure for setting the valves is the same as when setting the fresh steam valves installed behind the boiler (section 5.10.3).
If there is a need to adjust the reheat steam pulse valves after repairs, it can be done on a special stand. In this case, the valve is considered adjusted when the rise of the rod by the stroke value is recorded.
5.14. After checking the operation of the IPU, the control keys of all IPUs must be in the “Automatic” position.
5.15. After adjusting the safety devices, the shift supervisor must make an appropriate entry in the Maintenance and Operation Log of the safety devices.
6. PROCEDURE AND TIMELINES FOR CHECKING VALVES
6.1. Checking the proper operation of safety devices should be carried out:
when the boiler is stopped for scheduled repairs;
during boiler operation:
on pulverized coal boilers - once every 3 months;
on gas-oil boilers - once every 6 months.
During specified time intervals, the inspection should be timed to coincide with scheduled boiler shutdowns.
On boilers that are put into operation periodically, the check should be carried out during startup, if more than 3 or 6 months have passed, respectively, since the previous check.
6.2. Checking of the fresh steam IPU and reheat steam IPU, equipped with an electromagnetic drive, must be done remotely from the control panel with on-site response control, and the reheat steam IPU, which does not have an electromagnetic drive, by manually detonating the pulse valve at a unit load of at least 50% of the nominal load.
6.3. Testing of direct-acting safety valves is carried out at operating pressure in the boiler by alternately forcibly detonating each valve.
6.4. The inspection of safety devices is carried out by the shift supervisor (senior boiler operator) according to a schedule that is drawn up annually for each boiler based on the requirements of this Instruction, agreed with the operation inspector and approved by the chief engineer of the power plant. After the inspection, the shift supervisor makes an entry in the Maintenance and Operation Log of safety devices.
7. RECOMMENDATIONS FOR MONITORING THE CONDITION AND ORGANIZING REPAIR OF VALVES
7.1. Scheduled condition monitoring (inspection) and repair of safety valves are carried out simultaneously with the equipment on which they are installed.
7.2. Monitoring the condition of safety valves includes disassembling, cleaning and defective parts, checking the tightness of the valve, and the condition of the seal packing of the servo drive.
7.3. Condition monitoring and repair of valves must be carried out in a specialized valve workshop on special stands. The workshop must be equipped with lifting mechanisms, well lit, and have a compressed air supply. The location of the workshop should ensure convenient transportation of the valves to the installation site.
7.4. Monitoring the condition and repairing valves must be carried out by a repair team that has experience in repairing valves and has studied the design features of valves and the principle of their operation. The team must be provided with working drawings of the valves, repair forms, spare parts and materials for their quick, high-quality repair.
7.5. In the workshop, valves are disassembled and parts are defective. Before fault detection, parts are cleaned of dirt and washed in kerosene.
7.6. When inspecting the sealing surfaces of the valve seat and plate parts, pay attention to their condition (absence of cracks, dents, marks and other defects). During subsequent assembly, the sealing surfaces must be rough R a = 0.16. The quality of the sealing surfaces of the seat and plate must ensure their mutual contact, which ensures the mating of these surfaces along a closed ring, the width of which is not less than 80% of the width of the smaller sealing surface.
7.7. When inspecting the jackets of the servo drive piston chamber and guides, pay attention that the ellipse of these parts does not exceed 0.05 mm per diameter. The roughness of surfaces in contact with the stuffing box must correspond to the cleanliness class R a = 0.32.
7.8. When inspecting the servo piston Special attention You should pay attention to the condition of the stuffing box. The rings must be tightly compressed together. On work surface there should be no damage to the rings. Before assembling the valve, it should be well graphiteized.
7.9. The condition of the threads of all fasteners and adjusting screws must be checked. All parts with defective threads must be replaced.
7.10. You should check the condition of the coil springs, for which you should visually check the condition of the surface for cracks and deep scratches, measure the height of the spring in a free state and compare it with the requirements of the drawing, check the deviation of the spring axis from the perpendicular.
7.11. Repair and restoration of valve parts should be carried out in accordance with the current instructions for the repair of valves.
7.12. Before assembling the valves, check that the dimensions of the parts correspond to the dimensions specified in the form or working drawings.
7.13. Tightening the stuffing box rings in the piston chambers of the gas-piston chamber should ensure the tightness of the piston, but not impede its free movement.
8. ORGANIZATION OF OPERATION
8.1. Overall responsibility for technical condition, inspection and maintenance of safety devices is entrusted to the head of the boiler-turbine (boiler) shop on whose equipment they are installed.
8.2. The workshop order appoints persons responsible for checking valves, organizing their repair and maintenance, and maintaining technical documentation.
8.3. In the workshop, for each boiler, a log of repair and operation of safety devices installed on the boiler must be kept.
8.4. Each valve installed on the boiler must have a passport containing the following data;
valve manufacturer;
valve brand, type or drawing number;
nominal diameter;
serial number of the product;
operating parameters: pressure and temperature;
opening pressure range;
flow coefficient a, equal to 0.9 of the coefficient obtained on the basis of the valve tests;
calculated flow area;
for spring safety valves - the characteristics of the spring;
data on materials of main parts;
certificate of acceptance and conservation.
8.5. For each group of valves of the same type there must be: an assembly drawing, technical description and operating instructions.
9. SAFETY REQUIREMENTS
9.1. It is prohibited to operate safety devices in the absence of the documentation specified in paragraphs. 8.4, 8.5.
9.2. It is prohibited to operate valves at pressures and temperatures higher than those specified in the technical documentation for the valves.
9.3. It is prohibited to operate and test safety valves in the absence of outlet pipes that protect personnel from burns when the valves operate.
9.4. Pulse valves and direct-acting valves must be located in such a way that during adjustment and testing there is no possibility of burns to operating personnel.
9.5. It is not allowed to repair valve defects if there is pressure in the objects to which they are connected.
9.6. When repairing valves, it is prohibited to use wrenches whose jaw size does not correspond to the size of the fasteners.
9.7. All types of repair work and maintenance must be carried out in strict compliance with fire safety regulations.
9.8. When the power plant is located in a residential area, the exhausts of the GPK IPU must be equipped with noise suppression devices that reduce the noise level when the IPU is activated to sanitary permissible standards.
Annex 1
REQUIREMENTS FOR BOILER SAFETY VALVES
1. The valves must open automatically at the specified pressure without fail.
2. In the open position, the valves should operate steadily, without vibration or pulsation.
3. Requirements for direct acting valves:
3.1. The design of a lever-load or spring safety valve must include a device for checking the proper operation of the valve during boiler operation by forcing the valve to open.
The possibility of forced opening must be ensured at 80% of the opening pressure.
3.2. The difference between the response pressure (full opening) and the beginning of the valve opening should not exceed 5% of the response pressure.
3.3. Safety valve springs must be protected from direct heat and direct exposure to the working environment.
When the valve is fully opened, the possibility of contact between the coils of the spring must be excluded.
3.4. The design of the safety valve should not allow arbitrary changes in its adjustment during operation. The RGPC must have a device on the lever that prevents the movement of the load. For PPK, the screw that regulates the spring tension must be closed with a cap, and the screws securing the cap must be sealed.
4. Requirements for IPU:
4.1. The design of the main safety valves must have a device that softens the shock when they open and close.
4.2. The design of the safety device must ensure that the functions of protection against overpressure are maintained in the event of failure of any control or regulatory body of the boiler.
4.3. The design of the safety device must allow it to be controlled manually or remotely.
4.4. The design of the device must ensure its automatic closing at a pressure of at least 95% of the operating pressure in the boiler,
Appendix 2
METHOD FOR CALCULATING THE CAPACITY OF BOILER SAFETY VALVES
1. The total capacity of all safety devices installed on the boiler must meet the following requirements:
for steam boilers
G 1 + G 2 + ... + G n³ D k ;
for hot water boilers
G 1 + G 2 + ... + G n³ Q/g;
Calculation of the throughput capacity of safety valves of hot water boilers can be carried out taking into account the ratio of steam and water in the steam-water mixture passing through the safety valve when it is activated.
2. The capacity of the safety valve is determined by the formula;
G = 10 IN 1 a F (P 1 + 0.1) - for pressure in MPa;
G = IN a F(P 1 + 1) - for pressure in kgf/cm 2,
The values of this coefficient are selected from the table. 1 and 2 or determined by formulas.
At pressure P 1 in kgf/cm 2:
Under pressure R 1 to MPa:
Table 1
Coefficient values IN for saturated steam
table 2
Coefficient values IN for superheated steam
| Steam pressure R 1 , | Coefficient IN at steam temperature t n, °С | ||||||||
| MPa (kgf/cm 2) | 250 | 300 | 350 | 400 | 450 | 500 | 550 | 600 | 650 |
| 2,0 (20) | 0,495 | 0,465 | 0,445 | 0,425 | 0,410 | 0,390 | 0,380 | 0,365 | 0,355 |
| 3,0 (30) | 0,505 | 0,475 | 0,450 | 0,425 | 0,410 | 0,395 | 0,380 | 0,365 | 0,355 |
| 4,0 (40) | 0,520 | 0,485 | 0,455 | 0,430 | 0,410 | 0,400 | 0,380 | 0,365 | 0,355 |
| 6,0 (60) | 0,500 | 0,460 | 0,435 | 0,415 | 0,400 | 0,385 | 0,370 | 0,360 | |
| 8,0 (80) | 0,570 | 0,475 | 0,445 | 0,420 | 0,400 | 0,385 | 0,370 | 0,360 | |
| 16,0 (160) | 0,490 | 0,450 | 0,425 | 0,405 | 0,390 | 0,375 | 0,360 | ||
| 18,0 (180) | 0,480 | 0,440 | 0,415 | 0,400 | 0,380 | 0,365 | |||
| 20,0 (200) | 0,525 | 0,460 | 0,430 | 0,405 | 0,385 | 0,370 | |||
| 25,0 (250) | 0,475 | 0,445 | 0,415 | 0,390 | 0,375 | ||||
| 30,0 (300) | 0,495 | 0,460 | 0,425 | 0,400 | 0,380 | ||||
To calculate the capacity of safety valves of power plants with fresh steam parameters:
13.7 MPa and 560°C IN = 0,4;
25.0 MPa and 550°C IN = 0,423.
The formula for determining valve capacity should only be used if:
- for pressure in MPa;
For pressure in kgf/cm 2,
Where R 2 - maximum excess pressure behind the boiler in the space into which steam flows from the boiler (when it flows into the atmosphere R 2 = 0),
b - critical pressure ratio.
For saturated steam b cr = 0.577.
For superheated steam b cr = 0.546.
Appendix 3
FORMS OF TECHNICAL DOCUMENTATION ON BOILER SAFETY DEVICES, WHICH SHOULD BE MAINTAINED AT TPP
Form No. 1
I affirm:
Chief Engineer
______________________
"__" __________ 199__
Statement
response pressure of boiler safety devices
in ____________ workshop
Foreman ________________
Form No. 2
I affirm:
Chief Engineer
______________________
"__" __________ 199__
Decanter for checking boiler safety devices
| № | Number | Installed | Approximate timing for checking valves | ||||||||||||||||||||||||
| p.p. | boiler | periodicity | 199 | 199 | |||||||||||||||||||||||
| checks | Months | Months | |||||||||||||||||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | ||||
Foreman _______________
Note Depending on the length of time the boiler is under repair or in reserve, the timing of valve checks may be specified.
Form No. 3
Data
on forced testing of boiler safety valves
Form No. 4
Data
on scheduled and emergency repairs of boiler safety valves
Boiler No. _______
Appendix 4
BASIC TERMS AND DEFINITIONS
Based on the operating conditions of TPP boilers, taking into account the terms and definitions contained in various materials Gosgortekhnadzor of Russia, GOST and technical literature, the following terms and definitions are adopted in this Instruction.
1. Working pressure R p - maximum internal excess pressure that occurs during the normal course of the work process without taking into account hydrostatic pressure and without taking into account the permissible short-term increase in pressure during the operation of safety devices.
2. Design pressure R calculation - excess pressure for which the strength of the boiler elements was calculated. For TPP boilers, the design pressure is usually equal to the operating pressure.
3. Allowable pressure R extra - the maximum excess pressure allowed by accepted standards in the protected element of the boiler when the medium is discharged from it through a safety device
R additional = 1.1 P p.
Safety devices must be selected and adjusted in such a way that the pressure in the boiler (drum) cannot rise above R add.
4. Opening pressure R n.o - excess pressure at the valve inlet, at which the force aimed at opening the valve is balanced by the force holding the shut-off element on the seat.
Depending on the valve design and process dynamics P n.o = l.03¸l.08 P R. But due to the rapidity of the actuation process, there are a lot of lifting safety valves and IPU when adjusting them to determine P n.o. almost impossible.
5. Full opening pressure (set pressure) R cp is the maximum excess pressure that is established in front of the PC when it is fully opened. It should not exceed R add.
6. Closing pressure R h - excess pressure at which, after actuation, the shut-off element is seated on the seat,
For direct acting safety valves R z = 0.8¸0.9 R R. For IPU with electromagnetic drive R h must be at least 0.95 R R.
7. Bandwidth G- maximum mass flow steam that can be released through the fully open valve at response parameters.
Appendix 5
DESIGNS AND TECHNICAL CHARACTERISTICS OF BOILER SAFETY VALVES
1. Live steam impulse safety devices
1.1. Main safety valves
To protect boilers from increased pressure on fresh steam pipelines, GPC series 392-175/95-0 g, 392-175/95-0 g -01, 875-125-0 and 1029-200/250-0 are used. On old power plants with parameters of 9.8 MPa, 540°C, valves of the 530 series are installed, and on blocks of 500 and 800 MW - series E-2929, which are currently out of production. At the same time, for newly designed boilers with parameters of 9.8 MPa, 540°C and 13.7 MPa, 560°C, the plant has developed a new valve design 1203-150/200-0, and for the possibility of replacing exhausted valves of the 530 series , which had a two-way steam outlet, valve 1202-150/150-0 is produced.
The technical characteristics of the produced ChZEM GPK are given in table. 3.
Valves of the 392 and 875 series (Fig. 2) consist of the following main components and parts: connecting inlet pipe 1, connected to the pipeline by welding; housing 2 with a chamber in which the servo drive 6 is located; plates 4 and saddles 3, making up the shutter assembly; lower 5 and upper 7 rods; hydraulic damper unit 8, in the housing of which a piston and spring are located.
The steam supply in the valve is carried out to the spool. Pressing it against the seat with pressure from the working medium increases the tightness of the valve. Pressing the plate to the seat in the absence of pressure under it is ensured by a spiral spring placed in the damper chamber.
The valve of the 1029-200/250-0 series (Fig. 3) is fundamentally designed like the valves of the 392 and 875 series. The only difference is the presence of a throttle grille in the body and the removal of steam through two oppositely directed outlet pipes.
Table 3
Technical characteristics of the main safety valves IPU boilers
|
Valve designation |
Nominal diameter, mm | Steam operating parameters | Smallest area | Flow coefficient | Steam consumption at working | The course of the class | Weight, kg | ||||
| entrance- | exit- | Pressure | Tempe- temperature, °С |
for other | on the raft | passage- nogo section, mm 2 |
parameters, t/h | mm | |||
| Fresh steam valves | |||||||||||
| 1202-150/150-0 | 150 | 150 | 9,8 | 540 | 30,0 | 17,5 | 5470 | 0,5 | 120 | 20 | 415 |
| 1203-150/200-0-01 | 150 | 200 | 9,8 | 540 | 59,0 | 17,5 | 5470 | 0,5 | 120 | 20 | 345 |
| 1203-150/200-0 | 150 | 200 | 13,7 | 560 | 59,0 | 17,5 | 5470 | 0,5 | 165 | 20 | 345 |
| 392-175/95-0 g -01 | 175 | 200 | 9,8 | 540 | 30,0 | 17,5 | 4236 | 0,7 | 120 | 22 | 446 |
| 392-175/95-0 u | 175 | 200 | 13,7 | 560 | 30,0 | 20,0 | 4236 | 0,7 | 160 | 22 | 446 |
| 875-125-0 | 125 | 250 | 25,0 | 545 | 80,0 | 32,0 | 2900 | 0,7 | 240 | 22 | 640 |
| 1029-200/250-0 | 150 | 200 | 25,0 | 545 | 80,0 | 32,0 | 11300 | 0,7 | 850 | 28 | 2252 |
| E-2929 | 150 | 200 | 25,5 | 560 | 80,0 | 32,0 | 9400 | 0,7 | 700 | 28 | 2252 |
| Reheat steam valves | |||||||||||
| 111-250/400-0 b | 250 | 400 | 0,8-1,2 | 545 | 9,6 | 4,5 | 18700 | 0,7 | 50-80 | 40 | 727 |
| 111-250/400-0 b -0l | 250 | 400 | 1,3-3,7 | 545 | 9,6 | 4,5 | 18700 | 0,7 | 87-200 | 45 | 727 |
| 694-250/400-0 | 250 | 400 | 4,1 | 545 | 15,0 | 5,0 | 18700 | 0,7 | 200 | 45 | 652 |
| B-7162LMZ | 200 | 400 | 1,3-3,7 | 545 | 9,6 | 4,5 | 18700 | 0,7 | 87-200 | 45 | 590 |
The valves work as follows:
when the IR steam is opened, it enters the chamber above the servo piston through the pulse tube, creating pressure on it equal to the pressure on the spool. But since the area of the piston, which is affected by steam pressure, exceeds the similar area of the spool, a shifting force arises, moving the spool down and thereby opening the discharge of steam from the object. When the pulse valve is closed, the access of steam to the servo chamber is stopped, and the steam present in it is discharged through the drain hole into the atmosphere. In this case, the pressure in the chamber above the piston drops and due to the action of the medium pressure on the spool and the force of the spiral spring, the valve closes.
To prevent shocks when opening and closing the valve, its design includes a hydraulic damper in the form of a chamber located in the yoke coaxially with the servo drive chamber. The damper chamber contains a piston, which is connected to the spool using rods; According to the factory instructions, water or some other liquid of similar viscosity is poured or supplied into the chamber. When the valve opens, liquid flowing through small holes in the damper piston slows down the movement of the valve running gear and thereby softens the shock. When the valve running gear moves towards closing, a similar process occurs in the opposite direction 1. The valve seat is removable and is located between the connecting pipe and the body. The seat is sealed with comb metal gaskets. There is a hole in the side of the saddle connected to drainage system, where the condensate that accumulates in the valve body after its operation is drained. To avoid spool vibration and rod breakage, guide ribs are welded into the connecting pipe.
The peculiarity of the valves of the 1202 and 1203 series (Fig. 4 and 5) is that in them the connecting pipe is made integral with the body and there is no hydraulic damper, the role of which is played by the throttle 8 installed in the cover on the line connecting the above-piston chamber with the atmosphere.
Just like the valves discussed above, valves of the 1203 and 1202 series operate on the principle of “loading”: when the IR is opened, the working medium is supplied to the above-piston chamber and when a pressure in it reaches 0.9 R p, begins to move the piston down, opening the release of the medium into the atmosphere.
The main parts of fresh steam valves are made of the following materials: body parts - steel 20KhMFL or 15KhMFL (t > 540°C), rods - steel 25Kh2M1F, spiral spring - steel 50KhFA.
The sealing surfaces of the valve parts are deposited with TsN-6 electrodes. Pressed rings made of asbestos-graphite cord grades AG and AGI are used as stuffing box packing. At a number of thermal power plants, a combined packing is used to seal the piston, including rings made of thermally expanded graphite, metal foil and foil made of thermally expanded graphite. The packing was developed by UNICHIMTEK and was successfully tested at ChZEM stands.
1 As the operating experience of a number of thermal power plants has shown, the valves operate without shock even in the absence of liquid in the damper chamber due to the presence of an air cushion under and above the piston.
Rice. 2. 392 and 875 series main relief valves:
1 - connecting pipe; 2 - body; 3 - saddle; 4 - plate; 5 - lower rod; 6 - servo drive unit; 7 - upper rod; 8 - hydraulic damper chamber; 9 - housing cover;
10 - damper piston; 11 - damper chamber cover
Rice. 3. 1029 series main safety valve
Rice. 4. 1202 series main relief valve:
1 - body; 2 - saddle; 3 - plate; 4 - servo drive unit; 5 - lower rod; 6 - upper rod;
7 - spring; 8 - throttle
1.2. Pulse valves
All fresh steam IPUs produced by ChZEM are equipped with pulse valves of the 586 series. The technical characteristics of the valves are given in table. 4, a constructive solution in Fig. 6. Valve body - angular, flange connection housings with a lid. A filter is mounted at the inlet of the valve, designed to capture foreign particles contained in the steam. The valve is driven by an electromagnetic drive, which is mounted on the same frame as the valve. To ensure that the valve operates when the voltage in the electromagnet power supply system disappears, a weight is suspended on the valve lever, by moving which you can adjust the valve to operate at the required pressure.
Table 4
Technical characteristics of pulse valves for fresh steam and reheat steam
| Valve designation | Conditional passage | Work Environment Settings | Test pressure during testing, MPa | |||
| (drawing number) | D y, mm | Pressure, MPa | Temperature, °C | for strength | on density | Weight, kg |
| 586-20-EM-01 | 20 | 25,0 | 545 | 80,0 | 32,2 | 226 |
| 586-20-EM-02 | 20 | 13,7 | 560 | 80,0 | 17,5 | 206 |
| 586-20-EM-03 | 20 | 9,8 | 540 | 80,0 | 12,5 | 191 |
| 586-20-EMF-03 | 20 | 4,0 | 285 | 15,0 | 5,0 | 198 |
| 586-20-EMF-04 | 20 | 4,0 | 545 | 15,0 | 5,0 | 193 |
| 112-25x1-OM | 25 | 4,0 | 545 | 9,6 | 4,3 | 45 |
| 112-25x1-0 | 25 | 1,2 | 425 | 9,6 | 1,4 | 31 |
| 112-25x1-0-01 | 25 | 3,0 | 425 | 9.6 | 3,2 | 40 |
| 112-25х1-0-02 | 25 | 4,3 | 425 | 9,6 | 4,3 | 45 |
Rice. 5. 1203 series main safety valve
Rice. 6. Fresh steam pulse valve:
A- valve design; b - installation diagram of the valve on the frame together with electromagnets
To ensure minimal inertia of the IPU operation, pulse valves should be installed as close as possible to the main valve.
2. Pulse-safety devices for reheating steam
2.1. Main safety valves
GPK ChZEM and LMZ are installed on the cold reheating pipelines of boilers D at 250/400 mm. Technical characteristics of the valves are given in table. 3, the design solution of the reheat valve ChZEM is shown in Fig. 7. Main components and parts of the valve: body of pass-through type 1, connected to the pipeline by welding; a shutter assembly consisting of a seat 2 and a plate 3, connected via a thread to the rod 4; glass 5 with a servo drive, the main element of which is a piston 6 sealed with an stuffing box; spring load unit, consisting of two successively arranged spiral springs 7, the required compression of which is carried out by screw 8; throttle valve 9, designed to dampen the shock when closing the valve by regulating the rate of steam removal from the above-piston chamber. The seat is installed between the body and the glass on grooved gaskets and is crimped when tightening the cover fasteners. Centering of the spool in the seat is ensured by guide ribs welded to the spool.
Rice. 7. Main reheat steam safety valves of series 111 and 694:
1 - body; 2 - saddle; 3 - plate; 4 - rod; 5 - glass; 6 - servo piston; 7 - spring; 8 - adjusting screw; 9 - throttle valve; A - steam input from the pulse valve;
B - release of steam into the atmosphere
The main parts of the valves are made of the following materials: body and cover - steel 20GSL, upper and lower rods - steel 38ХМУА, spring - steel 50ХФА, stuffing box - cord AG or AGI. The sealing surfaces of the factory-made valve parts are welded with TsT-1 electrodes. The operating principle of the valve is the same as that of fresh steam valves. The main difference is the way the shock is damped when the valve closes. In the HPC reheat steam, the degree of shock damping is adjusted by changing the position of the throttle needle and tightening the spiral spring.
The main safety valves, intended for installation on the hot reheat line, series 694 differ from the cold reheat valves of the 111 series described above in the material of the body parts. The body and cover of these valves are made of 20ХМФЛ steel.
The GPKs supplied for installation on the cold reheat line, manufactured by LMZ (Fig. 8), are similar to the ChZEM series 111 valves, although they have three fundamental differences:
The servo piston is sealed using cast iron piston rings;
the valves are equipped with a limit switch, which allows information about the position of the shut-off element to be transmitted to the control panel;
There is no throttling device on the steam discharge line from the above-piston chamber, which eliminates the possibility of adjusting the degree of shock damping or valve closing and, in many cases, contributes to the occurrence of a pulsating mode of operation of the valves.
Rice. 8. Main safety valve for reheating steam, LMZ design
2.2. Pulse valves
Lever-load valves are used as pulse valves of the IPU ChZEM reheating system D for 25 mm series 112 (Fig. 9, Table 4). The main parts of the valve: body 1, seat 2, spool 3, rod 4, sleeve 5, lever 6, weight 7. The seat is removable, installed in the body and, together with the body, in the connecting pipe. The spool is located in the internal cylindrical bore of the seat, the wall of which plays the role of a guide. The rod transmits force to the spool through the ball, which prevents the valve from skewing when the valve closes. The valve is set to operate by moving a weight on the lever and then locking it in a given position.
Rice. 9. Pulse valve IPU ChZEM for reheat steam, series 112:
1 - body; 2 - saddle; 3 - spool; 4 - rod; 5 - bushing; 6 - lever; 7 - load
The parts are made from the following materials; body - steel 20, rod - steel 25Х1МФ, spool and seat - steel 30Х13.
For valves intended for IPU hot reheating, the body 112-25x1-OM is made of 12ХМФ steel. ChZEM pulse valves for the reheating system are supplied without an electromagnetic drive, LMZ valves are supplied with an electromagnetic drive.
3. Direct acting valves PA "Krasny Kotelshchik"
Spring safety valves T-31M-1, T-31M-2, T-31M-3, T-32M-1, T-32M-2, T-32M-3, T-131M, T-132M produced by the Krasny production association boilermaker" (Fig. 10).
Spring valves, full lift. They have a cast corner housing and are installed only in a vertical position in places with an ambient temperature not exceeding +60°C. When the pressure of the medium under the valve increases, the plate 2 is pressed away from the seat, and the steam flow, flowing at high speed through the gap between the plate and the guide sleeve 4, has a dynamic effect on the lifting sleeve 5 and causes a sharp rise of the plate to a given height. By changing the position of the lifting sleeve relative to the guide sleeve, it is possible to find its optimal position, which ensures both sufficiently rapid opening of the valve and its closing with a minimal decrease in pressure relative to the operating pressure in the protected system. To ensure that when the valve opens, a minimum release of steam into the surrounding space is made in the valve cover, a labyrinth seal is made, consisting of alternating aluminum and paronite rings. Setting the valve to operate at a given pressure is carried out by changing the degree of tightening of spring 6 using a pressure threaded bushing 7. The pressure bushing is closed by a cap 8, secured with two screws. A control wire is passed through the screw heads, the ends of which are sealed.
To check the operation of the valves during operation of the equipment, a lever 9 is provided on the valve.
Technical characteristics of the valves, overall and connecting dimensions are given in table. 5.
The valve is currently available with a welded body. Technical characteristics of valves and springs installed on them are given in table. 6 and 7.
Rice. 10. Spring safety valve "Krasny Kotelshchik":
6 - spring, 7 - pressure threaded bushing; 8 - cap; 9 - lever
Table 5
Technical characteristics of spring safety valves, old releases produced by PA "Krasny Kotelshchik"
| Cipher | Diameter | Working | Maximum | Coefficient | Least | Spring data | Pressure | Weight | |||
| valve | nominal diameter, mm | pressure, MPa (kgf/cm2) | working environment temperature, °C | consumption, d | flow path area F, mm 2 | Serial number of spring detail drawing | Wire diameter, mm | Outer diameter of spring, mm | Spring height in free state, mm | leak testing, MPa (kgf/cm2) | valve, kg |
| T-31M-1 | 50 | 3,4-4,5 | K-211946 | 18 | 110 | 278 | 4,5 (45) | 48,9 | |||
| Version 1 | |||||||||||
| T-31M-2 | 50 | 1,8-2,8 | 450 | 0,65 | 1960 | Version 2 | 16 | 106 | 276 | 2,8 (28) | 47,6 |
| T-31M-3 | 50 | 0,7-1,5 | Version 3 | 12 | 100 | 285 | 1,5 (15) | 45,5 | |||
| T-31M | 50 | 5,0-5,5 | K-211948 | 18 | 108 | 279 | 5,5 (55) | 48,3 | |||
| T-32M-1 | 80 | 3,5-4,5 | K-211817 | 22 | 140 | 304 | 4,5 (45) | 77,4 | |||
| Version 1 | |||||||||||
| T-32M-2 | 80 | 1,8-2,8 | 450 | 0,65 | 3320 | Version 2 | 18 | 128 | 330 | 2,8 (28) | 74,2 |
| T-32M-3 | 80 | 0,7-1,5 | Version 3 | 16 | 128 | 315 | 1,5 (15) | 73,4 | |||
| T-131M | 50 | 3,5-4,0 | 450 | 0,65 | 1960 | K-211947 Version 1 |
18 | 110 | 278 | 4,5 (45) | 49,7 |
| T-132M | 80 | 3,5-4,0 | 450 | 0,65 | 3320 | K-211817 Version 1 |
22 | 140 | 304 | 4,5 (45) | 80,4 |
Table 6
Technical characteristics of spring safety valves produced by Krasny Kotelshchik Production Association
|
Valve code |
Inlet flange |
Outlet flange |
Limit parameters of operating conditions | Design diameter, mm / design | Opening start pressure, MPa**/kgf/cm2 | Designation | Spring designation | Spring tension height | Valve weight, kg | Flow coefficient | ||||
| Nominal diameter, mm | Conditional pressure, MPa/kgf/cm2 | Nominal diameter, mm | Conditional pressure, MPa/kgf/cm2 | Working pressure, MPa/kgf/cm2 | Ambient temperature, °C | flow area, mm 2 | h 1 , mm | a | ||||||
| T-31M-1 | 50 | 6,4/64 | 100 | 1,6/16 | Steam | 3,5-4,5/35-45 | 425-350* | 48/1810 | 4.9±0.1/49±1 | 08.9623.037 | 08.7641.052-04 | 200 | 47,8 | 0,65 |
| T-31M-2 | 50 | 6,4/64 | 100 | 1,6/16 | -"- | 1,8-2,8/18-28 | Up to 425 | 48/1810 | 3.3±0.1/33±1 | 08.9623.037-03 | 08.7641.052-02 | 200 | 46,5 | 0,65 |
| T-31M-3 | 50 | 6,4/64 | 100 | 1,6/16 | -"- | 0,7-1,5/7-15 | Up to 425 | 48/1810 | 1.8±0.1/18±1 | 08.9623.037-06 | 08.7641.52 | 170 | 44,5 | 0,65 |
| T-32M-1 | 80 | 6,4/64 | 150 | 1,6/16 | -"- | 3,5-4,5/35-45 | 425-350* | 62/3020 | 4.95±0.1/49.5±1 | 08.9623.039 | 08.7641.052-06 | 210 | 75,8 | 0,65 |
| T-32M-2 | 80 | 6,4/64 | 150 | 1,6/16 | -"- | 1,8-2,8/18-28 | 425 | 62/3020 | 3.3±0.1/33±1 | 08.9623.039-03 | 08.7641.052-04 | 220 | 72,11 | 0,65 |
| T-131M | 50 | 10/100 | 100 | 1,6/16 | -"- | 3,5-4,5/35-45 | 450 | 48/1810 | 4.95±0.1/49.5±1 | 08.9623.048 | 08.7641.052-04 | 200 | 48,8 | 0,65 |
| T-132M | 80 | 10/100 | 150 | 1,6/16 | -"- | 3,5-4,5/35-45 | 450 | 62/3020 | 4.9±0.1/49±1 | 08.9623.040 | 08.7641.052-06 | 210 | 76,1 | 0,65 |
| *Lower temperature is the limit for higher pressure. | ||||||||||||||
| ** Limit of factory tests of valves for detonation. | ||||||||||||||
Table 7
Technical characteristics of springs installed on valves of the Krasny Kotelshchik Production Association
| Geometric dimensions | Spring force at | Working | Expanded | Weight, kg | ||||||
| Designation | Outer | Diameter | Spring height in | Step | Number of turns | working deformation | deformation | spring length, | ||
| springs | diameter, mm | rod, mm | free state, mm | windings, mm | working n | complete n 1 | F, kgf(N) | springs S 1, mm | mm | |
| 06.7641.052 | 27,9 | 8±0.5 | 12 | 340 (3315,4) | 3000 | 2,55 | ||||
| 08.7641.052-01 | 32,7 | 8±0.3 | 10 | 540(5296,4) | 3072 | 4,8 | ||||
| 08.7641.052-02 | 31,5 | 8±0.3 | 10 | 620(6082,2) | 2930 | 4,7 | ||||
| 08.7641.052-03 | 29,0 | 8±0.3 | 10 | 370(3623,7) | 3072 | 4,7 | ||||
| 08.7641.052-04 | 31,5 | 8±0.3 | 10 | 1000(9810) | 3000 | 6,0 | ||||
| 08.7641.052-05 | 36,5 | 7±0.3 | 9 | 1220(11968,2) | 2660 | 5,4 | ||||
| 08.7641.052-06 | 41,7 | 6.5±0.3 | 8,5 | 1560(15308,1) | 3250 | 9,8 | ||||
| 08.7641.052-07 | 41,7 | 6.5±0.3 | 8,5 | 1700(16677) | 3300 | 9,5 | ||||
List of used literature
1. Device rules and safe operation steam and hot water boilers, - M.: NPO OBT, 1993.
2. GOST 24570-81 (ST SEV 1711-79). Safety valves for steam and hot water boilers. Technical requirements.
3. Instructions for organizing the operation, procedure and timing of checking impulse safety devices of boilers with steam pressure above 4.0 MPa: RD 34.26.301-91.- M.: SPO ORGRES, 1993.
4. Instructions for organizing the operation, procedure and timing of testing impulse safety devices of boilers with operating steam pressure from 1.4 to 4.0 MPa (inclusive): RD 34.26.304-91.- M.: SPO ORGRES. 1993.
5. Pulse safety devices of the Chekhov plant "Energomash". Technical description and operating instructions.
6. Safety valves of JSC "Krasny Kotelshchik". Technical description and operating instructions.
7. GOST 12.2.085-82 (ST SEV 3085-81). Pressure vessels. Safety valves. Safety requirements.
8. Gurevich D.F., Shpakov O.N. Designer's reference pipeline fittings.- L.: Mechanical Engineering, 1987.
9. Power fittings for thermal power plants and nuclear power plants. Industry directory catalog. - M.: TsNIITEITyazhmash, 1991.
1. General Provisions
2. Basic requirements for protecting boilers from pressure increases above the permissible value
3. Instructions for installing safety devices
4. Preparing valves for operation
5. Adjustment of safety devices to operate at a given pressure
6. Procedure and timing for checking valves
8. Organization of operation
9. Safety requirements
Appendix 1. Requirements for boiler safety valves
Appendix 2. Methodology for calculating the capacity of boiler safety valves
Appendix 3. Forms of technical documentation on safety devices of boilers, which must be maintained at thermal power plants
Appendix 4. Basic terms and definitions
Appendix 5. Designs and technical characteristics of boiler safety valves
List of used literature
ADJUSTING SAFETY DEVICES TO ACTIVATE AT A SET PRESSURE
5.1. Adjustment of safety devices to operate at a given pressure is carried out:
after installation of the boiler is completed;
after major repairs, if safety valves were replaced or overhauled (complete disassembly, grooving of sealing surfaces, replacement of chassis parts, etc.), and for PPK - in case of spring replacement.
5.2. To adjust the valves, a pressure gauge with an accuracy class of 1.0, tested in the laboratory using a standard pressure gauge, must be installed in close proximity to them.
5.3. Safety valves are regulated at the valve installation site by raising the pressure in the boiler to the response pressure.
Adjustment of spring safety valves can be done on a steam bench with operating parameters, followed by a control check on the boiler.
5.4. The actuation of the valves during adjustment is determined by:
for IPU - at the moment of activation of the GPC, accompanied by impact and loud noise;
for direct-acting full-lift valves - by a sharp pop observed when the spool reaches the top position.
For all types of safety devices, operation is controlled by the beginning of the pressure drop on the pressure gauge.
5.5. Before adjusting the safety devices, you must:
5.5.1. Make sure that all installation, repair and adjustment work is stopped on the systems in which the steam pressure necessary for regulation will be created, on the safety devices themselves and on their exhaust pipelines.
5.5.2. Check the reliability of disconnecting systems in which pressure will increase from adjacent systems.
5.5.3. Remove all bystanders from the valve adjustment area.
5.5.4. Ensure good lighting of PU installation workplaces, service areas and adjacent passages.
5.5.5. Establish two-way communication between valve adjustment points and the control panel.
5.5.6. Conduct instruction for shift and adjustment personnel involved in valve adjustment work.
Personnel must be well aware of the design features of the PUs being adjusted and the requirements of the instructions for their operation.
5.6. Direct-acting lever-load valves are adjusted in the following sequence:
5.6.1. The weights on the valve levers are moved to their extreme position.
5.6.2. In the protected object (drum, superheater), a pressure is established that is 10% higher than the calculated (permitted) one.
5.6.3. The weight on one of the valves is slowly moved towards the body until the valve is activated.
5.6.4. After closing the valve, the position of the weight is fixed with a locking screw.
5.6.5. The pressure in the protected object rises again and the pressure value at which the valve operates is checked. If it differs from that set in paragraph 5.6.2, the position of the weight on the lever is adjusted and the correct operation of the valve is re-checked.
5.6.6. After the adjustment is completed, the position of the weight on the lever is finally fixed with a locking screw. To prevent uncontrolled movement of the load, the screw is sealed.
5.6.7. An additional weight is installed on the lever of the adjusted valve and the remaining valves are adjusted in the same sequence.
5.6.8. After completing the adjustment of all valves in the protected object, the operating pressure is established. Additional weights are removed from the levers. A record is made in the Maintenance and Operation Log of safety devices about the readiness of the valves for operation.
5.7. Adjustment of direct acting spring safety valves:
5.7.1. The protective cap is removed and the spring tension is checked h 1 (Table 6).
5.7.2. The pressure value in the protected object is set in accordance with clause 5.6.2.
5.7.3. By turning the adjusting sleeve counterclockwise, the compression of the spring is reduced to the position at which the valve will operate.
5.7.4. The pressure in the boiler rises again and the pressure value at which the valve operates is checked. If it differs from that set according to clause 5.6.2, then the spring compression is adjusted and the valve is re-checked for operation. At the same time, the pressure at which the valve closes is monitored. The difference between the actuation pressure and the closing pressure should be no more than 0.3 MPa (3.0 kgf/cm2). If this value is greater or less, then the position of the upper adjusting sleeve must be adjusted.
For this:
For TKZ valves, unscrew the locking screw located above the cover and turn the damper bushing counterclockwise to reduce the drop or clockwise to increase the drop;
For the PPK and SPPK valves of the Blagoveshchensk Valve Plant, the pressure difference between the actuation and closing pressures can be adjusted by changing the position of the upper adjusting sleeve, which is accessed through a hole closed with a plug on the side surface of the body.
5.7.5. The height of the spring in the adjusted position is recorded in the Journal of Repair and Operation of Safety Devices and it is compressed to the value h 1 to be able to adjust the remaining valves. After completing the adjustment of all valves, the spring height recorded in the log in the adjusted position is set on each valve. To prevent unauthorized changes in the spring tension, a protective cap is installed on the valve, covering the adjusting sleeve and the end of the lever. The bolts securing the protective cap are sealed.
5.7.6. After the adjustment is completed, a record is made in the Maintenance and Operation Log of safety devices indicating that the valves are ready for operation.
5.8. Pulse safety devices with IR, equipped with an electromagnetic drive, are regulated to operate both from electromagnets and when the electromagnets are de-energized.
5.9. To ensure that the IPU is triggered by electromagnets, the ECM is configured:
5.9.1. The ECM readings are compared with the readings of a standard pressure gauge with a class of 1.0%.
5.9.2. The ECM is adjusted to turn on the opening electromagnet:
Where h- correction for water column pressure
h= ρ D N· 10-5 MPa,
here ρ is the density of water, kg/m3;
D N- difference in marks between the place where the impulse line is connected to the protected object and the place where the ECM is installed, m.
5.9.3. The ECM is adjusted to turn on the closing electromagnet:
R zekm = 0.95 R p + h MPa.
5.9.4. The limits of IR operation are marked on the ECM scale.
5.10. Adjusting the IR to operate at a given pressure with de-energized electromagnets is carried out in the same sequence as adjusting direct-acting lever-load valves:
5.10.1. The weights on the IR levers are moved to their extreme position.
5.10.2. The pressure in the boiler drum rises to the IPU response set point ( R Wed = 1,1 R b); on one of the IR loads connected to the boiler drum, the load moves towards the lever to a position at which the IPU is triggered. In this position, the load is fixed to the lever with a screw. After this, the pressure in the drum rises again and it is checked at what pressure the IPU is triggered. If necessary, the position of the load on the lever is adjusted. After adjustment, the weights on the lever are secured with a screw and sealed.
If more than one IR is connected to the boiler drum, an additional weight is installed on the lever of the adjusted valve to allow adjustment of the remaining IR connected to the drum.
5.10.3. A pressure equal to the response pressure of the IPU behind the boiler ( R Wed = 1,1 R R) . In the manner prescribed in clause 5.10.2, it is regulated for the operation of the IPU, in which the steam on the IR is taken from the boiler.
5.10.4. After the adjustment is completed, the pressure behind the boiler is reduced to nominal and additional weights are removed from the IR levers.
5.11. Voltage is supplied to the electrical control circuits of the IPU. The valve control keys are set to the “Automatic” position.
5.12. The steam pressure behind the boiler is increased to the value at which the IPU should operate, and the opening of the gas pumps of all IPUs, the impulse to open which is taken behind the boiler, is checked locally.
When adjusting the IPU on drum boilers, the IPU control keys, triggered by a pulse behind the boiler, are set to the “Closed” position and the pressure in the drum rises to the IPU actuation set point. The operation of the GPK IPU, operating on an impulse from the drum, is checked locally.
5.13. Pulse-safety devices for reheat steam, which do not have shut-off elements behind them, are configured to operate after installation during the boiler firing for steam density. The procedure for setting the valves is the same as when setting the fresh steam valves installed behind the boiler (section 5.10.3).
If there is a need to adjust the reheat steam pulse valves after repairs, it can be done on a special stand. In this case, the valve is considered adjusted when the rise of the rod by the stroke value is recorded.
5.14. After checking the operation of the IPU, the control keys of all IPUs must be in the “Automatic” position.
5.15. After adjusting the safety devices, the shift supervisor must make an appropriate entry in the Maintenance and Operation Log of the safety devices.
RUSSIAN JOINT STOCK COMPANY OF ENERGY AND ELECTRIFICATION "UES OF RUSSIA"INSTRUCTIONS
ON OPERATION, PROCEDURE AND TIMELINES FOR CHECKING SAFETY DEVICES OF VESSELS, EQUIPMENT AND PIPELINES OF TPP
RD 153-34.1-39.502-98
UDC 621.183 + 621.646
Enters into force on December 1, 2000.
Developed by the Open Joint Stock Company "Company for setting up, improving technology and operating power plants and networks ORGRES"
Performer V.B. KAKUZIN
Agreed with Gosgortekhnadzor of Russia (Letter dated July 31, 1998 No. 12-22/760)
Deputy Head of Department N.A. HAPONEN
Approved by the Department of Development Strategy and Scientific and Technical Policy of RAO UES of Russia on July 27, 1998
First Deputy Chief A.P. BERSENEV
1. GENERAL PROVISIONS
1.1. This Instruction applies to safety devices (SD) installed on vessels, apparatus and pipelines of thermal power plants operating on steam and water.
1.2. The instructions do not apply to those control units of steam and hot water boilers that are subject to the requirements and.
1.3. The instructions contain the basic requirements for installing the control units and determine the procedure for their adjustment, operation and maintenance.
Appendices 1-4 of the Instructions set out the basic requirements for control systems of power plants, contained in the Rules and Gosgortekhnadzor of Russia and GOST 12.2.085-82 and GOST 24570-81, and provide the technical characteristics of valves used to protect the equipment of thermal power plants from pressure increases above the permissible values, methods for calculating the capacity of safety valves (SV) and a number of other materials of practical interest for operating personnel of power plants.
The instructions are aimed at improving the safety of operation of power plant equipment.
1.4. With the publication of this Instruction, the “Instructions for the operation, procedure and timing of inspection of safety devices of vessels, apparatus and pipelines of thermal power plants” (Moscow: SPO Soyuztekhenergo, 1981) becomes invalid.
1.5. The following abbreviations are adopted in the Instructions:
BROW- high-speed reduction-cooling unit;
Civil Procedure Code- main safety valve;
IR- pulse valve;
IPU- impulse safety device;
MPU- membrane safety device;
NTD- scientific and technical documentation;
PVD- high pressure heater;
PC- safety valve;
HDPE- low pressure heater;
PPK- direct acting spring safety valve;
PU- safety device;
PEN- electric feed pump;
RBNT- low point expansion tank;
RGPC- direct-acting lever-load valve;
RD- management documentation;
ROW- reduction-cooling unit;
TPN- turbo feed pump;
TPP- thermal power plant.
2. BASIC TERMS AND DEFINITIONS
Based on the operating conditions of vessels, apparatus and pipelines at thermal power plants, the operating principle of the control devices used to protect them, taking into account the terms and definitions contained in various GOSTs, regulatory documents Gosgortekhnadzor of Russia and technical literature, the following terms and definitions are adopted in this Instruction.
2.1. Operating pressureR slave – the maximum internal excess pressure that occurs during the normal course of the working process without taking into account the hydrostatic pressure of the medium and a short-term increase in pressure during the operation of the PU.
2.2. Design pressureR races - excess pressure for which the strength of elements of vessels, apparatus and pipelines was calculated.
The design pressure must be no less than the working pressure.
2.3. Allowable pressureR extra - the maximum excess pressure allowed by accepted standards that can arise in the protected object when the medium is discharged from it through the PU. Relationship between R extra And R slave (R races) is given in the table.
Safety devices must be selected and adjusted in such a way that the pressure in the vessel or apparatus cannot rise above the permissible pressure.
2.4. Opening pressureR But- excess pressure in the protected object, at which the shut-off element begins to move (the force tending to open the valve is balanced by the force holding the shut-off element on the seat)
The opening pressure must always be higher than the operating pressure.
2.5. Full opening pressureR open- the lowest excess pressure in front of the valve at which the required throughput is achieved.
2.6. Response pressureR Wed- maximum excess pressure that is established in front of the launcher when it is fully opened.
The response pressure should not exceed R extra .
Based on operating experience and tests, it has been established that for the IPU the response pressure is almost equal to the pressure at which the IR opens, while for the full-lift PPK the lifting time to the stroke value is 0.008-0.04 s. Hence, the value of the excess of the full actuation pressure over the opening pressure depends on the rate of pressure increase in the protected object. Taking into account possible fluctuations of the shut-off element, the use of full-lift valves is recommended in systems with a rate of pressure increase:
0.5 0 0.1 s
2.7. Closing pressure R zach - excess pressure in front of the valve, at which, after actuation, the shut-off element is seated on the seat.
2.8. BandwidthG - maximum mass flow of the working medium that can be discharged through a fully open valve at response parameters.
The methodology for calculating the throughput capacity of PC vessels, regulated by GOST 12.2.085-82, is given in Appendix 2. Calculation of the throughput capacity of PC pipelines is regulated by GOST 24570-81.
3. INSTALLATION OF SAFETY DEVICES
3.1. To protect vessels, apparatus and pipelines of thermal power plants from pressure increases above the permissible value, it is allowed to use:
direct acting safety valves: PPK and RGPK;
impulse safety devices;
safety devices with rupture membranes;
other devices, the use of which has been approved by the Gosgortekhnadzor of Russia.
3.2. Installation of PU on vessels, apparatus and pipelines, the design pressure of which is less than the pressure of the sources feeding them, is carried out in accordance with the normative and technical documentation and safety rules. The quantity, design, installation location of the PC and direction of discharge are determined by the project.
3.3. If the design pressure of the vessel is equal to the pressure of the source feeding them or exceeds it and the possibility of an increase in pressure from a chemical reaction or heating in the vessel is excluded, then installing a PU and a pressure gauge on it is not necessary.
3.4. When choosing the number and design of the PU, one should proceed from the need to exclude the possibility of increasing the pressure in the protected object above the permissible value. In this case, the choice of equipment protection method should include the following steps:
analysis of possible emergency situations (including erroneous actions of personnel) that can lead to an increase in pressure in the equipment or thermal circuit unit in question, and determination based on its calculated (most dangerous) emergency situation;
identification of the most weakened element of the protected object, which regulates the value of the design pressure that determines the triggering settings of the launcher;
determination of the mass and parameters of the process medium that must be discharged through the control unit;
based technological features protected system, construction of protection circuits and selection of the type and design of the control unit;
determination of PU response pressure values;
determination, taking into account the resistance of the pipelines, the required flow section of the PU and their number. A combination of various types PU with a shift in their response settings.
3.5. Safety devices must be installed in places convenient for their installation, maintenance and repair.
3.6. Safety valves must be installed vertically on the highest part of the apparatus or vessel so that when they are opened, vapors and gases are removed from the protected object first. It is allowed to install the PC on pipelines or special branches in close proximity to the protected object.
3.7. It is prohibited to install shut-off devices between the control panel and the protected object and behind the control panel.
3.8. The fittings in front of (behind) the PU can be installed provided that two PU are installed and there is a lock (switching device) that excludes the possibility of simultaneous shutdown of both PU. When switching from one control center to another, the total throughput of the PCs in operation must ensure that the requirements of clause 3.4 of this Instruction are met.
3.9. The internal diameter of the supply pipeline must be no less than the internal diameter of the PC inlet pipe.
3.10. When installing several PCs on one branch pipe (pipeline), the internal diameter of the branch pipe (pipeline) must be calculated based on the required PC throughput. In this case, when determining the cross-section of connecting pipelines with a length of more than 1000 mm, it is necessary to take into account the value of their resistance.
3.11. Connecting and impulse pipelines of the PU must be protected from freezing of the working environment in them.
3.12. Sampling of the working medium from the pipes (and in sections of connecting pipelines from the protected object to the control unit) on which the control units are installed is not allowed.
3.13. The environment from the PC must be diverted to a safe place. In cases where the working medium is water, it must be discharged into an expander or other vessel designed to receive water from the PC.
3.14. The internal diameter of the outlet pipeline must be no less than the internal diameter of the PC outlet pipe. In the case of combining the outlet pipes of several valves, the cross-section of the collector must be no less than the sum of the cross-sections of the outlet pipes of these valves.
3.15. The installation of noise suppression devices on the discharge pipeline of the control room should not cause a reduction in the throughput of the control unit below the value required by safety conditions. When equipping the outlet pipeline with a noise-attenuating device, a fitting for installing a pressure gauge must be provided immediately behind the PC.
3.16. The total resistance of the outlet pipelines, including the noise-attenuating device, must be such that at a flow rate equal to the maximum throughput of the control unit, the back pressure in the outlet pipe of these control devices does not exceed 25% of the response pressure of the control device.
3.17. The discharge pipelines of the PU and the impulse lines of the PU in places where condensate may accumulate must have drainage devices to remove it.
Installation of shut-off devices or other fittings on drainage devices pipelines are not allowed.
3.18. The riser (vertical pipeline) through which the medium is discharged into the atmosphere must be securely fastened and protected from precipitation.
3.19. In PC pipelines, the necessary compensation for temperature expansions must be provided. The fastening of the housing and pipelines of the PC must be calculated taking into account static loads and dynamic forces that arise when the PC is activated.
3.20. Pipelines supplying the medium to the PC along their entire length must have a slope towards the vessel. It is necessary to exclude sudden changes in the walls of these pipelines when the PC is activated.
3.21. In cases where the object is protected from increased pressure by IPU, the distance between the IK and GPC fittings must be at least 500 mm. The length of the connecting line between the IR and the GPC should not exceed 2.5 m.
3.22. When using an IPU with an IR equipped with an electromagnetic drive, the electromagnets must be powered from two independent power sources, ensuring that the IPU operates when the voltage disappears own needs. In those IPUs in which the GPC automatically opens when the power supply is turned off, one power source is allowed.
3.23. In thermal circuits of thermal power plants, the use of membrane PUs for protection against pressure increases is allowed only at those facilities, the shutdown of which does not lead to the shutdown of the main equipment (boilers, turbines). Examples of the possible use of MPU in thermal circuits of thermal power plants are discussed in Appendix 3.
3.24. To protect energy facilities, it is allowed to use MPUs designed and manufactured by enterprises that have permission from the State Mining and Technical Supervision Authority of Russia.
3.25. Clamping fixtures for installing membranes can be manufactured by the customer himself in strict accordance with drawings developed by a specialized organization. Each safety membrane must have a company mark indicating the response pressure and the permissible operating temperature during operation.
3.26. At least once every 2 years, it is necessary to carry out preventive replacement of membranes.
4. ADJUSTING SAFETY VALVES
4.1. Adjustment of the PC for operation is carried out:
after completing the installation of the vessel (apparatus, pipeline) before putting it into operation;
after repair, if the PC was replaced or overhauled (complete disassembly, grooving of sealing surfaces, replacement of chassis parts, etc.), and for PPK and in case of spring replacement.
4.2. Pulse safety devices and RGPC are regulated at the valve installation workplace; PPK can be adjusted both at the workplace and at a special stand with steam or air of appropriate pressure.
The basic design solution of the stand is shown in Fig. 1.
Rice. 1. PC test bench
4.3. Before starting work on adjusting the PC, the following organizational and technical measures must be completed:
4.3.1. Good lighting is provided for workplaces, passages, service areas and the PCs themselves.
4.3.2. A two-way connection has been established between the PC adjustment points and the control panel.
4.3.3. Shift and adjustment personnel involved in PC adjustment work were instructed. Personnel must know the design features of the PUs subject to adjustment and the requirements of the RD for their operation.
4.4. Immediately before starting adjustment and testing of the PU:
4.4.1. Check that all installation and adjustment work has been stopped in those systems in which the steam pressure necessary for adjusting the PC will be created, on the PUs themselves and their discharge pipelines.
4.4.2. Check the reliability of disconnecting those systems in which pressure will increase from adjacent systems. All shut-off valves in the closed position, as well as valves on open drainage lines, must be tied with a chain, and posters “Do not open, people are working” and “Do not close, people are working” must be posted on it.
4.4.3. All unauthorized people must be removed from the PC adjustment area.
4.5. To adjust PCs, a pressure gauge with an accuracy class of at least 1.0 must be installed in close proximity to them. Before installation, it must be tested in the laboratory using a standard pressure gauge.
4.6. Adjustment of the IPU with a lever-weight pulse valve should be done in the following order:
4.6.1. Move the IR weights to the edge of the lever.
4.6.2. Set the response pressure in the protected object in accordance with the requirements of the table.
4.6.3. Slowly move the weight on the lever towards the body to the position at which the GPC is activated.
4.6.4. Raise the pressure in the vessel again to the value at which the GPC opens. If necessary, adjust the position of the weight on the lever and recheck the correct operation of the valve.
4.6.5. Secure the weight to the lever with a locking screw. If several IPUs are installed at the facility, install an additional weight on the lever to be able to adjust other IPUs.
4.6.6. Adjust the remaining IPUs in the same order.
4.6.7. Set the required pressure in the object and remove additional weights from the levers.
4.6.8. Make an entry about the adjustment carried out in the “Logbook of operation and repair of safety devices” (Form 1 of Appendix 5).
4.7. Direct-acting lever-weight valves are adjusted in the same order as the IPU.
4.8. Adjustment of PPK should be done in the following order:
4.8.1. Install the valves on the stand (see Fig. 1), ensuring that the medium is removed from the valve to a safe place; Compress the spring to a gap between coils of 0.5 mm. For PCs produced by Krasny Kotelshchik JSC, the spring precompression value is indicated in the table. P4.14 of Appendix 4.
4.8.2. Open completely stop valve(valve) 1 and partially valve 3 (see Fig. 1); by gradually opening valve 2, ensure that air and water are displaced from under the PC and the stand is warmed up.
4.8.3. Guided by the requirements of the table, use valves 2 and 3 to set the required response pressure under the PC.
4.8.4. By rotating the PC adjusting sleeve counterclockwise, loosen the compression of the spring until the PC is activated.
4.8.5. Check the pressure at which the PC closes. It should not be lower than 0.8 R slave. If the closing pressure is less than 0.8 R slave, then you should check the position of the upper adjusting sleeve (damper sleeve) and the alignment of the chassis; if the PC closes with a delay at a pressure below 0.8 R slave, then the upper bushing should be lifted by rotating counterclockwise.
4.8.6. Raise the pressure again until the PC activates. Record this pressure. If necessary, adjust the response pressure value by tightening or loosening the spring.
4.8.7. If it is necessary to adjust several PCs directly at the installation site, after adjusting the PC, write down the spring tension value that ensures the PC operates at a given pressure, and then tighten the spring to the original value N 1 and adjust the next PC. After completing the adjustment of all PCs to the values recorded after adjusting each PC, close the adjusting sleeve with a cap and seal the screws securing the cap to the yoke.
4.8.8. When installed on a protected object, IPUs equipped with IR with a spring load, they are adjusted in the same order as PPK.
5. PROCEDURE AND TIMELINES FOR CHECKING SAFETY VALVES
5.1. Checking the proper operation of the PC by purging should be done at least once every 6 months. At power plants equipped with boilers running on coal dust, the operation of the PC should be checked once every 3 months.
5.2. On equipment that is put into operation periodically (expanders of ignition separators, ROU, BROU, etc.), before each putting them into operation by forced opening, the IR IPU should be opened and an entry should be made about this in the “Operation and Repair Log of Safety Devices”.
It is allowed not to pace the IR if the interval between switching on the protected equipment does not exceed 1 month.
5.3. Checking the PC by blowing is carried out according to a schedule (Form 2 of Appendix 5), which is drawn up annually for each workshop, agreed with the operation inspector and approved by the chief engineer of the power plant.
5.4. If the test is carried out by raising the pressure to the activation setpoint of the PC, then each PC is checked one by one.
If, due to operating conditions, it is not possible to increase the pressure to the set point for the activation of the pressure switch, then it is permissible to check the pressure switch by manual detonation at operating pressure.
5.5. The check is carried out by the shift supervisor or the senior driver and foreman of the repair organization carrying out PC repairs.
The shift supervisor makes an entry about the inspection carried out in the “Logbook of operation and repair of safety devices.”
6. RECOMMENDATIONS FOR MONITORING THE CONDITION AND ORGANIZING REPAIR OF SAFETY VALVES
6.1. Scheduled monitoring of the condition and repair of PCs must be carried out at least once every 4 years according to a schedule based on the possibility of shutting down the equipment on which they are installed.
6.2. Monitoring the condition of the PC includes disassembling, cleaning and defective parts, checking the tightness of the valve, and the condition of the seals of the piston drive of the GPC.
6.3. Monitoring the condition and repairing PCs should be carried out in a specialized fitting workshop on special stands. The workshop must be well lit, must have lifting mechanisms and a compressed air supply. The location of the workshop should ensure convenient transportation of the PC to the installation site.
6.4. Monitoring the condition and repairing PCs should be carried out by a permanent repair team that has experience in repairing fittings and has studied the design features of PCs and their operating conditions.
The team must be provided with PC working drawings, operation manuals, repair forms, spare parts and materials.
6.5. Before fault detection, parts of disassembled valves are cleaned of dirt and washed in kerosene.
6.6. When inspecting the sealing surfaces of the seat and plate, pay attention to the absence of cracks, dents, marks and other damage. When subsequently installed at the workplace, the sealing surfaces of the valve parts must have a cleanliness of at least 0.16. The quality of the sealing surfaces of the seat and disc must ensure their mutual fit in a closed ring, the width of the surface of which is at least 80% of the width of the smaller sealing surface.
6.7. The ellipse of the jackets of the GPC piston drives and guides should not exceed 0.05 mm per diameter. The surfaces in contact with the piston seals must have a roughness of 0.32.
6.8. When inspecting the GPC drive piston, special attention should be paid to the condition of the stuffing box. The packing rings must be tightly pressed together. There should be no damage to the working surface of the rings. Before assembly, it should be well graphiteized.
6.9. It is necessary to check the condition of the coil springs, for which it is necessary: to visually inspect the condition of the surface for the presence of cracks, deep marks, hairlines; measure the height of the spring in a free state and compare it with the requirements of the drawing; check the deviation of the spring from perpendicularity.
6.10. The condition of the threads of all fasteners and adjusting screws must be checked; All parts with defective threads must be replaced.
6.11. Repair and restoration of PC parts should be carried out in accordance with the current instructions for repairing fittings.
6.12. Before assembling the PC, you should check that the parts comply with the dimensions specified in the form or working drawings.
6.13. When assembling fastening joints, the nuts must be tightened evenly, without distortion of the parts being connected. In assembled PCs, the ends of the studs must protrude above the surface of the nuts by at least 1 thread pitch.
6.14. Tightening the oil seals in the piston chambers of the hydraulic pump should ensure the tightness of the piston, but should not impede its free movement.
7. ORGANIZATION OF OPERATION OF SAFETY VALVES
7.1. Overall responsibility for the condition, operation, repair and inspection of the control devices rests with the head of the workshop on whose equipment they are installed.
7.2. By order of the workshop, the workshop manager appoints persons responsible for checking PCs, organizing their repairs, and maintaining technical documentation.
7.3. Each workshop must maintain a “Logbook of operation and repair of safety devices,” which must include the following sections:
7.3.1. Statement of PC response pressure (Form 1 of Appendix 5).
7.3.2. Schedule for checking the serviceability of the PC by purging (Form 2 of Appendix 5).
7.3.3. Information about PC repair (form 3 of Appendix 5).
7.3.4. Information on forced testing of boiler PCs (Form 4 of Appendix 5).
7.4. Each PC must have a factory passport of the established type. If the TPP does not have a manufacturer's passport for each PC, it is necessary to draw up operational passport(according to form 5 of appendix 5). The passport must be signed by the workshop manager and approved by the chief engineer of the thermal power plant.
7.5. For each group of PCs of the same type, the workshop must have an instruction manual (operation manual) and an assembly drawing of the PC, and for the PPK, an additional drawing or passport of the spring.
8. TRANSPORTATION AND STORAGE
8.1. PCs must be transported to the installation site in an upright position.
8.2. When unloading the PC from any type of transport, dropping it from platforms, improper construction, or installing the PC on the ground without pads is not allowed.
8.3. Valves should be stored in an upright position on pads in a dry, enclosed area. The inlet and outlet pipes must be closed with plugs.
9. SAFETY REQUIREMENTS
9.1. Safety devices must be installed in such a way that personnel performing adjustments and testing have the ability to quickly evacuate in the event of unexpected releases of the medium through leaks in the exit of rods from caps and flange connections.
9.2. Safety devices must be operated at pressure and temperature not exceeding the values specified in the technical documentation.
9.3. It is prohibited to operate and test the PU in the absence of outlet pipes that protect personnel from burns.
When eliminating defects, use wrenches larger in size than the size of the turnkey fasteners.
9.5. When testing IR IPU and direct-acting valves, the valve lever should be raised slowly, away from places where the medium may be released from the valves. Personnel testing valves must have personal protective equipment: overalls, safety glasses, headphones, etc.
9.6. Preservation and re-preservation of valves should be carried out in accordance with the manufacturer’s instructions, using personal protective equipment.
9.8. It is prohibited to operate the PU in the absence of the information specified in section. 7 of this Instruction and technical documentation.
A safety valve (hereinafter referred to as PC) is a predominantly direct-acting pipeline fitting (there are also PCs controlled by pilot or pulse valves), designed for emergency bypass (discharge) of the medium when the pressure in the pipeline exceeds a predetermined one. After releasing excess pressure, the PC must close hermetically, thereby stopping further release of the medium.
In these instructions, 2 terms are used:
1. Setting pressure (hereinafter referred to as Рн) – this is the greatest redundant pressure at the valve inlet (under the spool) at which the valve is closed and sealed. When pH is exceeded, the valve must open to such an amount as to ensure the required flow of medium to reduce the pressure in the pipeline or vessel.
2. Opening start pressure (hereinafter referred to as Рн.о.) is the pressure at which the so-called “pop” in industrial jargon occurs, i.e. the pressure at which the valve spool opens by a certain amount, releases some of the pressure and then closes back. “Cotton” is clearly distinguishable in gaseous media; in liquid media, this concept is defined with great difficulty.
Checking the settings and functionality must be carried out at least once every 6 months in accordance with GOST 12.2.085 “Pressure vessels. Valves are safety safety requirements."
Pressure pH can only be checked on so-called "full-expendable» stands, i.e. those that repeat the operating parameters of the pipe (vessel) in terms of pressure and flow. Considering the variety of objects on which PCs are installed, even within one enterprise, it is not possible to have such a number of stands.
Therefore, when checking and configuring the PC, the determination of pressure pH is used. O. Based on numerous experiments over many years of practice, it has been established that Rn. O. should be higher than pH by no more than 5-7% (10% in Western standards).
Checking valves for functionality and pressure pH. O. held at "non-expendable" stands, a typical representative of which is the stand for testing and adjusting safety valves SI-TPA-200-64 produced by the Design Bureau of Pipeline Fittings and Special Works.
Stand for testing and adjusting safety valves SI-TPA-200-64 ensures the following pneumatic tests (medium - air, nitrogen, carbon dioxide, other non-flammable gases):
- tests for tightness of the seat-body connection;
- tests for tightness of the seat-spool pair (tightness in the valve);
- performance tests (operation tests);
- settings for response pressure.
It is possible to manufacture a stand complete with water testing.
The stand provides testing of pipeline fittings with a flange type of connection (threaded connection as an option)
maximum diameter 200. The maximum test pressure depends on the type of pressure regulator supplied as part of the control panel; the basic configuration of the control panel is a regulator of 0 to 1.6 MPa. Testing of valves with union connection is carried out using an adapter (not included in the delivery set).
The test pressure source is not included in the scope of delivery.
It is possible to equip it with a pressure source according to the customer’s technical specifications.
Test stand SI-TPA-200-64 passed UkrSEPRO certification, supplied complete with operating instructions and passport.
Adjustment (setting) of safety valves to operate at a given pressure is carried out:
Before installation. After a major overhaul, if safety valves were replaced or overhauled (complete disassembly, grooving of sealing surfaces, replacement of chassis parts, etc.), in case of spring replacement. During periodic inspection. After emergency situations caused by PC failure.
The actuation of the valves during adjustment is determined by a sharp pop accompanied by the noise of the ejected medium, observed when the spool is torn away from the seat. For all types of PCs, operation is controlled by the beginning of the pressure drop on the pressure gauge.
Before starting work on setting up (checking) the PC, it is necessary to instruct the shift and adjustment personnel involved in the work on adjusting the valves.
Personnel must be well aware of the design features of the PCs being adjusted and the requirements of the instructions for their operation.
GENERAL PROCEDURE FOR CHECKING SAFETY VALVES.
Install on the stand a flange of the type that matches the type of flange of the PC being tested. Install the required gasket. Install the valve onto the stand flange. Tighten the stand screw until the PC is fully secured in the clamps. Create the maximum possible backpressure force on the PC spool. Block the access of the medium under the valve spool using a shut-off device. Supply the medium to the control panel and set the required response pressure (start of opening) at the outlet of the control panel. Open the shut-off device and supply the test medium under the PC spool. Reduce the back pressure until the valve actuates. Block access to the medium under the PC spool. Re-supply the medium under the PC spool - the valve should operate at the required pressure. Repeat steps 10 and 11 at least 3 times. If it is not possible to adjust the PC properly, return the valve to the RMC for additional grinding of the seat and (or) spool. If the functionality of the PC is confirmed, remove the PC from the stand, having previously shut off the supply of medium under the spool and to the control panel. Fill out the PC operational documentation and the bench work log. Seal the PC and backpressure adjustment mechanisms. Turn off the stand. Drain the water (condensation) from the cavities of the stand, wipe dry, and apply protective lubricant. Ensure that the stand is protected from dust and moisture until the next use.
FEATURES OF ADJUSTING LEVER-WEIGHT VALVES.
Direct-acting lever-load valves are adjusted in the following sequence:
1. The weights on the valve levers are moved to their extreme position.
3. The weight on one of the valves is slowly moved towards the body until the valve is activated.
4. After closing the valve, the position of the weight is fixed with a locking screw.
5. The pressure rises again and the pressure value at which the valve operates is checked. If it differs from the required one, the position of the weight on the lever is adjusted and the correct operation of the valve is re-checked.
6. After completing the adjustment, the position of the weight on the lever is finally fixed with a locking screw. To prevent uncontrolled movement of the load, the screw is sealed.
7. If the backpressure created by the load is insufficient, an additional weight is installed on the lever of the adjustable PC and the adjustment is repeated in the same sequence.
FEATURES OF ADJUSTING DIRECT-ACTING SAFETY VALVES.
1. The protective cap is removed and the adjusting screw is tightened as much as possible (“to the bottom”).
2. The pressure on the bench pressure gauge is set to 10% higher than the calculated (permitted) pressure.
3. By turning the adjusting sleeve counterclockwise, the compression of the spring is reduced to a position at which the valve will operate.
4. The pressure rises again and the value at which the valve operates is checked. If it differs from the required one, then the spring compression is adjusted and the valve is re-checked for operation. At the same time, the pressure at which the valve closes is monitored. The difference between the actuation pressure and the closing pressure should be no more than 0.3 MPa (3.0 kgf/cm2). If this value is greater or less, then the position of the adjusting sleeve must be adjusted.
For this:
For TKZ valves, unscrew the locking screw located above the cover and turn the damper bushing counterclockwise to reduce the drop or clockwise to increase the drop;
For PPK and SPPK valves, the pressure difference between the actuation and closing pressures can be adjusted by changing the position of the upper adjusting sleeve, which is accessed through a hole closed with a plug on the side surface of the body.
5. After completing the adjustment, the position of the adjusting screw is locked using a locknut. To prevent unauthorized changes in the spring tension, a protective cap is installed on the valve, covering the adjusting sleeve and the end of the lever. The bolts securing the protective cap are sealed.
FEATURES OF ADJUSTMENT OF PULSE-SAFETY DEVICES WITH PULSE VALVES USED IN POWER PLANTS.
