Unofficial edition
GOST12.2.085-82
STATE STANDARD OF THE USSR UNION
SYSTEM OF OCCUPATIONAL SAFETY STANDARDS
Pressure vessels.
Safety valves.
Safety requirements.
Occupational safety standards system.
Vessels working under pressure. Safety valves.
Safety requirements
Date of introduction from 1983-07-01
until 1988-07-01
APPROVED AND ENTERED INTO EFFECT by resolution State Committee USSR according to standards of December 30, 1982 No. 5310
REISSUE. September 1985
This standard applies to safety valves installed on vessels operating under pressure above 0.07 MPa (0.7 kgf/cm).
Bandwidth Calculation safety valves is given in the mandatory Appendix 1.
Explanations of terms used in this standard are given in Reference Appendix 8.
The standard fully complies with ST SEV 3085-81.
1.1. The capacity of safety valves and their number should be selected so that a pressure is not created in the vessel that exceeds the excess operating pressure by more than 0.05 MPa (0.5 kgf/cm) with an excess operating pressure in the vessel of up to 0.3 MPa (3 kgf/cm) inclusive, by 15% - with excess operating pressure in the vessel up to 6.0 MPa (60 kgf/sq.cm) inclusive and by 10% - with excess operating pressure in the vessel over 6.0 MPa (60 kgf/cm2) cm).
1.2. The setting pressure of the safety valves must be equal to the operating pressure in the vessel or exceed it, but not more than 25%.
1.3. Increasing the excess pressure over the worker according to paragraphs. 1.1. and 1.2. must be taken into account when calculating strength according to GOST 14249-80.
1.4. The design and material of safety valve elements and their auxiliary devices should be selected depending on the properties and operating parameters of the medium.
1.5. Safety valves and their auxiliary devices must comply with the "Rules for Design and safe operation vessels operating under pressure" approved by the USSR State Mining and Technical Supervision.
1.6. All safety valves and their auxiliary devices must be protected from arbitrary changes in their adjustment.
1.7. Safety valves should be placed in places accessible for inspection.
1.8. On permanently installed vessels in which, due to operating conditions, it is necessary to turn off the safety valve, it is necessary to install a three-way switching valve or other switching devices between the safety valve and the vessel, provided that in any position of the shut-off element of the switching device, both or one of the safety valves will be connected to the vessel valves In this case, each safety valve must be designed so that no pressure is created in the vessel that exceeds the operating pressure by the value specified in clause 1.1.
1.9. The working medium leaving the safety valve should be taken to a safe place.
1.10. When calculating valve capacity, the back pressure behind the valve must be taken into account.
1.11. When determining the capacity of safety valves, the resistance of the sound suppressor should be taken into account. Its installation should not interfere with the normal operation of the safety valves.
1.12. A fitting for installing a pressure measuring device must be installed in the area between the safety valve and the sound muffler.
2. Requirements for safety devices
direct acting valves
2.1. Lever-weight safety valves must be installed on stationary vessels.
2.2. The design of the weight and spring valve must provide a device for checking the proper operation of the valve in operating condition by forcing it to open during operation of the vessel. The possibility of forced opening must be ensured at a pressure equal to 80% of opening. It is allowed to install safety valves without devices for forced opening if this is unacceptable due to the properties of the medium (toxic, explosive, etc.) or due to the conditions of the technological process. In this case, safety valves should be checked periodically within the time limits established by the technological regulations, but at least once every 6 months, provided that the possibility of freezing, sticking of polymerization or clogging of the valve with the working medium is excluded.
2.3. Safety valve springs must be protected from unacceptable heating (cooling) and direct impact working environment if it has a harmful effect on the spring material. When the valve is fully opened, the possibility of mutual contact of the spring coils must be excluded.
2.4. The weight of the load and the length of the lever of the lever-weight safety valve should be selected so that the load is at the end of the lever. The lever arm ratio should not exceed 10:1. When using a suspended weight, its connection must be permanent. The mass of the load must not exceed 60 kg and must be indicated (embossed or cast) on the surface of the load.
2.5. In the safety valve body and in the inlet and outlet pipelines, it must be possible to remove condensate from places where it accumulates.
3. Requirements for safety valves,
controlled by auxiliary devices
3.1. Safety valves and their auxiliary devices must be designed so that in the event of failure of any control or regulating element, or interruption of the power supply, the function of protecting the vessel from overpressure by redundancy or other measures is maintained. The design of the valves must meet the requirements of paragraphs. 2.3 and 2.5.
3.2. The safety valve must be designed so that it can be controlled manually or remotely.
3.3. Electrically actuated safety valves must be equipped with two independent friend from each other power sources. IN electrical diagrams where the loss of auxiliary power causes a pulse to open the valve, a single power supply is permitted.
3.4. The design of the safety valve must exclude the possibility of unacceptable shocks when opening and closing.
3.5. If the control element is a pulse valve, then the nominal diameter of this valve must be at least 15 mm. The internal diameter of the impulse lines (input and outlet) must be at least 20 mm and not less than the diameter of the output fitting of the impulse valve. Impulse and control lines must provide reliable drainage of condensate. It is prohibited to install shut-off devices on these lines. It is permissible to install a switching device if the impulse line remains open in any position of this device.
3.6. The working environment used to control safety valves must not be subject to freezing, coking, polymerization and have a corrosive effect on the metal.
3.7. The valve design must ensure that it closes at a pressure of at least 95%.
3.8. When using an external power source for auxiliary devices, the safety valve must be equipped with at least two independently operating control circuits, which must be designed so that if one of the control circuits fails, the other circuit ensures reliable operation of the safety valve.
4. Requirements for inlet and outlet pipelines
safety valves
4.1. Safety valves must be installed on branch pipes or connecting pipelines. When installing several safety valves on one branch pipe (pipeline), the area cross section The branch pipe (pipeline) must be at least 1.25 times the total cross-sectional area of the valves installed on it. When determining the cross-section of connecting pipelines with a length of more than 1000 mm, it is also necessary to take into account the value of their resistance.
4.2. The necessary compensation must be provided in the safety valve pipelines temperature extensions. The fastening of the body and pipelines of safety valves must be designed taking into account static loads and dynamic forces that arise when the safety valve is activated.
4.3. The supply pipelines must be made with a slope along the entire length towards the vessel. In supply pipelines, sudden changes in wall temperature (thermal shocks) should be avoided when the safety valve is activated.
4.4. The internal diameter of the supply pipe must be no less than the maximum internal diameter of the supply pipe of the safety valve, which determines the throughput capacity of the valve.
4.5. The internal diameter of the supply pipeline should be calculated based on the maximum capacity of the safety valve. The pressure drop in the supply line must not exceed 3% of the safety valve.
4.6. The internal diameter of the outlet pipe must be no less than the largest internal diameter of the outlet pipe of the safety valve.
4.7. The internal diameter of the outlet pipe must be designed so that at a flow rate equal to the maximum capacity of the safety valve, the back pressure in its outlet pipe does not exceed the maximum back pressure.
ANNEX 1
Mandatory
Bandwidth Calculation
The capacity of the safety valve in kg/h should be calculated using the formulas:
for water vapor 
- for pressure in MPa,
- for pressure in kgf/cm;
for gas - for pressure in MPa,
- for pressure in kgf/cm;
for liquids 
- for pressure in MPa,
- for pressure in kgf/cm,
where is the maximum excess pressure in front of the safety valve, MPa (kgf/cm);
Maximum excess pressure behind the safety valve, MPa (kgf/cm);
Specific volume of steam in front of the valve at parameters and , m/kg;
The density of real gas in front of the valve with parameters and , kg/m, is determined from tables or diagrams of the state of real gas or calculated using the formula
- for pressure in MPa (in J/kg, deg).
- for pressure in kgf/cm (in kg m/kg deg);
Gas constant; selected from reference Appendix 5;
The compressibility coefficient of real gas is selected according to reference Appendix 7; for an ideal gas =1;
Temperature of the medium in front of the valve at pressure, °C;
Valve cross-sectional area equal to smallest area cross-section in the flow part, mm;
Flow coefficient corresponding to area , for gaseous media;
Flow coefficient corresponding to area , for liquid media;
Liquid density in front of the valve at parameters and , kg/m;
The coefficient taking into account the physico-chemical properties of water vapor at operating parameters in front of the safety device is selected according to reference Appendix 2 for saturated steam and according to reference Appendix 3 for superheated steam or is calculated using the formula
- for pressure in MPa,
- for pressure in kgf/cm;
Adiabatic exponent;
The coefficient that takes into account the pressure ratio in front of and behind the safety valve is selected according to reference Appendix 4 depending on and ; coefficient =1 at ,
- for pressure in MPa,
For pressure in kgf/cm,
The critical pressure ratio is selected according to reference Appendix 5 or calculated using the formula
;
The coefficient, which takes into account the physicochemical properties of gases, at operating parameters, is selected according to reference appendices 5 and 6 or calculated using the formulas:
at ,
at
for pressure in MPa or
for pressure in kgf/cm.
The flow coefficients of safety valves for gaseous media () or () liquid media must be indicated in the safety valve data sheet.
APPENDIX 2
Information
Coefficient values for saturated water vapor at k=1.135
| MPa (kgf/cm) | 0,2 | 0,6 | 1,0 | 1,5 | 2,0 | 3,0 |
| 0,530 | 0,515 | 0,510 | 0,505 | 0,500 | 0,500 | |
| MPa (kgf/cm) | 4,0 | 6,0 | 8,0 | 10,0 | 11,0 | 12,0 |
| 0,505 | 0,510 | 0,520 | 0,530 | 0,535 | 0,540 | |
| MPa (kgf/cm) | 13,0 | 14,0 | 15,0 | 16,0 | 17,0 | 18,0 |
| 0,550 | 0,560 | 0,570 | 0,580 | 0,590 | 0,605 | |
| MPa (kgf/cm) | 19,0 | 20,0 | ||||
| 0,625 | 0,645 |
APPENDIX 3
Information
Coefficient value for superheated water vapor at k=1.31
Coefficient value for superheated
water vapor at k=1.31
APPENDIX 4
Information
B2 coefficient value
| The value at equal to | |||||
| 1,100 | 1,135 | 1,310 | 1,400 | ||
| 0,500 | |||||
| 0,528 | - | 1,100 | - | - | |
| 0,545 | 0,990 | ||||
| 0,577 | 0,990 | 0,990 | |||
| 0,586 | 0,980 | 0,990 | 0,990 | ||
| 0,600 | 0,990 | 0,957 | 0,975 | 0,990 | |
| 0,700 | 0,965 | 0,955 | 0,945 | 0,930 | |
| 0,800 | 0,855 | 0,850 | 0,830 | 0,820 | |
| 0,900 | 0,655 | 0,650 | 0,628 | 0,620 | |
APPENDIX 5
Information
Coefficient values for gases
| at | ||||||
| at t=0 °C and =0.1 MPa (1 kgf/cm) |
j/kg deg |
kg m/kg deg |
||||
| Nitrogen Acetylene Difluorodichloromethane Oxygen Methyl chloride Carbon monoxide Hydrogen sulfide Sulfur dioxide Carbon dioxide |
1,40 | 0,770 | 0,528 | 298 | 30,25 | |
Coefficient value for gases
1-xenon; 2-diphenyl mixture; 3-hydrogen iodide; 4-krypton; 5-chloro; 6-sulfur oxide;
7-butane, argon; 8-ozone, methyl chloride; 9-carbon dioxide; 10-methyl ether; 11-propane;
12-hydrogen chloride; 13-oxygen, hydrogen sulfide; 14-nitrogen, air; 15-carbon monoxide, ethane;
16-ethylene; 17-diethylene, generator gas; 18 neon; 19-ammonia; 20-methane;
21-domestic gas; 22-helium; 23-hydrogen
APPENDIX 6
Information
Coefficient values
|
MPa(kgf/cm) |
The value at equal to |
|||||||
| 1,135 | 1,20 | 1,30 | 1,40 | 1,66 | 2,0 | 2,5 | 3,0 | |
| 0,100 |
<, s, pan ,>0,548 |
|||||||
Russian FederationRD
RD 153-34.1-26.304-98 Instructions for the organization of operation, procedure and timing of inspection of safety devices of boilers of thermal power plants
set bookmark
set bookmark
RD 153-34.1-26.304-98
SO 34.26.304-98
INSTRUCTIONS
ON ORGANIZATION OF OPERATION, PROCEDURE AND TIMELINES FOR CHECKING SAFETY DEVICES OF BOILERS OF THERMAL POWER PLANTS
Date of introduction 1999-10-01
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 on December 25, 1997.
APPROVED by the Department of Development Strategy and Scientific and Technical Policy of RAO UES of Russia on January 22, 1998.
First Deputy Chief D.L. BERSENEV
1. GENERAL PROVISIONS
1.1. This Instruction applies to safety devices installed on TPP boilers.
1.2. The instructions contain the basic requirements for the installation of safety devices and determine 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, provides technical characteristics and design solutions for boiler safety devices, and recommendations for calculating the throughput of 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 testing 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. Methodology for calculating the throughput capacity of boiler safety valves, forms technical documentation on 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/cm) 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/cm) 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/cm), 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 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 steam superheating, safety valves with a capacity of at least the maximum amount of steam entering the intermediate superheater must be installed after the turbine high-pressure cylinder (HPC). 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. Total throughput 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.
Fig.1. Electrical diagram of the IPU
Note - The diagram is made for one pair of IPCs
For IPU installed on boilers with a nominal excess pressure of 13.7 MPa (140 kgf/cm) and below, by decision of the chief engineer of the thermal power plant, operation of the IPU without constant current flowing around the winding of the closing electromagnet is allowed. 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.
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 followed, the valves should be inspected before installation. The issue of compliance of the storage conditions for 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 should have cleanliness = 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 Prospect, 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.
Valves can be operated under the following 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 positioned 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 lever IR.
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. Electrical contact pressure gauges must be installed at the boiler service level. Acceptable Maximum temperature the environment in the ECM installation area should not exceed 60 °C. Stop 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 3 is checked.
4.2. The tightness of the valve fasteners, the condition and quality of fit of the supporting surfaces of the prism of lever-load 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, the 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.
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 height of the spring tension is checked (Table 6).
5.7.2. In the protected object, the pressure value 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 a 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/cm). 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 a value so that the remaining valves can be adjusted. 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 is the correction for water column pressure
Here is the density of water, kg/m;
Difference between the elevations 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:
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 setpoint (); 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 () is set in front of the GPC. 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 behind 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 rapid quality repairs.
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 have a roughness of =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 cleanliness class = 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 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
for hot water boilers
Where is the number of safety valves installed on the protected system;
Capacity of individual safety valves, kg/h;
Nominal steam output of the boiler, kg/h;
Nominal heating capacity of the hot water boiler, J/kg (kcal/kg);
Heat of evaporation, J/kg (kcal/kg).
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;
For pressure in MPa;
For pressure in kgf/cm,
where is the valve capacity, kg/h;
The calculated cross-sectional area of the valve, equal to the smallest free cross-sectional area in the flow part, mm (must be indicated in the valve passport);
Steam consumption coefficient related to the calculated cross-sectional area (must be indicated by the factory in the valve passport or in the assembly drawing);
Maximum excess pressure in front of the safety valve, which should be no more than 1.1 design pressure, MPa (kgf/cm);
A coefficient that takes into account the physical and chemical properties of steam at operating parameters in front of the safety valve.
The values of this coefficient are selected from Tables 1 and 2 or determined using formulas.
At pressure in kgf/cm:
Where is the adiabatic exponent equal to:
1.135 - for saturated steam;
1.31 - for superheated steam;
Maximum excess pressure in front of the safety valve, kgf/cm;
Specific volume of steam in front of the safety valve, m/kg.
At pressure in MPa:
Table 1
Coefficient valuesfor saturated steam
table 2
Coefficient valuesfor superheated steam
Steam pressure, MPa (kgf/cm) | Coefficient at steam temperature, °C |
||||||||
To calculate the capacity of safety valves of power plants with fresh steam parameters:
13.7 MPa and 560 °C = 0.4;
25.0 MPa and 550 °C = 0.423.
The formula for determining valve capacity should only be used if:
For pressure in MPa;
For pressure in kgf/cm,
where is the maximum excess pressure behind the boiler in the space into which steam flows from the boiler (when flowing into the atmosphere = 0),
Critical pressure ratio.
For saturated steam =0.577.
For superheated steam = 0.546.
Appendix 3
FORMS
TECHNICAL DOCUMENTATION ON BOILER SAFETY DEVICES, WHICH SHOULD BE MAINTAINED AT TPP
Statement
response pressure of boiler safety devices in the________ workshop
Boiler safety device inspection schedule
Boiler number | Established inspection frequency | Approximate timing for checking valves |
||||||||||||||||||||||||
Data
on scheduled and emergency repairs of boiler safety valves
Boiler N ____________
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 - the maximum internal excess pressure that occurs during the normal course of the working 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 - excess pressure at 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- 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
Safety devices must be selected and adjusted in such a way that the pressure in the boiler (drum) cannot rise above .
4. Opening pressure is the 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 design of the valve and the dynamics of the process. But due to the rapidity of the actuation process, it is almost impossible to determine the number of lifting safety valves and IPUs when adjusting them.
5. Full opening pressure (operation pressure) - the maximum excess pressure that is established in front of the PC when it is fully opened. It should not exceed .
6. Closing pressure - excess pressure at which, after actuation, the shut-off element is seated on the seat.
For direct acting safety valves. An IPU with an electromagnetic drive must have at least .
7. Bandwidth - 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, 392-175/95-0-01, 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.
Specifications produced ChZEM GPK are given in Table 3.
Table 3
Technical characteristics of the main safety valves IPU boilers
Valve designation | Nominal diameter, mm | Steam operating parameters | Smallest flow area, mm | Coefficient | Steam consumption at operating parameters, t/h | The course of the class | Mas- |
||||
entrance- | You- | Pressure | Tempe- | for other | on the raft | ||||||
Fresh steam valves |
|||||||||||
1203-150/200-0-01 | |||||||||||
Reheat steam valves |
|||||||||||
111-250/400-0-01 | |||||||||||
Valves of series 392 and 875 (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.
Fig.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
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.
Fig.3. 1029 Series Main Safety Valve
The valves work as follows:
when the PC is opened, steam flows through the impulse tube into the chamber above the servo piston, 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 moving the valve running part towards closing, a similar process occurs in the opposite direction*. 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 seat connected to the drainage system, into which the condensate that accumulates in the valve body after its operation is drained. To avoid vibration of the spool and breakage of the rod, guide ribs are welded into the connecting pipe.
________________
* 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.
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.
Fig.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
Fig.5. 1203 Series Main Safety Valve
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 , it begins to move the piston down, opening the discharge 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 (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.
1.2. Pulse valves
All fresh steam IPUs manufactured by ChZEM are equipped with pulse valves of the 586 series. Technical characteristics of the valves are given in Table 4, and the design solution is shown 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 (drawing number) | Conditional passage, mm | Work Environment Settings | Test pressure during testing, MPa | Weight, kg |
||
Pressure, MPa | Tempe- | for strength | on density | |||
586-20-EMF-03 | ||||||
586-20-EMF-04 | ||||||
Fig.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 250/400 mm are installed on the cold reheating pipelines of boilers. The technical characteristics of the valves are given in Table 3, the design solution of the ChZEM reheat valve is shown in Fig. 7. The main components and parts of the valve are: bore type 1 body, 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.
Fig.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 quality of the drawing in electronic version corresponds to the quality of the drawing shown in the paper original. - Database manufacturer's note.
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.
Fig.8. Main safety valve for reheat steam, designed by LMZ
2.2. Pulse valves
Lever-load valves 25 mm series 112 are used as pulse valves IPU ChZEM of the reheating system (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.
1 - body; 2 - plate; 3 - rod; 4 - guide sleeve; 5 - lifting sleeve; 6 - spring, 7 - pressure threaded bushing; 8 - cap; 9 - lever
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.
Table 5
Technical characteristics of spring safety valves, old releases produced by PA "Krasny Kotelshchik"
Spring data | |||||||||||
Class code | Dia- | Working pressure | Maxi- | Coefficient | Name- | Serial number of spring detail drawing | Dia- | External | Free spring height | Pressure | Mas- |
Version 1 | |||||||||||
Version 2 | |||||||||||
Version 3 | |||||||||||
3,5-4,5 (35-15)* | |||||||||||
Version 1 | |||||||||||
Version 2 | |||||||||||
Version 3 | |||||||||||
K-211947 | |||||||||||
K-211817 |
* Corresponds to the original. - Database manufacturer's note
The valve is currently available with a welded body. The technical characteristics of the valves and the springs installed on them are given in Tables 6 and 7.
Table 6
Technical characteristics of spring safety valves produced by Krasny Kotelshchik Production Association
Inlet flange | Outlet flange | Limit parameters of operating conditions | ||||||||||||
Class code | Us- | Conditions | Us- | Conditions | Wednesday | Working pressure, MPa/kgf/cm | Tempe- | Design diameter, mm | Opening start pressure, MPa**/kgf/cm | Designation | Spring designation | You- | Mas- | Coefficient |
4.95±0.1/49.5±1 | ||||||||||||||
4.95±0.1/49.5±1 | ||||||||||||||
*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 designation | External | Dia- | Spring height at free | Step on- | Number of turns | Spring force at working deformation, kgf (N) | Working deformation | Expand | Weight, kg |
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| (ST SEV 1711-79). Safety valves for steam and hot water boilers. Technical requirements.. - Database manufacturer's note. 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 catalog directory. - M.: TsNIITEITyazhmash, 1991. |
working under pressure
3.4.1. Vessels in which the operating pressure from the supply source, a chemical reaction, heating by heaters, solar radiation, or in the event of a fire near the vessel, etc. are subject to protection by safety valves.
3.4.2. The number of valves, their sizes and capacity must be be chosen so that pressure in the vessel cannot be created in excess of 2 design pressure by more than 0.05 MPa (0.5 kg/cm) for vessels with 2 pressure up to 0.3 MPa (3 kgf/cm), by 15 percent - for pressure vessels 2 over 0.3 to 6.0 MPa (from 3 to 60 kgf/cm) and by 10 percent - for vessels with 2 pressure over 6.0 MPa (60 kgf/cm).When the valves are operating, the pressure in the vessel may be exceeded by no more than 25 percent of the design pressure.
3.4.3. The design and materials of valve elements and their auxiliary devices must ensure reliable operation of the valve under operating conditions.
3.4.4. The design of the valve must ensure free movement of the moving elements of the valve and exclude the possibility of their release.
3.4.5. The design of valves and their auxiliary devices must exclude the possibility of arbitrary changes in their adjustment.
3.4.6. The valve design must exclude the possibility of unacceptable shocks when opening and closing.
3.4.7. Valves should be placed in places accessible for convenient and safe maintenance and repair.
When a valve requiring systematic maintenance is located at a height of more than 1.8 m, devices must be provided for ease of maintenance.
3.4.8. Valves on vertical vessels should be installed on the upper bottom, and on horizontal vessels - on the upper generatrix in the gas (vapor) phase zone. Valves should be installed in places that prevent the formation of stagnant zones.
3.4.9. Installation shut-off valves between the vessel and the valve, as well as behind the valve, is not allowed, with the exception of vessels with fire and explosive substances and substances of hazard classes 1 and 2, as well as for vessels operating at cryogenic temperatures. For such valves, a valve system consisting of a service and a reserve valve should be provided.
3.4.10. The working and reserve valves must have equal capacity, ensuring complete protection of the vessel from exceeding the permissible pressure. To ensure inspection and repair of valves, shut-off valves with a blocking device must be installed before and after them, excluding the possibility of simultaneous closing of shut-off valves on the working and reserve valves, and the flow area in the switching unit in any situation must be no less than the flow area of the installed valve.
3.4.11. Valves must not be used to regulate pressure in a vessel or group of vessels.
3.4.12. Lever-weight valves may only be installed on stationary vessels.
3.4.13. The design of the weight and spring valve must provide a device for checking the proper operation of the valve in operating condition by forcing it to open during operation of the vessel. Possibility of forced opening must be ensured at a pressure equal to 80 percent of the set pressure.
It is allowed to install valves without devices for forced opening if this is unacceptable due to the properties of the working environment (harmful, explosive, etc.) or due to the conditions of the working process. In this case, the valves should be checked periodically within the time limits established by the technological regulations, but at least once every 6 months. provided that there is no possibility of freezing, sticking, polymerization or clogging of the valve with the working medium.
3.4.14. Valve springs must be protected from unacceptable heating (cooling) and direct exposure to the working environment if it has a harmful effect on the spring material.
3.4.15. The mass of the load and the length of the lever of the lever-weight valve are determined based on the fact that the load is at the end of the lever.
3.4.16. Valves and their auxiliary devices shall be so designed that, in the event of failure of any controlled or regulating member or loss of power to the control valve, the function of protecting the vessel from overpressure by redundancy or other measures is maintained.
3.4.17. The valve must be designed so that it can be controlled manually or remotely.
3.4.18. Valves actuated by electricity must be equipped with two power sources independent of each other. In electrical circuits where a loss of power causes a pulse to open a valve, a single power source is permitted.
3.4.19. If the control element is a pulse valve, then the nominal diameter of this valve must be at least 15 mm.
3.4.20. The internal diameter of the impulse lines (input and outlet) must be at least 20 mm and not less than the diameter of the output fitting of the impulse valve. Impulse and control lines must provide reliable drainage of condensate. It is prohibited to install shut-off devices on these lines. It is permissible to install a switching device if the impulse line remains open in any position of this device.
3.4.21. The working environment used to control valves must not be subject to freezing, coking, polymerization and have a corrosive effect on the valve material.
3.4.22. The valve must be designed to close at a pressure of at least 95 percent of the set pressure.
3.4.23. The valve must be equipped with at least two independently operating control circuits, which must be designed so that if one of the control circuits fails, the other circuit will ensure reliable operation of the valve.
3.4.24. Valves should be installed on pipes or pipes directly connected to the vessel.
When installing several valves on one branch pipe (pipeline), the cross-sectional area of the branch pipe (pipeline) must be at least 1.25 of the total cross-sectional area of the valves installed on it.
3.4.25. The pressure drop in front of the valve in the supply pipeline at maximum capacity should not exceed 3 percent of the set pressure.
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 no more than 5-7% higher than pH (10% in Western standards).
Checking valves for functionality and pressure pH. O. held at "no expense" 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 force 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.
1. General provisions
1.1. This Instruction contains the basic requirements and defines the procedure for operating, checking and adjusting safety valves (hereinafter - PC) installed on the vessels and pipelines of the compressor unit (hereinafter - CU) of the substation.
1.2. The instruction is aimed at improving the safety of operation of pressure vessels, pipelines and compressors.
1.3. The instructions are compiled on the basis of the "Rules for the design and safe operation of pressure vessels", "Rules for the design and safe operation of stationary compressor units, air and gas pipelines."
1.4. Knowledge of these Instructions is mandatory for those responsible for implementation production control compliance industrial safety during the operation of pressure vessels, responsible for the good condition and safe operation of the vessels, an electrician for servicing the reactor plant (hereinafter referred to as the electrician), maintenance personnel authorized to repair and maintain vessels and the compressor unit.
2. Basic terms and definitions
The following terms and definitions are used in this manual:
2.1. Working pressure (PP) - the maximum internal excess or external pressure that occurs during the normal course of the working process;
2.2. Maximum permissible pressure (Pdop) - the maximum excess pressure in the protected vessel, allowed by accepted standards, when the medium is discharged from it through the PC;
2.3. Opening start pressure (Pno) - excess pressure at which the PC begins to open;
2.4. Response pressure (Psr) - excess pressure that is established in front of the PC when it is fully opened;
2.5. Closing pressure (Рз) - excess pressure at which the PC closes after activation (should not be lower than 0.8*Рр).
2.6. Throughput is the flow rate of the working medium discharged when the PC is fully open.
3. General requirements for safety valves
3.1. Spring safety valves are used as safety devices for vessels, pipelines and compressors of the substation.
3.2. The design of the spring valve must exclude the possibility of tightening the spring beyond the specified value, and the spring must be protected from unacceptable heating (cooling) and direct exposure to the working environment if it has a harmful effect on the spring material.
3.3. The design of the spring valve must include a device for checking the proper operation of the valve in working condition by forcing it to open at the installation site.
3.4. The design of the PC should not allow arbitrary changes in their adjustment. For PCs, the screw that regulates the spring tension must be sealed.
3.5. The valves must close automatically without fail at a closing pressure that does not violate technological process in the protected system, but not lower than 0.8*Рrab.
3.6. In the closed position at operating pressure, the valve must maintain the required seal tightness for a given period technical specifications resource.
4. Installation of safety valves
4.1. Installation of PC on vessels, apparatus and pipelines operating under pressure is carried out in accordance with the “Rules for the design and safe operation of vessels operating under pressure” and other current regulatory and technical documentation. The quantity, design, installation location of the PC, direction of discharge is determined by the above Rules, the vessel connection diagram and the installation design.
4.2. The number of PCs, their dimensions and throughput must be selected according to calculation so that a pressure is not created in the vessel exceeding the calculated one by more than 0.05 MPa (0.5 kgf/cm2) for vessels with a pressure of up to 0.3 MPa (3 kgf/cm2), by 15% - for vessels with pressure from 0.3 to 6.0 MPa (from 3 to 60 kgf/cm2) and by 10% - for vessels with pressure over 6.0 MPa (60 kgf/cm2 ).
When operating PCs, it is allowed to exceed the pressure in the vessel by no more than 25% of the working pressure, provided that this excess is provided for by the design and is reflected in the vessel passport.
4.3. PCs must be placed in places accessible for their maintenance.
4.4. PCs must be installed on pipes or pipelines directly connected to the vessel.
4.5. Installation of shut-off valves between the vessel and the PC, as well as behind it, is not allowed.
4.6. If it is possible to increase the pressure above the design value, safety devices must be installed on the pipelines.
4.7. At the entrance of the pipeline into production workshops, technological units and installations, if the maximum possible working pressure of the process medium in the pipeline exceeds the design pressure technological equipment where it is sent, it is necessary to provide a reducing device (automatic for continuous processes or manual for periodic ones) with a pressure gauge and a PC on the low pressure side.
6. Organization of operation, inspection, repair and maintenance of valves
6.1. Maintenance and operation of safety valves must be carried out in accordance with the regulatory and technical documentation, these instructions and technological production regulations.
6.2. Overall responsibility for the condition, operation, repair, adjustment and testing of the PC rests with the head of the PS group, who operates the installed valves and maintains technical documentation.
6.3. To monitor the operation of the PC, the following operational documentation must be available:
These instructions;
Factory or operational passports safety valves.
Schedule for checking the PC at the workplace using the manual blasting method on vessels and compressors at the substation;
6.4. Checking the PC for proper operation.
6.4.1 Checking the serviceability of the PC using the manual detonation method is carried out according to an annual schedule approved by the chief engineer. Checks are carried out at least once every 6 months.
6.4.2 The PC is checked by an electrician using the manual detonation method at operating pressure.
6.4.3 Before checking the serviceability of the air collector PC, the vessel on which the PC is installed is taken out of operation.
6.4.4 The results of checking the serviceability of the PC are entered into the shift log of the vessels and the schedule for checking the PC at the workplace using the manual blasting method.
6.5. Scheduled condition monitoring (audit) and repair of PCs are carried out simultaneously with the repair of the equipment on which they are installed.
6.5.1 Monitoring the condition of the PC includes disassembling the valve, cleaning and defective parts, checking the tightness of the valve, testing the spring, and adjusting the response pressure.
6.5.2 Produced by a specialized organization licensed to this type activities.
6.5.3 Personnel performing condition monitoring and repair of PCs must have experience in repairing valves and be familiar with design features valves and their operating conditions. Repair personnel must be provided with working drawings of the valves, spare parts and materials necessary for quick and high-quality repair of valves using a special stand.
6.5.4 Before inspection, parts of disassembled PCs are cleaned of dirt and washed in kerosene. After this, they are thoroughly inspected to identify defects.
6.5.5 After assembly, testing the safety valves for tightness is combined with adjustment on the bench with a pressure equal to the response pressure. After adjustment, the PC must be sealed.
6.5.6 Adjustment of safety valves for operation is carried out:
After completing installation of the vessel
After repair (if the valve was replaced or overhauled)
In cases of incorrect operation.
6.5.7 The activation pressure of the PC should be no more than those indicated in Table 5.1.
6.5.8 After completion of the repair, a report on the repair and adjustment of the safety valve is drawn up.
7. Transportation and storage
7.1. PCs received from the manufacturer, as well as used ones, must be transported and stored in packaged form. The PC must be stored in a dry, closed room. The inlet and exhaust pipes must be closed with plugs. For spring PCs, the springs must be weakened during transportation and storage.
8. Safety requirement
8.1. It is not allowed to operate the PC in the absence of the documentation specified in clause 7.2.
8.2. It is not allowed to operate the PC at pressures higher than those specified in the technical documentation.
8.3. It is not allowed to eliminate PC defects if there is pressure under the spool.
8.4. When repairing valves, use proper tools.
8.5. When adjusting valves, it is not allowed to raise the pressure on the stand above the response pressure of the PC.
8.6. All types of work must be carried out in compliance with fire safety rules.
8.7. Used rags should be stored in a special container and promptly sent for disposal.
