Production instructions for lapping valves. Adjustment of safety devices for operation at a given pressure

Unofficial edition

GOST12.2.085-82

STATE STANDARD OF THE UNION OF THE SSR

SYSTEM OF WORK 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

before 1988-07-01

APPROVED AND INTRODUCED BY Decree of the USSR State Committee for Standards of December 30, 1982 No. 5310

REPUBLICATION. September 1985

This standard applies to safety valves installed on vessels operating at pressures above 0.07 MPa (0.7 kgf/cm).

Bandwidth calculation safety valves is given in mandatory annex 1.

Explanations of the terms used in this standard are given in reference annex 8.

The standard fully complies with ST SEV 3085-81.

1. General requirements

1.1. The capacity of the safety valves and their number should be chosen so that the pressure in the vessel does not exceed the excess working pressure by more than 0.05 MPa (0.5 kgf/cm) with an excess working pressure in the vessel up to 0.3 MPa (3 kgf/cm) inclusive, by 15% - at excess working pressure in the vessel up to 6.0 MPa (60 kgf/cm2) inclusive, and by 10% - at excess working 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 working pressure in the vessel or exceed it, but not more than 25%.

1.3. The increase in excess pressure over the worker according to paragraphs. 1.1. and 1.2. should be taken into account when calculating the strength in accordance with GOST 14249-80.

1.4. The design and material of elements of safety valves and their auxiliary devices should be selected depending on the properties and operating parameters of the medium.

1.5. Safety valves and their accessories must comply with the Rules for the Design and safe operation vessels operating under pressure", approved by the USSR Gosgortekhnadzor.

1.6. All safety valves and their ancillaries 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, for which, due to operating conditions, it becomes 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 at any position of the locking 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 the pressure in the vessel does not exceed the working pressure by the value specified in paragraph 1.1.

1.9. The working medium leaving the safety valve must be discharged to a safe place.

1.10. When calculating the capacity of a valve, the back pressure behind the valve must be taken into account.

1.11. When determining the flow capacity of safety valves, the silencer resistance should be taken into account. Installing it should not break normal work safety valves.

1.12. In the area between the safety valve and the silencer, a fitting must be installed for installing a pressure measuring device.

2. Requirements for safety

direct acting valves

2.1. Lever-weight safety valves must be installed on stationary vessels.

2.2. The design of the cargo and spring valve should provide for a device for checking the correct operation of the valve in working condition by forcibly opening it during the operation of the vessel. The possibility of forced opening must be ensured at a pressure equal to 80% of the opening. It is allowed to install safety valves without devices for forced opening, if it is unacceptable due to the properties of the medium (poisonous, explosive, etc.) or according to the conditions of the technological process. In this case, the check of safety valves should be carried out 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 impermissible heating (cooling) and direct exposure to the working medium, if it has a harmful effect on the spring material. When the valve is fully opened, the possibility of mutual contact of the coils of the spring must be excluded.

2.4. The mass of the load and the length of the lever of the lever-weight safety valve should be chosen so that the load is at the end of the lever. The lever arm ratio must not exceed 10:1. When using a load with a suspension, its connection must be one-piece. The mass of the cargo must not exceed 60 kg and must be indicated (embossed or molded) on the surface of the cargo.

2.5. In the body of the safety valve and in the inlet and outlet pipelines, it must be possible to remove condensate from the places of its accumulation.

3.Requirements for safety valves,

controlled by assistive devices

3.1. Safety valves and their ancillaries must be designed so that in the event of failure of any control or regulatory body, or in the event of a power failure, the function of protecting the vessel from overpressure by duplication, or other measures, is retained. The design of the valves must meet the requirements of paragraphs. 2.3 and 2.5.

3.2. The design of the safety valve shall provide for the possibility of controlling it manually or remotely.

3.3. Electrically actuated safety valves must be supplied with two independent power supplies. In electrical circuits where the disconnection of the auxiliary power causes a pulse to open the valve, one power supply is allowed.

3.4. The design of the safety valve must exclude the possibility of impermissible shocks during 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 (inlet and outlet) must be at least 20 mm and not less than the diameter of the outlet fitting of the impulse valve. Impulse and control lines must ensure reliable condensate drainage. It is forbidden to install locking devices on these lines. It is allowed to install a switching device if, in any position of this device, the impulse line will remain open.

3.6. The working medium used to control safety valves must not be subject to freezing, coking, polymerization and corrosive effects on the metal.

3.7. The design of the valve must ensure its closing at a pressure of at least 95% .

3.8. When used for assistive devices external source 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 will ensure 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 branch pipe (pipeline) must be at least 1.25 of 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. In pipelines of safety valves, the necessary compensation for thermal expansion must be ensured. The fastening of the body and pipelines of safety valves must be calculated taking into account static loads and dynamic forces arising from the operation of the safety valve.

4.3. The supply pipelines must be made with a slope along the entire length towards the vessel. In the supply pipelines, sudden changes in wall temperature (thermal shocks) should be excluded when the safety valve is actuated.

4.4. The inner diameter of the inlet pipeline must be at least the maximum inner diameter of the inlet pipe of the safety valve, which determines the capacity of the valve.

4.5. The inner diameter of the supply line must 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 inner diameter of the discharge pipeline must be at least the largest inner diameter of the outlet pipe of the safety valve.

4.7. The internal diameter of the discharge pipeline must be calculated 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.

APPENDIX 1

Mandatory

Bandwidth calculation

The capacity of the safety valve in kg/h should be calculated using the formulas:

for steam - 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;

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 by the formula

- for pressure in MPa (in J/kg, deg).

- for pressure in kgf/cm(in kg m/kg deg);

Gas constant; choose according to the reference application 5;

The compressibility factor of a real gas is chosen according to reference Appendix 7; for an ideal gas =1;

Medium temperature in front of the valve at pressure , °C;

Valve cross-sectional area equal to smallest area section in the flow part, mm;

Flow coefficient corresponding to the area , for gaseous media;

Flow coefficient corresponding to the area , for liquid media;

Liquid density in front of the valve at parameters and , kg/m;

The coefficient taking into account the physical and 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 calculated by the formula

- for pressure in MPa,

- for pressure in kgf/cm;

Adiabatic exponent;

The coefficient taking into account the ratio of pressures before and after 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 taking into account the physicochemical properties of gases, with 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 passport.

APPENDIX 2

Reference

Coefficient values ​​for saturated steam at k=1.135

APPENDIX 3

Reference

Coefficient value for superheated steam at k=1.31

Coefficient value for superheated

water vapor at k=1.31

APPENDIX 4

Reference

B2 coefficient value

APPENDIX 5

Reference

Coefficient values ​​for gases

The value of the coefficient for gases

1-xenon; 2-diphenyl mixture; 3-hydroiodide; 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

Reference

Coefficient values

ADJUSTMENT OF SAFETY DEVICES TO ACTIVATE AT A SET PRESSURE

5.1. Adjustment safety devices for actuation at a given pressure is performed:

after the completion of the installation of the boiler;

after a major overhaul, if the safety valves or their overhaul (complete disassembly, groove of sealing surfaces, replacement of running gear parts, etc.), and for PPK - in case of replacement of the spring.

5.2. To adjust the valves, a pressure gauge with an accuracy class of 1.0 must be installed in the immediate vicinity of the valves, tested in the laboratory against a reference pressure gauge.

5.3. Safety valves are regulated at the workplace of the valve installation by raising the pressure in the boiler to the set pressure.

Adjustment of spring safety valves is allowed to be carried out at the stand with steam with operating parameters, followed by a control check on the boiler.

5.4. Valve actuation during adjustment is determined by:

for IPU - by the moment of operation of the GPC, accompanied by a blow and strong noise;

for full-lift direct-acting valves - by a sharp pop, observed when the spool reaches the upper 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 systems in which the steam pressure necessary for adjustment 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 for PU installation workstations, maintenance platforms and adjacent passageways.

5.5.5. Establish a two-way connection between the valve adjustment points and the control panel.

5.5.6. Instruct shift and adjustment personnel involved in valve adjustment work.

The personnel should be well aware of the design features of the launchers subjected to adjustment and the requirements of the instructions for their operation.

5.6. Adjustment of lever-load valves of direct action is carried out in the following sequence:

5.6.1. The weights on the valve levers move to the end position.

5.6.2. In the protected object (drum, superheater), the pressure is set to 10% higher than the calculated (allowed).

5.6.3. The weight on one of the valves moves slowly towards the body until the valve is actuated.

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 load on the lever is corrected and the correct operation of the valve is rechecked.

5.6.6. After the adjustment is completed, the position of the load 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 placed on the lever of the adjusted valve and the remaining valves are adjusted in the same sequence.

5.6.8. After the adjustment of all valves is completed, the working pressure is established in the protected object. Additional weights are removed from the levers. A record of the readiness of the valves for operation is recorded in the Safety Devices Repair and Operation Log.

5.7. Adjustment of spring-loaded direct acting relief valves:

5.7.1. The protective cap is removed and the height of the spring tightening is checked h 1 (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 the position at which the valve will actuate.

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 in accordance with paragraph 5.6.2, then the spring compression is corrected and the valve is rechecked 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 it is necessary to correct the position of the upper adjusting sleeve.

For this:

for TKZ valves, unscrew the locking screw located above the cover and turn the damper sleeve counterclockwise - to reduce the difference or clockwise - to increase the difference;

for PPK and SPKK 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 rest of the valves. After the end of the adjustment of all valves on each valve, the height of the spring recorded in the magazine is set in the adjusted position. To prevent unauthorized changes in the tension of the springs, 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 Safety Devices Repair and Operation Book about the readiness of the valves for operation.

5.8. Pulse-safety devices with an IR equipped with an electromagnetic drive are regulated for operation both from electromagnets and with de-energized electromagnets.

5.9. To ensure the operation of the IPU from electromagnets, the ECM is configured:

5.9.1. The readings of the EKM are compared with the readings of a standard pressure gauge with a class of 1.0%.

5.9.2. EKM is regulated to turn on the opening electromagnet:

where h- correction for water column pressure

h= ρ D H 10-5 MPa,

here ρ is the density of water, kg/m3;

D H- the difference between the marks of the place of connection of the impulse line to the protected object and the place of installation of the EKM, m.

5.9.3. EKM is regulated to turn on the closing electromagnet:

R zekm = 0.95 R p+ h MPa.

5.9.4. On the EKM scale, the limits of IR operation are marked.

5.10. The adjustment of the MC for actuation at a given pressure with de-energized electromagnets is carried out in the same sequence as the adjustment of direct-acting lever-weight valves:

5.10.1. The weights on the IR levers are moved to the extreme position.

5.10.2. The pressure in the boiler drum rises up to the setting of the IPU operation ( R Wed = 1,1 R b); on one of the IRs connected to the drum of the boiler, the load moves towards the lever to the position at which the IPU will be triggered. In this position, the load is fixed on the lever with a screw. After that, 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 fastened with a screw and sealed.

If more than one IR is connected to the drum of the boiler, an additional weight is installed on the lever of the adjusted valve in order to be able to adjust the remaining IRs connected to the drum.

5.10.3. A pressure is set in front of the CHP, equal to the pressure of operation of the IPU behind the boiler ( R Wed = 1,1 R R) . In accordance with the procedure provided for in paragraph 5.10.2, it is regulated for the operation of the IPU, from which the steam at the IR is taken from the boiler.

5.10.4. After the end of the adjustment, the pressure behind the boiler is reduced to the nominal value and additional weights are removed from the IK levers.

5.11. Voltage is applied 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 rises to the value at which the IPU should operate, and the opening of the CHP of all IPUs is checked at the place, the impulse to open which is taken behind the boiler.

When adjusting the IPU on drum boilers, the IPU control keys, triggered by an impulse behind the boiler, are set to the “Closed” position and the pressure in the drum rises to the IPU actuation setpoint. The operation of the HPC IPU, operating on an impulse from the drum, is checked locally.

5.13. Impulse-safety devices for reheating steam, behind which there are no shut-off devices, are configured to operate after installation during the firing of the boiler to steam density. The procedure for setting the valves is the same as when setting the live steam valves installed downstream of the boiler (clause 5.10.3).

If there is a need to adjust the pulse valves of the reheat steam after repair, then it can be done on a special stand. In this case, the valve is considered to be adjusted when the rise of the stem by the amount of stroke is fixed.

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 Journal of the repair and operation of safety devices.

A safety valve (hereinafter referred to as PC) is a predominantly direct-acting pipeline valve (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 the set value. After release of excess pressure, the PC must be hermetically sealed, thus stopping further discharge of the medium.

This manual uses 2 terms:

1. Setting pressure (hereinafter Рn) – this is the greatest excess pressure at the inlet to the valve (under the spool) at which the valve is closed and tight. If Рн is exceeded, the valve must open to such an extent that it would provide the required flow rate of the medium to reduce the pressure in the pipeline, vessel.

2. The pressure of the beginning of the opening (hereinafter Pn. o.) is the pressure at which the so-called “pop” in the jargon of the manufacturers occurs, i.e. the pressure at which the valve spool opens a certain amount, relieves 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 performance must be carried out at least once every 6 months in accordance with GOST 12.2.085 “Pressure vessels. Valves safety safety requirements.

The pH pressure can only be checked on so-called "full consumable» stands, i.e. on those that repeat the operating parameters of the pipe (vessel) in terms of pressure and flow. Taking into account the variety of objects on which PCs are installed even within the same enterprise, it is not possible to have such a number of stands.

Therefore, when checking and adjusting the PC, the determination of pressure Рн is used. about. Based on numerous experiments in the course of many years of practice, it has been established that Rn. about. should be higher than pH by no more than 5-7% (in Western standards 10%).

Checking valves for operability and pressure pH. about. held on "cost-free" benches, a typical representative of which is a bench for testing and adjusting safety valves SI-TPA-200-64 manufactured by the Design Bureau of Pipeline Valves and Special Works.

Stand for testing and setting safety valves SI-TPA-200-64 provides the following pneumatic tests (medium - air, nitrogen, carbon dioxide, other non-combustible gases):

- tightness tests of the saddle-body connection;

- tightness tests of the seat-spool pair (tightness in the valve);

- tests for performance (for operation);

- settings for actuation pressure.

It is possible to manufacture a stand in a complete set for testing with water.

The stand provides testing of pipeline fittings with a flange type of connection (threaded connection as an option)

with a maximum diameter of 200. The maximum test pressure depends on the type of pressure regulator supplied with the control panel, the basic equipment of the control panel is a regulator 0 to 1.6 MPa. The test of valves with a union connection is carried out using an adapter (not included in the delivery set).

Source test pressure not included in delivery.

It is possible to complete with a pressure source according to the technical specifications of the customer.

Test stand SI-TPA-200-64 passed the certification of UkrSEPRO, comes complete with instruction manual, passport.

Adjustment (adjustment) of safety valves for actuation at a given pressure is carried out:

Before installation. After a major overhaul, if the safety valves were replaced or overhauled (complete disassembly, sealing surfaces turning, replacement of running gear parts, etc.), in case of a spring replacement. During the periodic check. After emergencies caused by the inoperability of the PC.

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 separated from the seat. For all types of PC, the 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.

The personnel should 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 corresponds to the type of flange of the tested PC. Install the required gasket. Install the valve on the stand flange. Tighten the stand screw until the PC is fully fixed in the clamps. Create the maximum possible counterpressure force on the PC spool. Shut off the access of the medium under the valve spool using a shut-off device. Feed the medium into the control panel and set the required response pressure (beginning of opening) at the outlet of the control panel. Open the locking device and apply the test medium under the PC spool. Relieve the counterpressure force until the valve opens. Block the access of the medium under the PC spool. Re-supply the medium under the spool of the PC - the valve must operate at the required pressure. Repeat p. 10 and p. 11 at least 3 times. If it is not possible to properly adjust the PC, return the valve to the RMC for additional grinding of the seat and (or) spool. When the operability of the PC is confirmed, dismantle the PC from the stand, having previously blocked the flow of medium under the spool and into the control panel. Fill in the operational documentation of the PC and the log of the work of the stand. Seal the PC and backpressure adjustment mechanisms. Disable stand. Drain water (condensate) from the cavities of the stand, wipe dry, apply protective lubricant. Ensure the safety of the stand from dust and moisture until the next operation.

FEATURES OF ADJUSTING LEVER-CARGO VALVES.

Adjustment of lever-load valves of direct action is carried out in the following sequence:

1. The weights on the valve levers move to the end position.

3. The weight on one of the valves is slowly moved towards the body until the valve actuates.

4. After closing the valve, the position of the weight is fixed with the stop screw.

5. Pressurize again and check the pressure value at which the valve operates. If it differs from the required one, the position of the weight on the lever is corrected and the correct operation of the valve is rechecked.

6. After the end of the adjustment, the position of the load on the lever is finally fixed with the locking screw. To prevent uncontrolled movement of the load, the screw is sealed.

7. If the value of the counterpressure created by the weight is insufficient, an additional weight is placed on the lever of the adjustable PC and the setting is repeated in the same sequence.

FEATURES OF ADJUSTMENT OF SAFETY VALVES OF DIRECT ACTION.

1. The protective cap is removed and the adjusting screw is tightened as far as possible (“to the bottom”).

2. A pressure is set on the pressure gauge of the stand, which is 10% higher than the calculated (allowed).

3. Turning the adjusting sleeve counterclockwise reduces the compression of the spring to the position at which the valve will actuate.

4. Pressurize again and check the value at which the valve opens. If it differs from the required one, then the spring compression is corrected and the valve is rechecked 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 it is necessary to correct the position of the adjusting sleeve.

For this:

for TKZ valves, unscrew the locking screw located above the cover and turn the damper sleeve counterclockwise - to reduce the difference or clockwise - to increase the difference;

for valves PPK and SPKK, 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 the adjustment is completed, the position of the adjusting screw is locked with a lock nut. To prevent unauthorized changes in the tension of the springs, 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 ADJUSTING IMPULSE-SAFETY DEVICES WITH IMPULSE VALVES USED AT POWER PLANTS.

Russian FederationRD

RD 153-34.1-26.304-98 Instructions for the organization of operation, the procedure and terms for checking the safety devices of boilers of thermal power plants

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RD 153-34.1-26.304-98

SO 34.26.304-98

INSTRUCTIONS
ON ORGANIZATION OF OPERATION, PROCEDURE AND TERMS OF CHECKING SAFETY DEVICES OF BOILERS OF THERMAL POWER PLANTS

Introduction date 1999-10-01

DEVELOPED by the Open Joint Stock Company "Firm for the adjustment, improvement of technology and operation of power plants and networks ORGRES"

ARTIST 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 Head D.L.BERSENEV

1. GENERAL PROVISIONS

1.1. This Instruction applies to safety devices installed on TPP boilers.

1.2. The instruction contains the basic requirements for the installation of 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, provides technical characteristics and design solutions for boiler safety devices, recommendations for calculating the throughput of safety valves.

The purpose of the Instruction is to help improve the safety of operation of TPP boilers.

1.3. When developing the Instructions, the governing documents of the Gosgortekhnadzor of Russia, , , , , data on the experience of operating the safety devices of TPP boilers were used.

1.4. With the release of this Instruction, the "Instruction for the organization of operation, the procedure and terms for checking the pulse-safety devices of boilers with an operating steam pressure of 1.4 to 4.0 MPa (inclusive): RD 34.26.304-91" and "Instruction for the organization operation, procedure and terms for checking pulse-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- safety valve of direct action;

RGPC- Lever-load safety valve of direct action;

PPK- spring-loaded safety valve of direct action;

IPU- impulse safety device;

GIC- main safety valve;

IR- impulse valve;

CHZEM- JSC "Chekhov Power Engineering Plant";

TKZ- PO "Krasny Kotelshchik".

1.6. The method for calculating the 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 THE PROTECTION OF BOILERS AGAINST INCREASING PRESSURE OVER THE ALLOWABLE VALUE

2.1. Each steam boiler must be equipped with at least two safety devices.

2.2. As safety devices on boilers with pressure up to 4 MPa (40 kgf/cm) inclusive, it is allowed to use:

lever-load safety valves of direct action;

spring operated safety valves.

2.3. Steam boilers with steam pressure over 4.0 MPa (40 kgf/cm) must be equipped only with electromagnetically driven pulse safety devices.

2.4. The diameter of the passage (conditional) of lever-load and spring valves of direct action and impulse valves of the IPU must be at least 20 mm.

2.5. The nominal passage of the tubes connecting the impulse valve with the HPC IPU 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 dry steamer;

b) in steam once-through boilers, as well as in boilers with forced circulation - on the outlet headers or the outlet steam pipeline;

c) in hot water boilers - on the outlet manifolds 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 outlet and inlet of water.

2.7. If the boiler has a non-switchable superheater, a part of safety valves with a throughput of at least 50% of the total throughput of all valves must be installed on the outlet manifold of the superheater.

2.8. On steam boilers with a working pressure of more than 4.0 MPa (40 kgf / cm 3), impulse safety valves (indirect action) must be installed on the outlet manifold of a non-switchable superheater or on the steam pipeline to the main shut-off body, while for drum boilers for 50% of valves according to total throughput steam extraction for impulses must be carried out from the boiler drum.

With an odd number of identical valves, it is allowed to take steam for pulses from the drum for at least 1/3 and not more than 1/2 of the valves installed on the boiler.

On block installations, if the valves are located on the steam pipeline directly at the turbines, it is allowed to use superheated steam for the 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.

With an odd number of identical valves, it is allowed to apply an additional electrical impulse from a contact pressure gauge connected to the boiler drum, for not less than 1/3 and not more than 1/2 valves.

2.9. In power units with reheating of steam after the high-pressure cylinder of the turbine (HPC), safety valves with a capacity of at least the maximum amount of steam entering the reheater must be installed. If there is a shut-off valve behind the HPC, additional safety valves must be installed. These valves must be sized to take into account both the total capacity of the pipelines connecting the reheater system to sources of higher pressure not protected by their safety valves at the inlet to the reheat system, and possible steam leaks that may occur if the high pressure pipes of the steam and gas-steam heat exchangers steam temperature control.

2.10. Total throughput the safety devices installed on the boiler must be at least the hourly steam output of the boiler.

Calculation of the capacity of the safety devices of boilers in accordance with GOST 24570-81 is given in Appendix 1.

2.11. Safety devices must protect boilers, superheaters and economizers from pressure increase in them by more than 10%. Exceeding the steam pressure when the safety valves are fully opened by more than 10% of the calculated value can be allowed only if this is provided for by the strength calculation of the boiler, superheater, 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 element to be protected 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 impulse valves is not allowed.

2.15. To control the operation of the IPU, it is recommended to use the electrical circuit developed by the Teploelektroproekt Institute (Fig. 1), which provides for normal pressure in the boiler, pressing the plate to the saddle due to the constant flow of current around the winding of the closing electromagnet.

Fig.1. Electrical diagram of the IPU

Note - The scheme is made for one pair of IPK

For IPU installed on boilers with a nominal overpressure of 13.7 MPa (140 kgf / cm ) and below, by decision of the chief engineer of the TPP, it is allowed to operate the IPU without constant current flow around the closing electromagnet winding. In this case, the control circuit must ensure that the MC is closed using an electromagnet and turned off 20 s after the MC is closed.

The IR electromagnet control circuit must be connected to backup source direct current.

In all cases, only reversible 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 actuated.

2.17. The inner diameter of the inlet pipe must not be less than the maximum inner diameter of the inlet pipe of the safety valve. The pressure drop in the supply pipeline to direct-acting safety valves must not exceed 3% of the valve opening pressure. In the supply pipelines of safety valves controlled by auxiliary devices, the pressure drop must not exceed 15%.

2.18. Steam from safety valves must be vented to a safe place. The inner diameter of the discharge pipeline must be at least the largest inner diameter of the outlet pipe of the safety valve.

2.19. The installation of a silencer on the discharge pipeline should not cause a decrease in the throughput of the safety devices below the value required by safety conditions. When equipping the discharge pipeline with a noise suppressor, a fitting for installing a pressure gauge must be provided immediately after the valve.

2.20. The total resistance of the outlet pipelines, including the silencer, must be calculated so that when the medium flow through it is equal to the maximum capacity of the safety device, the backpressure in the valve outlet pipe does not exceed 25% of the response pressure.

2.21. The discharge pipelines of safety devices must be protected from freezing and equipped with drains to drain the condensate accumulating in them. Installation locking devices drains are not allowed.

2.22. The riser (vertical pipeline through which the medium is discharged to the atmosphere) must be securely fixed. This must take into account the static and dynamic loads that occur when the main valve is actuated.

2.23. In pipelines of safety valves, compensation for thermal expansion must be ensured. The fastening of the body and pipeline of safety valves must be calculated taking into account static loads and dynamic forces arising from the operation of safety valves.

3. INSTRUCTIONS FOR THE INSTALLATION OF SAFETY DEVICES

3.1. Valve storage rules

3.1.1. Safety devices must be stored in places that exclude 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 closed rooms in the absence of dust and vapors in them that cause the destruction of the windings of the electromagnets.

3.1.3. The shelf life of valves is no more than two years from the date of shipment from the manufacturer. More if needed long-term storage products must be re-preserved.

3.1.4. Loading, transportation and unloading of valves must be carried out with the observance of precautionary measures that guarantee them from breakage and damage.

3.1.5. If the above rules of transportation and storage are observed, the plugs are present and there are no external damages, the valves can be installed on workplace without revision.

3.1.6. If the rules of transportation and storage are not observed, the valves should be inspected before installation. The issue of compliance of the storage conditions of valves with the requirements of the NTD should be decided by a commission of representatives of the operating and repair departments of the TPP and the installation organization.

3.1.7. When inspecting valves, check:

the condition of the sealing surfaces of the valve.

After the revision, the sealing surfaces must have a cleanliness = 0.32;

the state of the gaskets;

the condition of the stuffing box packing of the servomotor piston.

If necessary, install a new packing of pre-pressed rings. Based on the tests carried out by ChZEM, for installation in the HPC servo drive chamber, a combined seal can be recommended, consisting of a set of rings: two packs of rings made of graphite and metal foil and several rings made of thermally expanded graphite. (The seal is manufactured and supplied by CJSC "Unihimtek", 167607, Moscow, Michurinsky prospekt, 31, building 5);

the condition of the working piston jacket in contact with the gland packing; traces of possible corrosion damage to the jacket must be eliminated;

the state of the thread of the fasteners (no nicks, scuffs, thread chipping);

the condition and elasticity of the springs.

After assembly, 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 indoors.

The valves may be operated under the following environmental limits:

when using valves intended for delivery to countries with temperate climate: temperature - +40 °С and relative humidity - up to 80% at a temperature of 20 °С;

when using valves intended for delivery to countries with a tropical climate; temperature - +40 °С;

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 their maintenance and repair, as well as assembly and disassembly at the place of operation without cutting out from the pipeline.

3.2.3. Installation of valves and connecting pipelines must be carried out according to the 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 upwards. The deviation of the stem axis from the vertical is allowed no more than 0.2 mm per 100 mm of the valve height. When welding the valve into the pipeline, it is necessary to prevent the ingress of burrs, splashes, scale into 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 fixed with the paws available in the design of the products to the support, which must perceive the reactive forces that occur when the IPU is triggered. The valve exhaust pipes must also be securely fastened. In this case, any additional stresses in the connection between the exhaust and connecting flanges of the exhaust pipes must be eliminated. From the bottom point, permanent drainage should be organized.

3.2.6. Impulse dampers for live steam and reheat steam manufactured by LMZ, mounted on a special frame, should be installed on sites that are convenient for maintenance and protected from dust and moisture.

3.2.7. The pulse valve must be mounted on the frame so that its stem is strictly vertical in two mutually perpendicular planes. The IR lever with a load suspended on it and an electromagnet core must not have distortions in the vertical and horizontal planes. To avoid jamming when opening the MC, the lower electromagnet must be located relative to the MC so that the centers of the holes in the core and the lever are on the same vertical; electromagnets must be located on the frame so that the axes of the cores are strictly vertical and are in a plane passing through the axes of the rod and the IR lever.

3.2.8. To ensure a tight fit of the MC 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 taking pulses on the MC and the electrocontact manometer (ECM) from the same element on which the HPC is installed, the places for sampling pulses must be at such a distance from the CHM that, when it is triggered, the perturbation of the steam flow does not affect the operation of the MC and ECM (at least 2 m). The length of the impulse lines between the impulse and main valves must not exceed 15 m.

3.2.10. Electrocontact pressure gauges must be installed at the boiler service mark. Permissible Maximum temperature environment in the EKM installation area should not exceed 60 °C. The shut-off valve on the line for supplying the medium to the ECM during operation must be opened and sealed.

4. PREPARING THE VALVES FOR OPERATION

4.1. The compliance of the mounted 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 the fit of the supporting surfaces of the prism of lever-load valves are checked: the lever and prism must be mated across the entire width of the lever.

4.3. The compliance of the actual magnitude of the GPC stroke with the instructions of the technical documentation is checked (see Appendix 5).

4.4. In the HPC of reheat steam, moving the adjusting nut along the stem provides a gap between its lower end and the upper end of the support disk, equal to the valve stroke.

4.5. At CHPK reheat steam manufactured 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 cores of the electromagnets is checked. They must be cleaned of old grease, rust, dust, washed with gasoline, sanded and rubbed with dry graphite. The rod at the point of articulation with the core and the core itself should not have distortions. The movement of the cores must be free.

4.7. The position of the damper screw of the electromagnets is checked. This screw must be screwed in so that it protrudes above the end of the electromagnet body by about 1.5-2.0 mm. If the screw is fully screwed in, then when the armature is lifted, a vacuum is created under it, and with a de-energized electrical circuit, it is almost impossible to adjust the valve to actuate at a given pressure. Over-driving the screw will cause the core to move violently when retracted, which will break the sealing surfaces of the pulse valves.

5. ADJUSTING THE SAFETY DEVICES TO ACTIVATE AT A GIVEN PRESSURE

5.1. Adjustment of safety devices for operation at a given pressure is carried out:

after the completion of the installation of the boiler;

after a major overhaul, if the safety valves were replaced or their major repairs were made (complete disassembly, sealing surfaces turning, replacement of running gear parts, etc.), and for the PPC - in case of a spring replacement.

5.2. To adjust the valves, a pressure gauge with an accuracy class of 1.0 must be installed in the immediate vicinity of the valves, tested in the laboratory against a reference pressure gauge.

5.3. Safety valves are regulated at the workplace of the valve installation by raising the pressure in the boiler to the set pressure.

Adjustment of spring safety valves is allowed to be carried out at the stand with steam with operating parameters, followed by a control check on the boiler.

5.4. Valve actuation during adjustment is determined by:

for IPU - by the moment of operation of the GPC, accompanied by a blow and strong noise;

for full-lift direct-acting valves - by a sharp pop, observed when the spool reaches the upper 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 systems in which the steam pressure necessary for adjustment 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 for PU installation workstations, maintenance platforms and adjacent passageways.

5.5.5. Establish a two-way connection between the valve adjustment points and the control panel.

5.5.6. Instruct shift and adjustment personnel involved in valve adjustment work.

The personnel should be well aware of the design features of the launchers subjected to adjustment and the requirements of the instructions for their operation.

5.6. Adjustment of lever-load valves of direct action is carried out in the following sequence:

5.6.1. The weights on the valve levers move to the end position.

5.6.2. In the protected object (drum, superheater), the pressure is set to 10% higher than the calculated (allowed).

5.6.3. The weight on one of the valves moves slowly towards the body until the valve is actuated.

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 the one specified in clause 5.6.2, the position of the load on the lever is corrected and the correct operation of the valve is rechecked.

5.6.6. After the adjustment is completed, the position of the load 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 placed on the lever of the adjusted valve and the remaining valves are adjusted in the same sequence.

5.6.8. After the adjustment of all valves is completed, the working pressure is established in the protected object. Additional weights are removed from the levers. A record of the readiness of the valves for operation is recorded in the Safety Devices Repair and Operation Log.

5.7. Adjustment of spring-loaded direct acting relief valves:

5.7.1. The protective cap is removed and the spring tightening height 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 the position at which the valve will actuate.

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 in accordance with clause 5.6.2, then the spring compression is corrected and the valve is rechecked for actuation. At the same time, the pressure at which the valve closes is monitored. The difference between the actuation pressure and the closing pressure should not exceed 0.3 MPa (3.0 kgf/cm). If this value is greater or less, then it is necessary to correct the position of the upper adjusting sleeve.

For this:

for TKZ valves, unscrew the locking screw located above the cover and turn the damper sleeve counterclockwise - to reduce the difference or clockwise - to increase the difference;

for PPK and SPKK 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 Safety Devices Repair and Operation Book and is compressed to a value that allows the remaining valves to be adjusted. After the end of the adjustment of all valves on each valve, the height of the spring recorded in the magazine is set in the adjusted position. To prevent unauthorized changes in the tension of the springs, 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 Safety Devices Repair and Operation Book about the readiness of the valves for operation.

5.8. Pulse-safety devices with an IR equipped with an electromagnetic drive are regulated for operation both from electromagnets and with de-energized electromagnets.

5.9. To ensure the operation of the IPU from electromagnets, the ECM is configured:

5.9.1. The readings of the EKM are compared with the readings of a standard pressure gauge with a class of 1.0%.

5.9.2. EKM is regulated 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 marks of the place of connection of the impulse line to the protected object and the place of installation of the EKM, m

5.9.3. EKM is regulated to turn on the closing electromagnet:

5.9.4. On the EKM scale, the limits of IR operation are marked.

5.10. The adjustment of the MC for actuation at a given pressure with de-energized electromagnets is carried out in the same sequence as the adjustment of direct-acting lever-weight valves:

5.10.1. The weights on the IR levers are moved to the extreme position.

5.10.2. The pressure in the boiler drum rises to the setpoint for the operation of the IPU (); on one of the IRs connected to the drum of the boiler, the load moves towards the lever to the position at which the IPU will be triggered. In this position, the load is fixed on the lever with a screw. After that, 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 fastened with a screw and sealed.

If more than one IR is connected to the drum of the boiler, an additional weight is installed on the lever of the adjusted valve in order to be able to adjust the remaining IRs connected to the drum.

5.10.3. A pressure equal to the IPU actuation pressure behind the boiler () is set in front of the CHP. In accordance with the procedure provided for in clause 5.10.2, it is regulated for the operation of the IPU, from which the steam at the IR is taken from the boiler.

5.10.4. After the end of the adjustment, the pressure behind the boiler is reduced to the nominal value and additional weights are removed from the IK levers.

5.11. Voltage is applied 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 rises to the value at which the IPU should operate, and the opening of the CHP of all IPUs is checked at the place, the impulse to open which is taken behind the boiler.

When adjusting the IPU on drum boilers, the IPU control keys, triggered by an impulse behind the boiler, are set to the "Closed" position and the pressure in the drum rises to the IPU actuation setpoint. The operation of the HPC IPU, operating on an impulse from the drum, is checked locally.

5.13. Impulse-safety devices for reheating steam, behind which there are no shut-off devices, are configured to operate after installation during the firing of the boiler to steam density. The procedure for setting the valves is the same as when setting the live steam valves installed downstream of the boiler (clause 5.10.3).

If there is a need to adjust the pulse valves of the reheat steam after repair, then it can be done on a special stand. In this case, the valve is considered to be adjusted when the rise of the stem by the amount of stroke is fixed.

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 Journal of the repair and operation of safety devices.

6. PROCEDURE AND TERMS OF CHECKING VALVES

6.1. Checking the correct operation of the safety devices should be carried out:

when the boiler is stopped for scheduled repairs;

during the operation of the boiler:

on pulverized coal boilers - once every 3 months;

on oil-fired boilers - once every 6 months.

During the specified time intervals, the check should be timed to coincide with scheduled shutdowns of the boilers.

On boilers put into operation periodically, the check should be carried out at start-up, if more than 3 or 6 months have passed since the previous check, respectively.

6.2. Checking of fresh steam IPU and reheat steam IPU, equipped with an electromagnetic drive, should be carried out remotely from the control panel with local operation control, and reheat steam IPU, which do not have an electromagnetic drive, by manual detonation of the pulse valve when the unit load is not less than 50% of the nominal.

6.3. Checking the safety valves of direct action is carried out at the operating pressure in the boiler by alternately forced undermining of each valve.

6.4. Checking of safety devices is carried out by the shift supervisor (senior boiler operator) according to the schedule, which 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 checking, the shift supervisor makes an entry in the Journal of the repair and operation of safety devices.

7. RECOMMENDATIONS FOR MONITORING THE CONDITION AND ORGANIZING THE REPAIR OF VALVES

7.1. Scheduled condition monitoring (revision) and repair of safety valves are carried out simultaneously with the equipment on which they are installed.

7.2. Checking the condition of safety valves includes disassembly, cleaning and flaw detection of parts, checking the tightness of the shutter, the condition of the gland packing of the servo drive.

7.3. Control of the condition and repair of valves should be carried out in a specialized valve workshop on special stands. The workshop must be equipped with lifting mechanisms, well lit, have a supply compressed air. The location of the workshop should ensure convenient transportation of the valves to the installation site.

7.4. Control of the condition and repair of valves should be carried out by a repair team with experience in valve repair, who has studied the design features of valves and the principle of their operation. The team must be provided with working drawings of valves, repair forms, spare parts and materials for their quick and high-quality repair.

7.5. In the workshop, valves are disassembled and parts are fault-detected. Before flaw detection, the parts are cleaned of dirt and washed in kerosene.

7.6. When examining the sealing surfaces of the parts of the valve-seat and plate, pay attention to their condition (the absence of cracks, dents, scratches and other defects). During subsequent assembly, the sealing surfaces must have a roughness = 0.16. The quality of the sealing surfaces of the seat and plate should ensure their mutual fit, in which the pairing of these surfaces is achieved 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 servo piston chamber jackets and guides, make sure that the ellipse of these parts does not exceed 0.05 mm per diameter. The roughness of the surfaces in contact with the gland packing must correspond to the cleanliness class = 0.32.

7.8. When inspecting the servo piston Special attention should pay attention to the condition of the gland packing. The rings must be tightly pressed together. On the working surface rings must not be damaged. Before assembling the valve, it should be well graphitized.

7.9. The thread condition of all fasteners and adjusting screws should be checked. All parts with defective threads must be replaced.

7.10. It is necessary to check the condition of the cylindrical springs, for which purpose to carry out a visual inspection of the surface condition for the presence of cracks, 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 fittings.

7.12. Before assembling the valves, check that the dimensions of the parts correspond to the dimensions indicated in the form or working drawings.

7.13. Tightening the stuffing box rings in piston chambers The GPC should ensure the tightness of the piston, but not interfere with its free movement.

8. ORGANIZATION OF OPERATION

8.1. The overall responsibility for the technical condition, testing and maintenance of safety devices rests with the head of the boiler and turbine (boiler) shop on whose equipment they are installed.

8.2. The order for the workshop appoints persons responsible for checking the valves, organizing their repair and maintenance, and maintaining technical documentation.

8.3. In the workshop, for each boiler, a Journal 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;

brand, type or drawing number of the valve;

conditional 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 tests carried out on the valve;

the estimated area of ​​the passage section;

for spring-loaded safety valves - the characteristics of the spring;

data on the materials of the main parts;

certificate of acceptance and conservation.

8.5. For each group of valves of the same type there must be: Assembly drawing, technical description and instruction manual.

9. SAFETY REQUIREMENTS

9.1. It is forbidden to operate safety devices in the absence of the documentation specified in clauses 8.4, 8.5.

9.2. It is forbidden to operate the valves at pressure and temperature higher than specified in the technical documentation for the valves.

9.3. It is forbidden to operate and test safety valves in the absence of outlet pipes that protect personnel from burns when the valves actuate.

9.4. Impulse valves and valves of direct action must be located in such a way that, during adjustment and testing, the possibility of burns to the operating personnel is excluded.

9.5. It is not allowed to eliminate valve defects in the presence of pressure in the objects to which they are connected.

9.6. When repairing valves, it is forbidden to use wrenches, the size of the "mouth" of which does not correspond to the size of the fasteners.

9.7. All types of repair and maintenance must be carried out in strict compliance with the requirements of the rules fire safety.

9.8. When the power plant is located in a residential area, the exhaust gases of the HPC IPU must be equipped with noise suppression devices that reduce the noise level when the IPU is triggered to sanitary-permissible standards.

Appendix 1

REQUIREMENTS FOR SAFETY VALVES OF BOILERS

1. Valves must open automatically at a given pressure without fail.

2. In the open position, the valves must operate steadily, without vibration and pulsation.

3. Requirements for direct acting valves:

3.1. The design of a lever-weight or spring-loaded safety valve must be provided with a device for checking the correct operation of the valve during operation of the boiler by forcibly opening the valve.

Forced opening must be possible at 80% of the set pressure.

3.2. The difference between the set pressure (full opening) and the beginning of the valve opening must not exceed 5% of the set pressure.

3.3. Safety valve springs must be protected from direct heating 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 must not allow arbitrary changes in its adjustment during operation. The RGPK on the lever must have a device that excludes 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 blows when they are opened and closed.

4.2. The design of the safety device must ensure the preservation of the functions of protection against overpressure 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 working pressure in the boiler.

Appendix 2

METHOD OF CALCULATION OF THE CAPACITY OF SAFETY VALVES OF BOILERS

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 - the number of safety valves installed on the protected system;

Capacity of individual safety valves, kg/h;

Nominal steam capacity of the boiler, kg/h;

Nominal heat output of a hot water boiler, J/kg (kcal/kg);

Heat of evaporation, J/kg (kcal/kg).

Calculation of the capacity of the safety valves of hot water boilers can be performed taking into account the ratio of steam and water in the steam-water mixture passing through the safety valve when it is triggered

2. The capacity of the safety valve is determined by the formula;

For pressure in MPa;

For pressure in kgf/cm,

where is the throughput of the valve, kg/h;

Estimated area of ​​the valve flow section, equal to the smallest area of ​​the free section in the flow path, mm (should be indicated in the valve passport);

Steam flow coefficient related to the calculated cross-sectional area (should be specified by the plant in the valve passport or in the assembly drawing);

Maximum overpressure in front of the safety valve, which should not exceed 1.1 design pressure, MPa (kgf/cm);

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 according to tables 1 and 2 or determined by the 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

To calculate the capacity of safety valves of power plants with live steam parameters:

13.7 MPa and 560 °C = 0.4;

25.0 MPa and 550 °C = 0.423.

The valve capacity formula should only be used if:

For pressure in MPa;

For pressure in kgf/cm,

where is the maximum overpressure behind the PC in the space into which steam flows from the boiler (when it flows into the atmosphere = 0),

Critical pressure ratio.

For saturated steam = 0.577.

For superheated steam = 0.546.

Appendix 3

FORMS
TECHNICAL DOCUMENTATION ON SAFETY DEVICES OF BOILERS, WHICH SHOULD BE MAINTAINED AT THE TPP

Vedomosti
operating pressure of the boiler safety devices according to _______ shop

Boiler safety device check schedule

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 of the Gosgortekhnadzor of Russia, GOST and technical literature, the following terms and definitions are adopted in this Instruction.

1. Working pressure - the maximum internal overpressure 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 pressure increase during the operation of safety devices.

2. Design pressure - overpressure, for which the calculation of the strength of the boiler elements was carried out. For TPP boilers, the design pressure is usually equal to the working pressure.

3. Permissible pressure- the maximum overpressure allowed by accepted standards in the protected element of the boiler when the medium is discharged from it through the safety device

The safety devices must be selected and adjusted in such a way that the pressure in the boiler (drum) cannot rise above .

4. Opening start pressure - excessive pressure at the inlet to the valve, at which the force directed to open the valve is balanced by the force holding the shut-off body on the seat.

Depending on the design of the valve and the dynamics of the process. But due to the transience of the process of operation of full-lift safety valves and IPU during their adjustment, it is almost impossible to determine.

5. Full opening pressure (setting pressure) - the maximum excess pressure that is set in front of the PC when it is fully opened. It must not exceed .

6. Closing pressure - overpressure at which, after actuation, the shut-off body is seated on the seat.

For safety valves with direct action. IPU with an electromagnetic drive must have at least .

7. Bandwidth - maximum mass flow steam that can be dumped through completely open valve at actuation parameters.

Appendix 5

DESIGNS AND TECHNICAL CHARACTERISTICS OF BOILER SAFETY VALVES

1. Live steam safety devices

1.1. Main relief valves

To protect boilers from pressure increase in live 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, valves of the 530 series are installed for parameters of 9.8 MPa, 540 ° C, and on blocks of 500 and 800 MW - of the E-2929 series, which are currently out of production. At the same time, for newly designed boilers for parameters 9.8 MPa, 540 °C and 13.7 MPa, 560 °C, the plant developed a new valve design 1203-150 / 200-0, and for the possibility of replacing exhausted valves of the 530 series , which had a double-sided steam outlet, the valve 1202-150 / 150-0 is produced.

Specifications produced CHZEM GPC are given in table.3.

Table 3

Technical characteristics of the main safety valves IPU boilers

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, which houses the servo 6; plates 4 and saddles 3 constituting the shutter assembly; lower 5 and upper 7 rods; hydraulic damper assembly 8, in the body of which a piston and a spring are located.

Fig.2. Series 392 and 875 Main Relief Valves:

1 - connecting pipe; 2 - body; 3 - saddle; 4 - plate; 5 - lower rod; 6 - servo drive assembly; 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 on the spool. Pressing it to the seat by the pressure of the working medium ensures an increase in the tightness of the shutter. Pressing the plate to the saddle in the absence of pressure under it is provided by a spiral spring placed in the damper chamber.

The 1029-200/250-0 series valve (Fig. 3) is fundamentally similar to the 392 and 875 series valves. The only difference is the presence of a throttle grate in the body and steam removal through two oppositely directed outlet pipes.

Fig.3. Series 1029 Main Relief Valve

The valves work as follows:

when you open the PC pairs by impulse tube enters the chamber above the servo piston, creating a pressure on it equal to the pressure on the spool. But since the area of ​​the piston, on which the steam pressure acts, exceeds the similar area of ​​the spool, a shifting force occurs, moving the spool down and thereby opening the release of steam from the object. When the pulse valve is closed, steam access to the servomotor chamber is stopped, and the steam present in it is discharged through the drain hole into the atmosphere.

At the same time, 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 provides for a hydraulic damper in the form of a chamber located in the yoke coaxially with the servo drive chamber. A piston is located in the damper chamber, which is connected to the spool with the help of rods; according to the instructions of the plant, water or some other liquid of similar viscosity is poured or supplied into the chamber. When the valve is opened, fluid flowing through small holes in the damper piston slows down the movement of the valve body and thereby softens the blows. When moving the valve stem towards the closing direction, the same process occurs in the opposite direction*. The valve seat is removable, located between the connecting pipe and the body. The seat is sealed with comb metal gaskets. A hole is made in the side of the saddle connected to drainage system, where the condensate accumulated in the valve body after its operation merges. To prevent vibration of the spool and breakage of the stem, guide ribs are welded into the connecting pipe.

________________

* As the operating experience of a number of TPPs has shown, the valves operate without impact 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 valves of the 1202 and 1203 series (Fig. 4 and 5) is that they have a connecting pipe made integral with the body and there is no hydraulic damper, the role of which is performed by throttle 8, installed in the cover on the line connecting the over-piston chamber with the atmosphere.

Fig.4. Series 1202 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. Series 1203 Main Relief Valve

Just like the valves discussed above, the 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 over-piston chamber and, when the pressure in it is equal to , it begins to move the piston down, opening the discharge of the medium into the atmosphere.

The main parts of live 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 shutter parts are welded with TsN-6 electrodes. Pressed rings made of asbestos-graphite cord of 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, which includes rings made of thermally expanded graphite, metal foil, and foil made of thermally expanded graphite. The packing was developed by "UNIKHIMTEK" and was successfully tested on the stands of ChZEM.

1.2. Pulse valves

All live steam IPUs produced by ChZEM are equipped with impulse valves of the 586 series. The body of the valve - angular, flange connection of the body with a cover. A filter is mounted at the inlet to the valve, designed to trap foreign particles contained in the steam. The valve is actuated by an electromagnetic actuator, which is mounted on the same frame with the valve. To ensure the valve actuation in the event of a power failure in the power supply system of the electromagnets, a load is suspended on the valve lever, by moving which it is possible to adjust the valve to actuate at the required pressure.

Table 4

Specifications for fresh and reheat pulse valves

Fig.6. Fresh steam pulse valve:

a- valve design; b- installation diagram of the valve on the frame together with electromagnets

To ensure the minimum inertia of the IPU operation, the pulse valves should be installed as close as possible to the main valve.

2. Impulse-safety devices for reheat steam

2.1. Main relief valves

GPK CHZEM and LMZ 250/400 mm are installed on pipelines of cold reheating of boilers. The technical characteristics of the valves are given in Table 3, the constructive solution of the ChZEM reheat valve is shown in Fig. 7. The main components and parts of the valve: body through passage type 1, attached to the pipeline by welding; valve assembly, consisting of a seat 2 and a plate 3, connected by means of a thread to the stem 4; glass 5 with a servo drive, the main element of which is a piston 6 sealed by stuffing box packing; a spring load assembly consisting of two successively arranged helical springs 7, the required compression of which is carried out by a screw 8; throttle valve 9, designed to dampen shock when closing the valve by controlling the rate of steam removal from the over-piston chamber. The saddle is installed between the body and the glass on corrugated gaskets and is crimped when the cover fasteners are tightened. The centering of the spool in the seat is ensured by guide ribs welded to the spool.

Fig.7*. Main reheat steam safety valves series 111 and 694:

1 - body; 2 - saddle; 3 - plate; 4 - stock; 5 - glass; 6 - servo piston; 7 - spring; 8 - adjusting screw; 9 - throttle valve; A - steam input from the impulse valve; B - discharge of steam into the atmosphere

* The quality of the drawing in the electronic version corresponds to the quality of the drawing given in the paper original. - Database manufacturer's note.

The main parts of the valves are made of the following materials: body and cover - 20GSL steel, upper and lower stems - 38KhMYUA steel, spring - 50KhFA steel, stuffing box packing - AG or AGI cord. The sealing surfaces of the parts of the shutter are welded with TsT-1 electrodes in the factory. The principle of operation of the valve is the same as for live steam valves. The main difference is the way the shock is damped when the valve closes. In GPK reheat steam, the degree of shock damping is adjusted by changing the position of the throttle needle and tightening the coil spring.

The 694 series main safety valves for installation in the hot reheat line differ from the 111 series cold reheat valves described above in the material of the body parts. The body and cover of these valves are made of steel 20KhMFL.

The HPC supplied for installation on the cold reheat line, manufactured by LMZ (Fig. 8), are similar to CHZEM valves of the 111 series, although they have three fundamental differences:

the sealing of the servo piston is carried out using cast iron piston rings;

valves are equipped with a limit switch that allows you to transfer information about the position of the shut-off element to the control panel;

there is no throttling device on the steam discharge line from the over-piston chamber, which excludes the possibility of adjusting the degree of shock damping or valve closure and, in many cases, contributes to the occurrence of a pulsating valve operation.

Fig.8. The main safety valve for steam reheating design LMZ

2.2. Pulse valves

Lever-weight valves 25 mm series 112 are used as pulse valves of the IPU CHZEM of the reheat system (Fig. 9, Table 4). The main parts of the valve: body 1, seat 2, spool 3, stem 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 inner cylindrical bore of the seat, the wall of which plays the role of a guide. The stem transmits force to the spool through the ball, which prevents the valve from tilting when the valve closes. The valve is set to operate by moving the load on the lever and then fixing it in a given position.

1 - body; 2 - plate; 3 - stock; 4 - guide sleeve; 5 - lifting sleeve; 6 - spring, 7 - pressure threaded sleeve; 8 - cap; 9 - lever

Valves spring, full-lift. They have a cast angular body, they are installed only in a vertical position in places with an ambient temperature not higher than +60 °C. With an increase in the pressure of the medium under the valve, the plate 2 is squeezed out of the seat, and the steam flow, flowing out from 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 predetermined 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 a fairly quick opening of the valve and its closing with a minimum pressure drop relative to the operating pressure in the protected system. To ensure minimum steam emission into the environment when the valve is opened, the valve cover is equipped with a labyrinth seal consisting of alternating aluminum and paronite rings. Setting the valve to actuate at a given pressure is carried out by changing the degree of tightening of the spring 6 using the pressure threaded sleeve 7. The pressure sleeve is closed by a cap 8, fixed 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 the operation of the equipment, a lever 9 is provided on the valve.

The 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 Krasny Kotelshchik

* 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 manufactured by Krasny Kotelshchik Production Association

Table 7

Technical characteristics of the springs installed on the valves of the production association "Krasny Kotelshchik"

The labor protection instruction is the main document that establishes the requirements for the safe performance of maintenance, repair and installation of safety valves.

This instruction has been developed in accordance with the Methodological Recommendations, taking into account the requirements of legislative and other regulatory legal acts containing state labor protection requirements, intersectoral labor protection rules (safety rules).

Knowledge of this labor protection instruction for working professions performing maintenance, repair and installation of safety valves is mandatory.

General requirements for labor protection.

This instruction applies to safety valves installed on pressure vessels and process pipelines.

1.1. To independent work maintenance, installation and repair of safety valves are allowed to persons at least 18 years of age who have passed:

• medical examination and having no contraindications to admission to this species work;
• introductory briefing on labor protection and fire safety;
• primary briefing on labor protection at the workplace;
• primary briefing on fire safety at the MGP facilities;
• training in labor protection and safe methods and techniques for performing work;
• internship from 2 to 14 shifts;
• training in the use of PPE;
• verification of theoretical knowledge of labor protection requirements and practical skills safe work in the examination committee of the branch for admission to independent work;
• training and testing knowledge on the provision of first (pre-medical) aid to victims of accidents at work;
• have studied the requirements of this manual;
• having a certificate of the established form with a mark on admission to independent work;
• having a permit to perform gas hazardous work according to the list of GRs;
• training and having a permit to perform steeplejack work and work at height;
• trained and licensed to service pressure vessels.

• The main dangerous and harmful factors affecting the worker at work are:

Table 1

1.3. To protect against dangerous and harmful production factors, the employee is given certified means free of charge personal protection(PPE), depending on the season and working conditions, as well as flushing and neutralizing agents:

• a suit made of heat-resistant antistatic fabric with oil-repellent impregnation with the following protective properties: To - protection against open flame; Es - protection against electrostatic charges and fields;

• cotton underwear;

• leather boots;
• protective coated gloves.
• anti-noise headphones

At low temperatures:

• a suit for protection from low temperatures with a fastened insulating pad made of antistatic heat-resistant fabric impregnated with oil and water;
• hat with ear flaps;

• felt boots;
• insulated mittens or frost-resistant gloves with a polymer coating.

To protect the hands of the employee is issued:

Cleansing hand paste, regenerating revitalizing hand cream.

1.4. Works on maintenance, installation and repair of safety valves belong to the category of increased danger and must be carried out in accordance with the list of gas hazardous work developed in the service with the issuance of a work permit.

1.5. During work, workers and employees are required to comply with the internal labor regulations, work and rest regime established at the enterprise.

1.6. When carrying out maintenance, installation and repair work on safety valves, a non-sparking tool must be used.

1.7. Employees must know and follow the rules of personal hygiene and sanitation.

1.8 The requirements of this instruction are mandatory. Failure to comply with these requirements is considered as a violation of labor and production discipline and is the basis for bringing the employee to responsibility. All employees performing maintenance, installation and repair of safety valves must familiarize themselves with this instruction against signature.

1.9. The employee is allowed to perform only the work provided for by his labor duties or on behalf of his immediate supervisors, as well as to carry out other lawful actions due to labor relations with the employer or in his interests.

2. Labor protection requirements before starting work.

2.1. The employee is obliged to receive an assignment from the immediate supervisor to perform a certain type of work or certain types of work, to familiarize himself with the content of the task in the journal of daily accounting for the issuance of service tasks against signature.

Performers of maintenance, installation and repair of safety valves must undergo a medical examination by a paramedic.

2.2. Prior to the start of work, all measures to prepare for the conduct of gas hazardous work must be completed. A work permit for carrying out gas hazardous work must be issued and all preparatory work must be completed in accordance with the work permit:

• conduct targeted training;
• measure gas contamination before starting work;
• turn off the gas pipeline section with shut-off valves (according to the attached scheme to the permit);
• take measures against erroneous or spontaneous rearrangement of stop valves;
• release gas;
• post signs “Do not open”, “Do not close”, “Gas hazardous work”;
• provide the place of work with fire extinguishers OP-10 (2 pcs.).

2.3. Prior to the start of work, employees must be instructed on the safe conduct of work and sign the work permit. Employees must put on overalls, special footwear established in accordance with current standards, check and make sure that the fixed tools and devices are in place and in good condition. It is forbidden to use protective equipment whose test period has expired.

2.4. Under the guidance of the person responsible for the preparation of the workplace, employees must complete all the preparatory activities specified in the work permit. It is also necessary to equip the workplace with primary fire extinguishing equipment in accordance with those specified in the work permit.

2.5. Installation and dismantling at existing installations is allowed only after the complete shutdown of the apparatus and pipelines, and their release from gas.

2.6. The frequency of inspections and repairs of equipment is determined by the operating conditions, features of the equipment and is established by the work instructions drawn up on the basis of the instructions for the repair and operation of manufacturers. The frequency of checking the operation of safety valves on equipment in accordance with STO Gazprom 2-3.5-454-2010 (clause 17.2.35.) at least once a year.

3 Labor protection requirements during work.

3.1. Occupational safety requirements for the installation of safety valves.

3.1.1. Start work after completing the preparatory measures and confirming the possibility of performing work by a labor protection engineer, a fire protection engineer and obtaining permission to work from the dispatcher.

When carrying out work:

• control of gas contamination in the working area after 30 minutes.

3.1.2. Persons with special education in the UKK, trained in safe techniques and methods for the specified type of work, who have mastered the requirements of the “Instructions on labor protection when working at height” No. VR. Immediately before carrying out such work, the work manager is obliged to conduct a target briefing for the workers with an entry in the target briefing log and the signature of the person who conducted the briefing and the persons who received it. When working on the installation of safety valves associated with climbing to a height, the employee must be in special shoes, antistatic overalls, a protective helmet, and use a safety belt. To climb to a height, use tested ladders, step ladders. Employees must be informed about the location of the nearest first-aid kit, know and be able to provide first (pre-medical) aid to the victim.

3.1.3. The number of safety valves, their dimensions and throughput must be selected according to the calculation indicated in the passport and operating instructions for process equipment.

3.1.4. Safety valves are installed directly on the vessel / equipment / in a vertical position. If due to the nature of the design of the vessel or the conditions of production, such an installation is not feasible, safety valves should be installed in the immediate vicinity of the vessel on a pipeline or a special offshoot, provided that there is no shut-off device between them and the vessel and monitoring it will not be difficult for persons serving the vessel.

3.1.5. The diameter of the through hole of the inlet fitting on which the valve is installed must be not less than the diameter of the through hole of the connecting flange on the side of the product inlet to the safety valve.

3.1.6 In some cases, a short vertical downpipe vented directly to atmosphere should be used. The diameter of the outlet pipe must not be less than the diameter of the outlet fitting of the valve.

3.1.7. In cases where this is not possible, apply drainage devices to prevent the accumulation of corrosive media in the valve body. Installation on outlet and drainage pipes locking devices are not allowed.

3.1.8. Spring valves must be equipped with special lockable caps that block access to the spring adjusting bolts.

3.1.9. Lever relief valve weights must be adjusted and locked onto the lever so that no movement of the weight is possible. Installation of lever-load valves on mobile vessels is not allowed.

3.1.10. The design of safety valves should include a device for checking the correct operation of the valve in working condition by forcibly opening it during operation of the vessel / equipment /

3.1.11. The connecting pipelines of safety valves must be protected from freezing of the working medium in them.

3.1.12. Safety valves installed on technological equipment working under pressure, should not violate its tightness. After installation, the tightness of the installation must be checked using a leak detector, washing the joint or in another way.

3.1.13. The results of the inspection and adjustment must be recorded in the log book. Safety valves operating to discharge the working medium must be provided with means that protect people from exposure to the discharged medium: screens, fluid receivers. Their serviceability is checked before each check of the valve.

3.1.14. Autonomous testing of safety valves for strength with increased pressure and tightness, as well as checking the adjustment of safety valves should be carried out at a specially equipped workplace that provides protection for personnel from active medium emissions and the consequences of destruction of the tested products.

3.2. Occupational safety requirements for the maintenance of safety valves.

3.2.1 Start work after completing preparatory measures and confirming the possibility of performing work by a labor protection engineer, a fire protection engineer and obtaining permission to perform work from the LPUMG dispatcher.

When carrying out work:

• to control the pressure in the bled area using standard instruments;
• work according to the schedule of the enterprise in antistatic overalls, special footwear;
• use PPE of hearing organs;
• perform work with a serviceable spark-proof tool;
• the constant presence of a person responsible for the performance of work;
• availability of fire extinguishing equipment OP-10;
• gas control after 30 minutes.

3.2.2. All safety valves before putting into operation must be adjusted on a special bench to the set pressure.

3.2.3. Safety valves whose working pressure is up to: 3 kgf / cm² are adjusted to 0.5 kgf / cm² above P working; from Z-x to 60 kgf / cm² are adjusted to 15% more than R working; over 60 kgf / cm² are set to 10% more than P working.

3.2.4. Checking and adjustment of the safety valve must be carried out at least once a year in accordance with the PPR schedule.

3.2.5. Inspection and adjustment of valves must be documented by the appropriate act, the valves are sealed and tagged with the date of adjustment, followed by the date of inspection and adjustment data.

3.3. Occupational safety requirements for the repair of safety valves.

3.3.1. Safety valves installed on equipment, tanks operating under pressure above 0.7 kgf / cm² are subjected to hydraulic test body strength with a pressure equal to the test pressure of the relevant equipment, at each adjustment of the valve.

3.3.2. Work related to the removal and installation of the safety valve on

equipment, refer to gas-hazardous work according to the list of GKS, performed on the basis of a permit for gas-hazardous work, in compliance with all measures to ensure the safety of the work.

3.3.3. Repair and adjustment of safety valves is carried out on a special stand in the room of the instrumentation and A workshop. To ensure safety, when disassembling the safety valve, it is necessary to remove the seal, the safety cap, loosen the spring with a calibration screw and disassemble the safety valve.

3.3.4. During the revision of the safety valve, its spring is thoroughly washed and checked:

• external inspection to identify surface defects and check the perpendicularity of the ends of the spring axis, while the surface of the spring should not have mechanical damage, dents, nicks, scratches. It is strictly forbidden to throw the spring, hit it:
• three times compression by a static load that causes maximum deflection, while the spring should not have permanent deformation. The maximum deflection is considered to be such compression of the spring, in which the gap between the turns in the area of ​​the middle coil of the spring should not exceed 0.1 of the diameter of the spring bar.

3.3.5. The springs are compressed on a manual mechanical stand. The frame of the stand must be limited from the possible ejection of the springs during compression.

3.3.6. All parts of the valve should be cleaned of dirt by washing them in kerosene. After that, inspect to identify defects in the details of the nozzle and spool. Faulty ones should be replaced or restored by machining in order to restore the geometry and remove defective areas, followed by grinding. The lapping of the sealing surfaces of the spool and the nozzle must be carried out separately and especially carefully with special lappings made of cast iron.

3.3.7. The sealing surfaces after grinding them must have a surface that ensures the tightness of the valve seal.

3.3.8. When assembling the safety valve, make sure that the parts of the safety valve are assembled correctly. Before adjusting the spring set pressure, you need to make sure that the spindle does not stick in the guides.

3.3.9. After revision and adjustment, the valve must be sealed, on lever valves the protective cover is sealed.

3.3.10. Each safety valve must be affixed with a 150 x 70 mm metal plate indicating the name of the valve, the pressure to which the valve is set and the date of the next adjustment.

3.3.11. A technical data sheet must be drawn up for each safety valve. The results of the revision and adjustment of the safety valve are recorded in the technical passport.

4.Requirements for labor protection in emergency situations.

4.1. During an accident, the employee must:

• in the event of a fire, immediately stop work, report a fire by phone, name the address of the facility, the place of the fire, and also give your last name, and proceed to extinguish the fire using the available fire extinguishing equipment;
• in case of an accident, first aid must be provided to the victim in accordance with the "Instructions for the provision of first aid first aid in case of accidents, call ambulance and report the incident to the immediate supervisor or head of the service. The place of the accident should be kept unchanged, if this does not endanger the workers and does not lead to an accident.

4.2. Upon detection emergency, expressed in false actuation of the valve and pressure release through the drainage, the employee must:

• report the malfunction to the person responsible for the management of gas hazardous work;
• by order of the person responsible for the management of gas hazardous work, make the necessary shutdowns to cut off the equipment on which the safety valve is installed;
• at the direction of the person responsible for the management of gas hazardous work, after taking the necessary safety measures, proceed with the dismantling, repair and adjustment of the safety valve.

5. Labor protection requirements upon completion of work.

5.1. After completing the installation, repair or maintenance of the safety valve, the personnel must:

• tidy up the workplace, clean the equipment from contamination;
• remove tools and fixtures;
• hand over the workplace, fixtures, tools and protective equipment to the work manager;
• clean and put special clothes in a special place;
• take the necessary personal hygiene measures.

5.2. Upon completion of the work, the person responsible for their implementation together with the shift dispatcher must check the quality of their performance, the presence of seals, information plates.

5.3. Check the filling of the technical passport for the safety valve.

5.4. Draw up a safety valve inspection report indicating the setting value, the date of the next valve inspection.

5.5 The work manager, after putting the equipment into working condition, must make a note about the time the work was completed in the work permit.