Checking the serviceability of safety valves. Adjustment of safety devices for operation at a given pressure

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 checking and adjusting safety valves SI-TPA-200-64 manufactured by the Design Bureau pipe fittings 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, turning of sealing surfaces, replacement of running gear parts, etc.), in case of replacement of the spring. 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 should operate when 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 load is insufficient, an additional load 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 timing of verification safety devices 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 invalidate 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 the "Instruction for the organization of operation, the 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. Method for calculating the capacity of boiler safety valves, forms technical documentation on safety devices, the main 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 manifolds or outlet steam pipeline;

c) in hot water boilers- on the output 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 capacity of at least 50% of the total capacity of all valves must be installed on the outlet header 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 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. The total capacity of the safety devices installed on the boiler must be at least the hourly steam output of the boiler.

Calculation of the 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 an electrical circuit developed by the Teploelektroproekt Institute (Fig. 1), which provides for pressing the plate to the saddle at normal pressure in the boiler due to the constant flow of current around the winding of the closing electromagnet.

Fig.1. Wiring diagram 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 a backup DC source.

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 of locking devices on drains is 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. Compensation must be provided in the piping of the safety valves temperature elongations. 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. Subject to the above rules of transportation and storage, the presence of plugs and the absence of external damage, the valves can be installed in the 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 within the following limits environment:

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 activated. 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 IC 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 installed valves with the requirements is checked project documentation and section 3.

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

4.5. At CHPK reheat steam produced by ChZEM, the screw of the throttle valve built into the cover is turned out by 0.7-1.0 turns,

4.6. The condition of the 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 works on systems in which the steam pressure necessary for regulation will be created, on the safety devices themselves and on their exhaust pipes.

5.5.2. Check the reliability of disconnecting systems in which pressure will increase from adjacent systems.

5.5.3. Remove all unauthorized people 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.

Personnel should be well aware of the design features of the PU subject 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 to the position at which the valve will actuate.

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 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 rest of the 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 should be equipped with lifting mechanisms, well lit, have a compressed air supply. 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 be paid 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 work must be carried out in strict compliance with the requirements of fire safety regulations.

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 provide it automatic closing at a pressure of at least 95% of the working pressure in the boiler.

Annex 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;

Bandwidth 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 flow section of the valve, equal to smallest area free section in the flow part, mm (should be specified 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 be no more than 1.1 design pressure, MPa (kgf / cm 3);

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 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. Throughput - the maximum mass flow rate of steam that can be discharged through a fully open valve at actuation parameters.

Annex 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 has developed new design valve 1203-150/200-0, and for the possibility of replacing exhausted valves of the 530 series, which had a double-sided steam outlet, valve 1202-150/150-0 is produced.

Specifications produced by 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 placed.

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 on the side of the seat, connected to the drainage system, where the condensate accumulating in the valve body after it is actuated 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 impulse 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. The degree of shock damping in the GPK steam reheat is controlled 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 corner body, are installed only in 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"

Safety valves are activated when, for extraordinary reasons, too much pressure is created in the tank. If a safety valve is known to have tripped, then it, like the entire system, should be immediately and thoroughly inspected to determine the cause. In case of operation due to fire, the valve must be replaced.

Safety valves should be inspected each time the tank is filled, but at least once a year. If there is any doubt about the serviceability of the valve, it must be replaced.

Wear eye protection when inspecting pressure relief valves. Never look directly into the pressure relief valve connectors or place any body parts where they may be touched by the pressure relief valve. In some cases, use a flashlight and a small mirror when performing a visual inspection.

To properly inspect the relief valve, check:

1. Protective cap.Check the protective cap located on the valve or at the end of the pipeline outlet to see what it is protecting. Protective caps help protect the relief valve from possible failure due to rain, sleet, snow, ice, sand, dirt, pebbles, insects, debris, and other contaminants.REPLACE DAMAGED OR MISSING CAPS IMMEDIATELY, KEEP THEM IN STOCK.
2. Open drainage holes.Dirt, ice, paint, and other foreign particles can interfere with proper flow from the valve body.IF THE DRAINAGE HOLES CANNOT BE CLEANED, REPLACE THE VALVE.
3. Wear and corrosion of safety valve springs.Frequent exposure to strong concentrations saline solutions, industrial pollution, chemicals and road pollutants can cause metal parts to fail.IF COVERAGE ONRELIEF VALVE SPRING IS CRACKED OR SHUTTERED, REPLACE VALVE.
4. Mechanical damage.Icing and improper installation can cause mechanical damage.REPLACE VALVE IF THERE IS ANY SIGN OF DAMAGE.
5. Damage or reconfiguration.Safety valves are set at the factory and operate at a certain pressure.IF THERE IS ANY SIGN OF DAMAGE OR RESETTING, REPLACE VALVE.
6. Seal seat leakage.Check for leaks in the seat area using a non-aggressive leak detection solution.REPLACE VALVE IF THERE ARE ANY SIGNS OF LEAKING. Never use force to close a leaking safety valve or leave it in service. Forced shut-off can damage the valve and possibly rupture the tank or pipeline in which it is installed.
7. Corrosion and pollution. REPLACE VALVE IF THERE ARE ANY SIGNS OF CORROSION OR CONTAMINATION ON IT.
8. Moisture, foreign particles or contamination in the valve.Foreign materials such as paint, resin or ice in safety valve parts can prevent the valves from working properly. Grease that enters the valve body can harden or accumulate dirt, thus interfering with normal operation safety valve. DO NOT ALLOW LUBRICANT TO GET INTO THE VALVE BODY AND IF THERE IS ANY SIGN OF MOISTURE OR FOREIGN MATERIAL INSIDE, REPLACE THE VALVE.
9. Corrosion or leakage in tank connection.Check the reservoir-valve connection with a non-corrosive leak detection solution. REPLACE THE VALVE IF THERE ARE ANY SIGNS OF CORROSION OR LEAKAGE IN THE CONNECTION BETWEEN THE VALVE AND RESERVOIR.

ATTENTION: Never close the safety valve outlet. Any device that stops a properly functioning safety valve that discharges an over-filled or over-pressurized tank will impair its safe operation!

Replace relief valves at least once every 10 years.

The safe life of safety valves can vary greatly depending on the operating environment. Relief valves must be operated under a wide range of conditions. Corrosion, aging of the elastic seat disc and friction act with different intensity depending on the aggressiveness of the given medium and the intensity of use. Impurities in gases, misuse of the product and incorrect installation may shorten the safe life of the safety valve.

Predicting the safe life of safety valves cannot be accurate. The stresses a valve is subjected to will vary widely and affect its shelf life. In such cases, you can only follow the basic instructions. For example, Liquefied Gas Association Booklet S-1.1 Safety Device Standards - Tanks, section 9.1.1 requires all tanks filled with industrial motor fuels to receive new or unused safety valves after twelve years from the date of manufacture of the tank and every ten years of subsequent service life. The LPG specialist must observe and determine the safe service life of the safety valves in his area. Valve manufacturers can only issue safe lifetime recommendations in the industry.

ATTENTION: The period of use of the safety valve under normal conditions is 10 years from the date of manufacture. But it can be reduced depending on the operating conditions of the valve, then the valve will need to be replaced sooner than in 10 years. It is very important to inspect and maintain safety valves. Failure to properly inspect and maintain safety valves can result in personal injury or property damage.

All additional information can be found in:

1. CGA S-1.1 Safety Device Standards - Vessels, Section 9.1.1.
2. Catalog L-500 ECII.
3. ESI warning No. 8545-500.
4. Safety Document NPGA 306, Inspection and Maintenance of LPG Regulators and Valves and LPG Training Guides.
5. NFPA No. 58 Storage and Handling of Petroleum Gases.
6. NFPA No. 59, " Liquefied gases in gas plants.
7. ANSI K61.1 "Safety Requirements for Storage and Handling of Anhydrous Ammonia".

Requirements to protectivevalves

High reliability.

Ensuring work stability.

Fail-safe and timely opening of the valve in case of excess of the working pressure in the system.

Providing the valve with the required throughput.

Implementation of timely closing with the required degree of tightness in the event of a pressure drop in the system and maintaining the established degree of tightness with increasing pressure.

Safety valves with spring loading must be manufactured with nominal diameters of the inlet and outlet pipes (DN inlet/DN outlet) 25/40; 40/65; 50/80; 80/100; 100/150; 150/200; 200/300 and nominal pressure of the inlet pipe PN 1.6 MPa, PN 2.5 MPa.

At the pumping station, a special spring-loaded safety valve of the SPPK type, shown in Figure 6.15, has received the widest application.

The technological parameters of the valve are regulated by a ring screwed onto the nozzle. On the top of the ring there is a narrow flat belt. When screwing, the ring approaches the end plane of the plate. By adjusting the gap between the planes of the ring band and the end of the plate, it is possible to regulate the pressure of the full opening of the valve and the pressure of its closing in a wide range, i.e. purge amount.

Installationsafety valves

The installation of safety valves on vessels and apparatus operating under excessive pressure is carried out in accordance with the current regulatory and technical materials and safety rules. Quantity, design, location of valves, the need to install control valves and the direction of discharge are determined by the project.

In any case, the installation of the valve must be provided with free access for its maintenance, installation and dismantling.

When replacing a valve, the flow coefficient of the newly installed valve must not be lower than that of the one being replaced.

Safety valves must be installed in a vertical position in the highest part of the vessel in such a way that, in the event of opening, vapors and gases are removed from the vessel first.

On horizontal cylindrical apparatuses, the safety valve is installed along the length of the upper position of the generatrix, on vertical apparatuses - on the upper bottoms or in places of the greatest accumulation of gases.

If it is impossible to fulfill these requirements due to design features, then the safety valve can be installed on a pipeline or a special outlet in the immediate vicinity of the vessel, provided that there is no shut-off device between the valve and the vessel.

Figure 2

1 - body; 2 - nozzle; 3 - spool; 4 - stock; 5 - spring; 6 - screw

On column-type apparatuses with a large number of trays (more than 40), with the possibility of a sharp increase in their resistance due to a violation of the technological regime, which can lead to a significant difference between the pressure in the bottom and upper parts of the apparatus, it is recommended to install a safety valve in the bottom of the apparatus in the steam zone. cube phases.

The diameter of the fitting for the safety valve must not be less than the diameter of the inlet pipe of the valve.

When determining the cross section of connecting pipelines with a length of more than 1 m, it is necessary to take into account the value of their resistance.

The diameter of the outlet pipe of the valve must not be less than the diameter of the outlet fitting of the valve.

When combining the outlet pipes from several valves installed on one apparatus, the cross section of the collector must be at least the sum of the cross sections of the outlet pipes from these valves.

In the case of combining the outlet pipes of valves installed on several devices, the diameter of the common manifold is calculated from the maximum possible simultaneous discharge of the valves, determined by the project.

The riser, which discharges the discharge from the safety valve into the atmosphere, must be protected from atmospheric precipitation and at the lowest point have a drainage hole with a diameter of 20 - 50 mm for draining the liquid.

The direction of discharge and the height of the discharge riser are determined by the project and safety rules.

The combined collector, which serves for discharges from safety valves into the atmosphere, must be laid with a slope and at the lowest point have a drain with a diameter of 50 - 80 mm with a drain into a drainage tank. "Bags" on such pipelines are not allowed.

The selection of the working medium from the branch pipes and in the sections of the connecting pipelines from the vessel to the valve, on which safety valves are installed, is not allowed.

It is not allowed to install any locking devices, as well as fire fuses between the apparatus and the safety valve.

Heating, cooling, separation and neutralization devices can be installed after the valve. In this case, the total reset resistance should not exceed that specified in paragraph

The resistance of the discharge pipeline of the valve must be no higher than 0.5 kgf / cm 2, taking into account the installation of a separator, heating-cooling devices, neutralization, etc.

At an operating pressure of less than 1 kgf / cm 2, the resistance of the discharge system should not be higher than 0.2 kgf / cm 2.

On devices of continuously operating processes equipped with safety valves, the duration of the overhaul period of which is less than the overhaul period of the installation or workshop, backup safety valves with switching devices can be installed.

If the safety valve is removed for inspection from tanks for storing liquefied gas, or flammable liquids with a boiling point of up to 45 ° C, under pressure, a pre-prepared valve must be installed in its place. It is forbidden to replace the removed valve with a valve or a plug.

Adjustment

Adjustment of safety valves to the pressure of the beginning of opening - the setting pressure (cotton) is made on a special stand.

The set pressure is determined based on the operating pressure in the vessel, apparatus or pipeline.

Working pressure - the maximum excess pressure at which the vessel, apparatus or pipeline is allowed to operate. At operating pressure (P p) the safety valve is closed and provides the tightness class specified in the relevant documentation for the safety valve (GOST, TU).

The set pressure of the safety valve when the discharge is directed from it into a closed system with back pressure must be taken into account the pressure in this system and the design of the safety valve.

The value of the set pressure, the frequency of revision and verification, the installation site, the direction of discharges from safety valves are indicated in the set pressure sheet. The statement is compiled for each installation (workshop) by the head and mechanic (senior mechanic) of the installation (workshop), agreed with the technical supervision service, chief mechanic and approved by the chief engineer of the enterprise.

Each valve body shall be securely affixed with a stainless steel or aluminum plate embossed with:

a) installation site - shop number, conditional name of the installation or its number, designation of the apparatus according to the technological scheme;

b) set pressure - P mouth;

c) working pressure in the apparatus - P p.

The frequency of revision and verification.

On vessels, apparatus and pipelines of oil refining and petrochemical industries, revision and testing of safety valves should be carried out on a special stand with the valve removed. At the same time, the frequency of inspection and revision is established based on the operating conditions, the corrosiveness of the environment, operating experience and should be at least every:

a) for continuously operating technological production:

24 months - on ELOU vessels and apparatuses, vessels and apparatuses working with media that do not cause corrosion of valve parts, in the absence of the possibility of freezing, sticking and polymerization (clogging) of valves in working condition;

12 months - on vessels and apparatuses working with media that cause the corrosion rate of the material of the valve parts up to 0.2 mm / year, in the absence of the possibility of freezing, sticking and polymerization (clogging) of valves in working condition;

6 months - on vessels and apparatus operating with media that cause the corrosion rate of the material of the valve parts to be more than 0.2 mm/year;

4 months - on vessels and apparatus operating in conditions of possible coking of the medium, formation of a solid precipitate inside the valve, freezing or sticking of the shutter;

b) 4 months - for intermediate and commercial storage tanks for liquefied oil gases, as well as flammable liquids with a boiling point up to 45 ° C;

c) for periodically operating productions:

6 months - subject to the exclusion of the possibility of freezing, sticking or clogging of the valve with the working medium;

4 months - on vessels and apparatuses with media, in which coking of the medium, formation of a solid precipitate inside the valve, freezing or sticking of the shutter is possible.

The need and timing for checking valves in working condition are determined by the chief engineer of the enterprise.

The value of the corrosion rate of the valve parts is determined based on the operating experience of the valves, the results of a survey of their technical condition during the revision or testing of samples of similar steel under operating conditions.

Checking and revision of safety valves is carried out according to the schedule, which is drawn up in accordance with clause 2.3.1. annually for each workshop (installation), is agreed with the technical supervision service, the chief mechanic and approved by the chief engineer.

The chief engineer of the enterprise is given the right, under his responsibility, in certain technically justified cases, to increase the period of periodic revision of safety valves, but not more than 30% of the established schedule.

Each case of deviation from the audit schedule is documented by an act, which is approved by the chief engineer of the plant.

Valves received from the manufacturer or from reserve storage, immediately before installation on vessels and apparatus, must be adjusted on the bench to the set pressure. After the expiration of the conservation period specified in the passport, the valve must be inspected with a complete disassembly.

Transportation and storage

To the place of installation or repair, safety valves are transported in a vertical position on wooden stands.

When transporting valves, dropping them from a platform of any type of transport or installation site, careless tilting, and installing valves on the ground without linings is strictly prohibited.

Safety valves received from the factory, as well as used safety valves, are stored in a vertical position, packed on linings, in a dry, closed room. The spring must be loosened, the inlet and outlet fittings must be closed with wooden plugs.

Responsible for operation, storage and repair.

The head of the installation (shop) is responsible for the installation of the valve after the revision on the relevant devices, the safety of the seals, the timely revision of the valve, the correct maintenance and preservation of technical documentation, as well as the storage of valves in the conditions of the process shop.

Responsible for the storage of valves received for revision, quality audit and repair, as well as the use of appropriate materials during repairs, is the master (head) of the repair shop section.

Responsible for the acceptance of safety valves from repair is the mechanic of the installation (workshop) or the mechanical engineer of the technical supervision department.

Responsible for the transportation of safety valves to the installation site is the mechanic of the installation (workshop). Responsible for the installation is the installation contractor (foreman, head of the repair site).

Revision and repair of safety valves

Revision. Revision of safety valves includes disassembly of the valve, cleaning and troubleshooting of parts, testing of the body for strength, testing of valve connections for tightness, checking the tightness of the shutter, testing the spring, adjusting the set pressure.

Revision of safety valves is carried out in a specialized repair shop (section) on special stands.

Safety valves dismantled for revision must be steamed and washed.

For valves that have been audited and repaired, an act is drawn up, which is signed by the foreman of the repair shop (section), the contractor, the mechanic of the facility where the valves are installed, or the mechanical engineer of the technical supervision department.

Disassembly

The valve is disassembled in the following sequence (Fig. 5.1. Appendix 1):

remove cap 1 mounted on studs above the adjusting screw;

release the spring from tension, for which loosen the lock nut of the adjusting screw 2 and unscrew it to the upper position;

evenly loosen and then remove the nuts from the studs 4 holding the cover 3. Remove the cover. Before removing the cover, apply marks on the flanges of the cover and body or cover, separator and body in case the valve is made with a separator;

remove the spring with support washers 6 and place it carefully in a safe place. It is strictly forbidden to throw the spring, hit it, etc.;

remove spool 7 from the valve body together with the stem and partition, carefully put it in a safe place to avoid damage to the sealing surface of the spool and deflection of the stem.

If there is a separator in the valve, first remove the separator from the body, releasing it from its fastening on the body;

release the locking screws 8 of the adjusting sleeves 9 and 10;

release the guide bush 11 and remove it from the body together with the adjusting bush 9. If the guide bush is firmly seated in the seat of the body, tap the valve body near the guide bush with a hammer to facilitate its release from the body;

remove the adjusting sleeve 10 and the valve nozzle 12. If the sealing surface of the nozzle is slightly damaged, it is recommended that the nozzle be restored without unscrewing the latter from its socket in the body.

Assembly

The assembly of the valve is started after cleaning, revision and restoration of all its parts. The assembly sequence is as follows (Fig. 5.1. Appendix 1):

install the nozzle 12 in the valve body 5, check with kerosene for tightness of the connection between the nozzle and the body; install the adjusting sleeve 10 of the nozzle;

install the guide sleeve 11 with the gasket and the upper adjusting sleeve into the valve body. The hole for the flow of medium in the guide sleeve must be turned towards the discharge pipe of the valve;

install spool 7, connected to the stem, into the guide sleeve;

install partition 13 and separator;

put the spring together with the support washers 6 on the rod;

place the gasket on the adjacent surface of the body and lower the cover onto the body, being careful not to damage the stem. Then center the cover on the boss of the guide bush and fasten it evenly to the studs. Checking the correct installation of the cover is determined by a uniform gap around the circumference between the cover flange and the body.

Before adjusting the spring, you need to make sure that the stem does not stick in the guides. In cases where the spring is freely located in the cover, the stem must rotate freely by hand.

If the spring has a height slightly greater than the height of the cover, and is clamped by it after installation, the check is also made by turning the rod around the axis. The uniform force obtained during the rotation of the stem around its axis will show the correct assembly of the valve;

Create a preliminary tension of the spring with the adjusting screw 2 and finally work it out on the stand;

Install cap 1, tighten the valve nuts.

Figure 2 - Scheme of installation of adjusting bushings.

1 - guide sleeve; 2 - spool; 3 - nozzle; 4 - lower adjusting sleeve; 5 - top adjusting sleeve.

To operate the valve on gas, the adjusting sleeves are installed as follows:

the lower adjusting sleeve 4 must be installed in the uppermost position with a gap between the end face of the sleeve and the valve spool within 0.2 ¸ 0.3 mm;

the upper adjusting sleeve 5 is pre-installed flush with the outer edge of the spool 2; final installation is made in the uppermost position, at which a sharp pop occurs during adjustment on the stand.

When the valve is operating on liquid, the lower adjusting sleeve is set in the lowest position, the upper adjusting sleeve is set in the same way as indicated above.

As a control medium for valves operating on vapor-gas products, air, nitrogen are used; for valves operating on liquid media - water, air, nitrogen.

The control medium must be clean, without mechanical impurities. The presence of solid particles in the test medium can cause damage to the sealing surfaces.

The valves are adjusted to the set pressure by means of an adjusting screw by tightening or loosening it. After each adjustment of the spring, it is necessary to fix the adjusting screw with a lock nut.

Measurement of pressure during adjustment is carried out using a pressure gauge of accuracy class 1 (GOST 8625-69).

The valve is considered adjusted if it opens and closes with a clean sharp pop at a given pressure and using air as a control medium.

When adjusting the valve on liquids, it opens without popping.

Tests

The tightness of the valve plug is checked at operating pressure.

The tightness of the shutter and the connection of the nozzle with the body after adjustment is checked as follows: water is poured into the valve from the discharge flange, the level of which should cover the sealing surfaces of the shutter. The required air pressure is created under the valve. The absence of bubbles within 2 minutes indicates the complete tightness of the shutter. When bubbles appear, the tightness of the connection between the nozzle and the body is checked.

To determine the tightness of the connection between the nozzle and the body, lower the water level so that the valve is above the water level. The absence of bubbles on the surface of the water within 2 minutes indicates the complete tightness of the connection.

If the valve does not have tightness in the gate or in the connection between the nozzle and the body, it is rejected and sent for additional revision and repair.

The test of detachable connections of the valve for tightness is carried out in each revision by supplying air to the discharge pipe.

Valves of the PPK and SPKK types are tested with a pressure of 1.5 R at the discharge pipe flange with a holding time of 5 minutes, followed by a decrease in pressure to R y and washing of the detachable connections. Valves with a diaphragm - pressure 2 kgf / cm 2, valves with a bellows - pressure 4 kgf / cm 2.

Hydraulic testing of the inlet part of the valves (inlet pipe and nozzle) is carried out with a pressure of 1.5 R at the inlet flange with a holding time of 5 minutes, followed by a decrease in pressure to R y and inspection.

The frequency of hydrotesting is established by the technical supervision service of the enterprise, depending on the operating conditions, the results of the audit, and should be at least 1 time in 8 years.

The results of valve testing are recorded in the inspection and repair report and the operational certificate.

Valves that have been audited and repaired are sealed with a special seal kept by the repairman. The locking screws of the adjusting bushings, detachable connections body-cover and cover-cap are subject to obligatory sealing.

Troubleshooting and Troubleshooting

Leakage of the medium - the passage of the medium through the valve plug at a pressure lower than the set pressure. Causes that cause an environment leak can be:

the delay on the sealing surfaces of foreign substances (scale, processed products, etc.) is eliminated by blowing the valve;

damage to the sealing surfaces is restored by lapping or turning, followed by lapping and checking for tightness. Lapping eliminates minor damage to the sealing surfaces of the nozzle and spool.

Restoration of sealing surfaces with a damage depth of 0.1 mm or more should be carried out by mechanical processing in order to restore the geometry and remove defective areas, followed by lapping. The repair dimensions of the sealing surfaces of the spools and nozzles are shown in fig. 3.2. The dotted line indicates the configuration of the sealing surface after repair, the numbers indicate the allowable values ​​for which the sealing surfaces can be processed during repair;

misalignment of valve parts due to excessive load - check the intake and exhaust lines, eliminate the load. Make a constriction of the studs;

spring deformation - replace the spring;

opening pressure too low - re-adjust the valve;

poor-quality assembly after repair - eliminate assembly defects.

Pulsation is the rapid and frequent opening and closing of a valve. This may happen for the following reasons:

excessively large valve capacity - it is necessary to replace the valve with a valve of a smaller diameter or limit the lift height of the spool;

narrowed cross-section of the inlet pipeline or branch pipe of the device, which causes the valve to “starve” and thereby causes pulsation - install inlet pipes with a cross-sectional area not less than the area of ​​​​the inlet section of the valve.

Vibration . Tapered and tight radii stacks create high back pressure at the outlet and can cause valve vibration. The elimination of this disadvantage is achieved by installing exhaust pipes with a passage not less than the nominal passage of the valve outlet pipe and with a minimum number of bends and turns.

Seizure of moving parts can occur when the valve is not properly assembled or installed due to misalignment and the appearance of lateral forces on the movement parts (spool, stem). Seizures must be removed by machining, and the causes that cause them are eliminated by a qualified assembly.

The valve does not open at the set set pressure:

the spring is incorrectly adjusted - the spring must be adjusted to the specified pressure;

the stiffness of the spring is high - install a spring of lesser stiffness;

increased friction in the guides of the spool - eliminate distortions, check the gaps between the spool and the guide.

Despite the constant warnings of buyers of electric heating equipment that such devices must be installed strictly according to the instructions without ignoring all the components, it still happens quite often that the safety valve for the boiler is not installed at all.

Safety valve device

The safety device consists of two parts:

check valve

blast valve

They are both placed under one body and each performs its function. The non-return valve prevents excess water (which results from heating the water) from flowing back into the system. The second valve, which is also subversive, works only if the threshold pressure value is exceeded, usually 7-8 bar.

Based on this information, it is clear that in the case emergency or sudden increase in pressure, the blast valve will release excess water and prevent damage to the electric heater. It also has a lever for forced descent of water, this is necessary when repairing or dismantling the boiler.

Although every water heater has thermostats that regulate the temperature, they can break, so a system that has a working safety device is safe and will serve you for years to come.

There are also situations with a lack of water in the system, the correct operation of the non-return valve, which is installed on the water heater, is very important here, because all the water will come out of the water heater, and if the thermostat is faulty, the empty boiler heats up very quickly and the heaters inside it will burn out.

Water leak from the valve

A water leak is a common occurrence for a safety device, this indicates its proper operation. But if the water is flowing too fast or constantly, then it may indicate one of these problems:

Spring stiffness incorrectly adjusted;

Too much high pressure in system;

If you have nothing to do with the last problem, then the spring rate can only be incorrectly adjusted in case of thoughtless handling of the regulators.

Jumps in the system can be eliminated with the help of another valve - a pressure reducing valve, it is installed before the safety valve and provides a stable pressure supply to the water heater.

No water dripping from safety valve

If, after installing the boiler, it did not work even once, even at maximum heating, it is worth thinking about the serviceability of the safety device. It is not worth changing it right away, perhaps excess water is leaking through a faulty mixer, or damage to the tubes.

Sometimes the boiler does not heat up to high temperatures, not higher than 40 degrees. In this case, the safety valve for the water heater does not work due to insufficient pressure inside the boiler, this is normal.

Choosing the Right Model

Usually, a safety device of the desired model is included with the boiler. But if it is not there, it is faulty, or you replace it after some time of operation of the water heater, then you will have to choose the right one yourself.

The main parameter after the thread (the size is very easy to choose, usually 1/2 inch) is the working pressure. From correct selection this parameter will depend on the correct and safe operation of the boiler. Required pressure indicated in the instruction manual that comes with each water heater.

Problems that may arise as a result wrong selection two safety devices:

Constant leakage from the device due to the choice of a lower operating pressure indicator than necessary;

The device will not work at all if a value greater than necessary is selected, such a safety valve will not save in case of an emergency;

Correct installation of the safety device

1. First, disconnect the boiler from the mains and drain the water from it.

2. Install the device for serving cold water at the heater inlet. We pack it in the usual way and connect cold water to the second side.

There is an arrow on the valve body that indicates the direction of the water, when installed, it must point to the boiler.

3. We connect the branch pipe that comes from the blast valve with the sewer. Sometimes it is bought transparent in order to observe the health of the protective valve.

4. After connecting the boiler completely, it is worth checking it. To do this, we fill the tank by prematurely opening the valve to release air.

5. Then, after collecting water, close the tap and turn on the boiler.

6. We monitor all joints for the presence of water and look at the performance of the safety valve. If a leak is detected, the inlet and outlet taps are closed, and desired area repackaged.

Can the safety valve be replaced with a check valve?

By no means, the safety device has inside it check valve, but he is not alone there, and the disruptive valve must not be missed. If the check valve prevents water from leaking into the system and, roughly speaking, saves you money, then the blast valve prevents the boiler from increasing the pressure inside to critical.

The boiler, which has a reverse valve instead of a safety valve, is a time bomb. The huge pressure inside the water heater will not destroy the boiler until you open the faucet. When the tap is opened, the pressure inside the boiler decreases, but the water, heated to a temperature higher than 100 degrees, immediately turns into steam, destroys the walls of the boiler and breaks out.

This is a rather strong explosion, which is accompanied not only by fragments of the hull, but also by hot steam and water. Take care of not only yourself, but also the people around you.

findings

Follow the instructions for use, even such a small-looking device makes your life safer. The safety device is very important element and it is strictly forbidden to operate the boiler without it. Always keep an eye on the operation of the installed protective device, water flows from it when it is needed or not. All these factors will save you time, money and health.