Care

Steam engine safety valve. Safety valves with pressure control setting Steam safety valve

STATE STANDARD OF THE USSR UNION

SAFETY VALVES
STEAM AND WATER BOILERS

TECHNICAL REQUIREMENTS

GOST 24570-81

(ST SEV 1711-79)

USSR STATE COMMITTEE ON STANDARDS

STATE STANDARD OF THE USSR UNION

SAFETY VALVES FOR STEAM AND WATER BOILERS

Technicalrequirements

Safety valves of stream and hot-water boilers.
Technical requirements

GOST
24570-81*

(ST SEV 1711-79)

By Decree of the USSR State Committee on Standards dated January 30, 1981 No. 363, the introduction date was established

from 01.12.1981

Verified in 1986. By Decree of the State Standard of June 24, 1986 No. 1714, the validity period was extended

until 01/01/92

Failure to comply with the standard is punishable by law

This standard applies to safety valves installed on steam boilers with absolute pressure above 0.17 MPa (1.7 kgf/cm2) and hot water boilers with water temperatures above 388 K (115 ° WITH).

The standard fully complies with ST SEV 1711-79.

The standard establishes mandatory requirements.

1. GENERAL REQUIREMENTS

1.1. To protect boilers, safety valves and their auxiliary devices are allowed that meet the requirements of the “Rules for the design and safe operation of steam and water-heating boilers” approved by the USSR State Mining and Technical Supervision.

(Changed edition, Amendment No. 1).

1.2. The design and materials of safety valve elements and their auxiliary devices must be selected depending on the parameters of the working environment and ensure reliability and correct operation under operating conditions.

1.3. Safety valves must be designed and adjusted so that the pressure in the boiler does not exceed the operating pressure by more than 10%. An increase in pressure is allowed if this is provided for in the boiler strength calculations.

1.4. The design of the safety valve must ensure free movement of the moving elements of the valve and exclude the possibility of their release.

1.5. The design of safety valves and their auxiliary elements must exclude the possibility of arbitrary changes in their adjustment.

1.6. Each safety valve or, by agreement between the manufacturer and the consumer, a group of identical valves intended for one consumer, must be accompanied by a passport and operating instructions. The passport must comply with the requirements of GOST 2.601-68. The section “Basic technical data and characteristics” should contain the following data:

name of the manufacturer or its trademark;

year of manufacture;

valve type;

nominal diameter at the inlet and outlet of the valve;

design diameter;

calculated cross-sectional area;

type of environment and its parameters;

characteristics and dimensions of the spring or load;

steam consumption coefficienta , equal to 0.9 coefficient obtained on the basis of tests;

permissible back pressure;

opening start pressure value and permissible opening start pressure range;

characteristics of the materials of the main elements of the valve (body, disc, seat, spring);

valve type test data;

catalog code;

conditional pressure;

permissible operating pressure limits for the spring.

1.7. The following information must be marked on a plate attached to the body of each safety valve, or directly on its body:

name of the manufacturer or its trademark;

serial number according to the manufacturer's numbering system or series number;

year of manufacture;

valve type;

design diameter;

steam consumption coefficienta;

opening start pressure value;

conditional pressure;

nominal diameter;

flow indicator arrow;

body material for fittings made of steel with special requirements;

designation of the main design document and symbol of the product.

The location of the marking and the size of the markings are established in technical documentation manufacturer.

1.6, 1.7.(Changed edition, Change № 1).

2. REQUIREMENTS FOR DIRECT ACTING SAFETY VALVES

2.1. The design of the safety valve must include a device for checking the proper operation of the valve during boiler operation by forcing the valve to open.

The possibility of forced opening must be ensured at 80% of the opening pressure.

2.1.

2.2. The pressure difference between full opening and the beginning of opening of the valve should not exceed the following values:

15% of the opening start pressure - for boilers with an operating pressure not higher than 0.25 MPa (2.5 kgf/cm 2);

10% of the opening pressure - for boilers with operating pressure above 0.25 MPa (2.5 kgf/cm2).

2.3. Safety valve springs must be protected from unacceptable heat and direct impact working environment.

When the valve is fully opened, the possibility of mutual contact of the spring coils must be excluded.

Design spring valves should exclude the possibility of tightening the springs beyond the set value due to the highest operating pressure for a given valve design.

2.3. (Changed edition, Amendment No. 2).

2.4. The use of valve stem seals is not permitted.

2.5. In the safety valve body, in places where condensate may accumulate, a device must be provided for its removal.

2.6. (Excluded , Change No. 2).

3. REQUIREMENTS FOR SAFETY VALVES CONTROLLED BY AUXILIARY DEVICES

3.1. The design of the safety valve and auxiliary devices must exclude the possibility of unacceptable shocks when opening and closing.

3.2. The design of safety valves must ensure that the function of protection against overpressure is maintained in the event of failure of any control or regulating body of the boiler.

3.3. Electrically driven safety valves must be equipped with two power sources independent of each other.

IN electrical diagrams, where the disappearance of energy causes a pulse to open the valve, a single source of electrical power is allowed.

3.4. The safety valve must be designed so that it can be controlled manually and necessary cases remote control.

3.5. The valve design must ensure that it closes at a pressure of at least 95% of the operating pressure in the boiler.

3.6. The diameter of the straight-through pulse valve must be at least 15 mm.

The internal diameter of the impulse lines (input and outlet) must be at least 20 mm and not less than the diameter of the output fitting of the impulse valve.

Impulse and control lines must have condensate drainage devices.

The installation of shut-off devices on these lines is not permitted.

It is permissible to install a switching device if, in any position of this device impulse line will remain open.

3.7. For safety valves controlled by auxiliary impulse valves, it is possible to install more than one impulse valve.

3.8. Safety valves must be operated in conditions that do not allow freezing, coking and corrosive effects of the environment used to control the valve.

3.9. When using an external power source for auxiliary devices, the safety valve must be equipped with at least two independently operating control circuits so that if one of the control circuits fails, the other circuit will provide reliable operation safety valve.

4. REQUIREMENTS FOR SUPPLY AND DISCHARGE PIPELINES OF SAFETY VALVES

4.1. It is not allowed to install shut-off devices on the inlet and outlet pipelines of safety valves.

4.2. The design of safety valve pipelines must provide the necessary compensation for temperature expansion.

The fastening of the body and pipelines of safety valves must be designed taking into account static loads and dynamic forces that arise when the safety valve is activated.

4.3. The supply pipelines of the safety valves must have a slope along their entire length towards the boiler. In the supply pipelines, sudden changes in wall temperature should be excluded when the safety valve is activated.

4.4. The pressure drop in the supply pipeline to direct-acting valves should not exceed 3% of the pressure at which the safety valve begins to open. In the supply pipelines of safety valves controlled by auxiliary devices, the pressure drop should not exceed 15%.

When calculating bandwidth valves, the indicated pressure reduction in both cases is taken into account.

4.4. (Changed edition, Amendment No. 2).

4.5. The working medium must be drained from the safety valves to a safe place.

4.6. Discharge pipelines must be protected from freezing and have a device for draining condensate.

Installation of shut-off devices on drains is not permitted.

4.6.(Changed edition, Amendment No. 2).

4.7. The internal diameter of the outlet pipe must be no less than the largest internal diameter of the outlet pipe of the safety valve.

4.8. The internal diameter of the outlet pipe must be designed so that at a flow rate equal to the maximum capacity of the safety valve, the back pressure in its outlet pipe does not exceed the maximum back pressure established by the safety valve manufacturer.

4.9. The capacity of safety valves should be determined taking into account the resistance of the sound muffler; its installation should not cause disruption to the normal operation of safety valves.

4.10. A fitting must be provided in the area between the safety valve and the sound muffler for installing a pressure measuring device.

5. FLOW CAPACITY OF SAFETY VALVES

5.1. The total capacity of all safety valves installed on the boiler must satisfy the following conditions:

for steam boilers

G1+G2+…Gn³ D;

for economizers disconnected from the boiler

for hot water boilers

n- number of safety valves;

G1,G2,Gn- throughput of individual safety valves, kg/h;

D- rated output of the steam boiler, kg/h;

Increase in enthalpy of water in the economizer at the nominal boiler output, J/kg (kcal/kg);

Q- nominal thermal conductivity of the hot water boiler, J/h (kcal/h);

g- heat of evaporation, J/kg (kcal/kg).

Calculation of the capacity of safety valves of hot water boilers and economizers can be carried out taking into account the ratio of steam and water in the steam-water mixture passing through the safety valve when it is activated.

5.1. (Changed edition, Amendment No. 2).

5.2. The capacity of the safety valve is determined by the formula:

G = 10B 1 × a× F(P 1 +0.1) - for pressure in MPa or

G= B 1 × a× F(P 1 + 1) - for pressure in kgf/cm 2,

Where G- valve capacity, kg/h;

F- design cross-sectional area of the valve, equal to smallest area free cross-section in the flow part, mm 2 ;

a- steam flow coefficient, related to the cross-sectional area of the valve and determined in accordance with clause 5.3 of this standard;

R 1 - maximum overpressure in front of the safety valve, which should be no more than 1.1 working pressure, MPa (kgf/cm2);

IN 1 - coefficient taking into account the physico-chemical properties of steam at operating parameters in front of the safety valve. The value of this coefficient is selected according to the table. 1 and 2.

Table 1

Coefficient values IN 1 for saturated steam

R 1, MPa (kgf/cm2)

R 1, MPa (kgf/cm2)

R 1, MPa (kgf/cm2)

Table 2

Coefficient values IN 1 for superheated steam

R 1, MPa (kgf/cm2)	At steam temperaturetn, ° WITH
R 1, MPa (kgf/cm2)
0,2 (2)	0,480	0,455	0,440	0,420	0,405	0,390	0,380	0,365	0,355
1 (10)	0,490	0,460	0,440	0,420	0,405	0,390	0,380	0,365	0,355
2 (20)	0,495	0,465	0,445	0,425	0,410	0,390	0,380	0,365	0,355
3 (30)	0,505	0,475	0,450	0,425	0,410	0,395	0,380	0,365	0,355
4 (40)	0,520	0,485	0,455	0,430	0,410	0,400	0,380	0,365	0,355
6 (60)		0,500	0,460	0,435	0,415	0,400	0,385	0,370	0,360
8 (80)		0,570	0,475	0,445	0,420	0,400	0,385	0,370	0,360
16 (160)			0,490	0,450	0,425	0,405	0,390	0,375	0,360
18 (180)				0,480	0,440	0,415	0,400	0,380	0,365
20 (200)				0,525	0,460	0,430	0,405	0,385	0,370
25 (250)					0,490	0,445	0,415	0,390	0,375
30 (300)					0,520	0,460	0,425	0,400	0,380
35 (350)					0,560	0,475	0,435	0,405	0,380
40 (400)					0,610	0,495	0,445	0,415	0,380

or determined by the formula for pressure in MPa

for pressure in kgf/cm 2

Where TO- adiabatic index equal to 1.35 for saturated steam, 1.31 for superheated steam;

R 1 - maximum excess pressure in front of the safety valve, MPa;

V 1 - specific volume of steam in front of the safety valve, m 3 /kg.

The formula for determining valve capacity should only be used if: ( R 2 +0,1)£ (R 1 +0,1)b kr for pressure in MPa or ( R 2 +1)£ (R 1 +1)b kr for pressure in kgf/cm 2, where

R 2 - maximum excess pressure behind the safety valve in the space into which steam flows from the boiler (when escaping into the atmosphere R 2 = 0 MPa (kgf/cm2);

b kr - critical pressure ratio.

For saturated steam b kr =0.577, for superheated steam b cr =0.546.

5.2. (Changed edition, Amendment No. 2).

5.3. Coefficient a taken equal to 90% of the value obtained by the manufacturer based on the tests performed.

6. CONTROL METHODS

6.1. All safety valves must be tested for strength, tightness, and tightness of gland connections and sealing surfaces.

6.2. The scope of valve testing, their order and control methods must be established in the technical specifications for valves of a specific standard size.

Safety valve

Installation conditions:

operating pressure: 40.5 bar

Design parameters:

suction side: PN/CL CL 600,
calc. pressure: 58.97 bar

calc. pressure:6.55 bar
corrosion thickness: body - 0.1 mm, seat/tips: 0.1 mm

hole diameter: 102.61 mm
inlet x outlet (DN): 6” x 8”
set pressure: 47.58 bar

Outlet pressure: 53.351 bar

Wednesday:

medium: water
testing temperature at p0: 267.94 °C
molecular weight: 18.02

superheated steam:

compressibility factor: 0.915
specific volume: 0.05099 m³/kg
adiabatic index: 1.28

required capacity: 189900 kg/h

calculated area: 79.68 (cm²)
useful capacity: 197076 kg/h
reaction force: 60535 N
noise level: 155 dB

Materials:

Safety valve

Installation conditions:

operating pressure: 40.5 bar
Max. ambient temperature Wednesday: -49/40 °C

Design parameters:

design temperature: -50… +400 °С
suction side: PN/CL CL 600,
calc. pressure: 58.97 bar
discharge side: PN/CL CL 150,
calc. pressure: 6.55 bar

Dimensions, type and technical characteristics:

hole diameter: 102.61 mm
inlet x outlet (DN): 6” x 8”
set pressure: 48.56 bar
flanges, suction x outlet: ANSI 600 RF x ANSI 150 RF
performance factor for gas and steam: 0.975
Outlet pressure: 54.429 bar
Overpressure/difference: 10/10 (% of p)
Flow coefficient for gas and steam: Kd=0.975

Wednesday:

medium: water
testing temperature at p0: 269.24 °C
molecular weight: 18.02

superheated steam:
discharge temperature: 371 °C
compressibility factor: 0.914
specific volume: 0.04991 m³/kg
adiabatic index: 1.28

Valve performance characteristics:

required capacity: 193700 kg/h
selected area: 82.69 (cm²)
calculated area: 79.62 (cm²)
useful capacity: 201168 kg/h
reaction force: 61830 N
noise level: 156 dB

Materials:

Safety valve

Installation conditions:

operating pressure: 40.5 bar
Max. ambient temperature Wednesday: -49/40 °C

Design parameters:

design temperature: -50… +400 °С
suction side: PN/CL CL 600,
calc. pressure: 58.97 bar
discharge side: PN/CL CL 150,
calc. pressure: 6.55 bar
corrosion thickness: body - 0.1 mm, seat/tips - 0.1 mm

Dimensions, type and technical characteristics:

valve type: 281-I
hole diameter: 102.61mm
inlet x outlet (DN): 6” x 8”
set pressure: 46.6 bar
flanges, suction x outlet: ANSI 600 RF x ANSI 150 RF
performance factor for gas and steam: 0.975
Outlet pressure: 52.273 bar
Overpressure/difference: 10/10 (% of p)
Flow coefficient for gas and steam: Kd=0.975

Wednesday:

medium: water
testing temperature at p0: 266.65 °C
molecular weight: 18.02
compressibility factor: 0.915
superheated steam:
discharge temperature: 371 °C
compressibility factor: 0.915
specific volume: 0.05206 m³/kg
adiabatic index: 1.28

Valve performance characteristics:

required capacity: 186000 kg/h
selected area: 82.69 (cm²)
calculated area: 79.66 (cm²)
useful capacity: 193094 kg/h
reaction force: 59228 N
noise level: 156 dB

Sometimes unpleasant circumstances arise when the heating system malfunctions and the pressure begins to fluctuate. If the pressure is not regulated, the consequences can be dangerous. To prevent this from happening, heating system and feeding system hot water should be equipped with safety valves. What they are and how they work – we will tell you in this material.

Safety valve in the heating system performs protective function in order to prevent high pressure. This is especially important for steam boilers.

Blood pressure rises most often due to the following reasons:

refusal automatic systems pressure adjustment;
a sharp increase in ambient temperature and the appearance of steam.

Safety products are mainly of two types:

spring;
lever-load.

In lever-load structures, the action of pressure on the spool is counteracted by a load, its force is transmitted through the lever to the rod. It moves along the length of the lever, and in this way you can adjust the force of pressure of the spool against the seat. Then it opens when the working medium begins to press on the lower part of the spool with a force greater than the force of the lever pressure and the water leaves through the pipe.

And the spring safety units work using an electromagnetic drive. A spring exerts pressure on the spool rod, and adjustment occurs by changing the degree of compression of the spring.

Small heating systems are best combined with spring products; their advantages in this case are as follows:

compactness;
the setting can only be changed when using the tools;
the spool rod may have different positions;
Possibility of combination with other products.

According to the principle of operation, safety valves are divided into the following:

Safety valve direct action can open only under pressure from the working medium, indirectly - under the influence of a pressure source.

And according to the type of lifting the constipation, the devices are:

low-lift;
medium-lift;
full lift.

Manufacturing materials

Safety products can be made from the following materials:

brass;
steel;
galvanized steel;
stainless steel

Features of the mechanism and design

Safety brass coupling valve for the boiler is equipped with threads on both sides, with entrance side there is a gasket. The mechanism is spring-loaded. External pressure can increase the blockage. After assembling the structure, it is pressurized, so the valve of this type very reliable and affordable.

Safety shut-off valve also can work in sewer system to protect against backflow pressure.

Features of three-way valves

The purpose and operating principle of three-way safety valves is somewhat different from other options, and so their key differences:

Such valves are most often used in heating systems that include “warm floors”. In this way, the water for heating the floors will be much cooler than the water in the radiator.

For the manufacture of three-way safety valves the following is used:

steel;
brass;
cast iron.

Brass structures are most common when installing home heating systems, while steel and cast iron are more typical for larger industrial installations.

It is also worth paying attention to the explosion safety valve, which can prevent the explosion of flammable gases or coal dust. They are made in such a way that if the substance explodes, only the membrane of the structure is damaged, and the pipeline remains unharmed.

This type of product operates automatically. Depending on the pressure, they There are several types of them:

with pressure up to 2 kPa;
up to 40 kPa;
150 kPa inclusive.

How to choose the right safety valve

When choosing a safety valve, you should consider huge amount certain factors. In particular, be sure to take the ambient operating pressure into account. If this pressure is higher than normal, then you need choose a product for 2 bar, which can withstand such operating conditions of the product. In addition, you can choose an option with the ability to adjust the pressure so that you can adjust the required mode and find out the exact parameters, in particular, the nominal diameter.

There are a number of standards regarding the performance of calculations; you can also find special ones on the Internet calculation programs. You can do without calculations and take a structure with a diameter no less than the diameter of the outlet pipe of your boiler, but such a calculation will not be accurate and cannot guarantee high level safety and performance.

In general, in order to choose the right product, you should consider the following parameters:

decide on the type of product;
with a size so that the pressure in the system does not exceed the permissible limits;
It is better to choose spring-type products for your home;
open devices are suitable only if the water goes into the atmosphere, and closed ones - if into the outlet pipeline;
after calculations, you can determine whether a low-lift valve or a full-lift valve is suitable;
calculate your budget.

Safety valve prices vary depending on the material and other features. For example, an Italian-made membrane structure can be buy for about 4 USD., and brass – starting from 12 USD. There are also some valve models whose cost exceeds $100.

Safety valve installation features

When installing the valve, you must strictly follow all the rules listed in regulatory documentation products. Also, the installation must be carried out taking into account the power and operating pressure.

But The key installation principles are:

We also must not forget that it is necessary to regulate and check the pressure at least once a year before the heating season.

How to set a safety valve

The valve must be adjusted at the installation location after completion installation work and after the system is flushed. Set the setting pressure, check the opening and closing pressure of the product.

The settings should be set slightly above the maximum operating pressure, which is permissible during normal operation of the structure. A full opening pressure should not be higher than the minimum level of the weakest element of the system. The closing pressure must exceed the minimum permissible value.

Adjust the pressure in spring design it is necessary by rotating a special screw that compresses the spring, and the lever structure is adjusted using the required mass of the load.

So, the valve is ready for operation, if he is able to ensure the tightness of the overlap, as well as the complete opening and closing of the shutter. In addition, the pressure may deviate within the permissible fluctuations, which are given in the technical data sheet of the product.

Safety valves are classified as safety valves. They are needed to protect the pipeline system from excessive pressure build-up in the pipeline system, as well as steam boilers, tanks and other containers. If the pressure is exceeded, they release part of the working fluid into the environment or into a special outlet pipe. They work automatically.

Safety valve design (using the example of a spring Flamco Prescor S 960)

Operating principle of safety valves

The valve spool is connected to a spring set to a certain compression at a certain pressure. IN in good condition pressure, the spring tightly presses the spool to the seat, the safety valve is closed and does not allow the working medium to pass through. Under the influence high blood pressure, acting on the spool, the spring is compressed, allowing the spool to move away from the seat and release the working fluid through the drain channel.

To avoid sticking of the spool to the seat (and this can happen often if the working medium of the pipeline is steam or superheated water), it is necessary to periodically open it forcibly. This is called “valve blowing”. To do this, install handles for manual control.

You can learn more about the design and operating principle of a spring safety valve from the video

Types of safety valves

All types of safety valves operate on the same principle described above. But they are divided into subspecies according to various parameters.

According to the type of device that exerts back pressure on the valve

Spring

Spring valves are most widely used due to their ease of operation and small size. They have a spring that regulates the valve opening pressure.

There are proportional and full-lift spring safety valves.

In proportional, the release of the medium occurs smoothly in proportion to the increasing pressure.
In full-lift valves, when the set pressure is reached, the valve opens immediately and completely, to a distance greater than or equal to the cross-section of the inlet opening. Excess working medium is quickly discharged.

Lever - cargo.

Lever-weight safety valve

In lever-weight safety valves, the maximum pressure is regulated by a lever and a weight mounted on the lever. The larger the weight and lever, the more pressure is needed to open the valve and release the fluid. They are used much less frequently than spring ones, as they are large in size, weight, and create vibrations. Not used on moving systems and where pipeline vibration is possible. They are used in boiler rooms with stationary steam boilers.

According to the lifting height of the spool

The higher the spool is able to rise above the seat, the greater its throughput and efficiency. It is very important to pay attention to this parameter of the safety valve, because valves with the same diameter (DN), but different lifts, have different characteristics.

Low lift. Valves in which the spool rises from 1/40 to 1/20 of the valve section size. These are the simplest safety valves that are used in systems without large throughput requirements, working mainly with water and other liquids.
Medium lift. The spool in such safety valves rises by 1/10 - 1/6 of the valve size. With a complicated design, they still do not provide full cross-country ability, so this type is not very popular.
High lifting. They ensure full cross-country ability by raising the spool to a height equal to or greater than the diameter of the inlet hole.

By type of working environment reset

Safety valves open type. They release the working environment directly into the outside world.
Safety valves closed type. They are sealed to environment and discharge the working medium through a special outlet channel.

According to the valve operation method

Direct acting valves. The opening/closing of the valve is directly influenced by the working medium, acting directly on the spool. This reliable type triggering. Unfortunately, it cannot be used for large pipelines with high pressure.
Pulse action valves. Have in their design additional device– pulse valve. In this type of valve, the working medium is released only after a command from the pulse valve. Applicable for large diameters and pressure.

Where are safety valves used?

The main task of safety valves is to ensure the safe operation of municipal, industrial, and energy equipment, which can be found in the oil and gas, chemical, food, and housing and communal services industries. In enterprises that use compressed air or steam, the system cannot do without safety valves.

Pipeline safety valves are especially relevant in household systems gas supply, where a violation of pressure can lead not just to equipment failure, but to a serious disaster that can claim many lives. That is why safety valves are produced in accordance with increased quality control requirements.

Order safety valves wholesale or retail from the “RU100” company!

Our company offers not only to buy all types of safety valves at affordable prices, but also not to worry about breakdowns for many years. We sell only proven and reliable pipeline fittings, which lasts a long time!

It should be noted that usually safety valves work in close symbiosis with. Our specialists will help you understand all the intricacies of the above tools so that your system can operate successfully for many decades. All our products are supplied necessary documents and comply with PCT and EAC standards.

Our engineers have been working in the industry since 2008. We know what we sell and will be happy to help you choose the right model.
We will deliver your order throughout Russia! Or pick up from ours is possible.
Place an order.
We work with both individuals and legal entities.
We provide complete set documents.
We accept payment in cash, non-cash, bank cards(for pickup)

Still have questions? Perhaps the answer is already in the section. And if not, then ask us:

by phone 8 800 707 16 86, 8 985 570 35 05;
By email.

STATE STANDARD OF THE USSR UNION

SAFETY VALVES
STEAM AND WATER BOILERS

TECHNICAL REQUIREMENTS

GOST 24570-81

(ST SEV 1711-79)

USSR STATE COMMITTEE ON STANDARDS

STATE STANDARD OF THE USSR UNION

SAFETY VALVES FOR STEAM AND WATER BOILERS

Technicalrequirements

Safety valves of stream and hot-water boilers.
Technical requirements

GOST
24570-81*

(ST SEV 1711-79)

By Decree of the USSR State Committee on Standards dated January 30, 1981 No. 363, the introduction date was established

from 01.12.1981

Verified in 1986. By Decree of the State Standard of June 24, 1986 No. 1714, the validity period was extended

until 01/01/92

Failure to comply with the standard is punishable by law

This standard applies to safety valves installed on steam boilers with absolute pressure above 0.17 MPa (1.7 kgf/cm2) and hot water boilers with water temperatures above 388 K (115 ° WITH).

The standard fully complies with ST SEV 1711-79.

The standard establishes mandatory requirements.

1. GENERAL REQUIREMENTS

(Changed edition, Amendment No. 1).

1.4. The design of the safety valve must ensure free movement of the movable elements valve and exclude the possibility of ejection.

1.5. The design of safety valves and auxiliary elements must exclude the possibility of arbitrary changes in their adjustment.

1.6. To each safety valve and whether, as agreed between the manufacturer and the consumer, pp For identical valves intended for one consumer, a passport and operating instructions must be attached. The passport must meet the requirements. The section “Basic technical data and characteristics” must contain the following data:

name of the manufacturer or its trademark;

serial number according to the manufacturer's numbering system or series number;

year of manufacture;

valve type;

nominal diameter at the inlet and outlet of valve a;

design diameter;

calculated cross-sectional area;

type of environment and its parameters;

characteristics and dimensions of the spring or load;

steam consumption coefficienta , equal to 0.9 coefficient obtained on the basis of the tests carried out;

permissible back pressure;

start pressure value opening permissible opening pressure range;

characteristics of basic element materials ent valve elements (body, disc, seat, spring);

valve type test data;

catalog code;

conditional pressure;

permissible limits of working pressure on the spring.

1.7. The following information must be marked on a plate affixed to the body of each safety valve, or directly on its body:

name of the manufacturing company or its trademark;

serial number according to the numbering system ai manufacturer or batch number;

valve type;

design diameter;

steam consumption coefficienta;

opening start pressure value;

conditional pressure;

nominal diameter;

flow indicator arrow;

designation of the main design document and symbol of the product.

The location of the marking and the dimensions of the markings are established in the technical documentation of the manufacturer.

2.1.

2.2. Pressure difference full opening and starting to open the valve should not be ev breathe out the next tasks en y:

2.3. The springs of the safety valves must be protected from unacceptable heating ev a and direct exposure to the working environment.

When the floor opening valve must be is the opportunity for a lot of contact is included turns springs.

The design of spring valves must exclude the possibility of tightening the springs beyond the set value determined by the highest operating pressure for a given valve design.

2.3. (Changed edition, Amendment No. 2).

2.4. Prim enen and al ikovyh lot nen and valve stem ae is allowed.

2.5. In the body of the safety valve, in places where condensate may accumulate, a device must be provided for its removal.

2.6. (Excluded , Change No. 2).

3. REQUIREMENTS FOR SAFETY VALVES CONTROLLED BY AUXILIARY DEVICES

3.1. The design of the safety valve and auxiliary devices must exclude the possibility of unacceptable shocks when opening and closing.

3.2. The design of safety valves must ensure that the function of protection against overpressure is maintained in the event of failure of any control or regulating body of the boiler.

3.3. Electrically driven safety valves must be equipped with two power sources independent of each other.

In electrical circuits where the loss of energy causes a pulse to open a valve, a single source of electrical power is permitted.

3.4. The design of the safety valve must provide for the ability to control it manually and, if necessary, remote control.

3.5. The valve design must ensure that it closes at a pressure of at least 95% of the operating pressure in the boiler.

3.6. The diameter of the straight-through pulse valve must be at least 15 mm.

The internal diameter of the impulse lines (input and outlet) must be at least 20 mm and not less than the diameter of the output fitting of the impulse valve.

Impulse and control lines must have condensate drainage devices.

The installation of shut-off devices on these lines is not permitted.

It is permissible to install a switching device if the impulse line remains open in any position of this device.

3.7. For safety valves controlled by auxiliary impulse valves, it is possible to install more than one impulse valve.

3.8. Safety valves must be operated in conditions that do not allow freezing, coking and corrosive effects of the environment used to control the valve.

4. REQUIREMENTS FOR SUPPLY AND DISCHARGE PIPELINES OF SAFETY VALVES

4.1. It is not allowed to install shut-off devices on the inlet and outlet pipelines of safety valves.

4.2. The design of safety valve pipelines must provide the necessary compensation for temperature expansion.

The fastening of the body and pipelines of safety valves must be designed taking into account static loads and dynamic forces that arise when the safety valve is activated.

When calculating the valve capacity, the indicated pressure reduction in both cases is taken into account.

4.4. (Changed edition, Amendment No. 2).

4.5. The working medium must be drained from the safety valves to a safe place.

4.6. Discharge pipelines must be protected from freezing and have a device for draining condensate.

Installation of shut-off devices on drains is not permitted.

4.6.(Changed edition, Amendment No. 2).

4.7. The internal diameter of the outlet pipe must be no less than the largest internal diameter of the outlet pipe of the safety valve.

4.9. The capacity of safety valves should be determined taking into account the resistance of the sound muffler; its installation should not cause disruption to the normal operation of safety valves.

4.10. A fitting must be provided in the area between the safety valve and the sound muffler for installing a pressure measuring device.

5. FLOW CAPACITY OF SAFETY VALVES

5.1. The total capacity of all safety valves installed on the boiler must satisfy the following conditions:

for steam boilers

G1+G2+…Gn³ D ;

for economizers disconnected from the boiler

for hot water boilers

n- number of safety valves;

G1,G2,Gn- throughput of individual safety valves, kg/h;

D- rated output of the steam boiler, kg/h;

Increase in enthalpy of water in the economizer at the nominal boiler output, J/kg (kcal/kg);

Q- nominal thermal conductivity of the hot water boiler, J/h (kcal/h);

g- heat of evaporation, J/kg (kcal/kg).

5.1. (Changed edition, Amendment No. 2).

5.2. The capacity of the safety valve is determined by the formula:

G = 10B 1 × a× F(P 1 +0.1) - for pressure in MPa or

G= B 1 × a× F(P 1 + 1) - for pressure in kgf/cm 2,

Where G- valve capacity, kg/h;

F- calculated cross-sectional area of the valve, equal to the smallest free cross-sectional area in the flow part, mm 2;

a- steam flow coefficient, related to the cross-sectional area of the valve and determined in accordance with clause 5.3 of this standard;

R 1 - maximum excess pressure in front of the safety valve, which should be no more than 1.1 working pressure, MPa (kgf/cm2);

Table 1

Coefficient values IN 1 for saturated steam

R 1, MPa (kgf/cm2)

R 1, MPa (kgf/cm2)

R 1, MPa (kgf/cm2)

Table 2

Coefficient values IN 1 for superheated steam

R 1, MPa (kgf/cm2)	At steam temperaturetn, ° WITH
R 1, MPa (kgf/cm2)
0,2 (2)	0,480	0,455	0,440	0,420	0,405	0,390	0,380	0,365	0,355
1 (10)	0,490	0,460	0,440	0,420	0,405	0,390	0,380	0,365	0,355
2 (20)	0,495	0,465	0,445	0,425	0,410	0,390	0,380	0,365	0,355
3 (30)	0,505	0,475	0,450	0,425	0,410	0,395	0,380	0,365	0,355
4 (40)	0,520	0,485	0,455	0,430	0,410	0,400	0,380	0,365	0,355
6 (60)		0,500	0,460	0,435	0,415	0,400	0,385	0,370	0,360
8 (80)		0,570	0,475	0,445	0,420	0,400	0,385	0,370	0,360
16 (160)			0,490	0,450	0,425	0,405	0,390	0,375	0,360
18 (180)				0,480	0,440	0,415	0,400	0,380	0,365
20 (200)				0,525	0,460	0,430	0,405	0,385	0,370
25 (250)					0,490	0,445	0,415	0,390	0,375
30 (300)					0,520	0,460	0,425	0,400	0,380
35 (350)					0,560	0,475	0,435	0,405	0,380
40 (400)					0,610	0,495	0,445	0,415	0,380

or determined by the formula for pressure in MPa

for pressure in kgf/cm 2

Where TO- adiabatic index equal to 1.35 for saturated steam, 1.31 for superheated steam;

R 1 - maximum excess pressure in front of the safety valve, MPa;

V 1 - specific volume of steam in front of the safety valve, m 3 /kg.

The formula for determining valve capacity should only be used if: ( R 2 +0,1)£ (R 1 +0,1)b kr for pressure in MPa or ( R 2 +1)£ (R 1 +1)b kr for pressure in kgf/cm 2, where

R 2 - maximum excess pressure behind the safety valve in the space into which steam flows from the boiler (when escaping into the atmosphere R 2 = 0 MPa (kgf/cm2);

b kr - critical pressure ratio.

For saturated steam b kr =0.577, for superheated steam b cr =0.546.

5.2. (Changed edition, Amendment No. 2).

5.3. Coefficient a taken equal to 90% of the value obtained by the manufacturer based on the tests performed.

6. CONTROL METHODS

6.1. All safety valves must be tested for strength, tightness, and tightness of gland connections and sealing surfaces.

6.2. The scope of valve testing, their order and control methods must be established in the technical specifications for valves of a specific standard size.