Pressure vessel safety valves? What safety devices are available for pressure vessels

Relief valve. safety valve

Valves used to prevent damage to equipment or pipelines such as boilers and pressure vessels due to overpressure. When the fluid pressure in the protected body reaches a specified value slightly higher than the normal working pressure (i.e., the valve opening pressure), the safety valve will automatically open and discharge part of the fluid, so that the pressure will drop. When the pressure drops to a certain value slightly below the normal operating pressure (i.e., the valve return pressure), the safety valve automatically closes, stopping the discharge of fluid and maintaining a seal.

The function of the safety valve is to prevent the medium pressure in the pipeline or device from exceeding the specified value, so as to achieve the purpose of safety protection.

The safety valve is a kind of safety protection valve, its opening and closing parts are in a normally closed state under the action of external force, when the medium pressure in the equipment or pipeline rises, it will be automatically opened when it exceeds the specified value, and the medium pressure in the pipeline or equipment will be prevented from exceeding the specified value by discharging the medium to the outside of the system. Safety valves belong to the automatic valve category, which are mainly used in boilers, pressure vessels and pipelines, and the control pressure does not exceed the specified value, which plays an important role in protecting personal safety and equipment operation.

According to the opening height of the safety valve disc, it can be divided into micro-opening safety valve and full-opening safety valve, and the opening stroke height of the micro-opening safety valve is: minimum discharge throat diameter); The opening height of the fully opened safety valve is the minimum discharge throat diameter).

The safety valve is divided into vertical hammer type, lever type, spring type and pilot type (pulse type) according to the structural form; According to the structure of the valve body, it can be divided into two types: closed type and non-closed type. The closed safety valve does not leak the discharged medium, and all of them are discharged to the designated place along the outlet, which is generally used in toxic and corrosive media. For air and steam safety valves, non-closed safety valves are often used.

For the selection of safety valve products, it should be determined according to the actual sealing pressure. For spring-loaded safety valves, springs with several working pressure levels within a nominal pressure (PN) range, in addition to indicating the safety valve model, name, medium and temperature, should also indicate the sealing pressure of the valve body, otherwise it should be supplied according to the maximum sealing pressure.

The safety devices of pressure vessels include the following:

Safety leakage devices, such as safety valves, explosion-proof plates, etc.;

Emergency shut-off of the interception and leakage stop device;

Parameter measuring instruments, such as pressure gauges, level gauges, thermometers, etc.

The safety valve is an important accessory for special equipment (boilers, pressure vessels, pressure pipelines, etc.) to limit and relieve pressure and play a role in safety protection. The safety valve is generally directly installed on special equipment, and its design, manufacturing, installation, use, inspection, etc. must meet the requirements of relevant regulations of special equipment, because its action reliability and performance are directly related to the safety of equipment and people, and are closely related to energy conservation and environmental protection.

1. Common safety valves are generally as follows:

1. According to the overall structure and the form of the loading structure, it can be divided into three types: hammer lever safety valve, spring safety valve and control type.

2. According to the ratio of the opening height of the disc type to the diameter of the valve flow, it can be divided into micro-opening type and full-opening safety valve.

3. According to the way of gas discharge of the safety valve, it can be divided into three types: fully enclosed, semi-enclosed and open.

Second, the selection of appropriate safety valves should be considered from the following aspects:

1. The structural form mainly depends on the process conditions of the equipment, the working medium and the characteristics. Generally, when the discharge capacity of boilers and pressure vessels is not large, spring safety valves are mostly used, otherwise it is better to choose full-opening safety valves.

2. If the medium is toxic, flammable and explosive, a closed safety valve should be selected.

3. Each safety valve has its own working pressure range, and the selection should be made according to the actual needs.

4. The discharge of the selected safety valve must be greater than the discharge amount of the equipment, so as to ensure that part of the medium is excluded and avoid the pressure from continuing to rise.

3. Precautions for installation.

1. All kinds of safety valves should be installed vertically.

2. There should be no resistance at the outlet of the safety valve to avoid pressure.

3. The safety valve should be specially tested before installation, and its tightness should be checked.

4. The safety valve in use should be checked regularly.

Fourth, the common failure of the safety valve in the application:

During the normal use and calibration of safety valves, various failures can occur due to improper design, manufacture or use. If these faults are not eliminated in time, the efficacy and service life of the safety valve will be affected, and in serious cases, the life safety of users will be endangered.

1. Leakage of safety valve.

Leakage exceeding the allowable degree occurs at the sealing surface of the valve disc and the valve seat, causes and solutions:

a. The leakage is due to the fact that there is a stolen object between the valve disc and the sealing surface of the valve seat, and the valve can be opened several times and flushed down.

b. The damage of the sealing surface can be repaired by grinding or grinding after turning according to the degree of damage.

c. The valve stem is bent and tilted. It should be reassembled or replaced.

2. When the specified pressure is not opened and the specified pressure is not closed, this is caused by the inaccurate positioning of the safety valve, and the compression of the spring or the position of the hammer should be readjusted or the spring can be replaced.

3. The pressure continues to rise after the safety valve is exhausted. This is mainly because the discharge of the safety valve does not reach the discharge of the equipment, and a suitable safety valve should be selected.

4. Disc frequency skipping or vibration. This is mainly due to the fact that the spring rate is too high, and it is time to use a spring with an appropriate stiffness instead.

5. The safety valve does not return to the seat after discharge, the reason: the spring is bent, the valve stem and valve disc are safe.

If the installation position is not correct or is stuck, it should be reassembled.

When selecting the safety valve, it is necessary to ensure that the maximum working pressure shall not be higher than the nominal pressure of the safety valve.

The leakage volume of the safety valve is appropriate. The discharge volume of the safety valve shall not be less than the required safety discharge capacity.

For the pressure vessel with gas, steam, liquefied gas or large steam boiler with large discharge capacity, the full-opening safety valve is selected, and the micro-opening safety valve is selected for the gas tank with small discharge capacity such as liquid medium and small steam boiler, and the pressure in the vessel is required to be relatively stable.

For toxic, flammable, explosive and other media, choose a closed safety valve. For harmless rings, an open safety valve should be used.

Summary. Or install an explosion-proof film, a safety valve, play a double insurance, there are also in order to prevent the safety valve micro opening or semi-opening when the pressure is insufficient, the explosion-proof film bursts open to protect the equipment, because the replacement of the explosion-proof film will lead to the system shutdown, most of the current two safety valves are installed, and the starting pressure of the two safety valves is slightly different.

Or install an explosion-proof membrane, a safety valve, play a double insurance, there are also in order to prevent the safety valve from opening or semi-opening when the pressure is insufficient, the explosion-proof film bursts open to protect the collapse of the equipment, because the replacement of the explosion-proof film will lead to the system shutdown, most of them are currently equipped with two safety valves, and the starting pressure of the two safety regiments is slightly different.

In the high-pressure equipment or the equipment of the danger is basically equipped with two safety valves, and the starting pressure of the two safety valves is not the same, one is higher, one is lower, I think their main significance is that after the first safety valve jumps can not meet the pressure relief requirements, the second safety valve jumps out of the protection equipment, the second meaning is to prevent a safety valve from breaking after another safety valve jumps, play a role in checking, so as to protect the equipment!

Hello, according to the provisions of the "Regulations for the Safety and Technical Supervision of Pressure Vessels", the pressure vessel in the following situations does not need to be equipped with a safety valve: 1If the working pressure of the pressure vessel is less than or equal to, there is no need to install a safety valve.

2.If the volume of the pressure vessel is less than or equal to cubic meters, and the working pressure is less than or equal to the working pressure, there is no need to install a safety valve. 3.

If the volume of the pressure vessel is less than or equal to cubic meters, and the working pressure is less than or equal to the pressure of the press, the safety valve needs to be installed without sending the early silver. 4.If the volume of the pressure vessel is less than or equal to the square meter of the dust banquet, and the working pressure is less than or equal to, there is no need to install a safety valve.

It is important to note that the pressure vessel in these cases still needs to be safely monitored and inspected to ensure its safe operation. <>

Summary. Dear, hello, dear, the following pressure vessels do not need to be equipped with safety valves:1

Pressure vessels with small size, less stored dielectric mass and lower working pressure; 2.Coolers with a liquid volume of no more than 10 L and a working pressure lower than that; 3.Gas reservoirs with small gas storage capacity and lower working pressure; 4.

Heaters in heat exchange equipment such as hot water boilers, steam boilers, hot blast stoves, water heaters, etc.; 5.Special equipment that omits the safety valve, but uses other safety measures to ensure its safety. It should be reminded that even pressure vessels that are exempt from the installation of safety valves need to be operated and supervised in strict accordance with relevant codes and standards during their design, manufacture and use to ensure their safe operation.

Dear, hello, dear, the following pressure vessels do not need to install safety valves: 1Pressure vessels with small size, less stored dielectric mass and lower working pressure; 2.

Coolers with a liquid volume of no more than 10 L and a working pressure lower than that; 3.Gas reservoirs with small gas storage capacity and lower working pressure; 4.Heaters in heat exchange equipment such as hot water boilers, steam boilers, hot blast stoves, water heaters, etc.; 5.

Special equipment that omits the safety valve, but uses other safety measures to ensure its safety. It should be reminded that even if the pressure vessel is exempt from the installation of a full valve, it needs to be operated and supervised in strict accordance with the relevant norms and standards in the process of its design, manufacturing and use to ensure its safe operation.

Hello dear, dear, safety valve is a device used to increase the safety protection of the system. Its main function is to protect the equipment or device from being affected by excessive or low pressure and temperature when working, so as not to cause damage, damage or damage to the equipment or device, so as to protect the safety of personnel and facilities. Safety valves can be divided into the following types:

1.Spring-vented safety valve: The most common type of safety valve, which is adjusted by a spring device so that the spring forces on the valve differently under different pressure conditions.

When the pressure is greater than the set value, the spring is compressed and the valve discharges part of the pressure. 2.Plug-in type safety valve:

This kind of valve is mainly set inside the valve by means of a plug-in plate or a vane device to realize the function of adjusting the pressure. It is generally made of steel or tungsten steel, which can adapt to higher working pressure. 3.

Heavy Hammer Safety Valve: This type of safety valve is opened by an external power supply to drive some device to open the valve to discharge excessive pressure or delayed temperature, which is suitable for large boilers and other occasions that require a high safety factor.

The safety valve inspection of the pressure vessel refers to the regular maintenance, testing and calibration of the safety valve.

Article 27 of the Regulations on the Safety Supervision of Special Equipment: The user of special equipment shall regularly calibrate and overhaul the safety accessories, safety protection devices, measurement and control devices and related ancillary instruments and meters of the special equipment in use, and make records. Article 16 of the Rules for Periodic Inspection of Pressure Vessels:

The inspection of safety accessories includes the inspection and calibration of pressure gauges, liquid level gauges, temperature measuring instruments and safety valves; Article 17: The safety valve is generally calibrated at least once a year.

Pressure vessels, pressure-bearing special equipment, the scope of gases, liquefied gases and liquids with a maximum working temperature higher than or equal to the standard boiling point is specified as the maximum working pressure greater than or equal to the gauge pressure, fixed containers and mobile containers with a volume greater than or equal to 30L and an inner diameter (non-circular cross-section refers to the maximum geometric size of the inner boundary of the cross-section) greater than or equal to 150mm.

The working pressure is greater than or equal to the gauge pressure), and the product of the pressure and volume is greater than or equal to the gas, liquefied gas and the standard vertical macro boiling point is equal to or less than 60 liquid cylinders; Oxygen chambers.

The statutory inspection of pressure vessels includes two types: supervision and inspection of pressure vessel installation and periodic inspection of pressure vessels, of which the periodic inspection of pressure vessels includes comprehensive inspection of pressure vessels and annual inspection of pressure vessels.