Precautions for installation and maintenance of high pressure safety valves

※Overview and scope of high pressure safety valve:

The high-pressure safety valve is a safety protection valve, and its opening and closing member is normally closed under the action of external force. When the pressure of the medium in the equipment or pipeline rises, it automatically opens when the specified value is exceeded, and the medium is discharged through the system. Prevent media pressure in pipes or equipment from exceeding specified values. High-pressure safety valves are automatic valves, mainly used in boilers, pressure vessels and pipelines. The control pressure does not exceed the specified value, which plays an important role in protecting personal safety and equipment operation. According to the safety valve flap opening height, it can be divided into micro-opening safety valve and full-opening safety valve. The opening stroke height of the micro- opening safety valve is: ≤0.05d0 (minimum discharge throat diameter); full-open safety valve is open The height is ≤ 0.25d0 (minimum discharge throat diameter).

※ The distinction of high pressure safety valve :

High-pressure safety valves are divided according to the structure, and are divided into vertical hammer type, lever type, spring type and pilot type ( pulse type ) . According to the structure of the valve body, they can be divided into closed type and non-closed type. Enclosed safety valves, ie, excluded media, are not leaked and are all discharged along the outlet to a designated location, typically used in toxic and corrosive media. For safety valves for air and steam, non-closed safety valves are often used. The selection of safety valve products 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 the safety valve type, name, medium and temperature, the valve body sealing pressure should be noted. Otherwise, it is supplied at the maximum sealing pressure.

※ Precautions for installation and maintenance of high pressure safety valve :

All safety valves should be installed vertically.

There should be no resistance at the exit of the high pressure safety valve to avoid pressure.

The high pressure safety valve should be specially tested before installation and checked for its official seal.

The safety valve in use should be inspected regularly.

※ Need to know the installation of high pressure safety valve :

( 1 ) Boilers with a rated evaporation of more than 0.5t/h shall be equipped with at least two safety valves: boilers with a rated evaporation of less than or equal to 0.5t/h , with at least one safety valve. Safety valves must be installed at the outlet of the separable economizer and at the outlet of the steam superheater.

( 2 ) The high pressure safety valve should be installed vertically at the highest position of the potter and the header. Between the safety valve and the drum or header, the outlet pipe and valve for steam should not be installed.

( 3 ) The lever type safety valve shall have a device for preventing the weight from moving by itself and a guide for restricting the deviance of the lever. The spring type safety valve shall have a device for lifting the handle and preventing the adjustment screw from being twisted.

( 4 ) For boilers with rated steam pressure less than or equal to 3.82 MPa , the safety valve throat diameter shall not be less than 25 mm : For boilers with rated steam pressure greater than 3.82 MPa , the safety valve throat diameter shall not be less than 20 mm .

( 5 ) The connecting pipe of the high-pressure safety valve and the boiler shall have a cross-sectional area not less than the inlet cross-sectional area of ​​the safety valve. If several safety valves are installed together on a short pipe directly connected to the drum, the cross-sectional area of ​​the short pipe should not be 1.25 times that of all safety valves .

( 6 ) High-pressure safety valves should generally be equipped with exhaust pipes. The exhaust pipes should be straight to a safe place and have sufficient cross-sectional area to ensure unobstructed exhaust. The bottom of the safety valve exhaust pipe should be fitted with a cavity. The drain pipe is connected to a safe place. No valves are allowed on the exhaust pipe and the drain pipe.