The installation of safety valves should meet the following requirements

(1) Boilers with a rated evaporation capacity greater than 0.5t/h shall be equipped with at least two safety valves; Boilers with a rated evaporation capacity of less than or equal to 0.5t/h shall be equipped with at least one safety valve. Safety valves must be installed at the outlet of the separable economizer and the outlet of the steam superheater.
(2) The safety valve should be installed vertically at the highest position of the boiler and header. There shall be no outlet pipes or valves for steam extraction between the safety valve and the drum or header.
(3) The lever type safety valve should have a device to prevent the heavy hammer from moving on its own and a guide frame to limit the deviation of the lever. The spring type safety valve should have a device to lift the handle and prevent the adjustment screw from being easily turned.
(4) For boilers with a rated steam pressure less than or equal to 3.82MPa, the throat diameter of the safety valve should not be less than 25mm; For boilers with a rated steam pressure greater than 3.82MPa, the safety valve throat diameter should not be less than 20mm.
(5) The cross-sectional area of the connecting pipe between the safety valve and the boiler should not be 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 exceed 1.25 times the exhaust area of all safety valves.
(6) A safety valve should generally be equipped with an exhaust pipe, which should lead directly to a safe location and have sufficient cross-sectional area to ensure smooth exhaust. The bottom of the safety valve exhaust pipe should be equipped with a drainage pipe connected to a safe location, and valves are not allowed to be installed on both the exhaust pipe and the drainage pipe.

Common faults and elimination methods of safety valves

The main cause of safety valve failure is improper design, manufacturing, selection, or use. If these faults are not eliminated in a timely manner, they will affect the effectiveness and lifespan of the valve, and even fail to provide safety protection. The common faults and their elimination methods are as follows:
(1) Leakage. Under normal working pressure of the equipment, there is leakage exceeding the allowable level between the valve disc and the valve seat sealing surface. The reason is that there is dirt between the sealing surface of the valve disc and valve seat. You can use a lifting wrench to open the valve several times and flush away any dirt; Damaged sealing surface. Repair should be carried out by grinding or grinding after turning according to the degree of damage; The valve stem is bent, tilted, or the lever is misaligned with the fulcrum, causing the valve core and disc to be misaligned. Should be reassembled or replaced; The elasticity of the spring decreases or loses its elasticity. Measures such as replacing the spring and readjusting the opening pressure should be taken.
(2) Do not open when the specified pressure is reached. The reason for this situation is inaccurate constant pressure. The compression amount of the spring or the position of the heavy hammer should be readjusted; The valve disc is stuck to the valve seat. Regular manual air release or water discharge tests should be conducted on the safety valve; The lever of the lever type safety valve is stuck or the heavy hammer is moved. The position of the heavy hammer should be readjusted and the lever should move freely.
(3) Opening below the specified pressure. Mainly due to inaccurate constant pressure; The spring's elasticity decreases due to aging. Adjust the screw appropriately or replace the spring.
(4) The pressure continues to rise after exhaust. This is mainly because the selected safety valve has a smaller displacement than the safety discharge capacity of the equipment, and a suitable safety valve should be selected again; If the centerline of the valve stem is not aligned or the spring rusts, causing the valve disc to not open to the desired height, the valve stem should be reassembled or the spring replaced; If the exhaust pipe section is insufficient, exhaust pipes that meet the safe emission area should be used.
(5) Valve disc frequency jumping or vibration. Mainly due to the high spring stiffness. Springs with appropriate stiffness should be used instead; Improper adjustment of the adjustment ring resulted in excessive reseating pressure. The position of the adjustment ring should be readjusted; The discharge pipeline has excessive resistance, resulting in excessive discharge back pressure. The resistance of the discharge pipeline should be reduced.
(6) The valve disc does not reseat after discharge. This is mainly caused by the bent valve stem of the spring, improper installation position of the valve disc, or jamming. Should be reassembled.