1. Safety valves must have a device to prevent the counterweight from moving on its own and a guide to limit the lever from going off track. Spring-loaded safety valves must have a lifting handle and a device to prevent unauthorized turning of the adjusting screw.
2. It should be installed vertically at the highest position of the boiler drum or header. No steam outlet pipe or valve should be installed between the safety valve and the boiler drum or header.
3. 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 on a short pipe directly connected to the boiler drum, the cross-sectional area of the short pipe should not be less than 1.25 times the total exhaust area of all safety valves.
4. For boilers with a rated steam pressure less than or equal to 3.82 MPa, the throat diameter of the safety valve should not be less than 25 mm; for boilers with a rated steam pressure greater than 3.82 MPa, the throat diameter of the safety valve should not be less than 20 mm.
5. Safety valves should generally be equipped with a vent pipe. The vent pipe should lead directly to a safe location and have sufficient cross-sectional area to ensure unobstructed venting. A drain pipe connected to a safe location should be installed at the bottom of the safety valve vent pipe. Valves are not permitted on either the vent pipe or the drain pipe.
6. Safety valves on pressure vessels should ideally be installed directly at the highest point of the pressure vessel body. Safety valves on liquefied gas storage tanks must be installed in the gas phase. A short pipe can generally be used to connect to the container; however, the diameter of this short pipe should not be less than the valve diameter of the safety valve.
7. Valves are generally not permitted between safety valves and containers. For containers handling flammable, explosive, or viscous media, a shut-off valve may be installed for easy cleaning or replacement of the safety valve. This shut-off valve must be fully open and sealed with a lead seal during normal operation to prevent unauthorized movement.
8. Boilers with a rated evaporation capacity greater than 0.5 t/h should be equipped with at least two safety valves; boilers with a rated evaporation capacity less than or equal to 0.5 t/h should 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.
9. For pressure vessels containing flammable, explosive, or toxic media, the media discharged by the safety valve must have safety devices and a recovery system. Lever-type safety valves must be installed vertically, and spring-loaded safety valves are also best installed vertically to avoid affecting their operation. During installation, attention should be paid to fit, coaxiality of parts, and ensuring even tension on all bolts.
10. The outlet of the safety valve should be unobstructed to avoid back pressure. If a drain pipe is installed, its inner diameter should be larger than the outlet diameter of the safety valve. The safety valve outlet should be protected against freezing. For containers containing flammable, toxic, or highly toxic media, the drain pipe should lead directly to a safe outdoor location or have proper treatment facilities. No valves are allowed to be installed on the drain pipe.
11. Newly installed safety valves should be accompanied by a product certificate of conformity. Before installation, they must be recalibrated, sealed, and a safety valve calibration certificate should be issued.
12. No valves shall be installed between pressure vessels and safety valves. For containers holding flammable, explosive, toxic, or viscous media, stop valves may be installed for easy replacement and cleaning. Their structure and diameter should not impede the normal operation of the safety valve. During normal operation, the stop valve must be fully open and sealed with a lead seal.
Safety valves are automatic valves, mainly used on boilers, pressure vessels, and pipelines to control pressure to within specified values, playing a vital role in protecting personal safety and equipment operation.