Views: 0 Author: Site Editor Publish Time: 2021-01-18 Origin: Site
Determination Of Safety Valve Setting Pressure And Setting Pressure Deviation
(1) Safety valve for steam boiler
a. The setting pressure of the safety valve on the drum (shell) and superheater should be in accordance with Table 1.
b. The setting pressure of the safety valve of the economizer, reheater, and once-through boiler start-up separator is 1.1 times the working pressure of the installation site.
c. Setting pressure deviation: when the setting pressure is less than or equal to 0.5MPa, it is ±0.015MPa; when the setting pressure is 0.5～2.3MPa, it is ±3% of the setting pressure; when the setting pressure is 2.3～7.0MPa, it is ±0.07MPa. When the set pressure is greater than 7.0MPa, it is ±1% of the set pressure.
Table 1 Setting pressure of safety valve on drum (shell) and superheater
Rated Working Pressure（MPa） | Setting Pressure of PSV（MPa） |
≤0.8 | Working Pressure +0.03 |
Working Pressure+0.05 | |
0.8＜P≤5.9 | 1.04 x Working Pressure |
1.06 x Working Pressure | |
＞5.6 | 1.05 x Working Pressure |
1.08 x Working Pressure |
Note: There must be a safety valve on the boiler, adjust according to the lower setting pressure in the table. For boilers with superheaters, the safety valve adjusted at a lower pressure must be the safety valve on the superheater to ensure that the safety valve on the superheater opens first. The working pressure in the table refers to the working pressure at the place where the impulse is taken out for the pulse safety valve, and refers to the working pressure at the place where the safety valve is installed for other types of safety valves.
(2) Safety valve for hot water boiler
a. The set pressure of the safety valve should be in accordance with Table 2.
b. Setting pressure deviation: when the setting pressure is less than or equal to 0.5MPa, it is ±0.015MPa, when the setting pressure is greater than 0.5MPa, it is ±3% of the setting pressure.
Table 2
hot water boiler Safety Valve Setting Pressure（MPa） |
1.12 x Working Pressure, But not less than Working Pressure+0.07MPa |
1.14x Working Pressure, But not less than Working Pressure +0.10MPa |
Note: There must be a safety valve on the boiler to adjust according to the lower set pressure in the table. The working pressure here refers to the working pressure of the parts directly connected to the safety valve.
(3) Safety valves for stationary pressure vessels
a. When only one safety valve is installed on a fixed pressure vessel, the set pressure of the safety valve should not be greater than the design pressure of the pressure vessel; when multiple safety valves are installed on a fixed pressure vessel, the set pressure of one of the safety valves should not be greater than The design pressure of the pressure vessel and the setting pressure of other safety valves can be appropriately increased, but it shall not exceed 1.05 times the design pressure.
b. Setting pressure deviation: when the setting pressure is less than or equal to 0.5MPa, it is ±0.015MPa, when the setting pressure is greater than 0.5MPa, it is ±3% of the setting pressure.
(4) Safety valve for mobile pressure vessel
a. The setting pressure of the safety valve is 1.05~1.10 times the design pressure of the tank, and the return pressure is not less than 0.8 times the opening pressure. The setting pressure of the safety valve of the low-temperature cryogenic tank truck must not exceed the design pressure of the tank.
b. Setting pressure deviation: when the setting pressure is less than or equal to 0.5MPa, it is ±0.015MPa, when the setting pressure is greater than 0.5MPa, it is ±3% of the setting pressure.
(5) Safety valve for pressure pipeline
a. The set pressure of safety valves for industrial metal pipelines is 1.05 to 1.1 times the maximum working pressure; the set pressures of safety valves for pipelines in oil and gas stations are 1.05 to 1.15 times the maximum working pressure.
b. Setting pressure deviation: when the setting pressure is less than or equal to 0.5MPa, it is ±0.015MPa, when the setting pressure is greater than 0.5MPa, it is ±3% of the setting pressure.
(6) Safety valve for medical hyperbaric oxygen chamber
a. The set pressure of the safety valve is the highest working pressure + 0.02 MPa.
b. The set pressure deviation is ±0.015MPa.
(7) Safety valve for compressor
a. The set pressure of the safety valve is the highest working pressure + 0.02 MPa.
b. Setting pressure deviation: when the setting pressure is less than or equal to 0.5MPa, it is ±0.015MPa, when the setting pressure is greater than 0.5MPa, it is ±3% of the setting pressure.
