Safety Valve
A safety valve is a special valve in which the opening and closing parts are in a normally closed state under external force. When the pressure of the medium in the equipment or pipeline increases beyond the specified value, the medium is discharged outside the system to prevent the pressure of the medium in the pipeline or equipment from exceeding the specified value. Safety valves belong to the category of automatic valves, mainly used in boilers, pressure vessels, and pipelines. They control the pressure to not exceed the specified value and play an important protective role in personal safety and equipment operation. The safety valve must undergo a pressure test before use.
Keyword： Safety Valve
Detail
Selection principles
1. Steam boiler safety valves generally use the open full open spring safety valve 0490 series;
2. Safety valves for liquid media generally use the micro opening spring safety valve 0485 series;
3. Safety valves for air or other gas media generally use fully open spring safety valves;
4. Safety valves for liquefied petroleum gas tank cars or liquefied petroleum gas railway tank cars generally use fully open internal safety valves;
5. Pilot operated safety valves are generally used for the outlet of oil extraction wells;
6. The high-pressure bypass safety valve of steam generating equipment is generally a pilot operated safety valve with both safety and control functions
7. If regular opening tests are required for safety valves, safety valves with lifting wrenches should be selected. When the medium pressure reaches over 75% of the opening pressure, a lifting wrench can be used to slightly lift the valve disc from the valve seat to check the flexibility of the safety valve opening;
8. If the medium temperature is high, in order to reduce the temperature of the spring chamber, a safety valve with a radiator should be selected when the operating temperature of the closed safety valve exceeds 300 ℃ and the operating temperature of the open safety valve exceeds 350 ℃;
9. If the back pressure at the outlet of the safety valve is variable and the change exceeds 10% of the opening pressure, a corrugated pipe safety valve should be selected;
10. If the medium is corrosive, corrugated pipe safety valves should be selected to prevent important parts from failing due to medium corrosion.
11. The installation and maintenance of safety valves should pay attention to the following construction and installation points: 1) The installation position, height, and inlet and outlet directions must meet the design requirements. It should be noted that the direction of medium flow should be consistent with the arrow direction marked on the valve body, and the connection should be firm and tight. 2) Before valve installation, a visual inspection must be carried out, and the nameplate of the valve should comply with the current national standard "General Valve Markings" GB 12220. For valves with a working pressure greater than 1.0 MPa and a shut-off effect on the main pipe, strength and tightness tests should be conducted before installation, and they can only be used after passing the test. During the strength test, the test pressure shall be 1.5 times the nominal pressure, and the duration shall not be less than 5 minutes. The valve shell and packing shall be deemed qualified if there is no leakage. During the tightness test, the test pressure shall be 1.1 times the nominal pressure; The duration of the test meets the requirements of GB 50243 1. All types of safety valves should be installed vertically.
12. There should be no resistance at the outlet of the safety valve to avoid pressure.
13. Safety valves should be specially tested and checked for sealing before installation.
14. Regular inspections should be conducted on safety valves in use.
15.Nominal diameter:1/8"(8mm)-4"(100mm)
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