Views:92 Author:Site Editor Publish Time: 2020-03-10 Origin:Site
Safety valves belong to the category of automatic valves, which are mainly used on 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. Proper maintenance measures can extend the service life of the safety valve. Let us look at the specific measures together.
1. The safety valve must have a device to prevent the weight from moving by itself and a guide frame to limit the derailment of the lever. The spring-loaded safety valve must have a device to raise the handle and prevent the adjustment screw from being turned casually.
2. It should be installed vertically at the highest position of the pot vendor and header. No outlet pipe and valve for taking steam shall be installed between the safety valve and the drum or header.
3. For boilers with a rated steam pressure of 3.82MPa or less, the throat diameter of the safety valve should not be less than 25mm; for boilers with a rated steam pressure of more than 3.82MPa, the throat diameter of the safety valve should not be less than 20mm.
4. The safety valve should generally be equipped with an exhaust pipe. The exhaust pipe should pass through to a safe place and have a sufficient cross-sectional area to ensure smooth exhaust steam.
5. The safety valve of the pressure vessel is best installed directly on the highest position of the pressure vessel body. The safety valve of the liquefied gas tank must be installed in the gas phase. Generally, a short tube can be connected to the container.
6. If several safety valves are installed on a short pipe directly connected to the drum, the cross-sectional area of the passage of the short pipe should not be less than 1.25 times the exhaust area of all safety valves.
7. For containers with flammable, explosive or viscous media, a shut-off valve can be installed for the convenience of cleaning or replacement of the safety valve. The shut-off valve must be fully opened and sealed during normal operation to avoid chaotic movement.
8. For boilers with a rated evaporation capacity greater than 0.5t / h, install at least two safety valves; for boilers with a rated evaporation capacity less than or equal to 0.5t / h, install at least one safety valve. Safety valves must be installed at the outlet of the split economizer and at the outlet of the steam superheater.
9. For pressure vessels with flammable, explosive or toxic media, the media discharged from the safety valve must have safety devices and recovery systems.
10. The safety valve discharge port should be protected against freezing. For containers containing flammable or toxic or highly toxic media, the drain pipe should be directly connected to an outdoor safe place or a facility for proper disposal.
11. The newly installed safety valve should be accompanied by a product certificate. Before installation, it should be recalibrated, sealed and issued a safety valve for verification.
12. No valve should be installed between the pressure-bearing equipment and the safety valve. For containers that contain flammable, explosive, toxic or viscous media, a stop valve can be installed for easy replacement and cleaning.
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