Key Points Of Installation And Maintenance Of Parallel Safety Return Valve

Installation and maintenance of parallel safety return valve:

1. The safety valve shall be installed vertically at the Zui high position of boiler supplier and header. The outlet pipe and valve for steam shall not be installed between the safety valve and the drum or header.

2. The lever type safety valve shall be equipped with a device to prevent the self movement of the heavy hammer and a guide frame to limit the derailment of the lever. The spring type safety valve shall be equipped with a lifting handle and a device to prevent the adjustment screw from being screwed casually.

3. For boilers with rated steam pressure less than or equal to 3.82MPa, the throat diameter of safety valve shall not be less than 25mm; For boilers with rated steam pressure greater than 3.82MPa, the throat diameter of safety valve shall not be less than 20mm.

4. The cross-sectional area of the connecting pipe between the safety valve and the boiler shall 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 drum, the passage cross-sectional area of the short pipe shall not be 1.25 times of the exhaust area of all safety valves.

5. Generally, the safety valve shall be equipped with a steam exhaust pipe, which shall be directly connected to the safe place and have sufficient cross-sectional area to ensure smooth steam exhaust. The bottom of the exhaust pipe of the safety valve shall be pretended to have a drain pipe connected to a safe place. Valves are not allowed to be installed on the exhaust pipe and drain pipe.

6. Boilers with rated evaporation capacity greater than 0.5t/h shall be equipped with at least two safety valves; Boilers with rated evaporation 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 separable economizer and the outlet of steam superheater.

7. The safety valve of the pressure vessel is directly installed at the Zui high position of the pressure vessel body. The safety valve of liquefied gas storage tank must be installed at the gas phase position. Generally, the short pipe can be connected with the container, and the diameter of the short pipe of the safety valve shall not be less than the valve diameter of the safety valve.

8. Generally, no valve shall be installed between the safety valve and the container. For the convenience of cleaning or replacing the safety valve, a stop valve can be installed for the container of flammable, explosive or viscous media. The stop valve must be fully opened and sealed with lead during normal operation to avoid random movement.

9. For pressure vessels with flammable, explosive or toxic media, the media discharged by the safety valve must have safety devices and recovery systems. The lever safety valve must be installed in a vertical position, and the spring safety valve must also be installed vertically to avoid affecting its action. During installation, attention shall also be paid to the fit, the coaxiality of parts and the uniform stress of each bolt.

10. The newly installed safety valve shall be attached with the product certificate. Before installation, it shall be re calibrated, lead sealed and issued with the safety valve verification certificate.

11. The outlet of the safety valve shall have no resistance and avoid back pressure. If a discharge pipe is installed, its inner diameter shall be greater than the outlet diameter of the safety valve. The discharge port of the safety valve shall pay attention to antifreeze. For containers containing flammable, toxic and highly toxic media, the discharge pipe shall be directly connected to the outdoor safety place or have facilities for proper treatment. No valve is allowed to be installed in the discharge pipe.

12. No valve shall be installed between pressure equipment and safety valve. For containers containing flammable, explosive, toxic or viscous media, stop valves can be installed for easy replacement and cleaning, and their structure and diameter shall not hinder the normal operation of safety valve. During normal operation, the stop valve must be fully opened and sealed with lead.