Requirements for Installation of Safety Valves on Boilers

The installation of safety valve on boilers should meet the following requirements:

1. For boilers with a rated evaporation greater than 0.5 t/h, at least two safety valves should be installed. For boilers with a rated evaporation less than or equal to 0.5 t/h, at least one safety valve should be installed. Safety valves must be installed at the outlet of distributed coal economizer and the outlet of steam superheater.

2. Safety valve should be installed at the highest position of boiler drum and set box. Between safety valve and boiler drum or set box, no steam outlet pipe and sanitary valve should be installed.

3. Lever-type safety valve should have device that prevents heavy hammer from moving on its own and guide rail that restricts the lever. Spring-type safety valve should have lift handle and device that prevents arbitrary screwing of the adjustment screw.

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

5. The cross-sectional area of the connection pipe between safety valve and boiler should not be less than the cross-sectional area of the inlet of safety valve. If several safety valves are co-installed in 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 area of exhaust of all safety valves.

6. Exhaust pipe should generally be installed in safety valve. It should have direct access to safe places and have enough cross-sectional area, which ensures the smooth exhaust flow. The bottom of the exhaust pipe of safety valve should have water exhaust pipe with access to safe places. No valves are allowed to be installed on steam exhaust pipe and water exhaust pipe.

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