Coated sand: installation requirements of safety valves on boilers. The installation of safety valves shall meet the following requirements: (L) boilers with rated evaporation 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 steam superheater.

(2) The safety valve shall be installed vertically at the highest position of the boiler supplier and header. The outlet pipe and valve for steam shall not be installed between the safety valve and the drum or header.

(3) The lever type safety valve shall be equipped with a device to prevent the weight from moving by itself and a guide frame to limit the lever deviating from the track. The spring type safety valve shall be equipped with a lifting handle and a device to prevent the adjustment screw from being screwed casually.

(4) 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.

(5) 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.

(6) Generally, the safety valve shall be equipped with 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.