Safety valve installation requirements
(l) For boilers with a rated evaporation greater than 0.5 t/h, install at least two safety valves: a boiler with a rated evaporation of less than or equal to 0.5 t/h, and at least one safety valve. Separable economizer outlets and steam superheater outlets must be equipped with safety valves.
(2) The high pressure safety valve shall be installed vertically at the high position of the pot dealer and the header. No outlet pipe and valve for access to steam shall be installed between the safety valve and the drum or header.
(3) The lever-type safety valve shall have means for preventing the hammer from moving by itself and a guide that restricts the derailment of the lever. The spring-type safety valve shall have means for lifting the handle and preventing the adjustment screw from being easily turned.
(4) For boilers with a rated steam pressure less than or equal to 3.82 MPa, the throat diameter of the safety valve should not be less than 25 mm: For boilers with a rated steam pressure greater than 3.82 MPa, the throat diameter of the safety valve should not be less than 20 mm.
(5) The connection pipe between the high pressure safety valve and the boiler shall have a cross-sectional area not less than the inlet cross-sectional area of the safety valve. If several safety valves are jointly installed on a short pipe directly connected to the drum, the cross-sectional area of the passage of the short pipe shall not be more than 1.25 times of the exhaust area of all safety valves.
(6) The safety valve should generally be equipped with an exhaust pipe. The exhaust pipe should pass through to a safe location and have sufficient cross-sectional area to ensure that the exhaust is unblocked. The bottom of the exhaust pipe of the safety valve should be installed with a cavity to receive a hydrophobic pipe in a safe place. Valves should not be installed on the exhaust pipe and the drain pipe.