Installation requirements for safety valves on boilers
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The installation of safety valves shall meet the following requirements: (l) Boilers with a rated evaporation capacity greater than 0.5 t/h shall be equipped with at least two safety valves; boilers with a rated evaporation capacity equal to or less than 0.5 t/h shall be equipped with at least one safety valve. Safety valves must be installed at the outlet of the fractional economizer and at the outlet of the steam superheater. (2) The safety valve should be installed vertically at the highest point of the boiler or header. No steam extraction outlet pipes or valves shall be installed between the safety valve and the boiler drum or header. (3) Lever-type safety valves shall be equipped with devices to prevent the weight from moving on its own and guides to restrict the lever from going out of track, while spring-type safety valves shall have lifting handles and devices to prevent the adjustment screws from being turned arbitrarily. (4) For boilers with a rated steam pressure of 3.82 MPa or less, the throat diameter of the safety valve shall 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 shall not be less than 20 mm. (5) The cross-sectional area of the connection pipe between the safety valve and the boiler shall be no smaller than the inlet cross-sectional area of the safety valve. If several safety valves are installed together on a short pipe directly connected to the boiler drum, the cross-sectional area of the passage in that short pipe shall be not less than 1.25 times the total venting area of all the safety valves. (6) Safety valves should generally be equipped with exhaust pipes, which should lead to a safe location and have sufficient cross-sectional area to ensure smooth exhaust. At the bottom of the safety valve exhaust pipe, a drain pipe that leads to a safe location should be installed; no valves are allowed to be fitted on either the exhaust pipe or the drain pipe.
The following points should be noted regarding the installation and maintenance of boiler safety valves: 1. All types of safety valves should be installed vertically. 2. There should be no resistance at the outlet of the safety valve to prevent pressure buildup. 3. The safety valve should be tested specifically before installation, and its sealing performance should be checked. 4. Safety valves in use should be inspected regularly.