6.5　Safety Valves

6.5.1　The manufacturer's certificate and inspection report shall be provided for the boiler safety valve:

6.5.2　The following inspections shall be carried out before the erection of boiler safety valves:

1　The packages of the valves and accessories shall be fine.There shall be no damage in the equipment，and all external ports shall be closed tightly.

2　The manufacturer's quality certification documents and the erection and commissioning technical documents shall be complete.The attached valve accessories，seals and special tools shall be complete.

3　The welding groove for the welding valves shall meet the requirements of the related specifications.

6.5.3　For boiler safety valves，the spring assembly should not be disassembled at the site，except for the special requirements of equipment technical documents.The materials for all components shall meet the requirements of the manufacturer's technical documents.The spring characteristics，the adjustable stroke and so on shall be adaptable to the safety valve adjustment pressure.The sealing surfaces shall be fine and tight，without any leakage.The spring quality shall meet the related technical requirements.

6.5.4　The erection of boiler safety valves shall meet the requirements of the manufacturer's technical documents.In addition，the following requirements shall also apply:

1　When lifting safety valves，the lifting lugs provided by the manufacturer shall be used，and it shall be forbidden to lift several valves together.

2　When installing safety valves，it shall be ensured that the valve stem is in the vertical position and enough space for maintence shall be reserved at the top of valve body.

3　When the inlet and outlet tubes of valves are welded，the grounding wires shall not be led through the valve body and the spring.

6.5.5　The erection of the butterfly（disc）spring safety valves with the load pressure control shall meet the following requirements:

1　Vent pipes of safety valves installed in headers or the main pipes shall not affect the free expansion of headers and main pipes.

2　During boiler hydrostatic test，the valve stem shall be locked with the locking blocks provided by the manufacturer，and the valve stem shall not be rotated under the locking state.For safety valves with the diameter of butt joint greater than DN200，its locking shall be strengthened by loading the compressed air.After hydrostatic test，the lock devices shall unload in time.

3　The drain of the outlet nozzle for safety valves and the drain of the lowest locations for vent pipes shall be respectively connected to the atmospheric drain main pipes.

6.5.6　The erection of the pure mechanical spring type safety valve shall meet the following requirements:

1　During boiler hydrostatic test，the special valve core for hydrostatic test shall be used.Before the test pressure rises to 80% of the minimum setting value of the safety valve，the pressure may be continuously increased after the compression device has been operated manually.After hydrostatic test，the pressure shall be lowered to the compression pressure value and then the compression device shall be disassembled in time.

2　The vent pipe load shall not be directly acted on the vent elbow drain disc.

6.5.7　The adjustment of the boiler safety valve shall be carried out under the guidance of the manufacturer's professional personnel or according to the requirements of the manufacturer's technical documents.

6.5.8　The boiler power control valve（PCV）shall not be involved in the overpressure test for boiler proper.When the test pressure is increased to 80% of the setting value of the power control valve，the manual valve upstream of the power control valve shall be closed.