7.2　Valves and Special Parts

7.2.1　This section is applicable to special piping components such as forced closing extraction check valve，HP exhaust check valve，gland seal pressure adjustor，emergency discharge valve，vent valve and valves in vacuum system.

7.2.2　For valves within the scope of steam turbine，in addition to the inspections specified in Part 5"Pipes and systems"of this Specification，high temperature fastener materials and tightening torque shall also be inspected and comply with manufacturer requirements.

7.2.3　For valves with electrical and control elements，the inspection and installation work shall be performed in cooperation with electrical，I&C and mechanical installation personnel.

7.2.4　For the inspection and installation of pneumatic or hydraulic valves，first the flexible and correct operation of pneumatic or hydraulic shall be confirmed，and the air and hydraulic pipes and connectors shall be through without blocking.

7.2.5　Inspection and installation of electromagnetic，hydraulic and counter-weighted extraction check valve，HP exhaust check valve shall comply with the following provisions:

1　Check valves shall be subject to tightness water filling test，to confirm they are free of leakage，and the spool and valve seat shall be in tight contact.

2　Buffer shall be able to move up and down smoothly and freely，the buffering hole shall be well through，the copper sleeve and buffer shall be securely fixed.At closing，there shall be surplus travel in buffering.

3　When the working medium of buffer is oil，the oil quality and level shall comply with manufacturer requirements.

4　The nuts on spool shall be locked，and moving gap shall be reserved according to manufacturer requirements.

5　The travel and gap of electromagnetic，hydraulic operating lever switch clutches，armature pilot valves shall comply with manufacturer requirements.

6　The springs of valve manipulating base shall be free of deflection or jamming.

7　In a counter-weighted check valve，the counter weight shall move vertically.

8　The packing shall be in proper tightness，the gap of packing box and its gland with the peripheral of valve stem shall be homogeneous，and free of jamming.

9　Operation test shall be made after assembling of valve，it shall operate flexibly and can be closed tightly.

7.2.6　For a water seal valve working under vacuum，the water seal ring of its stem shall be aligned to the water inlet pipe，and water shall overflow from the cock and plug.

7.2.7　For valves with press springs，such as vent valve and emergency discharge valve，the operating support and valve body shall join securely，the spring shall be at a correct position without jamming，the bolts of bonnet and support shall not be loose，and the valve lever steam leakage and compressed air port shall be well through.

7.2.8　Installation of valve driving devices shall comply with the following provisions:

1　Moving space shall be reserved for driving device，and it shall not hinder the expansion or operation of other equipment.

2　Driving rod shall have an angle less than 30 degrees，and the length of a single driving rod shall be less than 4m.

3　The driving device，support bearing and direction changeover box shall be flat，straight and secure.

4　Driving device operation shall be flexible and reliable.