(2) check whether the stem and disc opens flexible, presence of jam and askew phenomenon,
(3) check valve is damaged, the thread of the valve is correct and complete,
(4) check whether the combination of the seat and body, disc and seat, bonnet and valve body, valve stem and disc coupling,
(5) check valve packing, packing and fasteners (bolts) is suitable for the requirement of working medium properties,
6. The old, or put on hold for a long time of pressure reducing valve should be disassembled, dust, sand and other debris should be cleaned with water,
All landowners to clear his block, check the sealing degree, the disc must be closed tightly,
The valve pressure test
Low pressure, medium pressure and high pressure valves for strength test and leak test and alloy steel valves for spectral analysis of the shell should also be individually, review material,
1. Valve strength test
Strength test of the valve is in the condition of open valve test, the appearance of the leak check valve, PN acuities were 32 mpa valve, its test pressure is 1.5 times the nominal pressure, test time is not less than 5 min, shell, gland place no leakage for qualified,
2. The valve leak test
The experiment was carried out under the valve fully closed position, check for leakage valve sealing surface, the test pressure, in addition to the butterfly valve, check valve, bottom valve, throttle valve, outside the general should with nominal pressure, when can determine the working pressure, 1.25 times working pressure test are available, and also to the disc sealing surface does not leak for qualified,
