Inspection before valve installation
① Carefully check whether the valve model and specification meet the requirements of the drawing.
② Check whether the valve stem and valve disc can be opened flexibly, and whether they are stuck or skewed.
③ Check whether the valve is damaged and whether the thread of the threaded valve is correct and complete.
④ Check whether the combination of the valve seat and the valve body is firm, the connection between the valve disc and the valve seat, the valve cover and the valve body, and the valve stem and the valve disc.
⑤ Check whether the valve gasket, packing and fasteners (bolts) are suitable for the requirements of the working medium.
⑥ The old or long-standing pressure relief valve should be dismantled, and the dust, sand and other debris should be cleaned with water.
⑦ Remove the port cover, check the sealing degree, and the valve disc must be closed tightly.
Pressure test of valve
Low-pressure, medium-pressure and high-pressure valves should be subjected to strength test and tightness test, and alloy steel valves should also be subjected to spectral analysis of the shell one by one, and the material should be reviewed.
1. Strength test of valve
The strength test of the valve is to test the valve in the open state to check the leakage on the outer surface of the valve. For valves with PN≤32MPa, the test pressure is 1.5 times the nominal pressure, the test time is not less than 5min, and there is no leakage at the shell and packing gland to be qualified.
2. Tightness test of valve
The test is carried out with the valve fully closed to check whether there is leakage on the sealing surface of the valve. The test pressure, except for butterfly valves, check valves, bottom valves, and throttle valves, should generally be carried out at the nominal pressure. When the working pressure is used, it can also be tested with 1.25 times the working pressure, and it is qualified if the sealing surface of the valve disc does not leak.
About CVG Valve
CVG Valve is specialized in developing and manufacturing low and middle pressure butterfly valves, gate valves, ball valves, check valves, kinds of function valves, special design valves, customized valves and pipeline dismantling joints. It is also the main manufacturing base of large size butterfly valves from DN 50 to 4500 mm.
The main products are:
-Double eccentric butterfly valves
-Triple eccentric butterfly valves
-Rubber lined butterfly valves
-Wafer type butterfly valves
-Hydraulic control butterfly valves
-Gate valves series
-Eccentric ball valves
-Hydraulic control check valves etc.