1) the cause of valve leakage during construction:
① improper transportation and lifting caused the valve damage as a whole resulting in valve leakage;
② When leaving the factory, no pressure is applied to the valve for drying and antiseptic treatment, resulting in corrosion of the sealing surface to form internal leakage;
③ construction site protection is not in place, the valve is not installed at both ends of the blind, rain, sand and other impurities into the seat, resulting in leakage;
④ installation, there is no grease on the seat, resulting in impurities into the seat back, or welding caused by burns within the leak;
⑤ valve is not installed in the full position, resulting in ball damage, welding, if the valve is not fully open, welding spatter will cause damage to the ball, when the ball with welding spatter in the switch will further damage the valve seat , Resulting in internal leakage;
⑥ welding residue and other construction caused by the sealing surface scratches;
⑦ factory or installation limit is not accurate cause leakage, if the valve stem drive sleeve or other accessories with the wrong angle of the assembly, the valve will leak.
2) Run-time valve leakage caused by the reasons:
① The most common reason is that operators consider the more expensive maintenance costs of the valve does not maintain or lack of scientific management and maintenance of the valve is not preventive maintenance of the valve, resulting in premature failure of equipment;
② improper operation or maintenance procedures in accordance with the maintenance caused by internal leakage;
③ In normal operation, the construction residue scratches the sealing surface, resulting in internal leakage;
④ improper pigging caused by sealing surface damage caused by leakage;
⑤ long-term maintenance or inaction of the valve, resulting in valve seat and the ball lock, resulting in sealing the valve leakage caused by internal leakage;
⑥ valve switch is not in place to cause internal leakage, any ball valve regardless of open, closed position, the general tilt 2 ° ~ 3 ° may cause leakage [2];
⑦ many large-diameter ball valve stem stopper most have, if the use of a long time, due to corrosion and other reasons in the stem and stem stopper will accumulate rust, dust, paint and other debris, these debris will cause the valve Can not rotate in place and cause a leak - If the valve is buried, lengthening the stem will produce and drop more rust and impurities prevent the ball from rotating in place, causing the valve to leak,
⑧ general implementing agencies are also limited, if long-term cause corrosion, grease hardening or limit bolt loose limit will not be accurate, resulting in internal leakage;
⑨ electric actuator set the valve position in front, no place in place caused by internal leakage;
⑩ lack of periodic maintenance and repair, resulting in sealant dry, hardened, dried Sealing grease accumulation in the elastic seat, hinder the seat movement, resulting in seal failure.
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