1. Stem failure
The failure of valve stem normally mostly due to excessive operation resulting in threaded stem injury, stem caused by the bending or stem and nut with tolerances are not allowed, nut tilt, threads are caused by corrosive medium, corrosion and other reasons. In addition, the choice of materials can also cause stem failure, such as stem and stem nut for the same material, it is easy to bite, resulting in failure.
Solution:
useing a knife gate valve when workers should be careful operation, open, close to strictly control the discretion, not Meng Jin switch, to prevent stem bending; open don't open to the top dead center, moderate open handwheel reverse circle, thread on the upper side of the sealing, lest pushing the media stem to shocks; adjust the position of the nut; in can't avoid being corroded and rusted, need for timely replacement of the valve stem and nut; using different materials of nut and stem.
2. The valve stem rotation is not flexible or card dead
Main reason for stem rotation is not flexible or stuck by the packing pressed too tight; packing into the stuffing box when not in conformity with the specifications; stem and sleeve gap is not enough; stem bending; thread surface roughness does not meet the requirements; stem stem and sheath material choice is undeserved wait for a reason.
Solution:
The appropriate Panasonic packing gland screws; according to the standard add loading; clearance between the stem and the sleeve control within the standards; the thread machining surface roughness control within the standard.
3. The valve cover to suppress Kong Xielou
Some of the valve cover with a manufacturer to suppress the experimental pressure hole, use may cause leakage. The main reason is that the pressure hole is not tight.
Solution:
Retighten, or to suppress the bolt holes, the inside of the copper pad will be removed, then the screw polished and clean with screw, die welding.
4. The valve body and valve cover connection leakage
Flange bolt tightening force is not enough or fastening uneven so the flange tilt caused by the valve body and valve cover the junction leakage, or connect the body and the valve cover surface is damaged, the flange gasket damage caused by the junction leakage.
Solution:
Flange fastening the best use of flange fastening; the use of attention to protect the connection surface; select a better quality gasket, if the gasket can not adjust the binding surface, can be combined with surface processing.
5. Stuffing leakage
Does not adapt the corrosion of filler and the working medium, temperature, pressure, filling method of the error, the stem surface finish is not enough, corrosion, rust, or filler is used for a long time, deteriorate such that, these problems are the cause of packing leak letter.
Solution:
Choose the correct way of packing; packing in accordance with the correct method; choose the surface is bright and clean degree reach the requirements of stem; take the corresponding protective measures, to prevent corrosion, if it is found that the corrosion to the timely replacement.
