Faults and elimination methods for gate valve

 Common faults

 Reasons

Elimination methods

Leakage of body and bonnet

Damaged by heavy impact

Do not pile heavy objects on the valve, do not allow hand hammer impact valve, Yoke is necessary for large valve installation.

Leakage of sealing surface

Seal surface closure is not strict or due to the closure of cold shrinkage of the fine seam, resulting in erosion phenomenon.

Strictly follow the direction of the valve opening and closing.

For high temperature valves, after the closure of the cold shrinkage of the fine seam, should be closed at a certain interval after closing again

The valve has reached full closing position and continues to apply excessive closing force, including improper use of long lever operation, sealing surface is crushed.

Valve opening and closing should floow the refulation strictly.

The sealing surface is too worn and the line is dropped, that is, the seal cannot be well sealed

The sealing surface should be adjusted after the wire drop, and the unadjustable sealing surface should be replaced.

Leakage at sealing ring connection

Loseness for sealing ring connection thread, screw and press ring

Remove screws, press ring cleaning, replace damaged parts, grind seal and joint face, reassemble. Repair of parts with greater corrosion damage by means of welding and bonding

Sealing ring connection surface corroded

Repair it by ground, bonded, welding method. It should replacee if the sealing ring can not be repaired.

Foreign matter embedded between sealing surfaces

The sealing surface of infrequent opening and closing is easy to deposit some dirt

For the gate valves which not be opened and closed frequently, should open and close frquently. Leaving a fine seam when closed, repeated several times, so that the sediment on the sealing surface is washed off by high speed fluid, and then reduced according to the original opening and closing state

Medium is not clean, containing abrasive, rust, welding slag and other matters

Before the valve should be equipped with sewage, filtration and other devices, or regularly open and clean, the sealing surface mixed with iron slag and other things, do not forcibly close, the use of slit method to wash away these foreign bodies, difficult to wash away the larger foreign bodies, The cover should be opened and removed.

Stem operation not flexible

Trapezoidal threads are not cleaned and filled with dirt and abrasive particles

Stem, stem nut threads should be often cleaned and lubricated, high temperature valves should be coated with molybdenum disulfide or graphite powder for lubrication.

Stem nut loose, trapezoid thread slip

Stem nut loosening should be repaired and replaced

Poor operation, so that the valve stem and related parts are deformed, worn, damaged

Properly operate valve

The valve stem is stuck or the closing part is stuck

For the closed valve parts easy to heat expansion, the interval should be unloaded once, that is, the handwheel turn a little counterclockwise to prevent stem stuck.