①Handwheel, handle and transmission mechanism are not allowed for lifting, and collision is strictly prohibited.
②Double gate valves should be installed vertically (i.e. the stem is in a vertical position and the handwheel is at the top).
③In use, gate valves are only used for full opening or closing, and partial opening and closing are not allowed to be used to adjust the flow rate to prevent the sealing surface from being easily damaged when the medium flow rate is high.
④The gate valve shall be opened and closed by rotating handwheel and shall not be opened with the aid of other auxiliary levers.
⑤The gate valve should be oiled in the rotating part, and the trapezoidal thread part of the stem should be oiled to lubricate it, which is convenient for rotation and corrosion protection.
⑥Gate valve installation to clean the inner cavity and sealing surface, do not allow dirt attachment.
⑦Check that the connecting bolts are tightened evenly.
⑧Check that the packing is pressed, and ensure that the packing is sealed and does not hinder the stem rotation.
What are all the ways to troubleshoot gate valves?
Troubleshooting and elimination methods:
Common faults 1: Leakage of body and bonnet
Causes: Damaged valve after heavy impact
Exclusion methods: Do not pile heavy objects on the valve, do not allow hand hammer impact valve, large-caliber valve installation should be supported.
Common faults 2: Leakage of sealing surface
Causes 1: Seal surface closure is not strict or due to the closure of cold shrinkage of the fine seam, resulting in erosion phenomenon.
Exclusion methods 1: 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.
Causes 2: 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, extruded deformation.
Exclusion methods 2: Valve opening and closing are strictly regulated.
Causes 3: The wear of sealing surface is too large to produce the phenomenon of falling off, that is, the sealing pair can not close well.
Exclusion methods 3: The sealing surface should be adjusted after the wire drop, and the unadjustable sealing surface should be replaced.
Common faults 3: Leakage at sealing ring connection
Causes 1: Sealing ring connection thread, screw, press ring, loose
Exclusion methods: 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.
Causes 2: Sealing ring connection surface corroded
Exclusion methods: Seal ring connection surface is corroded, can be ground, bonded, welding method repair, can not be repaired should replace the sealing ring.
Common faults 4: Leakage of foreign body embedded between sealing surfaces
Causes 1: The sealing surface of infrequent opening and closing is easy to deposit some dirt
Exclusion methods: Unusual opening and closing valves should be opened and closed frequently, 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.
Causes 2: Medium is not clean, containing abrasive, rust, welding slag and other foreign bodies
Exclusion methods: 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.
Common faults 5: Stem operation not flexible
Causes 1: Trapezoidal threads are not clean and filled with dirt and abrasive particles
Exclusion methods: Stem, stem nut threads are often cleaned and lubricated, high temperature valves should be coated with molybdenum disulfide or graphite powder for lubrication.
Causes 2: Stem nut loose, trapezoid thread slip
Exclusion methods: Stem nut loosening should be repaired and replaced
Causes 3: Deformed, worn and damaged stem and related parts
Exclusion methods: Properly operate valve, close force
Causes 4: Stem dead or closure stuck
Exclusion methods: 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 top death.
