The valve box may be interfering with the operating key.
Stuffing box gate valve.
Look down the valve box to see if it is to close to the operating nut.
Note whether the gland nose is.
Deep stuffing boxes are standard on gate and globe valves.
If the stem of a globe valve is in good condition stuffing box leaks can usually be stopped by setting up on the gland.
Look for burrs or scaling.
Gate valves forum manufactures mud gate valves to meet the tough demands of deep high pressure drilling applications up to 7 500 pounds per square inch psi.
The stuffing box bolts and nuts may have been tightened down unevenly during assembly.
Loosen and retighten stuffing box bolts and nuts evenly.
Designed to provide long service in high pressure pump and standpipe manifold systems our rugged valves created tight shutoff at every closing cycle and outperform even after long.
The speaker mentioned that an ideal stuffing box contains 5 rings of packing and that deeper stuffing boxes are not preferred as only the two packing rings nearest the outside of the valve are fully compressed by the force from the packing follower.
Some factors to consider include.
Inspect the gland the gland should be able to freely enter the stuffing box all the way.
The gland must not be set up or packed so tightly that the stem binds.
Inspect all of stem gate the valve should be all the way open to inspect the entire stem gate.