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The stand or fall of knife gate valve maintenance is the key to the pipeline transportation,this is because in the process of conveying when equipment or pipeline network problems, you need to use the knife gate valve to shut down and seal, so that all kinds of equipment and pipeline repair work, so the problems of the valve must be handled in time, to ensure the maintenance smoothly.
knife gate valve is commonly used in conveying system equipment, belong to the full open all closed valve, main effect is opened and closed pipeline conveying system.Feeder can be installed in hydrocyclone, tailings or double circuit line, etc.
1, the cover down hole leakage
Some valve bonnet with manufacturers on the experiment of down hole, when use may cause leakage.The main reason is the down hole not tighten.
Solution: to tighten, or put down hole bolts removed, remove the inside copper pad, clean with screw, the screw hole grinding to use welding welding die.
2, the body and bonnet joint leakage
Flange joint bolt fastening uneven tension is not enough or make flange tilt caused the body and bonnet joint leakage, or body and bonnet junction surface damage, flange gasket damage caused problems such as the joint leakage.
The solution: flange had better use flange diagonal fastening;Pay attention to protect the junction surface when using;If choose better quality gaskets, gasket can't adjust in combination with surface problem, can be combined for reprocessing.
3, gland leakage
Packing and working medium corrosion, temperature, pressure does not adapt, the wrong loading method, the surface finish of the stem is not enough, corrosion, rust, or packing use time for a long time, and aging, these problems are the cause of stuffing box leaking.
Solution: choose the right way of packing;According to the correct method for packing;Choose the stem of surface finish is achieved;Take the corresponding protective measures to prevent corrosion, if discover rust, timely replacement
4, the valve stem failure
Stem failure is most commonly due to conduct operations, which causes the stem thread damage, the valve stem bending, and fit tolerance or the stem nut is allowed to tilt, nuts, thread is medium corrosion, rust and other causes.In addition, the choice of materials, can also cause stem failure such as valve stem and stem nut for the same material, it is easy to bite and cause failure.
Solution: workers when using the knife gate valve should elaborate operation, must strictly control the discretion when open and close, don't MengJin switch, to prevent stem bending;Opens don't drive to the top dead center, moderately back after open the handwheel, make the thread of the upper seal, in order to avoid the media to promote stem upward shocks;Adjust the position of the nut.In the case of can't avoid being corrosion, rust, need to change in time with stem nut;Use different material of nut and stem.
5, stem rotation is not flexible or jammed
Stem rotation is not the main reason of flexible or jammed by too tightly on the packing;Packing into the stuffing box is not in conformity with the specification;The clearance between the sleeve and the valve stem is not enough;Stem bending;Thread surface roughness is not in conformity with the requirements;The valve stem and valve stem set of causes such as the improper material selection.
The solution: panasonic packing gland screws can be appropriately;According to the specification to add loading;The clearance between the sleeve and the valve stem control within the standard;To control the thread processing surface roughness within the standard.
The above five is the most common problem, as long as the check each part carefully when buy inosculation and smoothness, and in use process in strict accordance with the instructions to operate, can greatly reduce the damage of the knife gate valve.