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Valve failure reasons, one is the valve itself quality problem, the second is the user due to its improper use.
In valve production, strict technology, perfect equipment, strict inspection and outside collaboration fittings factory quality level, these are major factors in determining the quality of the valve itself.
Valve selection in the design of the correctness of the actual working condition and scope prescribed by the consistency of the valve, as well as the operation right and serious, timely maintenance, and is directly related to the valve fault avoiding and longer service life.
The following sort out all kinds of common common faults in the valve and the reason for the manufacturing quality, user reasons and corresponding maintenance plan.
1, the valve leakage fault of gasket
Reason: manufacturing quality gasket assembly does not conform to requirements;The static sealing surface rough;The sealing pair is not clean, to join the foreign body.
User reasons: gasket selection is wrong, not heat resistance, pressure, corrosion resistance requirements;Operation is not smooth, temperature fluctuation is too large.
Solution: according to the requirements of working condition, choose correct gasket materials and type;Should carefully operation.
2, sealing ring joint leakage of valve failure
Manufacturing quality reasons: generally belongs to the manufacturing quality problems.
3, closing of valve failure parts fall off (valve failure risk of leakage)
Manufacturing quality: closed connected to the valve stem is not strong.
User reasons: shut down after the death of more than top dead center or card, continue to fracture operation;Fitting material selection is not correct.
Solution: correct operation, after the valve fully open, should be slightly back let go round, leave a gap;Choose medium corrosion and abrasion resistance should be considered.
4, between the sealing face of valve failure embedded foreign bodies
User reasons: long closed valves in the seal surface fouling;Medium not clean, the card on the seal;Valve selection is not correct, the media and their sedimentary consider not comprehensive.
Solution: the valve open a thin seam, make high speed liquid rinse dirt on the surface of the seal;Don't clean the medium, the valve should be set before the filter drainage device, large foreign bodies, should open the cover removed.Medium with hard grains, unfavorable choose gate valves, plug valves, ball valves and optional.
5, stem card resistance of valve failure
Manufacturing quality: the cause of the valve stem and its mating parts machining accuracy is low;Assembly is not straight, clearance, concentricity does not conform to specifications;Packing too close, lock the valve stem;Stem nut loose thread slippery silk;About joint loose or damaged.
User reasons: trapezoidal thread is too dirty, poor lubrication;Not for a long time operation and rust;Closing force is too large, the related parts deformation damage;The valve stem dead or close a jammed.
Solution: in thread should be clean, add lubricant, lubrication sliding surface should be good;The stem should be regularly check and activity;Correct operating valve, closing force.Correct operation of valve to shut down the valve still heat expansion, should stipulate time unloading operation procedures, in case of death.
6, valve handle of fault, the damage of the handwheel
User reasons: incorrect use handle, hand wheel damage;Fasteners loose;Handle, wrench, hand wheel, and the valve stem joint injury, can't transfer torque.
Solution: it is prohibited to use long pipe wrench, leverage, impact tool operation;Should repair or at any time;Shall, from time to time to repair, in order to avoid damage.
Pay (including 7, valve failure of gear worm gear and worm) transmission card to bite you
Manufacturing quality: assembly, clearance does not conform to specifications;Precision parts, degree of finish is poor;Shaft and bearing parts, axle sleeve gap is too small, poor lubrication;Shaft bending, loose or damaged fasteners and fittings.
User reasons: gear is not clean, embedded dirt, lubrication;Improper operation.
Solution: gear should be kept clean and lubricated periodically, grey environment should add more dust cover;If discover bite during operation, when the resistance is very big, can not continue the operation, otherwise damage increased.
8, pneumatic or hydraulic device of valve failure action is not flexible
Manufacturing quality: the cause of cylinder block and cylinder head casting quality is unqualified, resulting in leakage phenomenon, impact pressure;The piston rod bending or super tolerance range;Gasket, packing leak, impact pressure;Poor quality of parts or assembly is not straight;Reset spring relaxation in cylinder;The signal system failure;Packing pressure tight.
User reasons: o-rings, seals aging leads to crawl piston;Stroke of the piston rod is too long, ram stuck in the valve body;With foreign body inside cylinder body;Piston and piston rod joint wear;Within the cylinder wall wear and leakage increase;Small piston grinding, grinding cylinder;Enter the pressure inside the cylinder small fluctuations.
Solution: seals shall periodically inspect and replace;Adjust the piston rod work schedule, action to normal;Shall promptly remove foreign bodies, and wash it, cylinder body can be set before the filtering mechanism;Piston, piston rod, cylinder should be done to repair or replace measures;Enter the pressure inside the cylinder should comply with the specification requirements.
9, valve failure of electric actuator failure
Manufacturing quality: assembly is not correct, cause torque was damaged;Travel switch setting is not normal;The torque limit organization failure;The signal system failure;Operation transformation mechanism is ineffective.
User reasons: poor lubrication, the valve gets stuck, foreign body in it cause torque was damaged;Motor fault.
Solution: should come on, keep clean, make good lubrication;Packing pressure should be moderately;Should be excluded from foreign body in the valve in a timely manner;Working hours shall not be more than 15 minutes, motor power should be normal, should avoid to be affected with damp be affected with damp.
10, valve leakage failure of the valve body and valve cover
Reason: manufacturing quality casting sand holes, stoma defects;Weldments with slag, stress crack defects such as lack of penetration.
User reasons: pressure or impact damage;Frost crack.
Solution: cannot store area, are not allowed to tap on a cast iron and non-metallic valves, application support installation of large diameter valves;Should be below 0 ℃, heat preservation measures;Stop using the valve, should be ruled out water.
11, electromagnetic actuator faults of valve failure
Manufacturing quality: wire fall off;Loose parts, the installation is not correct;Electromagnetic transmission parts and valves sealed, medium to discharged into coil, lead to defective insulation, burn out the coil.
User reasons: due to foreign bodies stuck, cause overload and burn out the coil.
Solution: the foreign body should be immediately clear inside the valve;Correct connection, correct installation.
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