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All valves require inspection and periodic maintenance prior to being placed into service and at regular intervals. Leaks should be repaired as soon as
they are discovered in order to maintain optimum performance and also to prevent more serious damage to the valve. The recommended maintenance
schedule is tabulated below in Table.

Area	Purpose	Procedure	Frequency
Body	Prevention of leakage and improper action.	Visual check of seating surface and gasket contact surface for damage.	At the time leak is detected or every four (4) years.
Disc	Prevention of leakageat seat and improper action.	Visual check of seating surface for damage.	At the time leak is detected or every four (4) years.
Stem, PackingWasher& Gland	Prevention of Stem and packing leakage and improper action.	Visual check for scoring and seizing, especiallyalong sliding surfaces of stem and packing.	At the time leak is detected or every four (4) years.
Bolts &Nuts	Ensure proper tightness of joints.	Check for tightening force or retightening.	At the time looseness is detected or everyfour (4) years.
Packing	Prevention of leakageand improper action.	Check the Gland bolt for looseness and retighten as necessary.Replace packing.	At the time of leak or every two(2) years.
Gasket	Prevention of leakage	Check the nuts and bolts for looseness. Retighten as required. Replace the gasket.	At the time of leak or every two(2) years.
Seal Ring	Prevention of leakage	Check nuts and bolt for looseness and retighten as necessary.Replace SealRing	At the time of leak or every two(2) years.

Occasionally, valve age, type of service or other factors may result in problems such as packing leakage, Body-Bonnet/Cover joint leakage, seat leakage
or loss of operation smoothness. The troubleshooting chart presented in the following Table lists typical problems and methods for resolving them. It
should be noted that this chart does not present all possible problems and all possible solutions and is not a substitute for regular periodic maintenance.
It does, however, list the most common problems that can be encountered and the repair procedure that will most likely return the valve to its proper
operational condition.

Troubleshooting Chart

Problem	Cause	Repair Procedure
Packing Leakage	PackingCompression Worn Packing Stem Damage Stuffing Box Damage	Tighten Packing Replace Packing Repair or Replace Stem Repair Stuffing Box
Body-Bonnet/ Cover JointLeakage	Insufficient Bolting Tightness Gasket Worn or Damaged	Check Bolting Torque Replace Gasket
Seat Leakage	Damaged Seating Surfaces	Lap Disc and Seat Ring
Stem Binding	Insufficient Lubrication Packing Too Tight Damaged Stem Threads Damaged Sleeve	Lubricate Stem Adjust or Replace Packing Repair or Replace Stem Repair or Replace Sleeve
Valve Seat Leakage when fully closed	Differential pressure is larger than design condition Inadequate method of stopping valve Damage to valve seating surfaces	Decrease differential pressure Change method of stopping valve Change method of stopping valve Disassemble valve and lap seating surfaces
Seat Leakage	Damaged Seating Surfaces	Lap Disc and Seat Ring
Motor does not start operation	Wrong electric power supply source or low voltage Damage to motor due to buring, Disconnection of wire and deterioration of insulation Differential pressure is larger than design condition	Change to proper electric power supply source Exchange motor Decrease differential pressure
Motor stops during middle of opening or closing operation	Improper lubrication of threaded of stem Galling in threaded part of stem Galling or foreign matter in sliding parts inside of valve	Clean up threaded part and apply grease Lap engagement of threads or replace stem and stem nut Disassemble valve, inspect and repair the sliding part

The Maintenance of Valves

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