Common valve malfunctions and causes

Failure cause

Repair method

Incorrect packing method (e.g., spiral insertion of the entire rod)

Proper packing

Rod deformation or corrosion and rusting

Repair or replace

Filler aging

Replace the packing material

Improper or excessive force during operation

Slow opening and closing, smooth operation

Failure cause

Repair method

Rod damage, corrosion tripping

Replace the valve component

Rod bending and torsion

When the valve is difficult to open, do not use long tools to pry the handwheel. The bent valve stem requires replacement.

Tilt of stem nut

Replace the valve or valve components

Open air valve rust

Open-air valves require enhanced maintenance and periodic handwheel rotation.

Failure cause

Repair method

Wear of the sealing surface, mild corrosion

Regular grinding

Improper closure results in poor sealing surface contact

Slow, repeated opening and closing several times

Bend of the stem, with upper and lower sealing surfaces not aligned with the centerline

Repair or replace

The valve orifice is blocked by an impurity.

Open, clear debris, then close slowly. Add a filter if necessary.

The sealing ring does not fit tightly with the valve seat and valve disc.

Repair

The valve disc is not securely connected to the valve stem.

Repair or replace the part.

Hitch

Failure cause

Repair method

Gasket leakage

The gasket material is incompatible or fails due to medium exposure during daily use.

Use gaskets compatible with working conditions or replace the gaskets

Valve cracking

Freeze damage or excessive force during installation of threaded valves

Thermal insulation and anti-freezing, apply even and appropriate force during installation

The handwheel is damaged.

Impact from heavy object, long rod lever failure to open, internal square hole wear with chamfered edge

Avoid impact, apply even force during operation, ensure correct direction, file square holes or replace the handwheel

Cover fracture

Uneven force during compression of the cap

Symmetrical nut

Gate failure

The wedge gate fails to close properly due to corrosion, and the top wedge of the double gate is damaged.

Regularly grind and replace the carbon steel top wedge

Hitch

Failure cause

Repair method

Medium backflow

1. Damage to the sealing surface between the valve core and the valve seat

2. Contamination between the valve core and valve seat

1. Grinding the sealing surface

2. Remove contaminants

The valve core does not open

1. The sealing surface is adhered by scale

2. Shaft rust

1. Remove scale

2. Polish the rust to enhance its flexibility

Valve leaflet fracture

The pressure of the medium before and after the valve is in a state of close balance, which makes the valve disc made of brittle material beat frequently.

Use a resilient material for the valve flap

Hitch

Failure cause

Repair method

No drainage

1. The steam pressure is too low

2. Steam and condensate failed to enter the steam trap.

3. The buoy-type float is too light

4. The float-type valve stem is jammed in the sleeve

5. Valve or passage obstruction

6. The thermostatic valve core fractures, causing valve orifice blockage

1. Adjust steam pressure

2. Check whether the steam pipeline valves are closed and blocked

3. Appropriate dosage adjustment or buoy replacement

4. Overhaul or replace to ensure flexibility

5. Remove obstructions and install a filter before the valve

6. Replace the valve core

Exhaust steam

1. Valve core and seat wear, resulting in steam leakage

2. The drainage hole cannot close on its own

3. The buoy-type float has a small volume and cannot float.

1. Grinding the sealing surface

2. Check for any blockage caused by debris

3. Appropriately increase the buoyancy volume

Continuous working temperature drop

1. The drainage volume is lower than the condensation water volume. 2. The condensation water volume in the pipeline has increased.

1. Replace with a suitable hydrophobe

2. Installation of a steam trap

Hitch

Failure cause

Repair method

Valve after pressure instability

1. The pulse-type valve has improper diameter selection and significant pressure difference between the two ends.

2. Improper selection of the adjustment spring

1. Replace with an appropriate pressure reducing valve

2. Replace with an appropriate adjustment spring

The valve is not working.

1. The control channel is blocked by debris

2. Piston is stuck with internal rust and cannot descend to the highest position

1. Remove debris and install a filter before the valve

2. Inspect and lubricate the piston to ensure smooth operation

Valve straight-through

1. Piston is stuck in a certain position

2. Fracture of the lower spring of the main valve disc

3. The pulse valve handle is jammed at the closed position

4. There is debris stuck between the main valve disc and the valve seat sealing surface or severe corrosion

5. Film failure

1. Inspect the piston to ensure its smooth operation

2. Replace the spring

3. Maintenance to ensure flexibility

4. Remove contaminants and grind sealing surfaces periodically

5. Replacement of the film

Valve after pressure cannot be adjusted

1. Failure of the adjustment spring

2. The cap has leakage and cannot maintain pressure

3. Piston and cylinder wear or corrosion

4. The valve body is filled with condensate water.

1. Replace the adjustment spring

2. Perform timely maintenance and replace gaskets

3. Cylinder overhaul and piston ring replacement

4. Remove the plug and drain all condensate

Hitch

Failure cause

Repair method

Leakage of sealing surface

1. Contamination or wear on the sealing surfaces of the valve core and seat

2. The valve stem centerline is misaligned

1. Remove contaminants or grind the seal

2. Centerline alignment of the straightening valve stem

Do not turn on when overpressure occurs

1. Leverage jammed or pin rusted

2. The lever-type weight is moved

3. The spring undergoes thermal deformation or failure

4. Valve core sticking to valve seat

1. The lever or pin needs to be repaired.

2. Adjust the position of the weight

3. Replace the spring

4. Perform periodic exhaust tests

Enable before work pressure

1. The lever's weight moves inward

2. Insufficient spring elasticity

1. Adjust the position of the weight

2. Tighten or replace the spring

The valve core does not close automatically when enabled

1. Leverage bias

2. Spring-type spring bending

3. Misalignment of the valve core or stem

1. Maintenance lever

2. Adjust the spring

3. Adjust the valve core or valve stem