Possible faults, causes and elimination methods of knife gate valve

Packing leakage

1. The packing gland is not pressed tightly

2. The filler fails due to long-term use or improper storage

1. Tighten the nut evenly to compress the packing

2. Replace the packing

Leakage between sealing surfaces

1. There is dirt and debris attached to the sealing surface

2. Damaged sealing surface

1. Clean the dirt and sundries 2. Rework, trim or replace

Leakage at the connection between the valve body and the bonnet

1. Uneven tightening of connecting bolts

2. The flange sealing surface is damaged

1. Tighten evenly

2. Refinish

The handwheel is inflexible or the gate cannot be opened and closed

1. The packing is pressed too tightly

2. The stem nut is damaged

3. The thread of the stem nut is severely worn or broken

4. Stem bending

1. Properly loosen the nut on the packing pressure plate

2. Disassemble and trim threads and remove dirt and debris

3. Replace the stem nut

4. Correct the valve stem