1. When the closing component comes loose, leakage happens.

reason:

1. Inefficient operation causes the closing components to become stuck or to surpass the upper dead point, resulting in damaged and broken connections;

2. The closing part’s connection is flimsy, loose, and unstable;

3. The connecting piece’s material was not carefully chosen, and it cannot endure the medium’s corrosion and the machine’s wear.

Maintenance strategy

1. To ensure proper operation, close the valve gently and open it without going above the upper dead point. The handwheel needs to be slightly turned backwards when the valve has been fully opened;

2. There should be a backstop at the threaded connection and a secure connection between the closing section and the valve stem;

3. The fasteners used to join the valve stem and closing section should be able to tolerate medium corrosion and have a certain level of mechanical strength and wear resistance.

2. Packing leakage (aside of valve leakage, the packing leakage is the highest).

reason:

1. Incorrect packing choice; operation of the valve at high or low temperatures; medium corrosion resistance; high pressure or vacuum resistance; 2. Incorrect packing installation, including flaws such small for large substitution, inadequate spiral coiled connections, and tight top and loose bottom;

3. The filler has aged, outlived its usefulness, and lost its flexibility.

4. The valve stem’s precision is low, and there are flaws including bending, corrosion, and wear.

5. The gland is not tightly squeezed and there are not enough packing circles.

6. The gland, bolts, and other components are damaged, making it impossible to push the gland firmly;

7. Inefficient use, undue force, etc.;

8. The gland is crooked, and the space between the gland and the valve stem is either too short or too large, which causes the valve stem to wear out prematurely and the packing to become harmed.

Maintenance strategy

1. The filler material and kind should be chosen based on the operating circumstances;

2. Install the packing correctly in accordance with the applicable regulations. The junction should be at 30°C or 45°C, and each piece of packing should be placed and compacted individually. 3. The packing should be replaced as soon as it reaches the end of its useful life, ages, or becomes damaged;

4. The damaged valve stem should be promptly replaced after becoming bent and worn; it should then be straightened and fixed.

5. The gland should have a pre-tightening gap of more than 5mm, the packing should be fitted using the prescribed number of turns, and the gland should be tightened evenly and symmetrically.

6. Damaged bolts, glands, and other parts must be promptly repaired or replaced;

7. The operation instructions should be followed, with the impact handwheel working at normal force and consistent speed;

8. Tighten the gland bolts uniformly and equally. The space between the gland and the valve stem should either be enlarged suitably if it is too small, or it should be changed if it is too large.

3. The sealing surface is leaking

reason:

1. The sealing surface cannot form a close line and is not flat;

2. The valve stem-to-closing member connection’s upper center is misaligned, damaged, or hanging;

3. The closing components are twisted or off-center due to the valve stem being deformed or improperly constructed;

4. The valve is not chosen in accordance with the operating conditions or the sealing surface material quality is not correctly chosen.

Maintenance strategy

1. Properly choose the gasket’s kind and material in accordance with the operating environment;

2. Careful setup and streamlined operation;

3. The bolts must be equally and evenly tightened. A torque wrench should be utilized if required. The pre-tightening force should be enough and neither too high nor too low. Between the flange and the threaded connection, there should be a pre-tightening gap;

4. The force should be uniform and the gasket assembly should be centered. It’s forbidden to use double gaskets and to overlap the gaskets;

5. The static sealing surface has been processed and is corroded, damaged, and of low processing quality. To ensure that the static sealing surface satisfies the necessary criteria, repairs, grinding, and color examinations should be made;

6. Be mindful of cleanliness when inserting the gasket. Kerosene should be used to clean the sealing surface, and the gasket shouldn’t fall to the ground.