Factors Considered During Maintenance of High Pressure Ball Valves

The maintenance of high pressure metal-seated ball valves, which boast extended lifespans and maintenance-free periods, relies on several crucial factors: normal working conditions, maintaining a harmonious temperature/pressure ratio, and reasonable corrosion data.

Even when in the closed position, high pressure metal-seated ball valves retain pressurized fluid within the valve body.

Before conducting maintenance, it's imperative to release pipeline pressure and place the valve in the open position.

Additionally, disconnecting power or gas sources is necessary prior to maintenance.

Preceding maintenance, detach the actuator from the bracket.

1. Tightening Packing:

If there is a minor leak at the packing gland, the valve stem nut should be tightened again.

Care should be taken not to overtighten; typically, tightening by 1/4 to 1 full turn will stop the leakage.

2. Seat and Seal Replacement:

Disassembly:

• Position the valve halfway open and flush to clear any hazardous substances inside and outside the valve body.
• Close the ball valve, remove the connecting bolts and nuts from both flanges, and then completely remove the valve from the pipeline.
• Disassemble the driving device-actuator, connection bracket, anti-loosening gasket, valve stem nut, butterfly spring plate, G-Nylon, wear-resistant plate, and valve stem packing in sequence.
• Disassemble the body cover connecting bolts and nuts, separate the valve cover from the valve body, and remove the valve cover gasket.
• Ensure the valve ball is in the "closed" position, making it easier to remove it from the valve body, and then take out the valve seat.
• Lightly push the valve stem downwards from the hole in the valve body until completely removed, then take out the O-ring and packing below the valve stem.

Note: Handle with care to avoid scratching the valve stem surface and the sealing area of the valve body packing gland.

Reassembly:

• Clean and inspect the removed parts, and it's strongly recommended to replace the valve seat and valve cover gasket with spare parts from the spare parts kit.
• Assemble in the reverse order of disassembly.
• Cross-tighten the flange connecting bolts with the specified torque.
• Tighten the valve stem nut with the specified torque.
• After installing the actuator, input the corresponding signal to rotate the valve stem, driving the valve core to open and close.
• If possible, conduct pressure sealing tests and performance tests on the valve before reinstalling the pipeline according to relevant standards.

This meticulous maintenance process ensures the continued reliability and longevity of high pressure metal-seated ball valves in industrial applications.