Control valve leakage protection Part 2 - for Butterfly valve, Globe valve & Gate valve


#1

Leakage protection for Butterfly valve:

butterfly-valve-parts

Proper operation and periodic troubleshooting of the butterfly valve can extend service life. Generally, repairs can be done in inline conditions.

  • Leakage on piping flanges is caused by an improper piping position (misalignment) or failure of a flange gasket. The body that is coated (linning) with rubber or elastomer will have low durability if paired with a gasket.

  • The use of packing from graphite material, if operated at high temperatures will cause the movement of the valve that is not smooth (jerky). For a moderate level, this is in normal conditions.

  • Fluid breaks through the butterfly valve outside the conditions (according to the valve class) caused by the seat. If a leak occurs before the age limit of the seat, it may be caused by damage to the seat or valve (disc). Damage can be caused by erosion, mechanical failure in the seat, wearing due to friction between the seat and disc, or cavitation on the disc. Misalignment between shaft and disc will also cause damage to the seat. Galling damage on the shaft will also prevent full disc shift (the disc does not touch the seat).

  • Outer leaks also often occur in packing boxes. If the bolt tightening cannot stop the leak, chances are the packing has been damaged due to consolidation or extrusion. Packing of graphite material is more abrasive than other materials, and the movement of the ΒΌ round causes the concentration of the abrasive to concentrate.

  • The operation of the valve at a temperature outside the regulatory limits will cause thermal expansion and make some components sticking.

Leakage protection for Globe valve:

Check for external leakage that occurs on the end-connection, the gap between the bonnet flange and the body plug, the top side of the packing box where the shaft comes out of the bonnet or other parts that receive high pressure.

  • For liquid applications, leakage can be known physically. But to detect, leaks in the gas application, a gas detection device is needed. Generally an external leak can be stopped by tightening the bolt to increase compression pressure. If a leak still occurs after the tightening process, there is a gasket or packing that fails / breaks and needs to be replaced.

  • Globe Valve screening can be done to check for galling damage (damage that occurs in two moving parts that cause repetitive scratches and wear), packing tightness or damage to the functioning component causing and transmitting force, torque or movement operator ).

  • Deep leaks that occur before exceeding seat life, are generally caused by wearing damage between seat rings.

  • If damage occurs when you first start up, the possibility of the seating surface has been damaged due to foreign objects (furious welding).

  • If leakage occurs after service, it is generally caused by misalignment between seat and valve. During service, the laping process between the seat and the valve must be done perfectly to prevent any cracks that will cause leakage.

  • The body or bonnet can be damaged due to porosity, fracture erosion and cavitation. If enough light damage can be repaired by grinding and patched with welding. This method can be done if it is in accordance with the pressure conditions of the vessel.

  • Disruption to valve movement caused by outside operation. High temperatures will cause thermal expansion and increase friction. Pressure above the provisions will also cause the valve to be difficult to close.

Leakage protection for Gate Valve:

The interference and leakage on the gate valve is generally the same as the globe valve. One thing that specifically happens to the gate valve is:

If the valve operates at a temperature that changes suddenly, thermal expansion will cause the metal surface of the seat to be locked on the valve (wedge gate). This can cause wear on the surface of the seat to avoid the problem, the gate must be replaced with another form (split gate).