Troubleshooting of the Piston valve
Now in this article, we will discuss the troubleshooting of the Piston valve. The Piston valve is most commonly use with high temperature and high-pressure services like steam, syngas, and others. Piston valves troubleshooting is categorized into three parts.
- Seizing of piston valve handwheel
- Leakage of steam to atmosphere
- Leakage through line (Means valve pass)
Seizing of piston valve handwheel
in this case, the handwheel is difficult to operate, or to operate required more force this is happening due to the valve not being in use regularly basis installed in a very corrosive environment, To correct it needed to rousing and lubricate the valve spindle. The lubrication is to be provided through a small hole on the stem body or bonnets, Molykote M30 to be used for lubrication.
Leakage of steam to atmosphere
this type of leakage happens through the valve bonnets and body joints, this is common in another type of valve as well in some cases leakage to the atmosphere through gland packing used in it. but piston gland packing is not used, so this is measure advantages for piston valve than other types of the valve. so if leakages come out it means that the sealing ring has been worn out or damaged, please and replace it with a new sealing ring. But you can also try by tightening the body bonnets
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Leakage through line (Means valve pass)
This is common for all types of valves in high-temperature services if this is happening then please check and ensure that the valve is fully closed if found ok then check the sealing ring inside the body has worn out or damaged. And found damaged replaced with a new one by overhauling instructed by the manufacturer.
In some cases found that the piston has been damaged so it needs to replace it. To disengage the piston from the body need to open the body nut completely and open the valve and you will see the piston coming out slowly, removed and check the piston and seat ring if need to replace it.