Plug valve not sealing for natural gas - ideas?
Plug valve not sealing for natural gas - ideas?
(OP)
We have tried 3 replacements for this 3" Dezurik plug valve and still it does not seal. Gas leaked by the plug on all 3. It does reduce the flow but doesn't really come close to shutting it off like intended (reduces flow about 90%). See attached submittal for the valve. Any ideas why this could be happening???





RE: Plug valve not sealing for natural gas - ideas?
Also the indication that the valve is closed appears to be movable. Has this somehow been moved during transit / installation? Have you operated the valve before installation to see whether it looks like it is completely closed / fully open when on the stops?
just some thoughts.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Plug valve not sealing for natural gas - ideas?
RE: Plug valve not sealing for natural gas - ideas?
Other than replacing with a soft seated construction or a different type of valve, I have no suggestions.
RE: Plug valve not sealing for natural gas - ideas?
RE: Plug valve not sealing for natural gas - ideas?
Without going back to all the old discussions of all kinds of leaking valves: it is either wrong valvetype, wrong sealing (material surfaces), damaged surfaces or wrong lay-out or installation.
How was the replaced valves inspected, checked and tested? What was wrong?
Even if the valves where generally OK for the use, layout of pipeline and dirt, water or deposit and wrongly adjusted/mounted actuators and torque and limit switches could play a part.
RE: Plug valve not sealing for natural gas - ideas?
While I'm far from a fan of plug valves, did you consider the second part of LittleInch's first post? The travel stops are adjustable and you cannot tell by eye if they are properly adjusted. I've had a 1/8 turn of the shut-stop adjustment take a plug valve from copious leakage to mostly sealed. If that doesn't work and you've greased it then you'd need some hands-on diagnostics.
David Simpson, PE
MuleShoe Engineering
Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat
RE: Plug valve not sealing for natural gas - ideas?