Gate Valves

5 Feb 2007
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United Kingdom
The gate valve from my CW storage tank to the HW cylinder is feeling a bit dodgy... I can hear a rattling noise as I turn it (sounds like something loose inside the valve) and as I unscrew it, it occasionally goes a little tighter, then loose again. I suspect it's either already broken internally, or it's about to. I'll be replacing it with a full bore lever ball valve.

Question is, is there any risk of turning it anti-clockwise too far and the threaded portion coming out of the valve body with a resulting emergency leak situation occurring? I'm asking because I want to make sure the valve is as open as possible until I get around to replacing it.
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No risk of that.

But they can break inside and usually in the closed position.

Just replace it.

Quite normal operation...the threads are poorly machined, very course and often full of scale. Open if up as far as it will go...shouldn't be any risk. You may need to tighten down the gland nut to prevent leakage on the spindle.
Most tend to snap off in the shut position in my experience. Usually when I'm changing a cylinder and/or it's a Friday afternoon!
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I had the entire guts of a 28mm gate valve come out on me a few years ago. I was able to ram it back in and hold it in with electrical tape while I drained down to replace with a lever valve.

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