Water gauge cocks

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Water gauge cocks

Post  ChriX on Fri 29 Jun 2018, 5:51 pm

Having trouble with the seals on these, they always weep under steam and trying to prep for hydraulic test they start leaking profusely before I get anywhere close to double working pressure.

I guess the top two not so much of an issue as if they pass a little it's not leaking pressure out of the system but the bottom one of course is. I dismantled it and it looked like there were some bits of rust embedded in the PTFE, presumably from the boiler. Is there anything I can do other than buy/make more sleeves?
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Re: Water gauge cocks

Post  lynnr on Fri 29 Jun 2018, 7:12 pm

Hi

For the hydraulic. Just put blanking plugs in everywhere as the hydro is for the boiler not fittings.
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Re: Water gauge cocks

Post  Steve Traill on Sun 01 Jul 2018, 6:54 pm

Did you give the boiler a good beating with a wooden stick whilst it is stood on end?! Then use a telescopic magnet to fish out all the swarf?
If not then the swarf has damaged the seals as ptfe is much softer than swarf. It's not in the instructions but I have mentioned it a few times here.
Generally there is about half a mug full of swarf to be removed. Eventually it will rust away to nothing & get flushed out at the end of the second or third season. Before that it will cause problems like you have with damaged seals, leaking clacks etc.
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Re: Water gauge cocks

Post  ChriX on Sun 01 Jul 2018, 9:18 pm

I guess it had a good beating when I was hammering the smokebox on and then I attempted to flush it out but other than that no! What's the fix? Do STW sell just the PTFE sleeves that can be swapped out?

Chris
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Re: Water gauge cocks

Post  Steve Traill on Mon 02 Jul 2018, 7:18 am

I guess you'll have to ask Steve or Dean, I suspect it will be the whole body of the fitting as getting the old ptfe out might be tricky. I've only had swarf bung the hole up so the water was very slow to rise & fall. A good clean out fixed it. The good news is apart from swarf they virtually last forever!
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Re: Water gauge cocks

Post  lynnr on Mon 02 Jul 2018, 12:19 pm

Hi

Due to the thinness of the PTFE in the valve assembly. The PTFE has to be machined in place.
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Re: Water gauge cocks

Post  Capricorn1 on Tue 03 Jul 2018, 1:14 pm

If its the small PTFE ring that seals the stem of the shut off cock then what about measuring them up and trying to get hold of a few Viton O-rings as an alternative...? Or try R.A Barker or Live Steam Models - they might sell you spare seals if they are of a similar size.

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Re: Water gauge cocks

Post  sonick45 on Wed 04 Jul 2018, 5:50 pm

if you cant get the ptfe rings you can by discs of various sizes on ebay and drill the hole in the centre.

I have converted my globe valves to have a ptfe seat this way so they wont leak.
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Re: Water gauge cocks

Post  ChriX on Sat 14 Jul 2018, 10:50 pm

So I ended up getting a bit of 12mm PTFE bar. Initially I was threading the bar (M12 fine) to screw into the valve body but found you can actually just screw the 12mm bar straight into the body and it cuts the thread as it goes leading to a tighter fit. This then cut off flush, cross drilled and reamed 8mm for the valve itself. All now seals 100% even under twice working pressure - great success Very Happy
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Re: Water gauge cocks

Post  sonick45 on Sat 14 Jul 2018, 11:10 pm

nice work...
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Re: Water gauge cocks

Post  Steve Traill on Sun 15 Jul 2018, 8:28 am

The shell test is twice working pressure, after that it's only 1.5 times for the hydraulic test!
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