I want to replace the cold valve in the loft water tank. I can undo all the connecting nuts except the flange nut that holds the valve to the galvanised water tank. The nut is narrow and extremely soft brass.

Having tried various adjustable spanners, I have come to the conclusion to cut it off.

What is the best method to cut it off. If I cut the nut parallel and right next to the flange the flange itself will still be in place. How do I remove the flange as it will still be holding the valve in place because it also has thread

Any advice on methods to remove the flange nut would be appreciated.

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Originally Posted by hkstroud

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Hi Harold,

I hope you have had an enjoyable Christmas and thank you for your interest in my problem.

I hope I have attached three pictures o.k.

I do not have any power tools or a blow torch.

I was thinking of cutting off the nut and pipe with a hack saw as close to the flange as possible.

Because the flange has a thread the valve will still be attached to the tank. I am concerned that if I try to lever the flange off with say a screw driver blade hit down behind the flange, I might damage the tank.

Your advice would be appreciated.

Jim

Hello Jim,

Merry Christmas to you also.

Your tank appears to be an old galvanized tank that has been previously repaired. That flange nut is either welded or soldered onto the tank. Probably welded. I say that because of the missing galvanizing on the tank around the nut, what appears to be a weld bead around the flange, the fact that the nut is brass and most importantly, the fact that the walls of the tank would not be thick enough to thread. The original nut would have been steel, would have been welded on and would have also been galvanized. Or it would have been an additional piece of material thick enough to be threaded that was welded to the tank, just like the fitting you show in the last picture. It is my guess that there was a problem with the original fitting, it was ground down and the brass flange nut was welded onto the tank.

If you objective is re-plumbing, I suggest disconnecting the piping from the ell, removing the ell, then removing the close nipple (pipe between the ell and the flange nut) with a pipe wrench.

The piping appears to be copper and the fitting used to connect it to the ell appears to be a threaded female adapter. That means you will have to cut the pipe so you can unscrew it from the ell.

The flange nut is there to stay. The only way to remove it will to be grind it away and the weld the opening closed.

I do not want to be presumptuous but you seem to think that the flange nut is screwed into a hole in the tank. That cannot be correct because the material that the tank is made of, is just not thick enough to thread.

While a wrench (spanner) could be used to remove the copper pipe fitting and the ell, a small pipe wrench would be the proper tool. And is the only tool to remove the nipple.

I'm a bit confused as to why you would want to remove any of this piping to replace a valve.

Hi Harold,

The valve has a pipe and inner flange attached permanently to it. Unfortunately, I am unable to attach a photo of the new valve which is the same as the existing valve. I do not know the reason why I cannot a photo

There is no nipple. The pipe permanently fixed to the valve runs through the hole in the tank to the incoming water supply. To replace the valve the incoming water supply has to be disconnected. The valve and attached pipe is then withdrawn from inside the tank.

I am replacing the valve because having replaced the rubber washer and adjusted the ball and arm water still comes through the valve even in the closed position. I think the seat has become worn and uneven and leaks water. I do not think the flange on the inside is welded but there is residue left from the water. There does appear to be some kind of substance between the outside flange on the outside and the tank.

Any wrench I use on the flange nut slips. I have no problem with any of the other nuts.

Regards,

Jim

Boy was I wrong.
Strange plumbing world you live in.

A pipe wrench will grip and turn the nut, but you will have to remove the ell first.

If you can reach inside, can you turn the part inside and just hold the ell?

I assume you are UK or Australia. Are you familiar with Shark Bite fittings?

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Originally Posted by hkstroud

Boy was I wrong.
Strange plumbing world you live in.

A pipe wrench will grip and turn the nut.

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Hi Harold,

I have tried various wrenches including a precision auto wrench, none will grip the nut sufficiently, that is why I want to cut it off.

Thanks for your views.

Jim

Suggest that you cut the pipe, remove the ell, then remove the flange nut with a pipe wrench. The teeth of the pipe wrench will bite into the brass and grip the nut. After you have replaced the valve and reinstalled the ell, put the pipe back together with a Shark Bite coupling.

No open ended wrench will turn the flange nut. Any wrench will have to be an open ended wrench to get it on, and the brass will be so soft that the open ended wrench will round off the corners of the nut.

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Originally Posted by hkstroud

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Hi Harold,

Happy New Year,

This is how the issue of replacing the valve in loft cold water tank was resolved.

I concluded that I would either have to cut the nut off, which needed a hacksaw that could cut close to the tank, which I do not have or use a blow torch to heat the nut and then try to remove it with grips. I do not have a blow torch, the nut is so shallow that I was not confident that I could grip the nut without the grips slipping off and was also concerned about the fire risk to my home if I used a blow torch.

I did not make the cold water inlet elbow water tight after reassembling during one of my several attempts at replacement and caused a leak that stained a ceiling, which finally decided me to consider getting a plumber.

I e-mailed a plumber explained the situation and attached photos of the plumbing.

I hired the plumber. He preferred not to use a blow torch because of the fire risk. With the elbow disconnected he used a suitable hacksaw and cut the centre of the pipe from right to left and then cut the nut in half. After removing the nut he hit the pipe through the hole in the tank, because the valve is attached to the pipe on the inside of the tank the whole unit was released.

I had bought a similar brass valve to replace the existing valve. Despite its design drawbacks, all the maintenance the existing valve had ever needed was to replace a small rubber washer.

He would have installed my valve but I preferred the brass valve he brought that uses a diaphragm to stop the water and plastic retaining nuts that will not seize. He replaced the existing cold water supply elbow (one fixing nut) with a more suitable elbow (two fixing nuts).

The plumber was very helpful and provided other advice.

I was annoyed that I had not attempted to cut the nut off myself but relieved that the plumber had quickly and conveniently replaced the valve.

Best wishes,

Jim (UK)

Thanks for the update. It is always good to hear the end of the story.

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With the elbow disconnected he used a suitable hacksaw and cut the centre of the pipe from right to left and then cut the nut in half.

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Why didn't we think of that?

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preferred the brass valve he brought that uses a diaphragm to stop the water and plastic retaining nuts

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That was a good decision.

Come back and visit in the future.