What size washer/seal is needed for this fitting?

[Bordonbert]

Hi guys. I have a leaking hot water tank indirect connection. It seems to be just the washer/seal right on the tank surface crumbling. I'm fine to loosen that and refit with Hemp and something like Boss White, (yes, I am aware of the non-potable aspect), but I wondered if breaking down the whole joint and refitting with a new seal might be the better strategy.

It shouldn't be too onerous a job as both the hot water feed and central heating/water feed (3-way valve system) are gate valved and can be isolated just above the tank. Which would be the better way to go?

If the more correct job is to break the whole thing and fit a new washer, what size will that washer be? The picture shows the joint assembly, and the pipe feeding into the outer part of that joint is 22mm of course. The joint is made up of:

A - 22mm pipe
B - 22mm compression joint onto...
C - Larger fitting (not worked with this before so no idea of inner size or name)
D - Larger nut behind C to compress to tank
E - Displaced and crumbling fibre washer

What size would that replacement washer be, or does it need to be removed and individually measured?

 

[ShaunCorbs]

You sure the joint on the tank is leaking as I’ve never seen a lagged one with a diy heating coil

It’s not c that’s leaking correct ?

 

[Bordonbert]

You sure the joint on the tank is leaking as I’ve never seen a lagged one with a diy heating coil

It’s not c that’s leaking correct ?

Thanks for replying Shaun, all advice is good advice.

The joint between pipe A and adapter union C via nut B is fine. The leak is between nut D and the tank surface as washer E is breaking down. It doesn't look clear because of the crud around there but part D is actually a large hex nut. I could be wrong being no expert but it looks as though nut D is threaded onto the internal coil to seal it against the tank surface. The adapter C is then screwed onto the coil stub and the pipework is then jointed onto C.

It looks as though there is no space between C and D to be able to back off the nut D so I'm guessing that the whole lot, both joints, will have to be broken down and remade to get the tank surface joint sealed.

 

[ShaunCorbs]

Thanks for replying Shaun, all advice is good advice.

The joint between pipe A and adapter union C via nut B is fine. The leak is between nut D and the tank surface as washer E is breaking down. It doesn't look clear because of the crud around there but part D is actually a large hex nut. I could be wrong being no expert but it looks as though nut D is threaded onto the internal coil to seal it against the tank surface. The adapter C is then screwed onto the coil stub and the pipework is then jointed onto C.

It looks as though there is no space between C and D to be able to back off the nut D so I'm guessing that the whole lot, both joints, will have to be broken down and remade to get the tank surface joint sealed.

New cylinder then I’m sorry to say

 

[Dave Moore]

If you remove the nuts and clean up you could possibly use order to repair or Loctite 55. It will be a parallel thread, hence putting order on the thread will be useless but putting Loctite 55 on the thread and screwing the fitting on leaving a gap. Take some ptfe tape and rub in your palms to make it string like. Wrap it in the gap you left tightly, filling the gap up before tightening the fitting until it goes up as far as you can get. The ptfe will fill the gap and seal it. You can use this method for leaking glands on stop taps or gate valves if it’s difficult to remove them. Shut the valve, back the nut off, fill the gland with ptfe string , refit the nut and tighten.