Seeping threaded fittings... *stainless/brass plastic*

[Deuce]

My post may seem not to answer the question - we were posting at the same time.

If you are having fitting split after a while due to stress on the fitting due to PTFE tape, I would find another type of fitting.
I would put that down to the quality of the plastic in the fitting not the jointing method

We do keep crossing posts but all useful stuff!

Yes I agree. and per my last post, this may well be why Spears are OK with PTFE tape. The quality and conformity of their fittings is above average imo. Perhaps the worse fittings we have come across are the 'mega' fittings range. We once had a union roll off onto the workshop floor and split. We ripped it apart for a closer look and there were voids in the PVC wall!! I would think that more premium fittings are weighed during production for conformity.


But still the fact remains - PTFE can apply spot pressure to the female fitting which increases failure potential. And it will often drip if agitated after an initially successful seal. It's a common enough problem and if you google it, it's not hard to find examples and various experts explaining at length the reasons why it's not ideal.

 

[Deuce]

So.. the 5776 arrived this morning. I grabbed a couple of old 1.5" fittings, one brass, one stainless and applied to product to the male thread, and finger tightened. I left it about an hour and noticed the product was still fully liquid, I had expected it to gel over at least. But anyway, it said it would work after a few minutes so I hooked it up to a pressure tank we have and then wound the pressure up to 3 bar. That was 2 hours ago and no drips. Not bad for old fittings, finger tight and no real care in the application of the product.

So I'm very happy so far! It still hasn't 'cured' in any way. I'm not sure if it will - but clearly whatever it's doing inside the threads in working. It's also locked the two fittings together very well. I'm sure I could break them apart if I tried but already better than PTFE when it comes to resisting movement.

When i've broken the fittings apart I'll repeat the test, this time applying pressure after just a few minutes. I have a feeling it'll still work fine.

I haven't had chance to try the plastic thread sealant yet, but I'm optimistic based on how well the metal thread sealant works.

So thankyou to all who contributed to this thread - I'm very grateful!

 

[ShaunCorbs]

It won't cure for a long time you can wipe it away once you've finished tightening to make it look neat

 

[Deuce]

It won't cure for a long time you can wipe it away once you've finished tightening to make it look neat

Good to know. And yes it's certainly neater than general sealants we have bought over the counter in the past. This is far better. Even at the price, which is irrelevant really if it works this reliably.

 

[Chuck]

5776 is an 'anaerobic cure' adhesive. For it to cure it requires (a) absence of air (oxygen in fact) and (b) the presence of metal. See here for details:

Thread Sealant | Thread Sealing | LOCTITE® - Henkel Adhesives North America

So, the reason your excess doesn't cure is that it is in contact with air. Clever stuff.

 

[Deuce]

5776 is an 'anaerobic cure' adhesive. For it to cure it requires (a) absence of air (oxygen in fact) and (b) the presence of metal. See here for details:

Thread Sealant | Thread Sealing | LOCTITE® - Henkel Adhesives North America

So, the reason your excess doesn't cure is that it is in contact with air. Clever stuff.

Indeed. I had assumed it would cure due to moisture in the air as many other products do. Far cleverer this way though - gives me a virtually instant seal yet overspill can be easily cleaned no matter how long it's left.

It's exactly the type of high tech solution I was hoping to find. Bit neater than the old fashioned way too haha!

 

[rpm]

Hope that is a left handed thread in the picture.

 

[Deuce]

Hope that is a left handed thread in the picture.

Good spot! I was about to say maybe the image is reversed but looking closely I can see the direction of the thread

And that image was from some sort of guide/tutorial I think!

 

[rpm]

Good spot! I was about to say maybe the image is reversed but looking closely I can see the direction of the thread

And that image was from some sort of guide/tutorial I think!

TBH, anyone copying that would end up having the problems you experienced and some of the things you said about PTFE tape and fittings, lubricant, sealing and split fittings
I`ve never had any of the issues you talk of in 40yrs.

 

[Deuce]

I`ve never had any of the issues you talk of in 40yrs.

You've never used just PTFE on threads and had a drip occur? That's very good going! I'd say we get a drip/seep per 50 or so connections. But that's critical for us. We have to make hundreds in a single assembly sometimes and all extremely tight and hard to access. Also, we can't pressure test as the systems are not closed, or closeable. We really just needed a virtually impossible to fail solution - which it seems we have now.

 

[rpm]

Oh I`ve had drips and seepages which I nip up or add a smear of something on top of the PTFE, even binned fittings if in doubt but the other stuff you talk of, no never! Perhaps it is the quality of the tape and fittings or the experience of how tight is tight that makes the difference.

 

[Deuce]

Oh I`ve had drips and seepages which I nip up or add a smear of something on top of the PTFE, even binned fittings if in doubt but the other stuff you talk of, no never! Perhaps it is the quality of the tape and fittings or the experience of how tight is tight that makes the difference.

Failure to make a perfect seal is the only problem we have that is frequent enough to cause an issue. The splitting fittings was from a long time ago and due to PTFE combined with silicone. Which does make a perfect seal everytime, but also makes it extremely easy to over-tighten.

Sadly we just don't have the time to cope with little drips. If it was plumbing in my house I'd just sigh and do the connection again. But commercially, If I have 300 threaded fittings built into a slim case that requires makes access almost impossible without disassembly, then I stand to lose a lot of time for the sake of just one failed connection.