Need a Fitter and Turner's advice

[carlyai]

I have some gas fittings that I need to put together.

The brass male thread, connected to the gas hose, screws into a female metal thread on my gas regulator.

I've already cracked the brass once and had to get it machine out.

Everything was connected, and when I did the soap and water gas leakage test there were some tiny bubbles coming from the brass steel connection, so I just thought I'd carefully tighten a little more.....and I cracked the brass thread.

I bought some orange gas thread tape and will wrap it around the brass thread before screwing it into the gas regulator, but there in lies my problem.

1. How many times should I wrap the tape around the thread, the brass male fitting will only go in four threads finger tight at the moment?

2. With the tape installed, should I screw the male thread all the way into the female thread, even though it feels tight?

I don't want it to leak and don't want to break it again.

When I originally cracked it, I took it back to my nephew in Australia who has an engineering company. When he got it machined for me I asked him why he didn't put it together for me, and he said they didn't want to break it. Thanks.

Anyway, any help would be appreciated.

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[Strange]

Those threads are called NPT (in the US) or Taper Pipe Thread. They seal from the taper pulling the threads tight. 

 

Im american so the jargon is slightly different but here is a wiki.

 

https://en.wikipedia.org/wiki/National_pipe_thread

 

Use this kind of teflon tape. Any local Thai mom & pop hardware store has it. Just Bring a pic on your phone and show them. Costs Nothing. 

 

 

20 minutes ago, carlyai said:

1. How many times should I wrap the tape around the thread, the brass male fitting will only go in four threads finger tight at the moment?

 

No real set amount. Wrap the threads 3-4-5 times and test fit. Wrap the threads counter-clockwise so when you screw the pieces together, it will lay down on the threads and not bunch up. 

 

20 minutes ago, carlyai said:

2. With the tape installed, should I screw the male thread all the way into the female thread, even though it feels tight?

 

No, with taper pipe thread you just teflon tape it, thread it by hand together, and use an adjustable wrench (or whatever) until its 'snug' and 'feels tight'. 

 

If it still leaks, take it apart, clean the old teflon off, and add more than you did the last time. Cover all the threads, not just a portion. 

Edited November 5, 2016 by Strange

[Strange]

15 minutes ago, carlyai said:

brass male fitting will only go in four threads finger tight at the moment?

 

Another thing to note, the way NPT type fittings are made, they are not all EXACTLY the same. 4 threads isn't much and I would take that gas regulator into the local hardware store and test fit several more of the brass fittings in that female hole. The brass pieces are not all the same as they are on a taper, so its very, very likely that you will find one in the pile that gets you a lot more thread engagement. 

[BoonToong]

ddd

 

 

Edited November 5, 2016 by BoonToong

[Strange]

Of course all this is assuming that you have the right threads going together. 

[Strange]

To you have a pic of the entire regulator?

[carlyai]

To you have a pic of the entire regulator?

Here is a pic of the regulator.

The other pipes and fittings are already there and all fit well.

It was just the connection from the regulator to the gas supply that I needed, ie that brass bit.

The first time I put it together was outside (in case it went "bang"), but it didn't and didn't leak. It was when I buggered around with it getting it back in position inside that it started to leak.

Then also, I didn't put on the white teflon, cause I didn't know how it would react with gas. After that I learnt it was Ok to use...bit late brass cracked.

Thanks for your help, and I feel confident now to wrap on some teflon and install everything.



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[carlyai]

Here's the document of my thinggy, that the regulator goes in (don't laugh, getting cold out here now).

I could not find the fitting shown in the diagram, that's why I ended up with the brass bits.



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DV36.pdf


Sorry that file did not upload.

[rawhod]

PTFE is inert and will not react with anything (including hydrofluoric acid, which reacts with everything else) so there is no problem using it on a gas connector.

 

If you put too much tape on the male thread before you screw it in, the excess will just squeeze out. In otherwords, you can't put too much on.

[sipi]

White tape is thinner and for water. Yellow or pink is thicker and for gas. I never use white, even for water. Sorry but I am not familiar with orange. Does it feel thicker than the usual white stuff?

I assume you are refering to the high pressure between the supply and regulator, not the low pressure left hand thread (2.75kPa) after the regulator. Yes standard gas tape will do the job.

 

[Strange]

2 hours ago, rawhod said:

If you put too much tape on the male thread before you screw it in, the excess will just squeeze out. In otherwords, you can't put too much on.

 

Theoretically yes. 

 

But you still have to be able to start the thread and have enough 'meat' engaged to start to 'seat' it all together, without stripping anything. Brass and cast aluminum strip/crack pretty easy. 

 

Its pretty hard to put too much on though. 

[Strange]

3 hours ago, carlyai said:

Here's the document of my thinggy, that the regulator goes in

 

Hey Carl, your link is dead, I can't see it.

 

6 hours ago, BoonToong said:

ddd

 

Why did you delete your post? It was good, I saw it before you edited it. 

[carlyai]

White tape is thinner and for water. Yellow or pink is thicker and for gas. I never use white, even for water. Sorry but I am not familiar with orange. Does it feel thicker than the usual white stuff?

I assume you are refering to the high pressure between the supply and regulator, not the low pressure left hand thread (2.75kPa) after the regulator. Yes standard gas tape will do the job.

 

Yes I found out that there was a tape that is used for gas and as it's thicker. Sorry, got my colours mixed up.

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[carlyai]

 

Why did you delete your post? It was good, I saw it before you edited it. 

I saw the document too, I didn't delete it. ?

Will try and put it back. As I said in that post, I couldn't find a gas fitting connection locally like the one in the document, so that's why I went with the brass fitting.

Docs back, I think, as I can see it.

[carlyai]

This is the first time I've revisited this project in about 10 months. Now gota put it all back together. lucky I labelled everything.



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[carlyai]

Update

Put it all together, turned on the gas, did the soapy water leak test, and ......small bubbles around the brass/metal thread. Bugger.

So, going on previous advice here, I'll unscrew the brass fitting and wrap on more tape and try again. [emoji21]

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[Crossy]

Alternatively you could try one of the gloopy thread sealants rather than tape (which technically isn't a thread sealant).

 

This sort of stuff http://www.loctite.co.uk/thread-sealing-9170.htm

 

I have some black yukky stuff that came from HomePro a while back (not got it in front of me, I'll look at it later) which would do the job perfectly.

 

[sirmud63]

i havent bothered using tape for many years now . loqtite make a semi liquid paste in a tube that works first time ,every time . have seen it here before . 

 

[carlyai]

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Alternatively you could try one of the gloopy thread sealants rather than tape (which technically isn't a thread sealant).

 

This sort of stuff http://www.loctite.co.uk/thread-sealing-9170.htm

 

I have some black yukky stuff that came from HomePro a while back (not got it in front of me, I'll look at it later) which would do the job perfectly.

 

Good morning.

I may have to drive a couple of hundred km to get some, but will give it a go. This is how I busted the first brass fitting, just a little bit tighter...

Do I clean off all the tape on the thread first?

I just coat the male thread or both threads? Like putting on nail colour?

How long have I got to play with it before I can't move it?

And then if it still leaks I'm stuffed, or, it won't leak anymore?

Got the shed ceiling guys coming today, so will have to wait a bit.

Thanks

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It just leaked around the bottom of the brass thread, not all around

[Crossy]

Clean off all the tape then follow the instructions (I've always put it on the male only).

 

http://www.loctite.co.uk/thread-sealing-how-to-apply-instructions-9593.htm

 

Depending upon what type you get work time is certainly tens of minutes. Many of these sealants are anaerobic adhesives, they cure in the absence of air (air stops it setting), so when the thread is tightened and air excluded the stuff sets.

 

If it still leaks you can get it off with heat, but I doubt it will leak.

 

Failing that, Araldite is your friend, but it is never coming apart, ever!

 

[carlyai]

Clean off all the tape then follow the instructions (I've always put it on the male only).
 
http://www.loctite.co.uk/thread-sealing-how-to-apply-instructions-9593.htm
 
Depending upon what type you get work time is certainly tens of minutes. Many of these sealants are anaerobic adhesives, they cure in the absence of air (air stops it setting), so when the thread is tightened and air excluded the stuff sets.
 
If it still leaks you can get it off with heat, but I doubt it will leak.
 
Failing that, Araldite is your friend, but it is never coming apart, ever!
 

This look like the correct stuff?

Got it at the automotive shop.

Instructions look easy. ?





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[Crossy]

That looks like a thread locking compound rather than a thread sealant per-se.

 

Whether it will provide a gas-tight seal I cannot say, it may do the trick just fine but no warranty is implied or inferred.

 

I don't read Japanese either :)

[Hereinthailand]

From your pics it looks like you tried to thread a straight brass threaded fitiing into a tapered pipe threaded (NPT) regulator. If your brass fitting broke going into a cast metal regulator body im guessing your regulator threads or body are ruined, thats why its leaking nothing to do with the brass fitting, I mean you must have really wrenched it in there to crack a brass fitting going into cast metal. You would be better off buying a new regulator and the correct fitting. You can mess around with trying to seal it but when it blows up your house you only have yourself to blame.

[carlyai]

That looks like a thread locking compound rather than a thread sealant per-se.
 
Whether it will provide a gas-tight seal I cannot say, it may do the trick just fine but no warranty is implied or inferred.
 
I don't read Japanese either :)

Ahhh yes..it is a thread locking goo. I thought they were the same, but now I know. [emoji3]

They did have Loctite gasket sealant, is that the same? Probably not?

Glad I waited for a reply.

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[carlyai]

From your pics it looks like you tried to thread a straight brass threaded fitiing into a tapered pipe threaded (NPT) regulator. If your brass fitting broke going into a cast metal regulator body im guessing your regulator threads or body are ruined, thats why its leaking nothing to do with the brass fitting, I mean you must have really wrenched it in there to crack a brass fitting going into cast metal. You would be better off buying a new regulator and the correct fitting. You can mess around with trying to seal it but when it blows up your house you only have yourself to blame.

This gas log fire has definitely caused some problems, and probably many laughs.

It was imported from China, and is the same they use in Australia, although cheaper. So until someone blows up the Lam Chabang port mob, I won't be importing another regulator.

I had the regulator female thread machined out to the male thread, I thought. Maybe the machinist just used an easyout and screwed out the broken part? Will have to check. Good thought.

So maybe I have two different threads?

The male brass thread is a tapered thread. I'm fairly sure of that by looking at it. Maybe the female thread is a little different, that's why I can only get about 10 turns of the male inside the female.

Never-the-less, with locktite or tape, why won't I be able to stop the leak?

If I stop the leak, why should it blow up?

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[Hereinthailand]

With two different threads you would not get ten turns into it. What I think is happening is your brass fitting is now cutting its own thread pattern into the soft cast regulator body, thats why you have got in ten turns and now the threads are full of metal and not making a good seal. You could try some ptfe (Teflon pipe sealant) paste to seal it if you can find some. I never use tape for gas fittings. Maybe the best thing is to pull the reg. out and take to a real machine shop with your brass fitting and have them size everything to fit.

[Crossy]

41 minutes ago, carlyai said:

They did have Loctite gasket sealant, is that the same? Probably not?

 

 

The thread-lock would be better than the gasket-goo, but you really need the correct stuff.

 

Have you tried Lazada?

 

[carlyai]

With two different threads you would not get ten turns into it. What I think is happening is your brass fitting is now cutting its own thread pattern into the soft cast regulator body, thats why you have got in ten turns and now the threads are full of metal and not making a good seal. You could try some ptfe (Teflon pipe sealant) paste to seal it if you can find some. I never use tape for gas fittings. Maybe the best thing is to pull the reg. out and take to a real machine shop with your brass fitting and have them size everything to fit.

Hi Thanks HereinThailand.

I just sent a message to my nephew in Aus who has engineering shops in Aus, who gave the regulator with the broken brass fitting in the metal body to one of his workers to fix.

I've asked him if the threads were machined or just the brass easy outed. I'm now suspecting not machined. So will wait for his reply.

Then I'll unscrew the brass male and check for lose metal. Then I'll wind on a lot more yellow tape and have another go.

If that doesn't work I'll make the journey to get the loktite thread sealant, and if that doesn't work I'll take it back to Aus next month and give it back to the nephew and ask him to machine it to the correct fitting.

Chasing my tail here.

So can I ask you the question again (and thanks for your help by the way), if there are no more leaks, why should it blow up. [emoji4]

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[Hereinthailand]

If there are no leaks no problem unless your thread sealant shrinks or breaks down in some way. Gas leaks are nothing to play around with. Up to you, but i would wait and take it back to australia and have it properly done.

[Hereinthailand]

Oh and by the way they wont machine it, never did, just drill and tap it to the right thread size which I think is your problem all along.