Acheiving A Seal With Parallel Thread.

[RobB]

I have a 1/2 inch stainless ball valve which I would like to fit onto a threaded skin fitting, but I keep getting a very slow leak through the thread. The thread is BSP and is parallel, not tapered.

If I throw enough thread tape at it, should it seal? I've got four wraps on there so far.

Or, do I have to achieve a seal against the face of the 'nut' part of the valve. If so, I can trim the fitting (I have a stainless cutting disc) but I'd like to avoid this if at all possible.

Thanks.

 

[np1962]

I have a 1/2 inch stainless ball valve which I would like to fit onto a threaded skin fitting, but I keep getting a very slow leak through the thread. The thread is BSP and is parallel, not tapered.

If I throw enough thread tape at it, should it seal? I've got four wraps on there so far.

Or, do I have to achieve a seal against the face of the 'nut' part of the valve. If so, I can trim the fitting (I have a stainless cutting disc) but I'd like to avoid this if at all possible.

Thanks.

Don't be stingy with the thread tape, use heaps. People always seem to be scared to use too much, there is no such thing! I always wrap until I can barely see the thread impression coming through, 20 wraps or more. It will seal if you use enough.

Nige

 

[RobB]

Thanks Nige,

I hadn't used the stuff before, so when it didn't seal after one wrap I thought I was being generous using four.

Next time I'll just go nuts. It doesn't exactly cost much.

 

[Kleiny]

Tape up those threads and get rid of the leaks

I tape all my threads on my brewery and replace the tape when conducting a full clean

That reminds me time to clean the brewery before the next session

Goodluck
Kleiny

 

[blackbock]

If you use the white tape, you'll need a lot of layers, get yourself some of the pink stuff, it's about four times as thick and worth the extra outlay.

 

[pokolbinguy]

If you use the white tape, you'll need a lot of layers, get yourself some of the pink stuff, it's about four times as thick and worth the extra outlay.

+1, The pink stuff is the beez kneez

 

[RdeVjun]

:icon_offtopic: :
Am probably getting a bit offtopic with this, but I've used Loctite 567 for (roughly) this sort of application before (well, it wasn't homebrewing) and I'm sure it used to set hard, but now it doesn't set at all. It used to be a great liquid replacement for thread tape, like a decade ago, now I tried to use it again after a while out of the game and its gone to crap, leaving a sticky gooey mess everywhere that never sets and I've gone back to the good old orange and white stuff on reels. Any tradies out there know what the drum is with that?
Or did I just get a dud tube perhaps. Either back then or just now- I have probably only bought three or four tubes of it in my life... (Sorry, just wondering...)

 

[malbur]

:icon_offtopic: :
Am probably getting a bit offtopic with this, but I've used Loctite 567 for (roughly) this sort of application before (well, it wasn't homebrewing) and I'm sure it used to set hard, but now it doesn't set at all. It used to be a great liquid replacement for thread tape, like a decade ago, now I tried to use it again after a while out of the game and its gone to crap, leaving a sticky gooey mess everywhere that never sets and I've gone back to the good old orange and white stuff on reels. Any tradies out there know what the drum is with that?
Or did I just get a dud tube perhaps. Either back then or just now- I have probably only bought three or four tubes of it in my life... (Sorry, just wondering...)

Not sure about the loctite number, but if you are talking about the white goo thread sealant in the tube than yes it doesn't go hard. There is an alternative these days and it is yellow in colour and goes hard,not sure about the product number either,it's a lot better.
But i am not sure whether it is suitable for food grade.

 

[RdeVjun]

Not sure about the loctite number, but if you are talking about the white goo thread sealant in the tube than yes it doesn't go hard. There is an alternative these days and it is yellow in colour and goes hard,not sure about the product number either,it's a lot better.
But i am not sure whether it is suitable for food grade.

Thanks malbur & sounds good, I'll look the yellow one up.
It was such a PITA to wind on pesky tape to 3 & 4 inch fittings, usually in a relatively- inaccessible spot when a quick squirt of goo roughly around would sort it out and after a few days there was no drips of sticky crap everywhere. That's why I'm sure the white stuff used to go hard though & also why I used it back then. Anyway, maybe its changed, I just know I was so disappointed when I used it recently and it dripped everywhere when I said to everyone, "oh no, not this stuff, it'll not do that"- I looked a right goose. But, I'm getting used to that... :lol:

 

[GalBrew]

I know this is a reasonably old thread but anyway.....
I have the same problem as the OP, where I get a slow leak between my threaded pipe and the ball valve. However I get mine in a 70l pot I got to do double batches in and it only leaks when there is more than 30l of liquid in the pot. I have been using heaps of blue tape to no avail. Will the thicker pink tape mentioned above help or should I look elsewhere for a solution??

 

[wombil]

I think you will find that a BSPP thread will require a washer/seal where the faces meet.

 

[MHB]

I use quite a bit of 567 and it never sets and yes it can be very messy.
When organising a weld-less fitting two big stainless washers, two nylon washers and two half nuts, I usually cut the hole big enough to fit an O-Ring between the thread and the hole, cover well with 567 and tighten the bejesus out of the whole thing. Gives electrolytic separation between the bulkhead and the tank (only do this on Ally pots, if its a stainless pot weld the sucker in)
Cleanup any 567 that squeezes out with a bit of shellite or other light petroleum solvent and a lot of rag, never leaks.
Mark

 

[GalBrew]

I think you will find that a BSPP thread will require a washer/seal where the faces meet.

A washer that sits within the rear part of the ball valve?

I have never had this issue with my smaller pots and this was using the same ball valve and thred. So I am assuming that is is due to the increase in pressure on the fittings.

 

[JDW81]

A washer that sits within the rear part of the ball valve?

I have never had this issue with my smaller pots and this was using the same ball valve and thred. So I am assuming that is is due to the increase in pressure on the fittings.

It is the washer, O ring and locking nuts (which typically come with a weldless fitting) that give you the seal. Still need tape for the valve too though.

Put a washer, silicone O ring and locking nut on each side of the threaded pipe and tape the dickens out of it, then screw on your ball valve. Make sure you wind the tape on in the same direction as the thread runs (helps get a better seal - advice from a plumber of 60+ yrs). You want the tape to be thick enough so you have to put a fair whack of effort into screwing on your valve. I've done this on all of my weldless fittings and am yet to have a leak.

 

[GalBrew]

It is the washer, O ring and locking nuts (which typically come with a weldless fitting) that give you the seal. Still need tape for the valve too though.

Put a washer, silicone O ring and locking nut on each side of the threaded pipe and tape the dickens out of it, then screw on your ball valve. Make sure you wind the tape on in the same direction as the thread runs (helps get a better seal - advice from a plumber of 60+ yrs). You want the tape to be thick enough so you have to put a fair whack of effort into screwing on your valve. I've done this on all of my weldless fittings and am yet to have a leak.

Hi,
The leak I am getting is not through the wall of the pot, that one is under control with silicone o-rings. My leak is actually coming out between the threaded pipe and the ball valve join.

 

[shaunous]

Hi,
The leak I am getting is not through the wall of the pot, that one is under control with silicone o-rings. My leak is actually coming out between the threaded pipe and the ball valve join.

Normally a paralell piped thread will be tighted by a nut on the pipe up against the valve with an o-ring inside a washer. The threads should never have tape applied as you'll crack the valve and wont gain any sealing (most of the time). If I can find a picture Ill post it up.

The washer around the outside of the o-ring serves to stop the o-ring bursting out once tightened. Have you enough thread to put a nut and washer before the valve??

 

[JDW81]

Hi,
The leak I am getting is not through the wall of the pot, that one is under control with silicone o-rings. My leak is actually coming out between the threaded pipe and the ball valve join.

Lots of tape should sort you out. No need to be shy with it, teflon tape is cheap.

 

[shaunous]

Lots of tape should sort you out. No need to be shy with it, teflon tape is cheap.

DO NOT use tape with parallel threads, you might get lucky and it seals without breaking, or you might crack the valve, putting thread tape on parallel thread is only increasing its OD and they are made to be a tightish fit without tape.

 

[wombil]

DO NOT use tape with parallel threads, you might get lucky and it seals without breaking, or you might crack the valve, putting thread tape on parallel thread is only increasing its OD and they are made to be a tightish fit without tape.