Sealing malleable iron fittings for compressed air

[penfold]

The combined regulator/filter unit on the compressor has self-destructed, which given it's a good 30 years old isn't bad going, and as it doesn't flow that well and a new replacement is £50+ I've decided to cobble together some malleable iron bits along with a water trap and regulator from the 'come in handy' box. Other than lots of PTFE does anyone have recommendations for what to use to seal the joints, particularly given in order to get things lined up the right way it won't be possible to just wind everything up until it stops? I'm thinking perhaps Boss White or similar non-setting goo might work but am going to open the floor to experienced malleable iron wranglers.

 

[rtbcomp]

If you have tapered male threads and parallel female ones use plenty of tape, this will seal and still give scope for aligning the joints,

 

[zx9]

I have been using this http://www.laco.com/pipe-thread-sealants/slic-tite-paste-with-ptfe/ for compressed air fittings.

 

[awemawson]

Loctite do two pipe thread sealants that I find excellent to use:

Loctite 577 for 3/4" BSP upwards and

Loctite 452 for up to 3/4" BSP

Both have the huge advantage that pipe joints can be 'pointed' in the right direction without being murder tight, and will still set up leak free and rigid

 

[roofman]

Really load the threads up with plenty of PTFE and you can seal halfway down iff you wish...i use the thick stuff for air on steel fittings with 100% no leakages

 

[gaz1]

yellow ptfe tape also known as gas tape is thicker

 

[Burdekin]

I use Loctite 545, really excellent stuff. It won't leak and is suitable for air fed mask lines.

 

[brightspark]

jb weld and there going nowhere

 

[zzr1200]

Loctite do two pipe thread sealants that I find excellent to use:

Loctite 577 for 3/4" BSP upwards and

Loctite 452 for up to 3/4" BSP

Both have the huge advantage that pipe joints can be 'pointed' in the right direction without being murder tight, and will still set up leak free and rigid

+1

 

[daleyd]

Jet lube v2, used to use it on all sorts of compressed air and gas fittings on industrial dryers. Was stuck on a weekend working away and ended up having to buy some from a local b and q, wasn't expecting much but it turned out to be good stuff.

http://www.jet-lube.co.uk/pages/V-2_Plus.html

Loctite ptfe is also good but I can't remember the number off hand, but it's the one in a white tube.

 

[waldershelf]

I can't believe anyone who has ever done any pipefitting in the real world would advise using anything else but a couple of wraps of PTFE tape. Come on were talking about 120ish psi and small bore <1"? pipe. it's really not that difficult.

 

[daleyd]

I use either, but I find the paste/liquid varieties more convenient to use, and have never had to redo anything , whereas tape can be a bit more finicky (not by much, but I'm inherently lazy!). Our machines came from the factory piped with the joints done in liquid sealant so I guess the guys doing it day in day out would agree.

 

[Ton-up]

Some of the replies here say something like 'use plenty of tape' or simular. Lots of tape is not needed.
Two layers is plenty, i.e. Half cover the turn before.

And put it on the right way!

 

[roofman]

Some of the replies here say something like 'use plenty of tape' or simular. Lots of tape is not needed.
Two layers is plenty, i.e. Half cover the turn before.

And put it on the right way!

"use plenty of tape"...means the same,plenty being the key word. Now "lots" we now need to establish how much is lots

 

[Burdekin]

I can't believe anyone who has ever done any pipefitting in the real world would advise using anything else but a couple of wraps of PTFE tape. Come on were talking about 120ish psi and small bore <1"? pipe. it's really not that difficult.

We stopped using PTFE tape over 25 years ago.

 

[Hitch]

I made a load of manifold things for a customer in 1/2" and 1" BSP, it was important all the parts lined up, so they spec'd a loctite anaerobic pipe sealant, cant remember which number now, but ceratinly was good stuff. Never had any problems with hundreds of joints.
One of them money is no object, well have the best there is type customers, MOD subcontractor.

Put a run round the pipe, screw together until parts were aligned, even if it felt like it needed another half a turn the sealant did the job.

 

[awemawson]

PTFE tapes and pastes may seal, but usually leave a joint that will still screw / unscrew relatively easily, so things can vibrate into unwanted orientations. Anaerobic seals like loctite seal and then set and don't move without considerable force. I've pretty well given up with PTFE products for this reason.

 

[Mikey D]

Hemp and boss white

 

[awemawson]

I had to temporarily make some joints in 40 year old 2" BSP galv water pipe when I was refurbing one of my launderettes some yeas back, and the ONLY thing that would seal was Boss White and Hemp. PTFE just wouldn't bridge the 'age gaps'.

The advantage of the hemp is that if a leak occurs it swells and re-seals

Nowadays I'd use new fittings and Loctite but finances were a bit tight back then

 

[addjunkie]

Swak or loctite. Tape is bloody dangerous if you use too much