galvanised pipe sealing for compressor

[gjz30075]

Hi all. I'm having a heck of a time trying to get this coupler to seal. It continually leaks from where I'm pointing so I'm guessing the bronze ring inside isn't sealing against its mating steel ring. This is the second new fitting so far.

With this said, I recently moved and brought all this pipe with me and now am assembling it, so this (previous) coupler (along with another that leaks the same way) was used and NOT leaking. So what gives here? Am I getting weaker and not able to tighten these things properly? I cranked the livin' s*^t out of it until it just won't move any more and it still leaks. Are the new fittings junk?
Any tips? Help!
Thanks,
Greg Z

 

[mires]

Pics? Did you use thread tape?

 

[gjz30075]

Sorry, here's the pic. I used teflon paste on all my threads but the internal of this type of joint is bronze (or brass, I guess) against steel.

 

[EOC_Jason]

What about using teflon tape?

 

[MoonRise]

Ahhh, a "pipe union".

http://en.wikipedia.org/wiki/Piping_and_plumbing_fitting

Take the union joint apart, clean the sealing surfaces and inspect for any damage (erplace union if sealing surfaces are 'damaged'), apply -light- amount of pipe dope as insurance against leakage (shouldn't have to do this, but it's a bit of a belt-n-suspenders kind of approach), redo union joint until 'tight'.

You shouldn't have to "crank the living s#^t" out of it either.

If you did crank it super-tight, you may have cracked or deformed the sealing surfaces. In which case, remove leaking union joint and replace it with a new joint assembly.

 

[gjz30075]

Ahhh, a "pipe union".

http://en.wikipedia.org/wiki/Piping_and_plumbing_fitting

Take the union joint apart, clean the sealing surfaces and inspect for any damage (erplace union if sealing surfaces are 'damaged'), apply -light- amount of pipe dope as insurance against leakage (shouldn't have to do this, but it's a bit of a belt-n-suspenders kind of approach), redo union joint until 'tight'.

You shouldn't have to "crank the living s#^t" out of it either.

If you did crank it super-tight, you may have cracked or deformed the sealing surfaces. In which case, remove leaking union joint and replace it with a new joint assembly.

Sounds like a plan. I'll inspect and proceed from there. Thanks.

 

[DekeT]

I never use pipe dope on a union.

 

[gjz30075]

Update: found the problem! Take a look at the union pair on the left. That's the leaker. Eccentric casting, small bronze surface area. Thin wall around the hole. This is a new union from Home Depot.

Union on the right is from Ace. About a buck more. Doesn't leak.

Why the leaker didn't leak before, at the old house, is a mystery. Stars were aligned, or something. Going to Ace for all my fittings from now own. For those that care, both are from China.

 

[NUTTSGT]

When I did my airlines, I had a union that didn't want to seal. I replaced it and all was good.

 

[yeldogt]

I have always bought most of my plumbing supplies from a local supply house (better selection and price) ... only occasionally from other sources when I needed something quick - like the local hardware store.

It was not until the big box stores came along that I started to have any problems - they sell junk. The fittings have pin holes .... threads at angles and different sizes ... bad galvanized coating. Even the pipe at some places is bad .... and is it ever dirty.. China mostly ... shock.

It must be a problem for professional plumbers .... I try to buy the best line the supply house has ... the job is so easy with quality pipe and fittings.

 

[Jiles]

A few years ago, I plumbed a gas supply in my basement. I bought all the pipe and cut and threaded it myself. I bought all the fittings from Lowes. SEVEN out of eighteen joints leaked two of these were unions and they leaked from the brass ring and from the pipe threads. I had used Leaklock sealant on all threads.
At work, a professional pipefitter asked if I used China fittings and then suggested I replace ALL with USA. I did as he suggested and had ZERO leaks.
I bought the iron pipe from a local plumbing supply and already had the fittings.
I went back to the supply store and asked for American made.
Lesson learned and I will never use Communist made fittings again!

 

[kbs2244]

Remember those are water plumbing fittings.
Water is much thicker than air and under much less pressure.
Using water plumbing fittings in an air system is using them far beyond their design limits.
The galvanized China stuff will meet water system requirements but the US stuff is made to be used in both applications.

BTW Air systems should be black iron, not galvanized.

 

[Jiles]

"BTW Air systems should be black iron, not galvanized."

WHY?

 

[DekeT]

AI went back to the supply store and asked for American made.
Lesson learned and I will never use Communist made fittings again!

Communist fittings. Maybe you should try democracy fittings made in India.

 

[EOC_Jason]

I have always bought most of my plumbing supplies from a local supply house (better selection and price) ... only occasionally from other sources when I needed something quick - like the local hardware store.

It was not until the big box stores came along that I started to have any problems - they sell junk. The fittings have pin holes .... threads at angles and different sizes ... bad galvanized coating. Even the pipe at some places is bad .... and is it ever dirty.. China mostly ... shock.

I've noticed at the plumbing supply houses their prices are higher than big box stores. But when you take a closer look at the items (from fittings to faucets) they are usually made in USA (vs China) and of MUCH better quality... You get what you pay for...

"BTW Air systems should be black iron, not galvanized."

WHY?

Some people say the galvanized coating can flake off and clog your air lines. I'm kind of indifferent, whatever you can find will probably be adequate. Anything you are using that are concerned with particles / contamination you probably have a filter on the end of the line anyhow.

 

[stonesfan68]

BTW Air systems should be black iron, not galvanized.

Shell, Exxonmobil and Chevron use galvanized pipe for air systems installed offshore. If it is good enough for them then it will most certainly exceed the requirements in a home shop or industrial applications.

 

[Norcal]

Either black or galvy pipe will be fine for air lines. I would love to do air lines in stainless steel, but would be VERY costly & hard on threading equipment.

 

[kbs2244]

Off shore is an entirely different world.
You not only have a saltwater environment, but an install code with filters, strainers, and then a monthly inspection and maintaince requirement that you would never experience in a home, hobby, install.

 

[BD1]

Never seize is ideal for using on the union collar and mating threads. Extra heavy 250 pound unions are best. Made in USA pipe fittings and valves eliminates most issues.

 

[AP514]

I used Copper for my Shop AIR-lines