Sealing black iron pipe joints

[J Persons]

I've been using either Teflon tape or pipe joint compound to seal the pipe threaded joints, and I'm still getting small leaks at some of the joints. What is the correct procedure for sealing joints and what is your preferred compound. This is for an air compressor.
Thanks, John

 

[porschedude996TT]

I would try this stuff. Either #5 or #7.

Clean all oil from thread cutting operations and coat the male end from the second thread with enough to make a nice bead to form when finished.

 

[Mike007]

I would try this stuff. Either #5 or #7.

This works. Let it set 24 hours before applying pressure if possible. These days you may only be able to get imported fittings. Expect a lot of leaks.

 

[R6 Racer]

Use both.
I do a light wrap (never more than 2 layers) of T tape & then pipe dope. Very rairly do I ever get a leak using ths method.

Steve

 

[jerryd68]

Thats the methood that I use also, I have been using RectorSeal #7 for many years with black pipe fittings, both schedule 40 and 80, very seldom do we ever get a leak. We use it on small steam and condensate lines that are small enough to be threaded, as well as air and small ammonia lines.

 

[kbs2244]

You have to remember that plumbing stuff is 99% of the time for water.
Water is much thicker than air and used at much lower pressures.

The pipe will take it but joint compound meant for water often will not.
I use the blue gasket cement.

 

[djjsr]

This is better.

 

[Al Bundy]

I just use pipe dope that's made for gas lines. Never had a leak.

 

[trbomax]

My son (the union fitter) tells me that after 50 yrs of useing teflon tape on black pipe Ive been doing it wrong. No tape because the rough finish of the thread tears and fragments it,makeing it a source of small leaks. Where he works they use a dope thats made by permatex. They just call it black goo,it looks like permatex #2 to me,smells like it too.You wont have any small or large leaks with this stuff,I tried it and he is right( I hate it when he's right!).I wash all of the fittings in lacquer thinner and blow dry to get chips and oil out,and spray off the pipe ends with brake cleaner,then air.They just pull'em out of the box ,goo them upon the male side only, and screw 'em down.

 

[Bustawrench]

For low pressure air lines (under 150 psig) I'd use this...

http://www.hardwarestore.com/block-putty-690194.aspx

For high pressure (up to 5000 psi) I'd use this...

http://www.xpando.com/xpando.php

 

[fflintstone]

I gave up on tape 10 years ago and was using paste, Now I have been using Rectorseal for a while with good results (from a reference here years ago.) now I have more stuff to look at....

 

[jerryd68]

We have banned xpando long ago in the plants that I work in! I works but the end result is that fittings will not come back apart!

 

[rodm1]

Well I try to start with smooth threads not galled up. Then if its USA pipe just coat with Rectorseal and be done with it. If china pipe it will be a problem add 3 wraps (two threads back) of Blue Monster PTFE Tape and coat with Rectorseal then hope for the best.

 

[ctb]

glue and horse hair (or fine rope hair)

 

[jerryd68]

Well I try to start with smooth threads not galled up. Then if its USA pipe just coat with Rectorseal and be done with it. If china pipe it will be a problem add 3 wraps of Blue Monster PTFE Tape and coat with Rectorseal then hope for the best.

I agree, we have actually specified to our plumbing suppliers that we will not accept any pipe that is not made in the USA. we have just had to many problems with china pipe.

 

[Jackfre]

You have to understand that the purpose of teflon tape and/or pipe dope is to lubricate the threads so the tapered threads of ips can make up metal to metal. It is the metal to metal that makes the joint. Any sealing done by the dope is incidental and not to be relied upon. Perhaps you are putting the tape on incorrectly. Hold the ****** in your left hand. Place the tape under your left thumb and wind the tape away from you, (clockwise as you look at the threaded end). Wind the tape so it either just covers the starting thread or is back one thread. You only need a couple wraps. Be careful not to get to much ahead of the first thread as stings of cut-off tape can raise hell with faucets, aerators and while I use it on gas...until you're a lot better at it, you should not. Threads of tape can get into a gas valve.

If I am having problems I'll do tape and Rectorseal. In most cases, either one or the other is sufficient.

 

[pablo21]

Not sure if it's available in the US but loctite 545 (there are other types of similar loctite products if you are doing a lot of pipe work) is perfect for pneumatic pipe fittings. Thread tape is nigh on useless for pipes that will be under any kind of pressure.

Just clean off any cutting fluid used in the threading process, then smear a thin coating of the loctite over the threads.

I used to install commercial compressed air systems and used loctite after we tried many other products. We found this was the best product we could find. I'm don't have any connection with loctite's manufacturers by the way.

 

[Mr onetwo]

I've been a pipefitter for 30 years.We have tried everything that a saleman might bring you.I have settled on cleaning the threads with brake cleaner,wiping dry and using Rectorseal No.5. Something that most people miss with No.5 is that you use it on the male threads only up to 11/4" and on both male and female on 11/2" and up.This and letting everything set up overnight seems to eliminate most leaks.I am totally down on all tape, even Mega-lock. When it absolutely can't ever leak and won't be taken apart...I love Expando! It rocks!I would only use black Permatex on #2 fuel oil or gasoline.It is really good, but is sort of like roofing tar.It will get in places you can't imagine and it basically has to wear off! Another thing I have found is that most people over tighten fittings.You want things to seal up, but don't wrench things 'till your knuckles bleed.

 

[NUTTSGT]

I used some Oatley pipe joint compound, you can see it at the bottom of the picture. I also cleaned the threads with lacquer thinner before brushing it on.

 

[walrus]

Rectorseal no 5, red lead is the only thing better and its illegal I believe. I've fit many feet of 2" and 1.5" pipe in the gasoline world over the last 30 years. I've installed underground lifts and airlines all over eastern Maine with 3/4 or 1/2 pipe and Rector seal no 5, don't do lifts anymore but I still do gasoline work and nothing that I've found works better. A simple wire brushing before applying pipe dope can do a world of good especially on store bought *******. Any pipe or fittings from HD or Lowes is suspect before you even begin

 

[Mr onetwo]

Not sure if it's available in the US but loctite 545 (there are other types of similar loctite products if you are doing a lot of pipe work) is perfect for pneumatic pipe fittings. Thread tape is nigh on useless for pipes that will be under any kind of pressure.

Just clean off any cutting fluid used in the threading process, then smear a thin coating of the loctite over the threads.

I used to install commercial compressed air systems and used loctite after we tried many other products. We found this was the best product we could find. I'm don't have any connection with loctite's manufacturers by the way.

Very expensive, but you can get it on Amazon...http://www.amazon.com/dp/B000HZKU4O/?tag=atomicindus08-20 I have some hydraulic work to do on my Case garden tractors and was thinking of using 545.

 

[Thruxton]

I would try this stuff. Either #5 or #7..

I have been using RectorSeal #7 for many years with black pipe fittings, both schedule 40 and 80, very seldom do we ever get a leak.

This is better.

I've been a pipefitter for 30 years.We have tried everything that a saleman might bring you.I have settled on cleaning the threads with brake cleaner,wiping dry and using Rectorseal No.7.

^all of the above!

 

[Mr onetwo]

Good 'ol USA pipe and Ward pipe fittings will help alot!!!!

 

[mobiledynamics]

Tape is to LUBRICATE the joint. I only really use it sparingly....

I only keep 2 dopes in my stash. Gasoila for gas, and the rest get's Blue Monster dope.

 

[RPH]

Swak, and non-Chinese fittings!

 

[mobiledynamics]

For all you posters, do you know if your *supply house* has USA fittings...especially black pipe - which is a cheap commodity...

I go out of my way to use Charlotte Cast Iron cause that's USA made. Copper is USA made...

But black pipe....ain't nuthin special....

 

[walrus]

For all you posters, do you know if your *supply house* has USA fittings...especially black pipe - which is a cheap commodity...

I go out of my way to use Charlotte Cast Iron cause that's USA made. Copper is USA made...

But black pipe....ain't nuthin special....

Wards at the 2 places I shop and Canadian pipe

 

[brewchief]

Rectorseal tru-blue is my currant favorite, all of our suppliers have gone to offshore made pipe and fittings, even with **** fittings we don't get leaks with the tru-blue.

 

[Scott r c]

I use Teflon, two wraps, then blue monster. Funny comments about letting the joint set before applying pressure. As stated by a previous poster the Teflon/pipe dope does not seal anything and pressure can be applied immediately.

 

[trbomax]

I told you guys wrong,its not permatex,its loctite brand. It does look and smell like #2 permatex though.

 

[plinker]

I told you guys wrong,its not permatex,its loctite brand. It does look and smell like #2 permatex though.

+1 This stuff works great. Almost like a glue.

At work we've been using loctite 545 (IIRC) for hydraulic NPT threaded joint's/fittings's and it's been working well so far. I'm sure it's expensive though.

 

[Mike007]

Funny comments about letting the joint set before applying pressure. As stated by a previous poster the Teflon/pipe dope does not seal anything and pressure can be applied immediately.

Ive seen Rectorseal 5 pushed out of a joint under an air pressure test on large pipe when it's not allowed to cure. For fittings above 2" or 100psi a cure time is recommended right in the instructions.

 

[Spareparts]

I have found that on all the ******* we make for the hyd and air systems we made that a quick cleanup on the 8" bench grinder with a wire brush cleans the threads up. Even the chinese fittings seem to seal a lot better. Probally not fesible in the field but in the shop it saves a lot of headaches, especially if your dies have some wear on them.

 

[BD1]

If you buy the china stuff from big box store you may have problems. Pipe and fittings are poor quality. Neighbor bought some galvanized and I had trouble threading it. Pipe was so hard that the threads were getting chewed up.
Go and get MADE IN USA pipe and fittings from local plumbing pipe supply house.

 

[sberry]

**** happens, people don't follow the directions, miss something, simple human error, a flake a burr etc. Then there is the faulty fitting. I like the Teflon added stuff, I am not fussy and have installed hundreds of fittings with simple Liq Wrench or Kroil and even WD40.

Being cheaper has some advantages, means I buy more fittings at times and have more options, if its a dollar to add a T I am all over it. Even a **** thread in spots will work if it gets tight enough, I have fixed a lot of leaks by taking one more turn, screw them tight.
With small bore pipe a strong guy can twist a 1/2 till it galls tight at the shoulder fairly easily with a 12 inch Channelock, use an oversize pipe wrench and twist till you think its broke and go a turn.

 

[sberry]

Yes, you can tell the difference in quality especially in galvanized. The up side of it is that while I was at a store for other things I hadn't precisely fit my next project and bought 6 ******* in 3 or 4 lengths for around 5 bucks. Off the shelf selection at box stores is great, I have pipe threading, still prefer to grab a ****** if I can due to speed and convenience.

I got maybe about twice that on hand in 1/2 and 3/4, that's an early pic.

 

[ez-duzit]

Leak Lock

Very surprised no one has mentioned Leak Lock. Good up to 10,000 lbs.

 

[eric_koski]

2x Leak Lock

 

[Bustawrench]

We have banned xpando long ago in the plants that I work in! I works but the end result is that fittings will not come back apart!

He said he wanted them to seal....didn't say he wanted to take them off again. LOL.

Expando can be a ***** to tear apart, but I've seen it seal 6" screw pipe with multiple sawzall cuts in the female threads (don't ask) against 600# of steam, so it's my go to when nothing else will work.

 

[jerryd68]

He said he wanted them to seal....didn't say he wanted to take them off again. LOL.

Expando can be a ***** to tear apart, but I've seen it seal 6" screw pipe with multiple sawzall cuts in the female threads (don't ask) against 600# of steam, so it's my go to when nothing else will work.

I agree with you that it works, but being the guy who usually gets to fix it later we just mad the decision that we wont use it. all of our piping above 2" for steam is all welded and flanged connections. Everything above 3/4" for ammonia is welded.