Bubbles when checking connections in airlines

[DRJZ1974]

I put together the first few fittings, 3 ball valves, retractable air hose, filter and regulator. Everything looks good, I cannot hear any hissing of air and the gauge appeared to be holding well. I thought I would give it the soap bubble spray test and noticed there are bubbles from many of the fittings. I used brass fittings with teflon thread tape wrapped in the direction of the threads with about 3 layers of tape. When looking at the gauge on the compressor, I am losing about as much air in and hour as about a 2 to 3 sec blast with the air drill. When I check this forum, some seem to say that these bubbles and some leaking from the fittings is unavoidable, others seems to say there stuff is sealed tight like a drum. What do you guys think? If this seems abnormal, any suggestions on possible mistakes I may have made and how to go back and correct them?

Thanks

 

[Torque1st]

There should be no bubbles. Seal the system up tight. Use pipe dope.

 

[DRJZ1974]

I was hoping to not use pipe dope. Shouldn't tape be able to seal it up?

 

[Worsedog]

Another vote for pipe dope. I used to work on ag spray equipment and we used lots of stainless and I could never get it leak proof with tape, no matter how much or little I tried. Rector seal was like magic.

I have also found sometimes tape had tough time if the metals were different, ie; brass & steel, brass and plastic etc.

 

[trainer]

Tape will work. Use at least twice that much and stretch it tightly around the threads. Dont be shy about tightening the connections.

 

[akdiesel]

Careful using too much tape. There are different mils of tape and the more tape wraps you put on, the less threads you will engage and you may possibly pull the threads trying to get the appropriate amount of threads.
I always use tape and some sort of antisieze together.

 

[Torque1st]

Tape comes in many different quality levels. The cheap **** at the home box stores is like wrapping the joint with cheap scotch tape. -Worthless. Use pipe dope.

 

[mustangcrazy77]

I found that my drain fittings would leak air unless I used the thicker tape rated for natural gas. It makes sense, why would you used tape rated for water on a system pressurized with air? I'm sure the paste would work just as well (if not better) as it too was intended for sealing gas.

 

[Keep]

You can try tightening them up some more. I had some luck doing that.

But I have just blown the whole thing apart for some mods and I am will be using pipe dope to reconnect everything. The can only cost about $8 and it should last me a lifetime for how much it will be used.

 

[A_Pmech]

Three wraps of good tape followed by dope is my favorite method. I've never had a common plumbing pipe thread leak with that method.

I'm of the opinion that tape alone is not generally sufficient to seal the relatively large helical leak path built into the truncated profile of commercial tolerance threaded pipe connections. NPTF "Dryseal" threads are an example of a better design than NPT, but requires tighter gaging.

Tape alone is used with good success on high-quality connections made to significantly tighter tolerances.

 

[krusty the clown]

large helical leak path built into the truncated profile of commercial tolerance threaded pipe connections.

jaysus, can you say that as easy as you type it...........

you may have to translate that for us uneducated mekaniks

 

[A_Pmech]

LOL Krusty!

Look at it this way...

The "peak" of the NPT external (male) thread profile does not completely fill the "valley" of the NPT internal (female) profile when made up to average shop tolerances. That is, the external thread is more truncated than the internal thread, to allow a large tolerance range of fit-up. So, if you don't fill that space up with sealant, the joint will leak every time.

The NPTF profile has shallower (more truncated) internal threads than external threads. So, when you make up a joint the peak of the external thread will eventually contact the valley of the internal thread, deform, and seal the helical leak path though metal-to-metal contact.

jaysus, can you say that as easy as you type it...........

you may have to translate that for us uneducated mekaniks

 

[krusty the clown]

yeah, i know........i was just hacking on ya for using 20 cent words

 

[A_Pmech]

Ahah!



Can I have supercalafragalisticexpialadocious for $1 Alex?

yeah, i know........i was just hacking on ya for using 20 cent words

 

[DRJZ1974]

Ok guys, I just got done ripping it all apart and pipe doping it. Not as bad as I thought, made sure to used enough that it squeezed out some as I tightened it. Now my questions is: As I was assembling everything back together, some of my previously doped pipe joints would shift (loosen and then I would re-tighten. Does this moving of the joints disrupt the dope while it's drying. This was all within about an hour or so time. Thanks

 

[DRJZ1974]

By the way, I did clean out all the tape out of the threads to make sure it was clean before putting the dope in. I am letting it dry. How long do I need to let it dry? It didn't say on the bottle. It just said slow drying.

 

[bmwpower]

The dope I've used doesn't dry. You should be able to use the system right away.
Which dope did you use?

 

[DRJZ1974]

Harveyseal formula 55

Is the name of the pipe dope

 

[krusty the clown]

Which dope did you use?

is that a good idea to discuss when we have several LEO's here

 

[DRJZ1974]

It said it was specifically for air systems among some other gas pipe applications.

 

[bmwpower]

I've used Rectorseal, but I'm not sure which one. It's white, but I don't recall which version it is. It doesn't dry.

My plumber used some sort of gray dope on my natural gas pipes. It also does not dry.

I am not familiar with the kind you have, but I would assume it should be ok to pressurize the system now.

Others, please comment...

 

[bmwpower]

is that a good idea to discuss when we have several LEO's here

I don't smoke. Never have. Never will.

I do drink on ocassion and shoot my guns into the air though.

 

[DRJZ1974]

I was doing some reading about pipe dope in general and I found that if you are under 150psi, you can use your joints immediately, over 150, you need to wait 24 hours. I also read that you must tighten your joints pretty well. For the most part I did tighten well, but there was a couple of ball joints that I installed that were pretty tight, but not super tight since I could not make a full final rotation and have the ball joint lever facing the right way. Guess we will see!!!!

 

[rodm1]

You could have Made in China fittings! They can create a lifetime of problems.

 

[Shadowdog500]

Mine don't leak. I stopped using the cheap teflon tape a long time ago and switched to Hercules Tape Dope. It is way thicker than regular teflon tape and almost feels like a tape like form of pipe dope. It cost more but seems worth it. They have it at Lowes, but you have to look for it because it never seems to be in the section with the teflon tapes, I think I usually find it by itself near the black iron pipe for some reason.

Chris

 

[Andamo]

Someone in one of the posts mentioned the quality of the Teflon tape. In my working days, I used Teflon tape just about on a daily basis working on process lines in the oil/chemical industry. There was never a problem using the Teflon tape until one of our buyers started getting a different tape than we previously used. We had leaks everywhere using this new tape. If you felt the original tape and the new tape, you could actually feel the difference. The new tape felt like paper whereas the original tape felt soft and pliable. So buying those 10 rolls of Teflon tape for $1.00 might be the problem.

 

[DRJZ1974]

Ok, plan C, the joints I pipe doped leak way worse than the teflon tape. I am going to take it all apart for a 2nd time, buy the Hurcules tape and tape it up good. Do you guys think I should dope it on top of the tape too (as some here have mentioned doing)? As for Chinese fittings, all fittings were bought at Fastenal. I don't think they buy Chinese fittings, but not sure. I will be sure to wipe and clean all the old dope out of the pipe threads.

 

[DRJZ1974]

Another thing I am certain is contributing to the problem is that I can't tighten the fittings as much as I want because some of the valves and T's wont be facing in the right directions due to not being able to complete an additional full revolution of the fitting to face the correct direction. Any suggestion? Am I missing something? I am new to the plumbing stuff, so there may be something I am missing here? Thank everyone.

 

[JOHNMAN]

You need to tighten the fittings fully. Keep turning. You will get the final turn. Maybe you should get a bigger wrench.

 

[red]

Several years ago I was watching a "old-time" plumber work and I was shocked when I saw him use pipe dope with the teflon tape. I asked him about it and he said when he brought a case of teflon tape he read the directions with the case and it recommended using dope with the tape. Been using that process since Also there is teflon paste available which I had success with.

 

[DRJZ1974]

Ok, I was just worried about stripping the threads. I have stripped a few threads on bolts and whatnot in the past. hahaha

You need to tighten the fittings fully. Keep turning. You will get the final turn. Maybe you should get a bigger wrench.

 

[akdiesel]

Keep in mind the more you wrench the fittings together on and off you will stretch the threads, especially when you over tighten the fittings to stop the first leak.
This will also cause the threads to gauld. Tape and pipe dope/antisieze is the best choice.
Continue to clean your threads when you take them apart as you have done.
You may look at getting some compression fitting or unions for getting your valves in the correct position.
For those compression fittings and unions I have also found that a little dab of antisieze on the sealing surface of those fittings helps stop leaks when dealing with gasses/air.

 

[tcianci]

From what I have seen and experienced, the tape and pipe dope combination is the way to go. Also, if you need to orient the pipe or fitting for a special position, just haul up on it for another go-round, get a bigger wrench if you need it, you won't strip them.

 

[akdiesel]

A quick question. I am not sure if you are using black pipe for you main runs. You did say you were using brass fittings and valves which are most likely brass as well.
Question: If it is black pipe are the threads tapered or straight?
There was a discussion on here about the two types of threads purchased at Lowes/Home Depot. The tapered threads are what you want for this purpose. The straight threads will not seal.

 

[DRJZ1974]

I kinda wonder if I should have left it the first time, at least they didn't hiss, now they hiss. Well, lets hope i don't mess up the threads from disassembly and reassembly a 2nd time. I didn't know that tightening and loosening would harm the threads. It seems like there are several things that you need to tighten and loosen all the time, like the propane tank on the grill etc. Thanks for all the help guys, again, I am new to this.

 

[gorilla]

Use Loctite PST pipe dope or Loctite porosity sealer #290. Pipe threads are a taper thread and need to have the poop tightened out of them.
Merry Christmas.

 

[kbs2244]

Pipe dope and the tape are meant for water system pressures.
40 to 60 PSI.
Gas pipes are around 4 PSI in the house.

I use the blue gasket cement.
If it will stand up to head gasket pressures it will stand up the air system pressures.

 

[DRJZ1974]

I just bought some of the yellow thread tape and going to tape it up good and use the pipe dope and tighten the **** out of it. I also went and bought a good pipe wrench. Hoping for better results today!!! Thanks Guys

 

[A_Pmech]

That should solve your problem.

I just bought some of the yellow thread tape and going to tape it up good and use the pipe dope and tighten the **** out of it. I also went and bought a good pipe wrench. Hoping for better results today!!! Thanks Guys

 

[Torque1st]

Also use a backup wrench to avoid disturbing other connections.