Problems W/ Galvanized Fittings and Leakage

[nwcrosse]

Hey everyone,

first post here, I've read some of the articles found using the search function to see if I could find my answer but no luck... Anyway I have recently used galvanized 1/2" piping to hardwire my air from basement to garage, and at a few (2-3) of my fittings under 90 psi I have found leaks.

I have around 15 joints from beginning to end and at each joint have used a compound that is labled as a pvc joint compound but was told by store associate that it would suffice. Why are they leaking, I feel I put more than enough compound on each of the threads and used wrenches to tighten far beyond hand tightening?

A few of the reasons I have come up with are that I had the fittings extremley tight, but after working in all the other pieces some of the previous fittings were unscrewed a bit. Also, should I have just stuck with Teflon tape? Did I fill the lines with pressure too soon after applying, is there a sit and settle period for the compound.

Any info would be great, after about 3.5 hours of work and around 100.00 in material just to find leaks i'm a little disappointed.

Thanks,

Nick

 

[danski0224]

If you used "PVC glue" for threaded metal pipe, then what you have will not work. You will have no choice but to take it all apart, mechanically clean the joints, and start over.

You need to use either Teflon tape or liquid paste "pipe dope" (thread sealant) which may/may not have Teflon in it. Some types of pipe dope are not suitable for plastic connections, so read the label.

If you used the thread sealant, it is possible that not enough was used or the assembly isn't tight enough. Not to start a debate on the matter, but there is a quality difference between USA fittings and pipe and the China stuff. I have used both.

PVC glue is generally a clear liquid (but it can be an off white or green), it stinks, and the applicator looks like a cotton ball. Pipe dope is usually a thick white paste and the applicator looks like a brush.

Unless you use a product called Leak Loc, there is no cure time for thread sealant. Can you post the name/pic of the product you used?

If you did use PVC cement, please educate yourself a bit more on these projects before relying on the help at a home center- they don't pay enough to get the pro's in anymore and you are stuck with the headaches.

 

[camarojim]

Nick,
I'm not familiar with the pvc joint compound product. I've always used a teflon paste product. I did my extension pipe runs with some used 1" as that what was laying around the farm . I had 150 psi going thru it and no leaks by using that paste on the threads. The water pipes had 50 psi and the same product with no leaks. I know that when I didn't use it, I had water leaking everytime. Teflon tape will work too, but I kinda think the paste worked better . I wish I could remember the name and brand but it escapes me at the moment. I got it at my local hardware store and it was just a pipe joint compound with teflon.

if you have only a few places where its leaking you could install some unions rather than take it all apart.

wish I could help more.

jim

 

[bmwpower]

Don't ask someone at the big box stores for anything other than where to find the teflon tape.

PVC glue should only be used to PVC as it's formulated to "melt" 2 pieces of PVC together. It won't have the same effect on metal pipe.

I've heard others use teflon tape and pipe dope.

 

[nwcrosse]

hey guys, thanks for all the greate responses.

As for what I used its called, Harvey's TFE Paste with Teflon, Slow Setting... All sounds appropriate, and on the back under directions, it says ... apply to clean male threads on metals, PVC, CPVC, ABS, polypropylene and nylon.

 

[Ed ke6bnl]

Don't ask someone at the big box stores for anything other than where to find the teflon tape.

PVC glue should only be used to PVC as it's formulated to "melt" 2 pieces of PVC together. It won't have the same effect on metal pipe.

I've heard others use teflon tape and pipe dope.

The word around the shop as of now is 567 LOCTITE. This what they are using for the big chillers that heat cycle and high pressure. Non hardining and NO LEAKS Ed ke6bnl

 

[Brian]

I also recomend Teflon tape, paste or something else that says it is for iron pipe.
I have found that the threads on iron pipe (regardless of where it is made) are not always cut to very exact tolerances. If they don't feel like they are threading together smoothly I will sometimes tighten and loosen them several times to "break in" the threads and then apply the thread sealer and tighten them with some BIG pipe wrenches. At a place I used to work at we used alot of ordinary iron pipe for hydraulic fluid and with that method we rarely had leaks even with 3000 psi of pressure.

 

[nwcrosse]

Alright guys thanks for all the tips, will get back to this thread once I fix it up with what works.

Nick

 

[randii]

Best solution is to disassemble, clean, and reassemble. Some folks swear by teflon tape AND dope.

If you have just a few leaks, green 'creeping' loctite may work, if you depressurize the system first. I've used it as a stop-gap measure on a set of pipes that I really can't take apart without major deconstruction of adjoining plumbing (poor planning on my part!). I was suprised that it worked, but I had nothing to lose... and it has worked for a year, so I have pretty much stopped worrying about it.

Randii

 

[MarkH]

Pipe thread as stated before can be poorly cut. There are times if twisting then together a few times does not get them to seat right. I have had to go in a clean up the threads. Else leaks. It is just a nasty job as most stores have items sourced from 5 different countries and you get to put them together. It is kinda like shoes, a US, Italian, Brazilian, Indian, Spanish and Chinese 10.5 Medium is each cut slightly differently.

Then its the right joint compound or tape. It is right do not trust most sales people. My wife has learned that on a few pick-ups for me.

 

[Charles (in GA)]

hey guys, thanks for all the greate responses.

As for what I used its called, Harvey's TFE Paste with Teflon, Slow Setting... All sounds appropriate, and on the back under directions, it says ... apply to clean male threads on metals, PVC, CPVC, ABS, polypropylene and nylon.

Sounds like a teflon pipe dope to me, its intended for MALE threads,,,,,, all kinds of pipe as you mentioned. May not have enough on the threads, or as mentioned, you have foreign made parts, from all over Asia and no two from the same manufacturer. Copper is much better if you can afford it.

Charles

 

[nwcrosse]

Even if they are from different parts of Asia/China/etc. will I be able to stop these leaks or am I just completley SOL?

 

[Charles (in GA)]

Even if they are from different parts of Asia/China/etc. will I be able to stop these leaks or am I just completley SOL?

I would take the fittings apart, slop lots of good teflon pipe dope (thread tape doesn't work worth a flip on these "loose" fitting threads) and put them back together using BIG pipe wrenches and lots of torque.

Charles

 

[MarkH]

You will be able to get them to not leak, just follow the hints that have been running through this thread. That is the great thing about pipes you can make it work, unfortunately it takes a little more work than other mechanical things with nut and bolts connections.

 

[nwcrosse]

Alright guys thanks a lot for all these great tips, now all I need is the time and energy to finish the job.

Nick

 

[stimpy]

nick , if you bought those galv fittings at menards you might as well remove it and redo it (go to depot or lowes ) , they have been getting a bad supplier of these fittings and ******* , the threads stretch out or strip when you tighten them . we did a system down here in joliet and had some of the pipe split and threads stripout ( with six inch wrenches ) and when you dope the pipe don't be stingy with the stuff coat it thurally after the fitting is coupled then wipe off the excess with your finger.

 

[triptester]

A good way to check the pipe and fitting threads is to screw the fitting onto the pipe by hand. It should become tight in 3 full turns. Most of the pipe threads I have seen at those big box stores are cut to deep. They bottom out in the fitting before they seal. When using pipe dope it is important to get the dope to the bottom of the threads, dope that sits on top the threads will just be pushed out. Overtightning joints can cause leaks. On most pipe 2 turns passed hand tight is sufficient

 

[OI812]

A good way to check the pipe and fitting threads is to screw the fitting onto the pipe by hand. It should become tight in 3 full turns. Most of the pipe threads I have seen at those big box stores are cut to deep. They bottom out in the fitting before they seal. When using pipe dope it is important to get the dope to the bottom of the threads, dope that sits on top the threads will just be pushed out. Overtightning joints can cause leaks. On most pipe 2 turns passed hand tight is sufficient

BINGO........ Sound like threads are too deep. I am a firm believer in BOTH teflon and pipe dope.

 

[gerry]

If it were my shop and I did not want to dissassemble everything to reseal, I'd consider using Loctite sealant and try to **** it in the joints using a vacumm pump. Maybe a line run to your intake manifold with the engine at idle? My Uncle used to have a septic tank pumping truck piped up like this to pull a vac on his tank. To me, soldered copper tube is the only way to go

 

[OI812]

Okay,

If you really don't want to take it apart, cleanup the joint with alcohol or something else to remove the oil. Then get the joint damp, and take a bag with salt and wrap it around the joint. Give it a day or two and it will be rusted shut. I just don't want to give my age away by telling really old plumbers tricks.

 

[nwcrosse]

Alright guys, well finally got around to fixing it up. Ended up just taking the joints apart, cleaning up the dope and applying teflon tape, then cranking on them as tight as possible. I didnt end up getting any new materials or using loctite, so far no leaks up to 100 psi which is what my max psi will reach anyway. Thanks for all the tips I really appreciate it and wow have i found a great resource for the future.

Nick

 

[-lecroix-]

Teflon tape should NOT be used as a sealant. It is designed as a lubricant between the two different fittings/pipe to prevent "seizing."

Pipe dope should be used as a sealant.

 

[nwcrosse]

That's the first time I have ever heard of not using teflon tape for sealing. Are you sure were thinking of the same thing here.

 

[Roadster]

Teflon tape should NOT be used as a sealant. It is designed as a lubricant between the two different fittings/pipe to prevent "seizing."

Pipe dope should be used as a sealant.

"Teflon tape" is a PTFE thread sealing tape. While it does not seal as well as pipe dope, it is nevertheless designed to seal pipe threads.

 

[krooser]

Just finished plumbing my air system in my shop. I was forced to use the Chinese fittings 'cuz no one around here has any USA-made stuff anymore.

Anyway.....I probably have 150 to 200 feet of 3/4" black pipe...seven drops inside ...two outside...and no leaks.

I used three plus rolls of teflon tape during the install.

 

[nwcrosse]

Yeah good deal. I used all chinese material as well and used the teflon. Sounds like the way to go!