Permatex Pipe compound

depends on the quality of the threads. Teflon tape has a nasty habit of getting inside the system, lodging in valves, pump impellers, strainers, etc. But with the quality of the pipe and threads it's often the only way to seal some joints.

A good thick paste or pipe dope is still the best.

It use to be all you needed was a lubricant and the thread taper did the sealing.

In Europe everything is a straight thread, like a nut and bolt. Either a sealing gasket is used or the threads are wrapped with hemp that binds the seal. The beauty is you can stop threading together at any point.

Here is another Loctite product that is a replacement for hemp. It actually works well with tapered pipe threads also. One wrap up the pipe, and a small amount of teflon pipe dope.

Everybody here has a favorite method that works. I remember my grandfather using lead paint as a thread compound!

The brass fitting in this picture has a "hemp' thread, with tiny serrations intended to keep the hemp from sliding off the thread as you screw them together.

hr

I had really good luck with the Loctite 565 thread sealant. Good stuff.

Tape, then dope. Don't do dope, then tape, or try dope/tape/dope. Keep the tape a few threads back. All stuff I'm sure you've checked out. The first time I tried black pipe it looked like a water park when i pressurized the system. I took the advice of a plumber who told me not to overtighten the fittings. Then I asked a couple pipe fitters, and they said "tight as you can get 'em". I've never had a leak since, but there's a difference between turning as hard as you can with a 14" wrench and abusing a pipe that's strapped to a vice and getting worked over by two 24" with cheaters. You can walk the fitting right up the pipe if you use the power threader, closing off tees and constricting elbows, splitting it in the process and screwing up what you've done.

And while we're on this sticky subject...

Is there a sealant or grease that can help insure that the spherical mating surfaces on a threaded union don't leak. The various pipe thread sealants I have all have fibers in them and that doesn't sound like it would help. Might silicone grease be something to smear on lightly?

I've been told 1-1/2 turns past hand tight will produce a good joint without over tightening. Anyone else heard that? Also be sure to wrap teflon tape clockwise on threads.

These days with all the stuff coming from Thailand and China, there is definitely some variation. We use the locTite thread cord and a little dab of whatever thread compound we have along. The cord is the real deal. I had learned about using hemp for thread sealing via a couple of German boiler companies and it was the ONLY thing that would seal up the straight cut Euro style threads on some of that equipment.

I avoid teflon tape like the plague for the same reasons Hot Rod described.

jimdeq said:

Im doing some black iron pipeing and was wondering if I should use teflon tape first and then apply the black Permatex Pipe Compoud?

Click to expand...

yes

Anerobic pipe sealant, Locktite,Seals pipes, etc. It's expensive, doesn't leak though. Randy

A couple questions on the loctite 55 pipe sealing cord.

1. Is it compatible with Rectorseal 5, or should a teflon pipe dope be used?

2. Do you guys file the threads in a few places to keep the cord on the pipe?

I just bought loctite 55 and will start working on the fittings for my tank this week.

Thanks

white pine said:

A couple questions on the loctite 55 pipe sealing cord.

1. Is it compatible with Rectorseal 5, or should a teflon pipe dope be used?

2. Do you guys file the threads in a few places to keep the cord on the pipe?

I just bought loctite 55 and will start working on the fittings for my tank this week.

Thanks

Click to expand...

We use it with regular pipe dope. Rectorseal is good. I don't see any advantage to teflon/cord combo. We put 6-7 wraps on the thread (always wind it in the same direction as the rotation of the pipe going into the fitting) give it a light slick of dope and crank it on. It will bunch up and leave some of the fittings looking a little hairy but that can be cleaned up easily. Small price to pay for no drips.

We just assembled a 4' manifold with 9 zones + all the boiler room piping on a new boiler system in a school. I'd guess maybe 250 joints. No leaks.

Thanks Heaterman

One more question. I had a few pipes cut and threaded. How well if at all does the oil they use when cutting the threads need to be cleaned before joining fittings?

Thanks in advance.

Jason

I sure learned a lot trying to get small leaks and the unions to seal. Have used LOTS of large fittings on equipment we design and manufacture. Leaks never a big deal, but we always buy from a large, commercial supplier of fittings in a good sized industrial town. I thought basically alll fittings conformed to some spec. Well, when I did the boiler last fall, I'd just run to whatever, small town supplier was open and get nipples, unions, tees. etc when I ran out of a fitting. Soon learned why some suppliers boast they only sell U.S. made fittings. Amazed to see cheap fittings bought from hardware store vs bought from the supplier that bragged US made was a huge difference. I returned LOTS of fittings to the hardware store that just wouldn't seal. Used a commercial Rectorseal recommended by the suppliers and no Teflon tape on FIRST assembly. Just had weeping joints everywhere in the boiler room (but not in the house ???) Last summer took apart EVERY fitting in the boiler room and re-did with Rectorseal TRU-BLUE and teflon tape. I know people don't recommend both, but I was sick of taking all this stuff apart and retightening. TRU-BLU and teflon tape basically sealed all first time, including some of the hardware store fittings I reused.

Another thing I noticed on the non-US fittings was when turning them on I often felt nipples that you could feel were not round. In other words somehow the fitting was egg shaped or something was bad which caused required torque to vary as I assembled the fitting. Never felt that using fittings from the major supplier house. The supply house also stated that the industrial plumbers avoid Chinese fittings for the same reason. If I started over I'd ONLY purchase the large black iron fittings from a well established commercial plumbing supply house. And so far I'm sold on Rectorseal TRU-BLU. Sorry such a long post. I've used Loctite products which are typically very good. Oh.... and I learned to try to buy PINK tape, a little thicker. I'm not recommending dope and tape. The commercial installers here clearly have more experience doing lots of boilers vs this DIYer. I just got frustrated and used both. But I can recommend TRU-BLUE by Rectorseal.Whew... sorry so long, but I learned a lot about fittings, dope, and tape and wanted to pass on.

So when you use the cord (like the Loctite 55) do you wind it down along the thread into the bottom of the thread or do you wind it up across the tops of the threads?

You do not need to follow the valleys of the thread. Just wind it back and forth the number of wraps recommended by pipe size (info. is on product). The instruction video shows the installer file a few notches in the thread to help keep the thread cord in place. I guess the filing is done to mimic the threads on the fitting posted earlier in this thread. Filing the threads makes me a bit nervous though.

white pine said:

Thanks Heaterman

One more question. I had a few pipes cut and threaded. How well if at all does the oil they use when cutting the threads need to be cleaned before joining fittings?

Thanks in advance.

Jason

Click to expand...

When we're threading we just wipe 'em off with a paper towel or rag and assemble.

DaveBP said:

And while we're on this sticky subject...

Is there a sealant or grease that can help insure that the spherical mating surfaces on a threaded union don't leak. The various pipe thread sealants I have all have fibers in them and that doesn't sound like it would help. Might silicone grease be something to smear on lightly?

Click to expand...

Just pipe dope. Permatex does make a pipe dope with no fibers if you are worried.

pipe dope is a bit to thick for machined surfaces.

Faucet stem lube works great on the mating surfaces and on the large union thread. It's mainly a lubricant that you need.

Chap Stick works well also, and it comes in convenient size dispensers for one time or small jobs

hr

in hot water said:

pipe dope is a bit to thick for machined surfaces.

Faucet stem lube works great on the mating surfaces and on the large union thread. It's mainly a lubricant that you need.

Chap Stick works well also, and it comes in convenient size dispensers for one time or small jobs

hr

Click to expand...

Ha, chap stick... whatever works. I ran out of pipe grease one time and ran out the road to the supermarket... the guys all laughed
when I jumped out of the truck with a tub of crisco, but it finished the day!! It was for sewer pipe, I guess for water line I would use butter flavor crisco. ;-P

I worked in new construction plumbing for many years. While working in Montana I learned the Carmex/ ChapStick trick. There we used it on those compression type supply threads under sinks and toilets. A little smear on the threads and ferrules and a gentle tighten.

I was a ski bum and my plumbing partner lived in a teepee year around in NW Montana so we always had lip balm in pocket.

That grease that came with the old transite type sewer pipe looked and smelled like Crisco. Sure was a mess to spill in the truck.

hr

in hot water said:

pipe dope is a bit to thick for machined surfaces.

Faucet stem lube works great on the mating surfaces and on the large union thread. It's mainly a lubricant that you need.

Chap Stick works well also, and it comes in convenient size dispensers for one time or small jobs

hr

Click to expand...

That is not what my brother taught me. Not disagreeing with you, we have used pipe dope on ground joints for decades, unaware of any problems.

If it is a union with a brass seat, the intent of that machined surface it to provide a leak proof seal without any pipe dope, same for copper flare, CSST gas flex and copper head gaskets used on engines

This question was on the master plumber exams for years. Same technique was taught at the LP classes I have been to. No need to dope a precision ground seal.

He also taught me to use dope on ferules and flares. Sometimes I questioned his paranoia, he would shrug and say better sfe than sorry.

heaterman said:

These days with all the stuff coming from Thailand and China, there is definitely some variation. We use the locTite thread cord and a little dab of whatever thread compound we have along. The cord is the real deal. I had learned about using hemp for thread sealing via a couple of German boiler companies and it was the ONLY thing that would seal up the straight cut Euro style threads on some of that equipment.

I avoid teflon tape like the plague for the same reasons Hot Rod described.

Click to expand...

This was a timely comment as I was just going to start on the black pipe. I bought the Titebond 55. Does it matter which I put on first, the 55 or the dope?

Thanks!