My track record of a leak free black pipe assembly is less than spectacular. What is a fool proof way of assembling manifolds and such. Dope, teflon tape, wick, or any combo?? I'm usually afraid to go too tight also. How tight is too tight.

Thanks
John

 

It's hard to say how tight is too tight. As a rule, I use 12-14" pipe wrenches for up to 1/2", 3/4 - 1 1/2" get an 18" & over 1 1/2" I go to a 24" wrenchs. Most homeowners don't have that many wrenches but something I was taught & has served me well over the years is: "Hold with the big wrench & turn with the smaller one." Once threads are tight, do not back off. Better to stop tightening a little short on an ell or tee then pull it a little more, than to go beyond where you want it & have to back off the threads. A combination of teflon tape (one layer only) & Permatex or Blue Block pipe thread compound is the best I've found. Be sure to wear gloves because if you get this stuff on you it is hard to get off.

 

Thanks...Only one layer of teflon seems thin, but what do I know. I've got one very small seep that I hope rusts itself shut soon or I'll have to take it apart and tighten.

 

Is this the better/safer way to install black pipe for a hot water boiler?

 

To get a leak free joint, you want METAL TO METAL contact making the seal. That's why the threads are tapered.

Approximately EIGHT THREADS engaging is what this stuff is designed for. Some will be tighter, some looser, but this is a 'general' range.

Never run the teflon tape all the way to the end of the pipe, stop two threads back from the end. ONE LAYER of tape, with dope on top. Do NOT dope the 'female' threads, all this will do is push the dope into the system you are building. If when you apply the tape, you stop the tape at the 'eight thread' point, you have a visual indicator of thread engagement.

Tape and dope are basically 'lubricants', and not to be relied on to 'seal' the joint. (in spite of manufacturers sometimes calling these things 'sealant') If you glob a joint up with ten layers of tape, and a tablespoon of compound, and then tighten as you think it should be, come back two hours later and try again... I almost guarantee it will feel as though it has loosened up... because all that 'stuff' that's on the pipes has prevented getting the METAL TO METAL contact that's required.

WIRE BRUSH all threads before assembling, any debris or metal flakes can prevent getting a tight seal.

INSPECT all threads before using a part. The stuff they sell from 'overseas' is often inferior quality, both in the workmanship and in the quality of the actual steel used. If you can find it, and afford it, use American made products.

 

I have always used pipe dope alone - without teflon tape. Haven't had any problems.

The dope I buy at Ace Hardware has teflon in it.
Doug

 

I bet if you took a survey, you would find that MOST pipefitters do not use the tape either. The two doodz I know that do a lot of it like to use that black gooey nasty permatex tar...

 

Trooper has given excellent instructions. The biggest two problems with using threaded pipe is damaged threads and not enough "oomph" put on the wrenches when tightening. With the imported pipe and fittings damaged or poorly cut threads seems to be the norm. ALWAYS carefully inspect the threads of any pipe or fittings you purchase. Look for torn threads or threads that have loose pieces of metal. Understand that the big box mega mart homecenters often do not change the dies in their threading machines anywhere near often enough and therefore any pipe you have threaded is also suspect.

Grady gave good instruction on what size wrench to use for the size pipe. ALWAYS be sure that you adjust the wrench for full contact, the upper and lower jaws along with the "back" of the upper jaw being in contact with the pipe. If you adjust the wrench too tight the pipe will not contact the back of the upper jaw and may be crushed out of round when you try to tighten it. An oval pipe will never seal.

Over the years many different compounds have been devised to help in fitting threaded pipe. Generally speaking the newer ones are an improvement over the older ones. The professional pipefitters I have known mostly use Rectorseal number 5. This is a semi-liquid compound slightly yellowish in color. It approved for steam, hot water, fuel oil, gas and potable water if my memory hasn't failed me. Some fitters like to use a wrap or two of Teflon tape and then the Rectorseal whereas others use the Rectorseal alone.

I like the semi-liquid compounds that contain Teflon. If you are connecting threaded plastic pipe be sure to read the can/tube carefully. Some pipe joint compounds are not approved for plastics.

 

So the wick is/was used to lubricate or to seal?

 

Interesting on the single wrap of tape. I use the pricey pink natural gas rated teflon tape, start 2 threads back but I put on about 5 or 6 wraps. Then I dope the tape. I never have leaks.

If pipe and fittings were made of better quality steel and threaded right, I would skip the tape.

 

Wicking is a very old way of sealing threaded connections. Today it is rarely used and mostly it is used when making up connections to old fittings that have been stretched from overtightening. Unless you have old used fittings I suggest you forget about using wicking.

 

I wouldn't wait. I would go ahead and fix it now.
Doug