Leaking Black Pipe Joints

David_18

Hello all:

I'm an ambitious first time home renovator who knocked out the bathroom floor to jack up the floor and sister some joints under it. I had to re-run the cast-iron black pipe thru the center of the joints to the radiator. Tested the radiator system last night and at least four of the joints leaked (numerous joints because I had to install the pipes through existing joists, meaning about 15 inches was the longest section) just filling the system up.

I used lots of pipe dope...but...in making turns, sometimes the joint at full-tight was facing the wrong way, and I turned it back until it faced the right directon. So my question is, do black-pipe joints have to be cranked down as tight as humanely possible to be water-tight? Does tape work better than dope? Also, I used black pipe I bought at Lowes, and it's made in China. It didn't look anywhere near the quality of the old stuff I took out. Could this be a problem? And finally, should I try this again with the black pipe, or should I switch to copper? I read that the dialectric unions can really be a problem.

Thanks in advance to anyone who takes the time to help.

David

Jeff_17

It pays to

wander off the wall:

http://www.heatinghelp.com/newsletter.cfm?Id=102

Mike T., Swampeast MO

Are you using two wrenches in opposition to one another? If not, DO! If you're working with a number of sizes of pipes and want a good "stock" of wrenches, I'd suggest 1-12", 2-18" and 1-24". (2-24" if you're working with a lot of pipe over 1".)

Tight but not too tight--hard to describe as it seems to be something you just feel and learn.

Utterly avoid turning the joint "back" for alignment. Bring the joint close but not exactly to the point where it will end up. You have to judge, "Can I get another 360° rotation?" Tighten ONLY to bring into final alignment. If you have to back off, completely unscrew, clean, re-dope/tape and re-make. Avoid reducing bushings if at all possible--they're notorious for leaking and should NEVER be used with natural gas. Use reducing couplings (bell reducers) instead.

The Chinese pipe from Lowes may be part of the problem--try some from a good plumbing house and see if it makes a difference... If you were having lengths cut and threaded I'd say it's quite possible that their thread cutting dies are worn, improperly adjusted or the machine is being operated by someone who doesn't really know what they're doing...

Geo_4

I always assemble my black iron with 3-4 wraps of good teflon tape and then a thin coating of Gasoila pipe dope. Have had good luck with this combo and it doesn't harden up as bad as other dopes so removal is easier. Good luck

Larry_10

yea I use Teflon tape and make sure that it goes in the screw on direction so as you screw it on the tape dose not come off and also use pipe dope with Teflon after you use tape sticky stuff but with tape and dope you should be good
make it tight.

hr

I'll bet $50

that you are using the phoney thread protectors, not actual couplings. They are often sold a couplings but they do not have a tapered NPT thread cut in them. Not uncommon to see the pipe threaded al the way down to the coulpling and still have leaks. You will see them on threaded lengths of pipe to protect the threads. Discard them!

A true coupling will have a thread cut from both ends. The thin "protector" sleeves have one, non tapered, thread running continous from end to end.

I see plenty of pros use them too! Easy to spot as they use about 1/2 roll of teflon tape to get them to "make up"

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

bob young

lamp wick = no leaks

if it a hot water system use lampwick and any pipe dope and your problems will go away. the wick will also cushion the joint so that it does not bottom out so suddenly and will help a novice as yourself get the fitting headed in the right direction. wick not usually recommended for steam but will work and you need all the help you can get.

Chuck_12

Pipe Tightening Class 101

It is always recommended to use the least amount of joints. Why? cause less % chance of leaks...comon sense. When you need to do multiple joints always start at one end and add each section on at a time and there will be no need to BACK UP your turns and have possible leakage. Use a good joint sealant such as Rectorseal and use only on the male portion of threads. Use appropiate size pipe wrench to help you judge proper tightness. Use your arm to the outermost part of the handle which will most likely give you the right torque on the joint. (research shows thats how tools have been designed) you do not want to overtighten as much as under tighten. Now the finishing touch. You can complete your connection with use of a union in your line run or work your way to the valve which will have a connector union at the radiator. A note about unions...be sure to use two wrenches against each other when you tighten the union.

Jeff_17

which one are we using....the left one

or the RIGHT one!?

I would love to k now.

David_18

Joints

Hot Rod:

I may be a novice but I try and do my homework. I was using the correct couplings, as you have shown in the left hand picture. From all the good posts I've received (THANKS to everyone) I suspect the problem was that I did not tighten the pipes/joints enough, and/or that the custom cut pipes from Home Depot may not have been done very well. Also,a few times I had to turn a 90 degree joint back a bit when I couldn't get it to go another 360...I've been told this was BAD practice, and not to be done.

David_18

Thanks

Mike:

Thanks for all the great feedback. I appreciate it.

David

David_18

Tape/Dope

George and Rooster:

Thanks for the advice. I'll try tape and dope and see how it goes. Really appreciate the suggestions.

Bruce M.

Black Pipe from Home Depot

Black pipe from Home Depot is made in China and the quality is not the best. Ask for US made black pipe in your friendly plumbing supply house.

David_18

The Solution

Thanks to everyone who provided feedback.

As I'm out of town this week on business, my wife called a plumber to fix the issues we discovered Sunday night. Based on all your suggestions however, I figured that copper pipe with brass fittings was the best way to go; and lo and behold, that's what the plumber recommended. So thank you to everyone for helping me be sure the right long-term solution was installed. I like things to be done right!

David