Gas Plumbing Advice : How to clean old ID threads for new pipe install?

Question

I've done a lot of water plumbing and some copper gas before. I'm no expert, but an engineer, auto-mechanic and quite handy. I plan on moving the gas line for the kitchen range for a remodel. The gas is on the front of the house (built in 1985) runs to under the furnace/hot water about 25" into the house (4' crawl space). From there it splits to the (range R) and (hot water/furnace/fireplace HFF). The range currently runs out, left, out and up from the T. The (HFF) line runs directly up from the T.

The new location for the Range is merely 70 inches straight out from the T. VERY easy, so I plan on running the 70" out, having a T with a nipple and cap under (to catch debris) and then go the 14" up pas the joist and thru the floor.

BLACK PIPE

First, I plan on shutting off the gas and letting the pipe I'm working on air out for a while.
Then I plan on WD-40ing the joints I plan on removing for ease-of-removal.

Then I disassemble the entier range line so I can remove it.

Then I remove the last LONG pipe out of the R/HHF T-piece.

My question is, is there some preparation needed to "clean" old black-pipe inner-diameter threads before using rectorseal (what I have for dope) and installing the new pipe. I can't really remove the T that is in there. I also don't have the tools necessary to just make a cut in the current pipe and re-thread the old pipe where it lies. (I wish, maybe I should call a plumber just to make it easier).

But regardless, I was wondering, assuming I remove the old pipe will the old pipe dope still be cruddy in the threads, and is there an easy/required way to clean it other than maybe a wire brush?

Answer 1

Not to sure what the gas piping code is like where you live, but here in the great white north of Canada we have strict rules for reusing any black pipe for gas conduit. You DO NOT EVER.



Makes sense. You wire brush as one answerer suggested and any pitting or scaring of internal threats will lead to a leak no matter how tight or lubricated thread it is.



You might be wiser to re-install the gas pipe with proper sized copper (for gas, not the stuff for water) and run the lines that way. At least you would be safe and less time to do so.

Answer 2

How To Clean A Pipe

Answer 3

If you extend the gas line , you need to test for any gas leakd after the job is done. An acurate way to do this is to use a manometer. The old method of using soapy water is not as good as this method. use gas jointing paste on all compression joints to ensure the pipe is gas tight. Just smear the pipe threads with it.

Answer 4

It should be relatively clean when you unscrew the pipe. Most of the pipe dope will be near the opening of the fitting. I've never used rectorseal. But with good ol fashion pipe dope all you need to is peal away any large clumps of the old stuff. Then reapply new dope to the threads of the pipe going back in, inside the fitting too if you want to be extra safe. I've never had to do any major cleaning to get a good seal.

Answer 5

for the most part it will be clean but you should with a wire brush remove any debris that remain a copper cleaning wire brush is good for this . be careful when you put the pipe dope on the threads to re pipe you should avoid dope on the first thread to prevent it from getting in the line and causing gas flow probems

Answer 6

I think you have it all figured out. The piping isn't old enough to be a problem and should clean with a wire brush. Just remember to use black iron and NO galvanized pipe, NO teflon tape, and I would add a shutoff at the new kitchen stub. Take a little extra time and leak check the joints with bubble soap, better safe than sorry.

Answer 7

494

Answer 8

get Black