View Full Version : How Do I Loosen Galvanized Pipe

04-26-2007, 06:30 PM
I'm updating the kitchen sink in our 40 year old house. Naturally, the drain locations on the new sink will be totally different than the old one. This requires that I undo a portion of the existing wall pipe (which drains into an iron stack within the wall).

Between the wall & sink trap there are 3 pieces of 1 1/2" galvanized pipe and a couple of black (I believe iron) elbows; which were sealed with white (lead?) pipe dope. If I can get one of the galvanized pipes to unscrew from the iron elbow, then connecting the new sink will be fairly easy.

The hard part is how do I break the old, probably frozen, threads loose without breaking some thing else? I have done a bit of this in the past so I'm aware that old pipe can some times be fragile. Are there any good ways to loosen these threads before starting to put a big pipe wrench on them?

Your help here will be very much appreciated.


master plumber mark
04-26-2007, 06:58 PM
the safest way to get them apart is to heat
the joint with a torch...

if you heat the joint to red hot,
usually the nipples will usually
come out of the joint pretty easily.

with a wrench on the joint and one on the
offending nipple.....

just dont set the place on fire
or lay the hot pipe somewhere wher eit
might do damage.

04-26-2007, 09:20 PM
A sawzall can very easily cut the pipe off where you want it. A mission band will allow you to transition from the galvanized (durham) pipe into an easier to use plastic.

Much easier and safer than a torch.

Gary Swart
04-26-2007, 11:16 PM
Sometimes a cheater bar on a big pipe wrench is needed. I recently disassembled a 3/4" galvanized irrigation pipe from an elbow. Even after heating and using penetrating oil, I had to put a 4' pipe on the handle of a 24" pipe wrench and even then I had lean pretty hard to break the joint. Damn, I hate galvanized pipe!

04-27-2007, 06:27 AM
Thanks to all for replying, your suggestions are very helpful.

About how long might it take to heat 1 1/2" pipe to "red hot"? I would be using a Bernzamatic torch with Mapp or butane gas. I also have 24" wrenches and a cheater if it's needed.

Transitioning to plastic sounds interesting. It would sure make the rest of the installation (double bowl sink with disposal) a lot easier too. What kind of Sawzall cuts 1 1/2" galvanized? Will a garden variety work or does it take a bigger one? I'm sure it takes a metal cutting blade but how heavy is the blade, how fine a tooth & how many blades? I also have a 4 1/2" abrasive wheel grinder with cutoff wheels but it would take multiple cuts to get through 1 1/2" pipe.

Best regards, Richard

04-27-2007, 08:48 AM
The fitting is heated to expand it, making the pipe fit looser in the fitting.

If you heat the pipe, then that expands and gets tighter.

Cutting galvanized can be done with an 18 tooth per inch blade.

04-27-2007, 10:47 AM
Cutting galvanized can be done with an 18 tooth per inch blade.

Thanks for the reply Terry, it's much appreciated. Your forum is very helpful as well. I've decided to cutoff the 1 1/2" galvanized wall pipe then transition from it's stub to plastic tubing for the sink.


So I can have enough reciprocating saw (Sawzall) blades on hand when I start to cut the galvanized; about how many blades will it take to get through the galvanized?

Best regards, Richard

04-28-2007, 06:39 AM
One blade will make a couple of cuts. I had a job the other day where the 50 year old galvanised arm to the tub trap had eaten away. It was under the slab. I had to kneel under the kitchen countertop and hammer up the floor. My 24" wrench wouldn't budge the pipe. I sawed off the pipe at the hub and used a small chisel to peel the 1/2" of threads out. The line was clogged and the kitchen sink, tub, and lav had been draining out the pipe and into the tub box for a couple of years. It was Vicks in the nostrils time. I still almost puked when I had to bail the sludge out with a coffee cup.