I am in the process of redoing my bathroom. I have dug up the floor (wetbed tile) and cut a lead drain pipe leading from the tub drain to a female threaded input to the side of the cast iron pipe that has a closet flange and another female input for the sink. I cut the lead pipe not only because it had a leak, but also, it is the only way I could unscrew the fitting from the cast iron. The problem is, the fitting will not unscrew. I sprayed wd-40 on it to penetrate the threads but it won't budge. I don't want to risk breaking the cast iron, but I have to get it off so I can replace it with a PVC fitting and drain pipe. Does anyone have any suggestions? Would heating the fitting with a torch help? How likely is the cast iron to break? Thanks.

 

Cast iron does break but it is pretty tough unless it is already cracked. Put pressure on the wrench and tap (not beat) on the side of the cast iron. Vibration is a great loosener. Thats why WD-40 suggests spraying and then tapping on bolts and nuts. Good luck.
If you are using a pipe wrench, you can hit on the top jaw of the wrench.

 

A little heat may help also. But be careful, WD-40 burns.

 

If pipe dope was used on the joint, nothing will get into the threads.
A drastic method that I have used a few times with success is to cut off the pipe almost flush with the cast iron (leave an inch). Then, using a reciprocating saw with a 24 tooth blade, cut through the pipe stub just to the threads. Do this in 3 or 4 places. Then you can remove the pipe a section at a time. You may have to clean up the threads, but probably not.

 

Thanks for the replies. One thing...how can I tell if pipe dope was used? Will there be any evidence that is visible? thanks.

 

There will normally be at least a small bead of dope where the pipe and cast iron meet. Being that your joint is so old, the dope may have dried up and crumbled off.

 

Hello, A possible solution would be to cut the steel pipe off leaving about
1 1/2 then use a hubless connector to attach your abs or pvc.
Good Luck Woodbutcher

 

It would be a good solution, but unfortunately the pipe is made of lead and will not support being clamped with the hubless connector. I've tried tapping, wd40, propane torch...the damned thing won't budge. i think what happened is there is a metal (maybe brass) fitting that screws into the cast iron. The lead drain pipe was then welded to that fitting. i suspect that the lead actually sealed up the threads from the inside. I've already cut the pipe all the way to the hex-head of the fitting and plan to hacksaw through the fitting from the inside and take it out in pieces. I don't have a sawzall, so i hope the hack saw will suffice. I plan to get a new sharp blade. Any thoughts on this method would be appreciated.

 

Make two cuts. About 3/8" to 1/2" apart. Remove that piece and then with channel-locks, crush the remaining piece together and it should pull out of the cast iron. If it is a heavy brass fitting, use a pipe wrench in the counter-clockwise direction. With the piece missing, it should crush it for you. Good luck.

 

Thanks. I'll try that tonight. At least I know I'm on the right track. I'll let you know how I make out.

 

I am relieved to announce that I have succeeded in removing the wretched brass pipe fitting from the cast iron stack. I had to cut it in about 5 places and take it out piece by piece...what a pain in the ass. The $25 pipe wrench I bought was of no use, I couldn't cruse the piece at all. But it came out, and the threads in the cast iron are in good shape. Now I'm contemplating removing the one on the other side where the sink drain connects. The problem is that it is very close to the joist and I'm not sure I can get a good angle on it. The pipe isn't broken, but it is an s-trap coming out of the floor (as are all the sink drains in the house). It is my understanding that these s-traps are often forbidden by code because the trap can get sucked out? The other reason I want to replace it with a p-trap is for asthetics, and also, the cabinet I plan to install would have to have a hole cut into the bottom of it and I really don't want to do that. Any comments would be appreciated.

And thanks again for the advice on removing the fitting; I doubt I would have thought of cutting it from the inside.