any tricks for cleaning out rotten cast iron threads

Reply

  #1  
Old 01-16-06, 05:07 PM
Member
Thread Starter
Join Date: Oct 2005
Location: U.S.A.
Posts: 49
Received 0 Votes on 0 Posts
any tricks for cleaning out rotten cast iron threads

Ok, so I took out my old steel tub and am replacing with a new one, and the thing must have been in there 40 years, because when I took the old one out, the cast iron p-trap pipe just fell to the ground(crawl space). The old male fitting was badlly rusted and bonded to the female threads. I picked up something called mouse milk at the plumbing supply and that helped a lot to clean out the majority of the male threads, but not all. Can anyone provide me some advise on removing the last bit of remaining cast iron threading from the female fitting where the tub p-trap line ties into the main sewer line?

Also, I'm planning on using ABS for the new p-trap. Currently the threads of the male abs fitting go in about half a rev before stopping hard. How much of an issue is it if I can't clean the old threads out completely?

Thanks
Brian
 
Sponsored Links
  #2  
Old 01-16-06, 05:53 PM
majakdragon's Avatar
Member
Join Date: Jul 2003
Location: N.E. Arkansas
Posts: 7,827
Received 0 Votes on 0 Posts
If you do not get the threads cleaned out, it will leak. Try calling a plumbing shop and ask if they have a pipe tap the size of the fitting. They may "chase" the threads for you. Not likely you will find a tool rental place with a pipe tap but you might try. Good luck.
 
  #3  
Old 01-16-06, 06:23 PM
Member
Thread Starter
Join Date: Oct 2005
Location: U.S.A.
Posts: 49
Received 0 Votes on 0 Posts
I figured as much, but the pipe tap was so expensive for a one-off, was trying to avoid that. Hadn't thought about asking to borrow one. Can't hurt I guess - will give it a try

Thanks!
Brian
 
  #4  
Old 01-18-06, 02:24 AM
bolide's Avatar
Member
Join Date: Jan 2006
Location: PA
Posts: 1,909
Received 0 Votes on 0 Posts
Lightbulb make your own thread chaser

Definitely you should thread in a metal pipe and remove it before you try to thread in plastic.

The mouse milk should have loosened the rust.
A steel (black iron) nipple with tapered (NPT) ends should cost about $2.

You could carefully cut a big notch intothe nipple from one end using a high-speed grinder and a grinding wheel.
The notch should give the rust a place to escape or perhaps bend the rotted remains enough that you can grab them with pliers.
Wind your home-made tap in and out until you work everything loose that is blocking the threads.

Once the notched end screws in and out, switch to the factory end and repeat.

Be very careful that the ABS doesn't crossthread going into the imperfect old threads. Use a soft joint compound (pipe dope) for the final connection.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: