[Matt[_7_]]

My house has a drain pipe for the kitchen sink, and the pipe gets
plugged sometimes. Then you have to remove the plug or bung from the
cleaning hole and run a snake down the pipe.

Last time I had to unplug the drain, I wanted to replace the (60mm
plastic) plug. The drain hole is in a fitting that looks like cast
iron, and the house is about forty years old.

I had a lot of trouble getting the new plug to engage the threads of the
cleaning hole because the threads were rusty. I took a stainless-steel
wire brush (and I think some Liquid Wrench) to the threads, but that
didn't seem to do much.

So I just put the old plug back in---that wasn't too hard to do. But I
am afraid of cross-threading the plug and ruining it sometime.

Next time I have the plumber over to do some work I thought I might ask
him to do something about those threads.

Would he have some kind of tool to clean out the threads without much
risk of messing things up?

[N8N]

On Oct 24, 2:31*pm, Matt wrote:
My house has a drain pipe for the kitchen sink, and the pipe gets
plugged sometimes. *Then you have to remove the plug or bung from the
cleaning hole and run a snake down the pipe.

Last time I had to unplug the drain, I wanted to replace the (60mm
plastic) plug. *The drain hole is in a fitting that looks like cast
iron, and the house is about forty years old.

I had a lot of trouble getting the new plug to engage the threads of the
cleaning hole because the threads were rusty. *I took a stainless-steel
wire brush (and I think some Liquid Wrench) to the threads, but that
didn't seem to do much.

So I just put the old plug back in---that wasn't too hard to do. *But I
am afraid of cross-threading the plug and ruining it sometime.

Next time I have the plumber over to do some work I thought I might ask
him to do something about those threads.

Would he have some kind of tool to clean out the threads without much
risk of messing things up?

Probably the easiest thing to do would be to get *two* new metal plugs
for the hole - preferably iron. Take one, and with your 4" angle
grinder, cut slots across the threads so it looks similar to a very
large tap. Thread that into the hole and tighten it well, letting it
clean the threads of the old pipe. Then remove it and install the
second, unmodified one as normal with pipe dope.

I don't even want to think about what a tap would cost for that size
of a pipe thread; I do have a thread chaser that works on large/
unusual threads but it was about $100, and only works on straight,
external threads.

nate

[dpb]

Matt wrote:
....
So I just put the old plug back in---that wasn't too hard to do. But I
am afraid of cross-threading the plug and ruining it sometime.

Next time I have the plumber over to do some work I thought I might ask
him to do something about those threads.

Would he have some kind of tool to clean out the threads without much
risk of messing things up?

Sure, but might mention it specifically when you call so he's sure to
have the threading tap w/ him on the truck -- it's likely it's in his
standard kit, but for a routine call threading a fitting would be pretty
unusual so might not carry them all the time.

What you need to do while it's fairly recently been out is take it back
out and use white lead or a non-drying plumber's thread dope on it
liberally.

That will help keep the threads from "growing together" w/ time/ corrosion.

I have several which have the plastic plugs in cast as well and they do
tend to gall. The nice thing is they can always be destructively
removed w/o hurting the cast if it ever does come to that, but by using
a dope or grease liberally you can prevent a goodly amount of the problem.

--

[[email protected]]

On Oct 24, 3:04�pm, dpb wrote:
Matt wrote:

...

So I just put the old plug back in---that wasn't too hard to do. �But I
am afraid of cross-threading the plug and ruining it sometime.

Next time I have the plumber over to do some work I thought I might ask
him to do something about those threads.

Would he have some kind of tool to clean out the threads without much
risk of messing things up?

Sure, but might mention it specifically when you call so he's sure to
have the threading tap w/ him on the truck -- it's likely it's in his
standard kit, but for a routine call threading a fitting would be pretty
unusual so might not carry them all the time.

What you need to do while it's fairly recently been out is take it back
out and use white lead or a non-drying plumber's thread dope on it
liberally.

That will help keep the threads from "growing together" w/ time/ corrosion.

[dpb]

wrote:
....

take it apart thread in a plasic extension fitting or new permanent
metal fitting. so you have a new fitting to work with

This is cast drain line, not galvanized...

--

[Don Young]

"dpb" wrote in message ...
wrote:
...

take it apart thread in a plasic extension fitting or new permanent
metal fitting. so you have a new fitting to work with

This is cast drain line, not galvanized...

--
A small wire wheel turned by a drill does a pretty good job of cleaning
threads. Be sure to wear protective glasses so you don't get wire or debris
in your eyes. If you want to take the time you can use auto valve grinding
(lapping) compound and the plug to clean the threads. Just apply the
compound to the threads and screw the plug back and forth while slowly
working it in. Renew the compound when it quits cutting. This works for any
kind of threads but can take a long time.

Don Young

[Bob F]

"N8N" wrote in message
...
On Oct 24, 2:31 pm, Matt wrote:
My house has a drain pipe for the kitchen sink, and the pipe gets
plugged sometimes. Then you have to remove the plug or bung from the
cleaning hole and run a snake down the pipe.

Last time I had to unplug the drain, I wanted to replace the (60mm
plastic) plug. The drain hole is in a fitting that looks like cast
iron, and the house is about forty years old.

I had a lot of trouble getting the new plug to engage the threads of the
cleaning hole because the threads were rusty. I took a stainless-steel
wire brush (and I think some Liquid Wrench) to the threads, but that
didn't seem to do much.

So I just put the old plug back in---that wasn't too hard to do. But I
am afraid of cross-threading the plug and ruining it sometime.

Next time I have the plumber over to do some work I thought I might ask
him to do something about those threads.

Would he have some kind of tool to clean out the threads without much
risk of messing things up?

Probably the easiest thing to do would be to get *two* new metal plugs
for the hole - preferably iron. Take one, and with your 4" angle
grinder, cut slots across the threads so it looks similar to a very
large tap. Thread that into the hole and tighten it well, letting it
clean the threads of the old pipe. Then remove it and install the
second, unmodified one as normal with pipe dope.

************************************************** **************

I recently did exactly that on the thread for a sink drain. It cleaned them up a
bit, but notthe heavier rust further in. Maybe I should try it again, but try
hardening the modified thread before use.

[[email protected]]

Matt wrote:
My house has a drain pipe for the kitchen sink, and the pipe gets
plugged sometimes. Then you have to remove the plug or bung from the
cleaning hole and run a snake down the pipe.

Rather than looking for a way to make removing the clogs easier, why
not look for a way to keep the drain from getting clogged in the first
place? The best thing you can do is stop putting junk down the drain
that doesn't belong there. If you don't have a garbage disposal, stop
putting food down the drain. Scape leftovers into the garbage can.
Scrape as much grease and fat out of pots and pans as you can and toss
in the trash before washing the pots and pans. Hot grease can be
easily drained into an old tin can where it will congeal, and you can
throw the can in the trash.

I had a lot of trouble getting the new plug to engage the threads of the
cleaning hole because the threads were rusty. I took a stainless-steel
wire brush (and I think some Liquid Wrench) to the threads, but that
didn't seem to do much.

Baloney. You have the wrong plug. If the old plug screwed right back
in there is nothing wrong with the threads so much that a clean new
plug would not screw in. The new plug should fit easier.

[Matt[_7_]]

wrote:
Matt wrote:
My house has a drain pipe for the kitchen sink, and the pipe gets
plugged sometimes.


Maybe about once in five or ten years.


Then you have to remove the plug or bung from the
cleaning hole and run a snake down the pipe.

Rather than looking for a way to make removing the clogs easier, why
not look for a way to keep the drain from getting clogged in the first
place? The best thing you can do is stop putting junk down the drain
that doesn't belong there. If you don't have a garbage disposal,


Oh, but I do.


stop
putting food down the drain. Scape leftovers into the garbage can.
Scrape as much grease and fat out of pots and pans as you can and toss
in the trash before washing the pots and pans. Hot grease can be
easily drained into an old tin can where it will congeal, and you can
throw the can in the trash.


garbage, not trash


I had a lot of trouble getting the new plug to engage the threads of the
cleaning hole because the threads were rusty. I took a stainless-steel
wire brush (and I think some Liquid Wrench) to the threads, but that
didn't seem to do much.

Baloney. You have the wrong plug. If the old plug screwed right back
in there is nothing wrong with the threads so much that a clean new
plug would not screw in. The new plug should fit easier.


Did it register with you that the old and new plugs are plastic?

If the hole is not 60mm, what size other than 60mm would be about 60mm?

[[email protected]]

Matt wrote:
If the hole is not 60mm, what size other than 60mm would be about 60mm?

A 2" NPT pipe thread is approximately 60mm in diameter.

See, the NOMINAL diameter of the inside of a 2" iron pipe is 2". The
wall thickness is approximately 3/16" thick. 60mm is approximately
2-3/8". You do the math.

You say the new plug is plastic? You won't hurt the cast threads a bit
if with a plastic plug if you happen to cross-thread it. The plastic
threads will simply strip out.

I'll bet if you compare the two plugs closely you will see they aren't
quite the same...

[Matt[_7_]]

wrote:
Matt wrote:
If the hole is not 60mm, what size other than 60mm would be about 60mm?

A 2" NPT pipe thread is approximately 60mm in diameter.

See, the NOMINAL diameter of the inside of a 2" iron pipe is 2". The
wall thickness is approximately 3/16" thick. 60mm is approximately
2-3/8". You do the math.

You say the new plug is plastic?


Yes, and so is the old one.


You won't hurt the cast threads a bit
if with a plastic plug if you happen to cross-thread it. The plastic
threads will simply strip out.


Right, well, I can't get the new plug to stay in. I get the threads to
barely engage, but the plug pops out when I turn it. Then I look at the
threads and see that they are deformed. Isn't this explained by rust
filling the threads of the drain hole?


I'll bet if you compare the two plugs closely you will see they aren't
quite the same...


I don't much want to take the plug out just to check. My explanation of
the old plug going in easily and the new one going in hard is that the
plastic threads of the old one are deformed (somehow crushed and/or
shaved) so as to conform to the rust-reduced size of the threads in the
drain hole. It seems basically that the end threads of the old plug are
smaller than the other threads, as if the plug is tapered more. The new
plug is not so deformed and the threads are too big to go in.

I come back to the question of whether there is some size close to 2
3/8" that isn't 2 3/8". I don't believe anymore that there is such a
thing as a 60mm nominal plug.

In what way(s) do you think the old and new plugs might differ---I mean
how might they have differed when they were both new?

[[email protected]]

On Fri, 24 Oct 2008 13:31:17 -0500, Matt
wrote:

My house has a drain pipe for the kitchen sink, and the pipe gets
plugged sometimes. Then you have to remove the plug or bung from the
cleaning hole and run a snake down the pipe.

Last time I had to unplug the drain, I wanted to replace the (60mm
plastic) plug. The drain hole is in a fitting that looks like cast
iron, and the house is about forty years old.

I had a lot of trouble getting the new plug to engage the threads of the
cleaning hole because the threads were rusty. I took a stainless-steel
wire brush (and I think some Liquid Wrench) to the threads, but that
didn't seem to do much.

So I just put the old plug back in---that wasn't too hard to do. But I
am afraid of cross-threading the plug and ruining it sometime.

Next time I have the plumber over to do some work I thought I might ask
him to do something about those threads.

Would he have some kind of tool to clean out the threads without much
risk of messing things up?

Simple. You probably can't find the correct tap for the pipe and if
you did it would cost more than you want, but you don't really need
that particular tap.

Instead find or borrow any smaller tap with the same thread pitch
and use it as a thread file. You'll have to manually hold the tap in
the proper orientation and scrape the rust from the threads.

Use the link below to determine the pitch of the tap
http://www.plumbingsupply.com/pipethreadsizing.html

Example: If you pipe is 2" then you need any 11-1/2 pitch tap.
A 11-1/2 pitch tap is only common to pipe threads, not screw threads.

http://www.engineersedge.com/screw_threads_chart.htm

[Smitty Two]

In article ,
Matt wrote:

Right, well, I can't get the new plug to stay in. I get the threads to
barely engage, but the plug pops out when I turn it. Then I look at the
threads and see that they are deformed. Isn't this explained by rust
filling the threads of the drain hole?

I'm going to throw out a WAG here, since the problem persists. I think
it's possible that you're cross threading the new plug. Maybe the
lead-in thread is chewed up from the rusty drain pipe. But if the old
one threads in well, then the new one should, too. There isn't any pipe
that's so close in size to another pipe that the two could be confused.

[DanG]

The most simple solution would be to install either a Benjamin cap
or a test plug:

http://www.mobilemart.com/product.aspx?sku=11981

http://www.plumbingsupply.com/testing.html (scroll down to see 3
types)

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"Matt" wrote in message
...
wrote:
Matt wrote:
If the hole is not 60mm, what size other than 60mm would be
about 60mm?

A 2" NPT pipe thread is approximately 60mm in diameter.

See, the NOMINAL diameter of the inside of a 2" iron pipe is
2". The
wall thickness is approximately 3/16" thick. 60mm is
approximately
2-3/8". You do the math.

You say the new plug is plastic?


Yes, and so is the old one.


You won't hurt the cast threads a bit
if with a plastic plug if you happen to cross-thread it. The
plastic
threads will simply strip out.


Right, well, I can't get the new plug to stay in. I get the
threads to barely engage, but the plug pops out when I turn it.
Then I look at the threads and see that they are deformed.
Isn't this explained by rust filling the threads of the drain
hole?


I'll bet if you compare the two plugs closely you will see they
aren't
quite the same...


I don't much want to take the plug out just to check. My
explanation of
the old plug going in easily and the new one going in hard is
that the plastic threads of the old one are deformed (somehow
crushed and/or shaved) so as to conform to the rust-reduced size
of the threads in the drain hole. It seems basically that the
end threads of the old plug are smaller than the other threads,
as if the plug is tapered more. The new plug is not so deformed
and the threads are too big to go in.

I come back to the question of whether there is some size close
to 2 3/8" that isn't 2 3/8". I don't believe anymore that there
is such a thing as a 60mm nominal plug.

In what way(s) do you think the old and new plugs might
differ---I mean how might they have differed when they were both
new?