On Jun 11, 8:24*am, "
wrote:
On Jun 11, 8:22*am, "
wrote:





On Jun 10, 3:22*pm, "Pete C." wrote:

RBM wrote:

On 6/9/2013 8:43 PM, wrote:
I have a gas pool heater that has a 1/4"-18 NPT brass plug
that goes into a cast iron manifold. *Over time the threads in
the cast iron have deteriorated and now I can't get the plug
in. *I tried a new plug and one of the other plugs from another
location.

I checked to see if there is a helicoil for npt and they have it.
I'm not sure how the helicoil works for a pipe fitting so that it
doesn't leak, but I guess it must work. *Problem is that so far,
I can only find the insert in packs of 12 for $25, the tap is $45..
Then I think you need an insertion tool?

So, any other ideas? * It doesn't have to be the most 100%
reliable solution, ie if it drips a bit or fails, it's not the end of
the world. * Also, I'm not even using the pool heater, but I'm
not keen on ripping it out either. * The area of the plug just
has warm water going through it, not super hot. *So, I'm
thinking to just epoxy it closed. *In the Fall to winterize it I
can just knock it out. * Any other ideas?
can you get a tap and just try chasing the threads?

A helicoil relies on re-drilling and re-tapping to a larger size. Can
you simply re-drill and re-tap to 3/8" NPT and use a 3/8" NPT plug? That
would require only ordinary drills and taps that are cheap and available
singly, and of course a new plug.- Hide quoted text -

- Show quoted text -

That's a good point too. *You're right. *If you have to drill it for
a helicoil, might as well just re-tap it to 3/8". *I've never tapped
cast iron, but I guess it can be done, as the threads got there
somehow to begin with.

So, first plan is to try running a 1/4" tap through it to clean up
the threads. *I found a tap yesterday, that wasn't easy. *HD
had some tap, but no NPT. *Lowes had no taps at all. *Tried
Autozone parts store, I figured they probably would not have
NPT either. *Not only didn't they have any NPT, they hardly
had any taps at all!

But the Autozone guy suggested trying a old hardware store
just up the street. *I didn't even know that store existed. *It
looked like it was out of the 60's. * But the guy was sitting there,
waiting for me. *Told him what I wanted, he walked behind the
counter and in 30 secs I had it for $8.

So, I'll let you know how I make out....- Hide quoted text -

- Show quoted text -

Oh, and forgot to mention. *I also got a short brass nipple and
a valve, per nestork's suggestion. *Assuming I get it back together,
I won't have to take it apart again.- Hide quoted text -

- Show quoted text



Update. I ran the 1/4" tap and then installed a short brass nipple
with a lot
of Teflon tape, followed by a valve. It sent in easier than it
should, didn't want
to make it up tight, so I didn't push it. But it's not leaking and
with the valve, no
need to screw with it again. IF anything, I would expect as the cast
iron rusts
some more, it may tighten itself up a bit.

Thanks to all for the suggestions!