Very small job but need a 2" NPT pipe tap. Ideas?

muddstopper · Sep 21, 2016

Go to your local auto parts store and buy a thread file. They are pretty cheap, heres one on zoro, Nicholson SAE Thread Restoring File, Specialty 337 | Zoro.com

4570Man · Sep 21, 2016

muddstopper said:
Go to your local auto parts store and buy a thread file. They are pretty cheap, heres one on zoro, Nicholson SAE Thread Restoring File, Specialty 337 | Zoro.com

That's going to be pretty useless for cleaning up female threads.

Egon · Sep 22, 2016

Dadnatron said:
I need to clean and refurbish the threads on a diesel tank. There are 6 total holes needing cleaned mainly of rust etc.

I've tried a wire brush to no avail. Only thing I can think of is a tap... but the only taps I can find are online and for sale. While I don't believe anyone should forgo payment for their wares, I just can't stomach a $150 tap to clean out 6 holes. A literal 5 minute job.

Any thoughts? I've thought about getting a 2" nipple, cutting grooves vertically along the threads and using it... but I have no idea whether that will work at all. The metals are going to be roughly the same hardness... maybe even softer than the tank, with galvanized 2" pipe.

Any thoughts would be appreciated. I haven't been able to find a rental. Even Harbor Freight doesn't have one, at least that I can find. The cheapest I can find on Amazon is $88 and they are back-ordered for 2 months.

My goal is quick... I was going to take the tanks to a sandblaster/welder tomorrow evening and have him clean them up. I was removing old fittings this evening, and while there are a couple I can't remove, there are also a few that are acting almost 'cross-threaded' because the threads are so bad.

Welder? Thread in a short nipple and back weld it. Then use a new coupling on the nipple.

SPYDERLK · Sep 22, 2016

4570Man said:
That's going to be pretty useless for cleaning up female threads.

Some have a 4 sided rounded stinger on each end for internal threads.

4570Man · Sep 22, 2016

SPYDERLK said:
Some have a 4 sided rounded stinger on each end for internal threads.

Not the one you posted a link to.

SPYDERLK · Sep 22, 2016

4570Man said:
Not the one you posted a link to.

OK. ... But I didnt post the link - or even look at it.

ultrarunner · Sep 22, 2016

Maybe Ebay or Craigslist?

Pipe Tap GTD 2 11 1 2 NPT HS USA M

5 P New Condition Never Used | eBay

4570Man · Sep 22, 2016

SPYDERLK said:
OK. ... But I didnt post the link - or even look at it.

Ok, I didn't go back to look who posed the link. The one linked was a external only one.

Cougsfan · Sep 22, 2016

I have re-furbished female pipe threads by lubing up a sacrificial nipple with never-seize and screwing in and out, going just a little bit more every time, just like you would with a tap, but not as aggressive with each pass. Might wear out a nipple or two, but they are dirt cheap compared to a tap. You need to clean and re-apply never-seize fairly often. If you can start the nipple at all, this would probably work. Then use pipe dope when you assemble the final pieces. I have found pipe dope to work best if you apply, diss-assemble, re-apply and re-assemble.

SPYDERLK · Sep 23, 2016

Cougsfan said:
I have re-furbished female pipe threads by lubing up a sacrificial nipple with never-seize and screwing in and out, going just a little bit more every time, just like you would with a tap, but not as aggressive with each pass. Might wear out a nipple or two, but they are dirt cheap compared to a tap. You need to clean and re-apply never-seize fairly often. If you can start the nipple at all, this would probably work. Then use pipe dope when you assemble the final pieces. I have found pipe dope to work best if you apply, diss-assemble, re-apply and re-assemble.

Thats why you go at it with a gorilla tooth brush 1st.

SPYDERLK said:
Since the threads are not deformed - just rusty I think you can do fine with your grooved thread idea. ... 1st tho, use a toothbrush sized wire brush and Kroil round and round on the inside threads to soften and mobilize the rust. A couple cleanings like that and the threads should look much better. - Then screw in your grooved pipe , back and forth, while still using Kroil to emulsify the rust. Should clean up well. ... Then you can tighten in a regular pipe or plug, etc with antisieze on the threads to finish the reforming. A tap wouldve been spoiled anyway. Rust is pretty abrasive.