Cap off 1/2" non-threaded galvanized water pipe

[Rayven]

I can't re-plumb the whole house. Not yet.

I have galvanized pipes running from the basement to the second floor. The cold weather has caused havok. They have been patched and repaired by the previous owner.

On the first floor, I have this 1/2" pipe that was cut and repaired with a dresser coupling. The coupling has failed twice during the last freezes. I replaced it once successfully but this time I can't seem to get it seated.

Since the last guy just cut the pipe, it's unthreaded. I can't get anything to unscrew from anything else further down in the basement. For a temporary immediate fix, I was thinking I could just cap the pipe but all the caps I'm finding are threaded.

Is there any way to cap an unthreaded galvanized pipe that is under pressure?

I am handy but I'm not a plumber. I can't afford to spend hundreds of dollars on this one issue. I'm saving up to just get the whole thing done in one shot. The dresser couplings are about $10 each and I don't know why this last one is giving me fits.

Thank you so much for any guidance you can offer.

 

[Reach4]

Do you have room to thread that pipe end?

 

[Sponsor]

 

[GrumpyPlumber]

Barring Reach's suggestion, I can only suggest a dresser.

 

[PGB1]

If you can't thread, per Reach4's best idea & you have had bad success with dressers, maybe a Compression x M-NPT fitting on & then put a cap on the NPT? I don't know of this is a long-term fix, or temporary.

They're made for schedule 40 & 80 iron pipe (galvanized, black & stainless and hydraulic pipes).
Where I used to work, I remember seeing the fire protection guys using compression-for-schedule 40 steel pipe x M-NPT or F-NPT adapters (valves, too). The machine repair guys in the milk processing area used stainless versions on stainless schedule 40 when the sanitizing chemicals would damage the threads on a pipe.

I doubt a hardware would have one, so you may have to on-line. Perhaps Grainger, Zoro or McMaster Carr?

 

[Jeff H Young]

only thing to do is a do over another dresser. but you cant let the pipe freeze put some kinda heat down there