Seems I have a pinched thread on this valve.

[Gone for diving]

Could you just bend the thread back some and use the tank to retrace the threads? Steel is stronger than brass.

Very unlikely, bad part is right at the start of the threads, will be hard to start, correctly, and you risk damaging the tank,
Use an other piece of pipe if you are going to try that,,, but I would say thats pretty hacky,
What's so hard about using a 3 cornered file, in brass like that, it would take me 45 seconds, done! Carry on!!!
I do this alot, especially if the customer took something apart,
As for being worried about missing thread, will most likely be some thread left there, and even if 3/8'' was missing it will not effect it, just means someone wasn't to careful with the valve in the past,
Hey if your worried, send it to me! I will use it, !!
This thread is getting long winded for a simple 4 or 5 careful strokes of a file,
I could have fixed 6 valves like that in the time it took to type this!

 

[Ulfhedinn]

I appreciate it though. Lots of ideas. I have been in class all week so I have not had the time to get to it. Will let you know how it goes once I do. Thanks again to all!

 

[rob.mwpropane]

Very unlikely, bad part is right at the start of the threads, will be hard to start, correctly, and you risk damaging the tank,
Use an other piece of pipe if you are going to try that,,, but I would say thats pretty hacky,
What's so hard about using a 3 cornered file, in brass like that, it would take me 45 seconds, done! Carry on!!!
I do this alot, especially if the customer took something apart,
As for being worried about missing thread, will most likely be some thread left there, and even if 3/8'' was missing it will not effect it, just means someone wasn't to careful with the valve in the past,
Hey if your worried, send it to me! I will use it, !!
This thread is getting long winded for a simple 4 or 5 careful strokes of a file,
I could have fixed 6 valves like that in the time it took to type this!

I can't imagine that little part being bent back 80% of the way not catching when you start to thread. And I really can't imagine brass hurting steel at all.

Just an opinion. I rethread damaged brass into steel like this all the time (given I'm not talking a scuba valve holding 3500psi).

 

[Gone for diving]

I can't imagine that little part being bent back 80% of the way not catching when you start to thread. And I really can't imagine brass hurting steel at all.

Just an opinion. I rethread damaged brass into steel like this all the time (given I'm not talking a scuba valve holding 3500psi).

That may be doable ....
but someone that doesn't have experience has a a good chance of cross threading or galling it up, especially with a tapered thread,
I would use a high moly lube on top of that, and use a different fitting,

 

[Bob DBF]

It's the crossthreading issue that always makes me nervous when dealing with bunged up threads. I f'd up a lot of threads learning how not to. Getting the thread mostly right will be the difference between having the tank finish straightening the valve thread, or crossthreading the valve and ruining it. From personal experience, it will be a lot easier than a steel thread.

 

[rob.mwpropane]

It's the crossthreading issue that always makes me nervous when dealing with bunged up threads. I f'd up a lot of threads learning how not to. Getting the thread mostly right will be the difference between having the tank finish straightening the valve thread, or crossthreading the valve and ruining it. From personal experience, it will be a lot easier than a steel thread.

I agree. I think there's a bit of an art to knowing what feels like the thread being worked out (slight resistance), and cross threading (a lot more resistance). If it feels too tight it's probably not right.

 

[PBcatfish]

I have thread files. I have triangular files. I have a lathe that does single point threading. I have draws full of taps & dies. I've cut & repaired a lot of threads over the years. The parts I manufactured went into a wide variety of equipment in a wide variety of industries including high pressure gas handling equipment.

For that little ding, in a plated brass triangular thread form that had that many threads of engagement, I would probably just take a dull cold chisel or piece of steel flat bar and a small hammer & bang the thread back out straight. That would reduce the likelihood of causing the plating to chip, compared to a cutting process.

Alternately, you could also take a fine flat file & file off that small damaged area down to flush with the root (AKA minor diameter) of the thread, so that it doesn't interfere with thread engagement. That little ding happens to be in the "imperfect" portion of the thread that is considered to be a lead & not used in calculating the thread's loading capacity.

If you use a thread restoration file or a triangular file, you will likely damage the plating on adjacent threads. That's not the end of the world, but it's best to be avoided if possible.

As others have said, I too would be perfectly happy to take that valve, fix the thread & use it, if someone were getting rid of it.

 

[PBcatfish]

Accidental duplicate post
Is there a way for me to delete this?