Repairing Stainless Steel threads, or learning the hard way about Galling

island_dude · 01-01-2012, 04:56 PM

I got this really nice polarware brew pot for Christmas. It is an awesome piece with a drain valve and it also accommodates a thermometer insert. I got the great idea to just check out how the valve attaches to the drain tube.

I neglected to read the little warning about placing four layers of Teflon tape on the threads firsts. Even though all I did was gently screw the valve on to the tube a couple of turns, the thing seized up. Major sigh. I did manage to work the two pieces apart and three of the threads are damaged.

Is there any way to fix this without tossing the whole thing? I am not mechanically inclined, so I don't know where to start.

red-beard · red-beard's Garage

Drill out and re-tap at a larger size.

cgarr · cgarr's Garage

What part are the threads screwed up on? both?

We work with this stuff everyday and hate the galling problem with SS we started using plated steel nuts on anything stainless if you ever want to take it apart.

island_dude · 01-01-2012, 06:24 PM

Quote:

Originally Posted by cgarr

What part are the threads screwed up on? both?

We work with this stuff everyday and hate the galling problem with SS we started using plated steel nuts on anything stainless if you ever want to take it apart.

There is a threaded nipple the extends out of the pot (it is welded on). The valve mechanism screws on to this nipple. The first three threads are slightly damaged. I can try to post a picture of it, but I don't have a camera handy today. I can't tell if the threads on the valve are damaged, but this part isn't as expensive as the pot.

Attached is a picture of the pot with the valve attached. This might make it easier to see what I am working with.

Thanks

lendaddy · 01-01-2012, 06:27 PM

I'm sure the threads can be repaired. Run a tap through it or thread repair tool if it's the external threads that are jacked. Should be a piece of cake.

cgarr · cgarr's Garage

You should be able to run a die over it but its going to be a pipe thread which is good because its tapered and you should be able to cut it a bit deeper and clean it up nice.

If you want to fix it for future use get a brass ball valve.

1990C4S · 01-02-2012, 08:15 AM

Quote:

Originally Posted by cgarr

If you want to fix it for future use get a brass nipple.

Home Depot will have them. Assuming it is NPT.

911pcars · 01-02-2012, 09:56 AM

....and apply anti-seize to the threads before assembly.

Sherwood

rick-l · 01-02-2012, 11:35 AM

Is this the size? What kind of a bung did they weld on? Does it look like a TIG weld? Does the weld look pretty?

1/4 In. -18NPT Hanson Pipe Taps-8203 at The Home Depot

I smell a business venture. How expensive are we talking?

Zeke · 01-02-2012, 11:41 AM

I think teflon tape is the sanitary way to go. Once you clean these threads up, they should go together nicely. When working with new SS fasteners, it's a good idea to run a SS wire brush over the male threads to "polish" them. Most of the time you can't get into the female side, but running a thread chaser is a good idea. Not completely necessary though.

rick-l · 01-02-2012, 11:43 AM

Looking at the picture again.... How is that attached to the pot inside?

island_dude · 01-02-2012, 01:54 PM

Quote:

Originally Posted by rick-l

Is this the size? What kind of a bung did they weld on? Does it look like a TIG weld? Does the weld look pretty?

1/4 In. -18NPT Hanson Pipe Taps-8203 at The Home Depot

I smell a business venture. How expensive are we talking?

The weld looks great. Since I was just trying test putting the valve on, I was just gently turning it. I was shocked that this happened. The male threads are cut into a nipple that is welded on very well. The whole pot as shown is about $240. Not massively expensive, but a real waste if it had been a total loss.

The male threads don't look too bad. The female threads on the valve are in better shape. The valve costs about $20, so replacing it would not be the end of the world.

island_dude · 01-02-2012, 01:57 PM

Quote:

Originally Posted by rick-l

Looking at the picture again.... How is that attached to the pot inside?

There is a threaded nipple that is welded to the pot. I think some of the material of the pot is extruded to provide more material to work with. Sorry that I don't have any pictures. I'll try to post something later on with my cell phone camera.

TimT · 01-02-2012, 02:28 PM

If you cant get the threads cleaned up enough to thread in in the valve, you could always weld another coupling to the threadolet that is already welded on the brew pot..kind of sucks to have to fix a new brew pot though

Here is a brew system I welded together a few years ago using some kegs I got from my friends bar..

island_dude · 01-02-2012, 02:39 PM

Quote:

Originally Posted by TimT

If you cant get the threads cleaned up enough to thread in in the valve, you could always weld another coupling to the threadolet that is already welded on the brew pot..kind of sucks to have to fix a new brew pot though

Here is a brew system I welded together a few years ago using some kegs I got from my friends bar..

That is a cool set up!

Thanks to all of your for the great inputs.

Here are some images of the thread damage:

lendaddy · 01-02-2012, 02:49 PM

Looks like it would be easily fixed with a die or thread file.

Zeke · 01-02-2012, 02:59 PM

Thread file to start and clean up with a die. After that use the SS wire brush to debur.

And it looks like you didn't suffer from the common galling, you may have cross threaded your valve to flatten the threads like that.

As already mentioned, since it's a tapered thread, no harm has been done. It will seal perfectly once repaired.

TimT · 01-02-2012, 03:32 PM

Those threads really don't look to bad, not damage from galling just like mentioned before..cross threaded...

I know what I would do...

"what would Eddie do?"