Screwed up welding

A guy I know welded my kegs. One of the fittings is full of slag on one edge like he burned through it a bit. Is it possible to repair female pipe threads or am I screwed? If you cant fix it, how would you suggest I get the fitting out and a new one welded back in?

Just get the right size pipe tap and chase the threads, Use plenty of tapping fluid.

You can chase the threads w/ a tap. Or simply attempt to thread the fitting in...one trick is to cut 2 or 3 lengthwise grooves w/ a hacksaw into a spare male fitting or a bolt to make a "poor mans" tap.

Thirteen said:

Just get the right size pipe tap and chase the threads, Use plenty of tapping fluid.

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+1 Try this. Don't skimp on the lube though. Go easy on the tap too. I have fixed buggered up threads with a tap or die set.

I am not so sure I agree with the idea of using a plug as a tap. I do however agree on the use of lube and plenty of it. Stainless likes to seize up when put under pressure. The heat generated will lock things up right before you know it. Good luck. I hope it works out for you.

wilserbrewer said:

You can chase the threads w/ a tap. Or simply attempt to thread the fitting in...one trick is to cut 2 or 3 lengthwise grooves w/ a hacksaw into a spare male fitting or a bolt to make a "poor mans" tap.

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I think this would work if the foul up is not too bad. But you gotta mess up a SS fitting to do it.... I'd get the real thing first or ask to borrow one.

Thirteen said:

Just get the right size pipe tap and chase the threads, Use plenty of tapping fluid.

Click to expand...

I agree with your suggestion. I had a similar issue and fixed it with a tap. It took some "persuasion", lots of tapping fluid and some leverage (I use my ratchet breaker bar)!

Oh, one more suggestion, once in a while back the tap out to make sure the flutes are clear and to add more tapping fluids...

Good luck!

wilserbrewer said:

You can chase the threads w/ a tap. Or simply attempt to thread the fitting in...one trick is to cut 2 or 3 lengthwise grooves w/ a hacksaw into a spare male fitting or a bolt to make a "poor mans" tap.

Click to expand...

I'd be far more comfortable doing this on carbon steel than stainless. Even with the grooves you're deforming the damaged threads more than you are cutting them. With stainless the risk of galling and a seize up is just too high.

Use a good sharp tap. Lots of fluid. Back the tap off 1/2 turn to break chips every so often. DO NOT try to power through it. If you can't go forward go backwards. There have been plenty of internal stainless threads I've had to repair an 1/8th of a turn or less at a time (usually smaller sizes though where breaking the tap is a concern).

Thanks guys. One more thing' I leak tested the kegs last night, dried them out well, but this morning when I put my false bottom in I saw te inside of the fitting was rusting. He only welded the outside and told me it would be fine that way, but the inside was all jagged from welding. Do your kegs do that too?

Sounds like he didn't back gas or flux the inside of the weld. That part is now no longer stainless

Can I have the inside wire brushed and welded with flux to fix this?

The process you are looking for is call re-passivisation and there are multiple ways to accomplish it.

Can you post some pictures so we can better see what happened?

http://emob924.photobucket.com/albums/ad81/islandboy85/SU1HMDAwMjAtMjAxMDA0MTQtMTQzOS5qcGc.jpg

Sorry these are on separate posts. It's how I had to do it from my phone. You can see how bugged up my kegs turned out

Ya, didn't back gas the weld and it's contaminated.

Research re-passivisation and find the option that's best for your budget/ability/availability.

acid wash and re-passivate. (maybe hit it with a scrungee.

brewmonk said:

acid wash and re-passivate. (maybe hit it with a scrungee.

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I agree, polish the schit out of it with a scotchbrite pad and follow up with a strong acid wash. Well polished will help a lot. Dont use any carbon steel wool or equiv. The carbon steel will embed in the ss.

Should I have the inside welded to clean it up since it's so jagged or use a grinding wheel to flatten it? Also, is repassivating a DIY thing or should I have it done by a pro? Oh yeah, pic one and four show you how bugged up the threads got...

I would think that grinding it down to fresh metal would work, but I'm not sure on that.

Looks worse than the crap job my moron welder did. I tried grinding down but it is really hard to get at most of it unless you have the right tools and are skinny with a good back. I just scrubbed with bar keepers friend, left a layer of paste on it for a few days and it's mostly good. The bumps should not be of concern as you are boiling the wort.

Paste? Are you talking about the flux paste like used for sweating pipes?

Islandboy85 said:

Paste? Are you talking about the flux paste like used for sweating pipes?

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I believe he's talking about making a paste from Bar Keeper's Friend.

Islandboy85 said:

Paste? Are you talking about the flux paste like used for sweating pipes?

Click to expand...

I believe he is talking about a paste of bar keepers friend?


Welding over the sugar isn't going to really help. If the front isn't purged when this is done it will just push it right through and then it will be on the front side. Plus welding down inside will be a real PITA. Lots of patience, gas, and dexterity with the torch are needed. If it did work you would just have brittle contaminated material. Take your time with a dremel tool and the sanding drums to get in close. You can use a large grinder and a flapper wheel to get the big stuff out of the way fast. If you have air tools, a small 90 would be nice in this situation.

I myself would use a carbide bit to get things down and where I wanted them. If your worried then go over it with fresh sanding drums to remove any possible surface carbon that might be there. The thing with carbides though is, they don't go away when you use them. They cut the material your removing, so its not really like using a grinding/sanding pad.

I would make sure that what ever you use is new or has never been used on carbon steel. I kinda get the feeling that the wire brush that was used was either not SS or, was a used SS brush which was contaminated. The reason I say this is cause it looks to me like you have some rust outside the weld area. Like where one would be brushing. "IF" the area I am talking about was rusting due to the heat, I would think it would be worse out and around the weld area. (the heat affected zone)

Good Luck.

Ok, I'll give it a try...pray for me guys

I was.able to clean the welds up some last night with a 1/8 in burr and a Bright Boy. Still needs some work.

Greenmonti made some really good points. I went at my first weld job not thinking about contamination and wished I had. After the fact I wish I'd had bought some new disk pads and did as little as possible. One of the other guys talks about cleaning up your kegs with a Gator pad from Lowe's. I can attest to how well they work. Before you use it on the outside, use the brand new one (fine) on the inside. It should clean up pretty good. Hopefully there isn't alot of carbon imbedded into the stainless at this point.
Good luck,
BB

Looking at your pictures 3 and 4, are you sure your couplers are stainless? There's a lot of rust on the surface of the coupler and inside the threads. I'm not a metallurgist however I would suspect some deposits of iron there to have that much rust develop.
You might be able to coat the surface with gasket grease to try and retard oxidation during storage.
my 2 cents.
BB

Yeah, they were SS. My welder had them cherry red for a loooonnnnggg time. I told him how screwed up it is, and he told me he would "reweld it with more gas this time to stabilize the chromium." He had prep sanded it with a really old jacked up pad...probably was contaminated with steel from his kid's car project.

You can take a look at the section on passivation and select the link for how to do it.

http://brewingtechniques.com/library/backissues/issue2.4/millspaw.html

Let us know how things come out for you.

BB

Well, I cleaned up the welds. I still. Need to passivate them. In the mean time, I bent up my pickup tube. It looks like crap. I filled it with glass sand blasting media, capped it, and lubed it before I bent it, but it still kinked on the inside of the bend. It may just be too hard. I may have to aneal it before I bend it. I thought .5 x .020 stainless tube would be ok on a 1.5 in radius, but not quite. Ill probably just live with it. I think it will still be ok, and I can get a brush in it to clean it.

Forgot the link.
http://emob924.photobucket.com/albums/ad81/islandboy85/SU1HMDAwODgtMjAxMDA1MjAtMTcxNC5qcGc.jpg

Boy, you've just haven't had much luck with stainless. I bent a 0.500" O.D. x 0.06" wall last week but it took alot of heat. I just happen to have one of those propane + oxygen torches laying around (nothing fancy I think Home Depot sells them). And when you're done with it, you can use the oxygen tank with valve on your wort. I picked up a disposable aquarium filter for the end of the hose. Anyhow, heat that thing up until it cherry red and slowly work it around some type of form.

Your tube should work. One other suggestion, you might want to grind out a U section in the end just in case it does hit the bottom of your pot, you'll will still be able to draw through the opening.

BB

I was worried about corrosion if I heated it up in an unknown tempurature such as a torch. If it doesn't work out, a guy at work in our hydraulic shop said he would bend one up for me from stainless tube he has that isn't quite as hard. I think mine was just too hard to begin with. As for cutting the end, I was thinking about that, or flaring it.

Well, I was able to clean out the threads. One of the contractors at work lent me a pipe tap. I will tell you what, that took some effort and a lot of tapping compound to get it cleaned up. It's not perfect, but I was able to get my fittings installed with little fuss.

I'm glad things are coming together for you on your build. Your right about the heat issue and SS. Bending it cold is a much better way as you wont loose the corrosion resistance. I would be interested in knowing what SS tubing he has that isn't as tough. If the grade of it is a higher number then 304-304L then it is better tubing. If its a lower number, then it is just a low grade SS and that's why its easier to bend. I wouldn't use it if that's the case.