[Rick_H]

I wondered about using silicon bronze. Thanks for saving me the effort!

I put four evenly spaced tacks on and then welded 1/4, opposite 1/4, backstep 1/4, and then the remaining 1/4. I let it cool a bit after each section and then removed the heatsink and dunked it in water. Does that sound workable or do I need to take all of remaining heat out of the stainless too with the wet rag? I'll do it anyway BTW just to be safe, but I'm curious how much is really required?

I wouldn't see why that would not work. When I'm working with some 16g-13g tanks I tack 4 quads, then weld about 25% of the bead each time. General just with a purge dome of some sort , I usually can't get a backer or larger heat sink clamped where I need it. I had some red paste a few years back that you dam around the area you weld and it soaks up some of the heat, worked ok.

[exnailpounder]

I wondered about using silicon bronze. Thanks for saving me the effort!

I put four evenly spaced tacks on and then welded 1/4, opposite 1/4, backstep 1/4, and then the remaining 1/4. I let it cool a bit after each section and then removed the heatsink and dunked it in water. Does that sound workable or do I need to take all of remaining heat out of the stainless too with the wet rag? I'll do it anyway BTW just to be safe, but I'm curious how much is really required?

What you did was perfect. You don't need the metal to be room temp when you start welding you just need to take out most of the heat. Stainless doesn't conduct heat worth a dang so if you don't draw it out in some fashion, the heat builds up and cooks your parent metal and then you have problems. I always err on the side of caution and it has worked out better than crossing my fingers and hoping.

[glassTransition]

Thanks again guys.

I'll post pics when it's done.

[exnailpounder]

I wondered about using silicon bronze. Thanks for saving me the effort!

I put four evenly spaced tacks on and then welded 1/4, opposite 1/4, backstep 1/4, and then the remaining 1/4. I let it cool a bit after each section and then removed the heatsink and dunked it in water. Does that sound workable or do I need to take all of remaining heat out of the stainless too with the wet rag? I'll do it anyway BTW just to be safe, but I'm curious how much is really required?

I wouldn't see why that would not work. When I'm working with some 16g-13g tanks I tack 4 quads, then weld about 25% of the bead each time. General just with a purge dome of some sort , I usually can't get a backer or larger heat sink clamped where I need it. I had some red paste a few years back that you dam around the area you weld and it soaks up some of the heat, worked ok.

Hey Rick I'm curious, when you weld thicker material such as pipes do you worry so much about heat or do you weld as much as you can and then reposition? The only real experience I have with SS is the work I do on kegs and once in awhile a repair. I know you sanitary guys don't use filler so there is no inter-pass temp to worry about. What is the typical procedure? I have been tempted to apply for a job as a sanitary welder in a brewery so if it's not real hard I might apply.

[Rick_H]

On the sanitary stuff like .065" wall or .083" wall, I'll go all the way around (no filler, full purge). If I'm welding say sch 40 or sch 80 piping, valves or fittings (socket weld or butt weld) I pay attention to my interpass temps, especially with the Stainless. Generally I tack and run a root pass, let cool till I can put my hand on it then do the next pass.

If I'm hanging upside down or welding in a mirror, I may stop more then I'd like to... but I try to eliminate ties in when ever possible to prevent possible issues. If I have to stop sanitary I just make sure I start about 1/2" back in the old weld to make sure I get complete pen (the puddle has the little "devils eye") black dot dancing, I know I'm through and good to go.

[exnailpounder]

Do you do open roots on a butt weld? I know you don't use filler on the root but do you use it for your cap? The way I understand it you don't use filler on the root to not introduce contaminants but after that pass you almost have to use filler don't you?

[bruce991]

I often welded outlets and steam jacket fittings to very large SS vats. And no matter how you do it over time the thin to thick material situation will stress crack at some point. We had a tool to flare out the hole in some cases, or on electrical junction boxes. Made for a butt type weld, but the flaring process thinned the material right where you weld and made for a very touchy situation and easy to blow through. Larger container internal purges really uses up the argon. If you can get inside a vessel make a purge box.

[Rick_H]

Do you do open roots on a butt weld? I know you don't use filler on the root but do you use it for your cap? The way I understand it you don't use filler on the root to not introduce contaminants but after that pass you almost have to use filler don't you?

For sanitary piping no filler ever, very good fit up near perfect, full purge, full pen. Sch 40 and 80 pressure piping, open root for butt welds, filler at all times. If using socket welds, after setting the gap I run an autogenous root or very thin filler .030", then fillet with 3/32"+ filler depending on how many passes or the WPS

[exnailpounder]

Thanks Rick. Very pretty welds by the way

[exnailpounder]

I often welded outlets and steam jacket fittings to very large SS vats. And no matter how you do it over time the thin to thick material situation will stress crack at some point. We had a tool to flare out the hole in some cases, or on electrical junction boxes. Made for a butt type weld, but the flaring process thinned the material right where you weld and made for a very touchy situation and easy to blow through. Larger container internal purges really uses up the argon. If you can get inside a vessel make a purge box.

What you just described is the reason why I think dimpling is setting up for failure. It stretches the metal. I have a competitor who dimples in fittings and he touts that as a better fitup for a more sanitary weld I don't know what his failure rates are but as far as stress cracking, I have only had one keg come back with cracks after I sil-brazed it. I have a friend who uses his keg/boiler ALOT and he is happy as a clam so we will see if it cracks at some point but he has been boiling away for almost 2 years. I do know that repeatedly heating a thin-walled keg will work harden it and brittle it out. I researched everything I could find about using kegs as brewing equipment before I started because it has been a steady part of my business.

[glassTransition]

sink.jpg (68.28 KiB) Viewed 1086 times

This is the heatsink that I made. It's radiused to match the inside surface of the keg. There is a quick disconnect on the back and a hollow threaded rod on the other side that passes through the fitting. I will cap the hollow and drill a couple of small holes to allow the argon to flow in the vicinity of the weld.

I'm conflicted about whether or not to mill a circular channel in (gap below the weld bead) for the argon to directly back the weld or to leave it as-is so that it supports the back side while it's hot and wicks away the heat directly from the back of the weld. Without the channels, I don't think the argon will flow there, but based on previous results, I really don't think sugaring will be a problem anyway - especially with such a tight fit. This question is in the vein of Jody's video about "good enough". What do you guys think?

[exnailpounder]

Nice work! You got some skills there man! One thing I wish I could do is machining.

[glassTransition]

Thanks. What do you think about using it like it is versus adding a circular channel under where the weld bead will be?

[exnailpounder]

Thanks. What do you think about using it like it is versus adding a circular channel under where the weld bead will be?

If you can assure it will fit tight then you could use it as is but to eliminate any variables and since you have the tools and ability, I would groove it out for argon backing. I use to play around making all sorts of purge boxes and gas diffusers and it always seemed that they would never work out in a new spot so I just purge the whole keg and be done with it. I bought a 150cf. bottle off Craigslist and I use it exclusively to purge kegs. Once I know the keg is full of argon(I check by holding a lit log match inside) when the match goes out, I set my flow for about 5cf and weld. It doesn't use as much gas as you would think and I shut the bottle off while I am waiting for stuff to cool.
Building all that stuff is fun until one day it hits you that you have shelves full of improvised tools that you only had a need for once. Now I kind of just improvise what I need when I need it....frees up my hands to relax with a few cold ones from time to time.

[glassTransition]

Thanks. I hear you about the special tooling, but I inherited a machine shop and 70 years worth of accumulated stock. I'm trying to use it!

[exnailpounder]

Thanks. I hear you about the special tooling, but I inherited a machine shop and 70 years worth of accumulated stock. I'm trying to use it!

You're golden then. When I look at my collection of one-off projects and purge boxes that I "just had to have" I realize all the money I tied up and get kind of embarrased.....then I go open my gun safe

[noddybrian]

If you got more than Burt Gummer I'm worried !!

[Rick_H]

Thanks. I hear you about the special tooling, but I inherited a machine shop and 70 years worth of accumulated stock. I'm trying to use it!

Awesome! Id also groove it out and drill a few holes so your not starving any of the surface. Where are you located?

Like exnail, I stopped making purge boxes unless its something I can re-use. I make a lot with triclover stuff, so I have end caps I've modified, Ive also made some silicone plugs, even cork plugs, and I have some ceramic backing tape I use as well.

You can also purge with Nitrogen

[Rick_H]

I had to weld a fitting into a 10 year old glue bucket today, didn't have to be food sanitary but I purged anyway, until it fell off I fought this wonderful thing for a bit, I was welding right the at the bend where it was stretched.. so Stretched thin as paper + old = Im drinking tonight...lol Blowing through at 20amps :lol

I've got a tank repair later this week, I'll take lots of pics

[exnailpounder]

I think we should create a thread on purge dams. There are times when you have to get pretty creative to make something work. I use foil tape also, it works great. Has anyone ever made a makeshift cup to get into and area that no ceramic would fit? I did it once but never took any pics.

[Otto Nobedder]

I have a #4 cup for standard collet-body for a -20 that I ground down until it's only an 1/8" longer than the collet-body itself. That, with a button back-cap and a short tungsten stick-out, gives me an overall head length of, if I recall, 1 7/8". If I ever need anything shorter, I guess the boss is just going to have to buy a micro-torch.

Steve S

[exnailpounder]

I actually used a piece of duct tape wrapped around my cup to extend my tungsten about 3 inches as I had a little pin hole leaker and could not get to it with any conventional sized cups. Luckily it was just a short weld but the tape held up and once again, duct tape saved the day!

[glassTransition]

Here is the modified heatsink:

hs2.jpg (55.93 KiB) Viewed 1028 times

Here is the outside as welded. It got a little hotter than I wanted but I was trying to ensure I go full penetration.

tw2.jpg (49.31 KiB) Viewed 1028 times

Here are the inside on my test piece where I could see what I was doing and the inside on the actual where I couldn't:

inside sample.jpg (108.99 KiB) Viewed 1028 times

inside actual blind fused.jpg (61.76 KiB) Viewed 1028 times

Here is the outside cleaned up after I fused the inside. It sucked in a little which I didn't expect.

outside clean.jpg (44.74 KiB) Viewed 1028 times

Welding the outside was no problem.

For the inside, I machined a shoulder on the welded side of the fitting and drilled the hole a bit smaller so it sat on a ledge. This made fusing it inside really easy when I could see it because about half of the wall thickness protruded through the hole so the seam was clearly visible and I had plenty of material to work with. I would just go all the way through in the future because it would be way easier to get full penetration and not have to worry about fusing inside. I didn't drill afterward as I had planned because it was impossible to fuse the inside that way.

[exnailpounder]

WOW! Your filet weld on that coupler is fantastic. Heat control looks really good too. Your other welds look great too! You definitely got a great start. See, it's not hard it just takes practice. Nothing in welding is new. Great job! How did your purge puck work for you? I can kind of understand how welding on kegs can be a little intimidating but some guys try to make a complete science of it. Very nice work!

[glassTransition]

Thanks so much for the kind words. It took me way longer to get the confidence to weld on the actual keg than it should have, but I just have to be sure of myself before I start something like that. I can't stand the feeling of screwing something up and THEN realizing an obvious mistake. I'm very happy with the outcome.

The heatsink / purge worked perfectly. The back was shiny silver after welding. I taped around it and punched one small hole. I ran it at about 5 cfh.