Welding questions

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What I can see in the photo's I would say they did back flow the welds. Its not like rough sand or sugar. Its not the best weld in the book and the holes where drilled too large for the couplers. But if the don't leak use them. The will not cause any problems. I have welded a lot of couplers and the one I forgot to turn on the back flow gas was one of mine. It looks like heck but I used a pacification acid on it and been using it for many many years.


My 1 cent.

Dominus Vobiscum

Swagman:cool:
 
Just finished Tig welding a 1 inch half coupler for a local brewer thought you might like to see the back of a back flow weld.

Mvc-761s.jpg



Passed sea trail in other words didn't leak lol


Dominus Vobiscum

Swagman:cool:
 
Swagman... You said earlier that you make a foil tent and tape it to the inside of a keg to back gas. What kind of foil and what kind of tape?

I went back to the shop that welded the two couplings for me and showed him the pictures I posted here. I also showed him the pictures that GreenMonti posted. First, I learned that the guy I talked to was the owner but NOT a welder!! So the stuff I talked to him about back gassing probably never made it to the welder. But when I showed him the pictures and explained what I was looking for, he said he would talk to the welder and see what he had to say. He called me back in about 30 minutes and said the welder would like to try again. But he said the problem is keeping the gas on the backside... I told him about a foil tent taped to the backside but I'm not 100% sure he understood. I was thinking about a coffee can or soup can and was thinking about trying to fabricate something for the welder to see/use as an example.

The owner is a real nice guy. The conversation could have been tough had he been defensive about the work but he wasn't. I was actually a bit surprised when he called back. He seemed to be genuinely interested in getting it right.

Ed
 
Not to hijack but since this is a thread on welding questions. How bad an idea would it be to MIG weld a coupler in with triple gas for shielding?
 
Ed, IMO your not to far off with the can idea. This is what I made to do the back gassing.

The tube goes all the way in and theend is welded shut. I then cut slots in the tube to make the gas go tward the back of the purge bolck. It is then lightly stuffed with sttel wool for a difuser and make the gas come out even. I then welded on the SS mesh that you see, I don't know the name of it right now. I will probly have to ask at work to jar my memory. I put it right behind the coupler and wedge it in place with a wooden stick. I use a brass reducing bushing to go from 1/2" to 3/8", then I screw in a 3/8" to 1/4" hose barb fitting. This gives me some length to the coupler and reduces the size of the hole. Adjust the purge accordingly and weld. Hope this helps.

P1010124.jpg



Azrac,
This is going to depend on your skill level.
 
ill quit belly aching then and move on to finishing the prep work for use. I just wanted to get a some professional eyes on them. Hopefully after running a tap through I should be good to go.
 
GreenMonti said:
Ed,

Do you have any progress to report?
Click to expand...

A bit... In a message on the 12th, I mentioned that I had talked to the welding shop owner and he was interested in trying again.
Meanwhile I cleaned up the two welds they did with a carbide bur so I think I can live with them.
I took a coffee can, a big spring and a piece of 2x4 and fashioned what I think they may be able to use to back gas.
I dropped off the same keg at the shop to give them one more chance to weld an additional coupling. The owner is a real nice guy and I think he is genuinely interested in getting this right. I'll find out in a day or two.

Thanks for following up...

Ed
 
Yea, I remembered you said he wanted another try.

You made a purge? Sweet. Do you have a pic?

I was looking at your pictures again, I think with the back gas and if the welder slows down a bit you should be happy. At least I hope that is how it goes for you.
 
Swagman said:
Just finished Tig welding a 1 inch half coupler for a local brewer thought you might like to see the back of a back flow weld.

Mvc-761s.jpg



Passed sea trail in other words didn't leak lol


Dominus Vobiscum

Swagman:cool:
Click to expand...

Swagman,

Not to bad. Do you have a pic of the front side?:D
 
GreenMonti said:
Yea, I remembered you said he wanted another try.

You made a purge? Sweet. Do you have a pic?

I was looking at your pictures again, I think with the back gas and if the welder slows down a bit you should be happy. At least I hope that is how it goes for you.
Click to expand...

Well... I don't know what a purge is (other than the pic you posted) and don't know how to apply one. I don't have a picture but here's what I did... I put a 1lb coffee can against one side of the keg and then a spring about 3" long behind it and cut a 2x4 to fit tight between the spring and the other side of the keg. I didn't know how to "seal" the can against the keg, so I took a roll of aluminum foil for him to sorta roll into a gasket. I had no idea what kind of connector he may need for a gas line, so I left it for him to put a hole in the can as needed.

Ed
 
Ohio-Ed said:
Well... I don't know what a purge is (other than the pic you posted) and don't know how to apply one. I don't have a picture but here's what I did... I put a 1lb coffee can against one side of the keg and then a spring about 3" long behind it and cut a 2x4 to fit tight between the spring and the other side of the keg. I didn't know how to "seal" the can against the keg, so I took a roll of aluminum foil for him to sorta roll into a gasket. I had no idea what kind of connector he may need for a gas line, so I left it for him to put a hole in the can as needed.

Ed
Click to expand...


Sounds to me like you made a purge. It is nothing more then a device to provide backing gas. Some are just more fancy then others.

The spring would not be needed since the can isn't pressing up aganst a part that is being welded. If it were, the spring would be a great idea to compensate for the shrinkage of the weld. In this case any and all shrinking/movement is happening inside the can.

With a 1lb can, what would you say the diameter was? 5-6"? If so, then all that is needed is some tape to seal off the can. Just prop it in place and then tape the two together to create a seal. Same thing can be done with the hose for the gas. Just drill a hole in the can and tape it in place. Tapping the hose along the inside would be a good idea to releave the strain while moving the keg about.

Hope this helps.
 
GreenMonti said:
Sounds to me like you made a purge. It is nothing more then a device to provide backing gas. Some are just more fancy then others.

The spring would not be needed since the can isn't pressing up aganst a part that is being welded. If it were, the spring would be a great idea to compensate for the shrinkage of the weld. In this case any and all shrinking/movement is happening inside the can.

With a 1lb can, what would you say the diameter was? 5-6"? If so, then all that is needed is some tape to seal off the can. Just prop it in place and then tape the two together to create a seal. Same thing can be done with the hose for the gas. Just drill a hole in the can and tape it in place. Tapping the hose along the inside would be a good idea to releave the strain while moving the keg about.

Hope this helps.
Click to expand...

I appreciate any input...

The can is probably about 4-5" in diameter... I was looking for something kind of small but big enough to cover a 2" coupling.

The spring is just meant to make it a little easier to keep the can pressed to the side of the keg without having a wedge cut to exact length. It appears the diameter of the keg is a little larger in the center than the top or bottom.

I thought about taping the can in place or using tape to seal but wasn't sure about the temperature.

I also left them with a 1/2" x 4" long brass nipple and a 1/2 barbed fitting. I mentioned they might be able to thread the nipple into the coupling to be welded and gas through the coupling and into the "purge" can from the outside.

Ed
 
How I back flow for kegs foil and foil tape.

Mvc-757s.jpg


Make a small packet in the foil


When it comes to holes keep it simple one hole saw.

Coupler turned down on lathe to 1 inch plus for a tight fit

Mvc-752s.jpg



Mvc-753s.jpg



MVC-854S-1.jpg



Tight fit no gaps

Been doing this for several years with no problems


Dominus Vobiscum

Swagman:cool:
 
That's nice Swagman.

I need a metal lathe here at the house. My wood lathe just doesn't do enough.

How much meat do you have left in the coupler? In the area where the threads are the deepest. Just a guess.

Do you chase the threads when your done welding? If so, have you seen much distortion with the thinner walls?
 
Swagman said:
How I back flow for kegs foil and foil tape.
Make a small packet in the foil


When it comes to holes keep it simple one hole saw.

Coupler turned down on lathe to 1 inch plus for a tight fit

Tight fit no gaps

Been doing this for several years with no problems


Dominus Vobiscum

Swagman:cool:
Click to expand...

As they say... a picture is worth a thousand words.
So a question... when back gassing, does the gas flow continuously? Does the foil "tent" become a balloon? Is there a means for the gas to vent without popping the balloon? How much pressure is there in the gas?

I guess my concerns are this...
I don't know if the welder has a tee and regulator in his gas line that will even allow him to back gas and control the gas output. (is this something that should be standard?) And will my "tin can" and aluminum foil gasket method waste too much gas?

Ed
 
GreenMonti said:
That's nice Swagman.

I need a metal lathe here at the house. My wood lathe just doesn't do enough.

How much meat do you have left in the coupler? In the area where the threads are the deepest. Just a guess.

Do you chase the threads when your done welding? If so, have you seen much distortion with the thinner walls?
Click to expand...

The 1/2 full China coupler run anywhere from .135 to .030 over one inch. No distortion what so ever. There is plenty of meat left after turning. The turn down part is inside the keg and the bead is applied to the regular coupler.

I have an extra tank of argon for back flow with a flow meter. The foil does not make like a balloon the flow is low but steady. I just put in a plug on the outside just in a thread or two. Don't thread it in too far or the heat will cause them to jump thread and than you have a mess on your hands of drilling out the plug and a lot hand saw to get it out. The loose fitting plug allows the gas to escape. If you don't want to use a plug a piece of the foil tape over the coupler will also work.

Been doing this work for several years like to help where I can I charge 12.00 a coupler and I furnish the coupler and drill the holes. I'm by no means a stack of dimes every time tig welder. I taught myself but my welds don't leak or break. Being retired and having the tools it keeps me out of the boss's hair out in the shed.

Suggestion: Do you have a dairy close. Ask them where they get the tig welding done it has to be sanitary welds.

Have a speed shop ask them if they know of any tig welders.

Have micro brewery ask them where they get welding done it also has to be sanitary.

Here in the KC area I know of five shops some good some so so some high priced and the others making a living.

Just remember its JUST BEER.

This is more than I ever typed on the subject I'm done.

Stop by anytime some thing is on tap and the shed is warm this time of year.

God Bless you all

Have a MERRY CHRISTMAS

Dominus Vobiscum

Swagman:cool:
 
Swagman - Thanks for taking the time to respond. I know what you mean, I have read more, typed more, thought more, and learned more about welding than I ever would have dreamed. If it's any consolation, your input has been a big help!

Ed
 
Hey Ed,

Here is mine in action. I also use a couple of brass piecse for the purge exit.
P1010130.jpg

P1010131.jpg
 
GreenMonti said:
Hey Ed,

Here is mine in action. I also use a couple of brass piecse for the purge exit.
Click to expand...

GreenMonti - Thanks, now that I see it, I think I get it. So there is really not a seal between the purge and the keg... And we are not looking for pressure inside the purge. I think I gave the welder everything he should need. Although the "coffee can purge" is much larger, I'm thinking it should do the job. Now I'm just hoping he has a separate gas line with flow meter/regulator so he can keep gas on the backside of the weld. Hopefully, I'll find out later today or tomorrow.

Dog House Brew - I think the idea is to have gas on the backside, but not have the "purge" pressurized. I'm sure GreenMonti, will correct me if I'm wrong :) .

Ed
 
You definitely would not want to create pressure with the purge. As you would finish the weld, you cut off the means for the gas to escape. As the molten metal would approach the start of the weld, the pressure from the purge gas would blow up through the puddle. You wouldn't be able to close it.

Your purge gas is going to be heavier than ambient atmosphere, so you need just enough positive pressure to displace the ambient and not create a pressure vessel. Think of water filling up a cup. As the heavier water collects in the cup, it displaces the air. You need to think of gas as a fluid, just like water. Use gravity or the shape of your weld joint to your advantage.

Since Green Monti uses a flared joint (which is freakin ingenious over a butt joint :ban:) the gas is filling the cavity created by the flare, displacing the ambient atmosphere and creating the favored environment.
 
Ohio-Ed said:
GreenMonti - Thanks, now that I see it, I think I get it. So there is really not a seal between the purge and the keg... And we are not looking for pressure inside the purge. I think I gave the welder everything he should need. Although the "coffee can purge" is much larger, I'm thinking it should do the job. Now I'm just hoping he has a separate gas line with flow meter/regulator so he can keep gas on the backside of the weld. Hopefully, I'll find out later today or tomorrow.

Dog House Brew - I think the idea is to have gas on the backside, but not have the "purge" pressurized. I'm sure GreenMonti, will correct me if I'm wrong :) .

Ed
Click to expand...


I don't tape mine up since it is such a small diameter. If the diameter was larger then I would cause of the curve of the keg.

I like to have an exit. Plugs will work if you are carefull. I always thought my hand going around might catch it and tighten it or loosen it.

No, as mentioned. No pressure. There must be a vent, other wise how would you exchange the air for the gas? If under pressure when the puddle pushes out it could do so violently. Molten metal is not what you want raining down on you. The other reason is, (should you get away with it) it will cause the back side of the weld to be concaved. You wont get drop through. Not a big deal in this case but, in a sanitay or a purged weld it is.
 
mordantly said:
intriguing wording here.
Click to expand...

Sorry for the confusion its an old term. In carpentry its a measurement and the use of the word proud, meaning a bit more than the actual measurement.
The amount's varies, could mean to leave the line.

On a lathe the word plus varies, larger than the measurement shown. Like 1.003 the .003 = plus




Swagman:cool:
 
mordantly said:
then how do you maintain accuracy?
Click to expand...


Just how much accuracy do you want on a welded item? Depending on what your welding, the start and stop of said weld will shrink up to if not more than .015".

Not to speak for Swag, but....An increase of .003" is not much to worry about. A tight fit is far better then a coupler that flops around. When cutting the hole in the keg, there is some variance I am sure using a hole saw. Three thou is probly enough to cover it. Heck, three thou could come from deburring the hole. If one wanted to be anal, a ream would be needed to get the hole just right. If you wanted to be super anal, the ambient temp of the room would make a difference along with the temp of the part being worked on.


Not sure what kind of work you do but. Someone calling out for a heavy 25 and 3/16" measurement isn't un common. When reading a tape, you have to have some sort or "lingo" for the space inbetween the graduations. So if someone called out for a heavy ???? you would leave the line or cut it inbetween the graduations giving the person the extra 1/32".
 
GreenMonti said:
Just how much accuracy do you want on a welded item? Depending on what your welding, the start and stop of said weld will shrink up to if not more than .015".

Not to speak for Swag, but....An increase of .003" is not much to worry about. A tight fit is far better then a coupler that flops around. When cutting the hole in the keg, there is some variance I am sure using a hole saw. Three thou is probly enough to cover it. Heck, three thou could come from deburring the hole. If one wanted to be anal, a ream would be needed to get the hole just right. If you wanted to be super anal, the ambient temp of the room would make a difference along with the temp of the part being worked on.


Not sure what kind of work you do but. Someone calling out for a heavy 25 and 3/16" measurement isn't un common. When reading a tape, you have to have some sort or "lingo" for the space inbetween the graduations. So if someone called out for a heavy ???? you would leave the line or cut it inbetween the graduations giving the person the extra 1/32".
Click to expand...


Will Said all I can add is AMEN

Everybody have a MERRY CHRISTMAS

and A HAPPY BREWING YEAR


From the Shed at WACK God Bless


Dominus Vobiscum

Swagman:tank:
 
GreenMonti said:
Not sure what kind of work you do but. Someone calling out for a heavy 25 and 3/16" measurement isn't un common. When reading a tape, you have to have some sort or "lingo" for the space inbetween the graduations. So if someone called out for a heavy ???? you would leave the line or cut it inbetween the graduations giving the person the extra 1/32".
Click to expand...


i can't help it... in my manufacturing dimensions are routinely called in tenths. say 2.500 +0 -.0002 for a 416 ss sleave pressed into this 6061-t651 billet impeller.
 
So now I have a delima... The welder called and my keg is ready to be picked up. There is a once a month beer tasting very near my office right after work tonight. Do I go get the keg that I have been fretting over, or do I go to the beer tasting?

There's beer to be drank and the keg will be there tomorrow... easy decision, thanks for all your help with this one. :D

Ed
 
For anybody that's still following or interested; Today I picked up my keg from from the same welder that put the first two couplings in. I had him add one more coupling based on my conversation with him that he'd like another shot. I provided him with the "purge" pictured in the previous post, a brass npt plug for the coupling, and explained to the best of my ability what I thought he needed to do. When I picked up the keg, he explained that he did not have a separate hose & regulator to use for the purge, so he flowed gas into the purge through the coupling and then inserted the plug. He said he did this 3 times during the weld.

Here is the outside of coupling #3:
Coupling3-Outside-A.jpg


Here is the inside of coupling #3:
Coupling3-Inside-A.jpg


And another shot of the inside of #3:
Coupling3-Inside-B.jpg


He recognized that he needed to have constant gas flow and said he would get a hose and regulator for the next ones. I don't think these are to Swagman, or GreenMonti standards but I think I can live with this result.

So, what do you think... would you have him do the other two kegs I have?

Thanks,
Ed
 
Now that looks a lot better.

Your purge is great. Only thing missing that I can see is the hole for the gas line.
 

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