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View Full Version : How to setup backpurge with one tank?



Gamble
03-18-2011, 12:18 AM
Anyone know how? I have been searching this forever and can't find much. I'm new so baby steps please. What do I need and say I use a Y or a T fitting. It comes from the tank to the regulator, then to the Y or T fitting, and 1 goes to the torch, where in the world do you connect the other?

SundownIII
03-18-2011, 12:41 AM
Have you tried the search feature. Much has been written lately about how to set up a purge using only one bottle.

Don't you think you'd be better served worrying about learning to tig weld than you are worrying about purging. From what I see in your other posts, you've going to need a lot of "hood time" with mild steel before you ever get to SS.

In other words, don't put the cart before the horse.

Gamble
03-18-2011, 01:12 AM
I have been searching and can't find anything really.

I want to experiment with back purging on ss. I have lots of scrap SS at the moment.

SundownIII
03-18-2011, 01:38 AM
Try a search on the Hobart board.

Just saw a long thread regarding purging with one flowmeter.

Just a hint. Learn one process--tig welding mild steel, before you worry about SS. Heat control on SS, especially without a remote amp control, is going to be a real bi....

DiabolicZ
03-18-2011, 03:11 AM
http://weldingweb.com/showthread.php?t=51341

WeldorWes
03-18-2011, 03:57 AM
i am with SDIII you might want to Learn puddle control on some steel as was discussed in your other post

Baila La Pinza
03-18-2011, 05:59 AM
Something like this?
64652

Gamble
03-18-2011, 06:09 AM
So one hose goes to the gun and where does the other go?

DiabolicZ
03-18-2011, 11:13 AM
So one hose goes to the gun and where does the other go?

:laugh:

Donoharm
03-18-2011, 11:15 AM
So one hose goes to the gun and where does the other go?
where the sun will never shine :)



(inside the pipe)

Matt922
03-18-2011, 11:56 AM
do you guys put any sort of valve on the end of the back purge line so you don't use any more gas than you have to?

farmall
03-18-2011, 12:05 PM
Search Function.
There are lots of posts, including one recent one that answers your questions with various examples.

Spend the time to read HEAVILY like the rest of us did.
There is a reason. This will help.
It is NOT to bust your chops. Do eeet!

Weld LOTS of carbon steel before bothering with stainless. Our students spent weeks
of 10-hr days on carbon for good reason.

Also, Google is your friend.

Baila La Pinza
03-18-2011, 12:15 PM
where the sun will never shine :)



(inside the pipe)

:laugh:


do you guys put any sort of valve on the end of the back purge line so you don't use any more gas than you have to?

No, the gas flow is controlled by the flow meter, although I suppose you could do , in order not to waste the gas that is left over in the line when the jobs finished (although unless you had a very long purge line the wastage would be minimal). Some people do however put some form of diffuser on the end of the purge line, anything from old gas lenses, stainless tube with hole drilled into it, to wrapping a bit of stainless wire wool around it.




Also, Google is your friend.

I googled this topic and have never come across so much BS in all my life. One guy was even saying that you need to purge stainless tube in order to tack it:dizzy:

SundownIII
03-18-2011, 12:30 PM
Here we have a poster who's trying to tig weld with a $200 Harbor Freight stick welder, without remote amp control or a gas solonoid.

He has yet to produce a bead on mild steel. (Lots of bird droppings)

Now he's worried about back purging stainless steel.

What's wrong with this picture?

"Where the sun don't shine" seems like excellent advice for this poster.

yorkiepap
03-18-2011, 01:39 PM
Hey Gamble,
Well, surprisingly, you haven't "flipped out" with the responses so far. Listen, the members are making honest attempts to allow you to grasp a full comprehension of learning the TIG process. Ok, now you started your initial post stating: "I'm new so baby steps please.". Being you are ready to take those "baby steps", the first step is to research the TIG process by reading all the posts here & other forums that have been posted in the hundreds, get the Miller Student Pak, & start with some regular steel.....CLEAN steel. Learn the arc, puddle control, gas type/coverage, & manipulation of the filler rod. All these procedures take time.....LOTS of time.... & PRACTICE..... BEFORE you are even ready for SS. Getting to be proficient with TIG will be up to you & the efforts you are willing to engage to use the proper techniques. It's not gonna happen overnight.....weeks.....months.....years will eventually make you perform TIG with optimum results. Just sit back & open your thoughts that you really need to do some serious homework to get to a destination of fruition. It will happen if you are willing to accept the needed "steps" to get there. Keep your skin on the "thick" side to gain knowledge & you may fare well.

Denny

Gamble
03-18-2011, 05:05 PM
I have lots and lots of welds. I went through a full 80cf tank of gas in the past 2 weeks. I bought the miller student package and the miller tig welding dvd.
I asked about SS because I have lots of it, more than mild steel

I just was curious about where the other line went for back purging for when I decide to do it. The search feature on this forum is a bunch of fail. There are no concrete answers, everything is bs.
I'll post pics of my welds in my other thread. Thanks to those that have helped.

WeldorWes
03-18-2011, 08:32 PM
I have lots and lots of welds. I went through a full 80cf tank of gas in the past 2 weeks. I bought the miller student package and the miller tig welding dvd.
I asked about SS because I have lots of it, more than mild steel

I just was curious about where the other line went for back purging for when I decide to do it. The search feature on this forum is a bunch of fail. There are no concrete answers, everything is bs.
I'll post pics of my welds in my other thread. Thanks to those that have helped.
Lots and lots of Bird Droppings don't count for lots of Properly achieved welds keep practicing on mild steel as you are being directed to do

farmall
03-18-2011, 08:43 PM
Yup. The process of training is repetitious but WORTH it and you came to the right forum.

Persist, hang in there, and post pics for evaluation!

Gamble
03-18-2011, 11:11 PM
Thanks everyone.
http://weldingweb.com/showthread.php?t=52232

Baila La Pinza
03-19-2011, 07:59 AM
Whether you're ready to tackle this kind of weld or not, I'll post an answer as it might be of help to someone else, or yourself when you get a bit more experiance.

The purge line goes into one open end of the tube, if there are a series of bends/outlets etc, then you put it into the lowest point of entry. There are many ways to secure it, some use foam discs, some use silicoln bungs, some wrap tinfoil/wire wool around the tube and some just tape it in place with aluminium or masking tape. Whatever you use, you will most likely need to tape over it, as the last thing you want is any air to be drawn in at this (or any) point. Next, tape over all joints (masking tape works best for this IMO), and weld them one at a time removing the tape only from the the one you are going to weld. The reason for this is, again, air can be drawn in from even the tightest fitted butt joints. At the highest point of exit (Argon is heavier than air) you need to make a small hole for the air to escape, about 6/8mm should do it. I don't know CFM, but normally put about 8/12LPM in for the inital purge, and then back it down to about 4LPM when I decide to start welding. Before you even start welding make sure you give the purge enough time to do its job, there is a formular to calculate this, but TBH if its only small tube (less than say 3" ), then a cigarette and coffee break will be plenty, although I normally check the purge by holding the flame of my lighter to the escape hole (not the most accurate method, I know).


I think that covers the basics, although this method refers to hygenic tube, and obviously others will have their own ways of doing things. Stainless pipe needs to be tackled slightly differently, and is a bit more involved.

Pressure_Welder
03-19-2011, 08:46 AM
Iam not sure why you are welding on exhaust tubing? thats probably some of the worst stuff to tig weld unless its not coated. With any sort of tig welding perfect fitup and CLEAN parts are required, take the time to work on your fitup skills and make sure the parts are free of mill scale and or any other surface contaminants. High pressure stainless pipe welding is definatly an art in its own, i quite enjoy it. Their are a few fairly talented guys on this site i have seen, stainless is in my opinion quite similar to welding on mild steel or alloyed steel like chromoly 2 1/4% (boiler tube). Stainless you have to watch your distortion more, and be careful not to overheat the material as you will "BURN" the chromium and get carbide precipitation. The stainless will lose its corrosion resistance in the weld zone. With certain grades of stainless and their applications you get into pre/post heat treatments, and be sure to always match the filler metal to base material.

Gamble
03-19-2011, 10:01 AM
Wow great info thank you.
How do you mean match the filler to the base metal?

weldjet
03-19-2011, 12:38 PM
victor makes a nice dual flowmeter setup that hooks to argon tank and has a flowmeter for your torch and one for your backup box. you really want dual flow so they can be adjusted independently depending on cup size you may want to flow more to torch or more to backup box if it is a larger one.

DiabolicZ
03-19-2011, 01:20 PM
Wow great info thank you.
How do you mean match the filler to the base metal?

Meaning if you are welding 304 stainless steel then you need to use 308 stainless rod. Whatever your base metal is, your filler rod should be a slightly higher grade. Stainless steel is a very picky type of material to weld on. ESPECIALLY thin tubing.

The search function on this forum is not a bunch of fail. I have been able to find anything I have searched for here so far and I am pretty new here. You need to hone your searching skills. I have seen people on this forum spoon feed answers left and right where on other forums (car forums) they would simply ban you for being lazy or incompetent.

Taking a full two weeks to only go through 80cf of argon is not steady practice. There are times I go through 80cf of argon in two days. Im sure there are others on here that go through that much in just a day.