weiRtech

First you will need some hose, here is mine all assembled:



This is the input end, you can do it differently than I have, but these were the fittings that i had available and they seem to work well. You NEED a ball valve (for turning your back purge on and off) and the other valve is a needle valve to adjust the amount of flow coming out of the hose. I just adjust it by listening to it.



Here is a T you will need to add to your bottle regulator. Again, I used these particular fittings because that was what was available at the time. I wanted to make mine removable as well so I added a high end quick disconnect that is designed to prevent any types of leak.



Here is the hose connected:



Next, gap your pipe slightly so that you have room to add filler when welding your joint. Some people like to take a piece of filler and bend it into a "V" and stick it inbetween the two pipes for setting a nice even gap and then pulling it out after tacking. For this example i used 1.75" .083" wall 304ss piping. Tack it together so it will not move on you once you start welding.



Once you have it tacked together cap both ends with some cap plugs. These fit like a glove and are much nicer and cleaner to use than tape. They also withstand a bit of heat as long as you don't get to close with your torch. Add a hole into one of the cap plugs that the tube/hose will fit snug into so as to prevent argon from leaking back out the hole you made.



When you get close to the end of welding your joint you will need to slip the end plug slightly off the pipe to let the argon escape or it will try to exit through your joint and that makes for difficult welding.



I just did a single pass on this at 70 amps but with thicker base metal you can do multiple passes with purging only being nescassary on the first pass as long as you don't blow through it. The inside should look something similar to the pic below. Once you get really good, the inside should look just as good as the outside... I'm not there yet.

Jonathan_ED3

Cool!!

Bakeoff

it's really cool to see a write up like this on things that I think a lot of people hear about, but haven't done. Gives people with no tig experience a good idea of what they can get into and a few tricks to make the learning process faster.

eddie_ek

meotch

good writeup man

dfoxengr

you should also turn up your flow rate alittle when tee'ing of the main tank, varying the amount by roughly how open the needle valve is.

vestalfootball72

what does backpurging do?

dfoxengr

shields the back side of the weld from oxygen

Agtronic

The end cap should be vented all the time, not just at the end. The way it is now, your argon will leave the pipe from the gap, and won't make its way past the gap. This might be why there seems to be some minor contamination on the underside.

Ideally, you should not see any color at all on the inside.

I have to say though, thanks for posting this, it's great to see how much you guys help each other out on this forum!

vestalfootball72

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfoxengr &raquo;</TD></TR><TR><TD CLASS="quote">shields the back side of the weld from oxygen</TD></TR></TABLE>

What is the benefit to the backside of the weld being shielded? sorry if I sound like a complete fool lol. I just started attempting some tig stuff a few weeks ago after takign a oxyacet. class at college

B18C1CYA

how come you are gapping the joints ??? if you are having a hard time getting all the way through the material , you can just bevel them more and your gas will not escape the pipe ???

dfoxengr

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vestalfootball72 &raquo;</TD></TR><TR><TD CLASS="quote">What is the benefit to the backside of the weld being shielded? sorry if I sound like a complete fool lol. I just started attempting some tig stuff a few weeks ago after takign a oxyacet. class at college</TD></TR></TABLE>

cause people are concerned with "flow" characteristics, it looks better, which means its "better"

its a good idea for manifolds etc i believe though if you have the setup.

FastCougar

No, you backpurge purely for weld strength ... a weld of this type is exposed on both sides. You could have what looks like a great clean weld on the surface, but it's contaminated on the "backside". Backpurging ensures a more "pure" weld and will thus hold up longer/better to a non-backpurged weld.

ManBearPig4silly

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Agtronic &raquo;</TD></TR><TR><TD CLASS="quote">The end cap should be vented all the time, not just at the end. The way it is now, your argon will leave the pipe from the gap, and won't make its way past the gap. This might be why there seems to be some minor contamination on the underside.

Ideally, you should not see any color at all on the inside.

I have to say though, thanks for posting this, it's great to see how much you guys help each other out on this forum! </TD></TR></TABLE>


Yeppers.

Punch a hole a about a 1/4 in in diameter in one of the plugs. If you are going to gap the pipe then you need to use purge tape to cover the joint in the areas that you aren't welding. If you dont the argon will fall out the joint on the bottom side causing shitty gas coverage. You arent experiancing this as much with your current setup as you aren't venting out the end like you should. I'm too cheap for that special tape so I bent a few peices of filler rod into a circle with about a third of the complete circle chopped out. I then used those 2/3 circles to pinch a folded piece of tinfoil against the pipe in the areas where wasn't welding. It leaves a 1/3 of the joint exposed so you can weld a 1/4 of the way, slide the tinfoil around the pipe to expose your next 1/4 and weld away. Worked like a charm and it's so cheap it's as good as free.

Also the welds are hot as *****. You WILL have better success if you give the pieces a chamfer, gap it with .035 mig wire, bump your gas flow to about 30 with a lenses and speed up your rate of travel.

dfoxengr

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FastCougar &raquo;</TD></TR><TR><TD CLASS="quote">No, you backpurge purely for weld strength ... a weld of this type is exposed on both sides. You could have what looks like a great clean weld on the surface, but it's contaminated on the "backside". Backpurging ensures a more "pure" weld and will thus hold up longer/better to a non-backpurged weld.</TD></TR></TABLE>

right thats what i was getting at with the better comment. however many people are concerned with looks and what little roughness factor you lose by doing this.

SMSP

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vestalfootball72 &raquo;</TD></TR><TR><TD CLASS="quote">what does backpurging do?</TD></TR></TABLE>

Check about mid way down this page http://sms-products.com/Construction.html

Here's my post on this subject https://honda-tech.com/zerothread?id=588002

Also, it's a lot easier to have a dedicated Ar bottle just for purging. That's how I do it and then I just run 1/4" teflon tubing from the regulator with a 1/4 turn ball valve for flow control. Simple and sweet.

InfamousDC2FI

wow thanks! Great info! Where do you get the plugs at?

cua0

looks good, except for those of us without deep pockets a flow-meter is much better than a standard regulator for keeping track of and setting your shielding gas flow.

RCautoworks

Where did you pick the ball fitting up and that t ?

Race Egr

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RCautoworks &raquo;</TD></TR><TR><TD CLASS="quote">Where did you pick the ball fitting up and that t ? </TD></TR></TABLE>

maybe lowes or home depot

F20Cteg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Agtronic &raquo;</TD></TR><TR><TD CLASS="quote">The end cap should be vented all the time, not just at the end. The way it is now, your argon will leave the pipe from the gap, and won't make its way past the gap. This might be why there seems to be some minor contamination on the underside.</TD></TR></TABLE>

Read more carefully next time.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by weiRtech &raquo;</TD></TR><TR><TD CLASS="quote">
When you get close to the end of welding your joint you will need to slip the end plug slightly off the pipe to let the argon escape or it will try to exit through your joint and that makes for difficult welding.


</TD></TR></TABLE>

tony1

Why would you have to slip the cap off the end of the pipe if the cap had a small hole in it like it should. You want argon flow through the tube, not to pressurize the tube with argon. He had to slip the cap off because it wasn't vented properly.

standbackimapro

Whats the point of Back purging?

tony1

In short, it increases the strength of the weld.

Agtronic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by F20Cteg &raquo;</TD></TR><TR><TD CLASS="quote">Read more carefully next time.</TD></TR></TABLE>

You didn't read what I wrote. Scroll up and read again. You have to vent the end cap ALL THE TIME, not only when you get to the end of your weld. The argon cannot fill the pipe if it is not vented.