Aluminum external corners

[Wozzaaah]

Thread tidied!
Keep it civil and on topic please.

 

[Richard.]

Yep. I agree buddy pre heat on thick Alu section helps a lot to make your current more useful if the part is heat soaked. He mix is also a good way of utilising the current available as like a preheat it makes your 150 amps go much further. I'd be preheating 6mm Alu if limited on current no question. Regards X Ray I know little about it which is why I didn't comment. I know what it's purpose is for but regarding X-ray quality standards it's not my expertise. Rrunnarch I don't doubt for a second you know your stuff and same for wmj. We all have our backgrounds and are prepared to be corrected or I am at least. I knew what you meant by no ep! You meant fixed ep so there was no need to jump on that as I knew exactly what you meant. All posts related to the topic I think have been spot. The bitch slapping was not so much but hey it wasn't aimed at me so I've no reason to worry about it.

 

[Rrunnach]

Well I was gonna make a point that you don't "need" to remove the oxide layer on the back side as it's not going to offer any advantage. But then wmj did say he'd read it helps with X-ray Quality and I can't argue with that . I don't think it makes any odds if It's removed on either side if the Alu is clean. The EP doesn't need to remove it on the back side because it doesn't remove it on the front either. It temporarily pushes it to the sides before the Alu itself regenerates a new one an hour after. The other side the root pushes through the Alu easy but tends to stay blanketed behind the oxide layer so granted it's not as attractive as the front side.
From a joint strength PoV I don't think it makes a difference but regard to what is gonna be picked up on X-ray and failed then yes I can quite believe it needs to be removed. Same with the etched zone on the front side id imagine.

It's now turned into a slagging match. X-ray and dye pen are not comparable I but I do agree with Runnarch's first comment it's not needed, it's Welded often with the backsides left as they are. I agree with wmj also for X-ray standard of welding it may well be the standard required.

A wee sneaky argon trap would take care of root side, when welding from face side.

 

[Richard.]

A wee sneaky argon trap would take care of root side, when welding from face side.

A backside purge on Alu. I have not done that before. What does it do to the root side?

 

[Rrunnach]

Keeps root side clean and, free from oxides. G'nite, Richard.

 

[mark williams]

Any of you guys coded in ally?

 

[wheresmejumper]

In plate,not pipe

 

[mark williams]

Aluminium oxide cause you any problems getting your cross sections passed? Porosity from the oxide containing hydrogen?

 

[wheresmejumper]

I havent welded it in 2 years!

 

[Richard.]

Aluminium oxide cause you any problems getting your cross sections passed? Porosity from the oxide containing hydrogen?

Hydrogen is a common cause of contamination in Alu. If stored very cold it sucks in moisture like a sponge and can be a big problem.

 

[backpurge]

Any of you guys coded in ally?

A few years back, 6G pipe TIG and 3G plate MIG

 

[Rrunnach]

Aluminium oxide cause you any problems getting your cross sections passed? Porosity from the oxide containing hydrogen?

Are you welding plate or pipe? More info required.

 

[Rrunnach]

Keeps root side clean and, free from oxides. G'nite, Richard.

I meant to come back to this, as it was a late and vague post.

Not only does argon trap keep root side clean, it also ensures good root fusion of rear edges of plate. Simple traps can be manu'd, for example. Piece of 50/50/3mm angle, grind to a decent depth the shoulder of angle \_/ then lay tacked up al/al along angle for welding, tacked with at least 3mm gap, which allows gas to travel through and purge the inner corner/root side of job.

One downside, more pre heat, as the angle trap will soak up a fair bit heat, once up to temp, there will be no problem completing a weld of good integrity. It is similar to using ceramic purge tiles.