Dirty fuel gas -what to do? (sticky?)
 

I thought I would post this because of a long-standing problem with dirty gas from fuel-gas suppliers that does not seem to be going away.

Dirty fuel gas on aluminum is very evident, but is also seen on steel. Hydrogen does not seem to suffer from dirt as much as acetylene, although propane, propylene, chemolene, and etc also suffer from dirt, contamination, impurities.

If your aluminum gas weld is rough, bumpy or wrinkly, this can be caused by contaminated fuel gas. Just like water and dirt can be found in gasoline, so also are contaminants found in fuel gases. For many decades the gas has been delivered in a very clean state, but this seems to be changing.

One solution is to ask for a "re-purified" bottle of gas, if available. And this is about double the price.

The second solution is to add a filter, like this ($135. or so):
http://www.perkinelmer.com/catalog/product/id/n9301399
Available for atomic absorption processes, the filter element is easily replaceable, and the flow rate is very adequate for welding.

Looks like this next to a gasaver:
Attachment 34792

The fuel gas comes out clean and your welds show the improvement in quality.

I had some weld samples around here for the last class series .... have to dig them up and photo them to show dirty aluminum welds vs clean.

Hope this helps,

Thanks for the info, Kent. Up front, the filter seems far more economical than the re-purified gasses. It also puts you more directly in control over quality, which, sadly, is a pervasive manufacturing theme these days.

Have you had it long enough to comment on filter maintenance costs?

Filter elements are fairly cheap, Wil. With estimated gas volume, probably can run 4-6 122cf bottles before thinking about a new $20 filter element.

Dirty gas = rasty welds
 

I Found my weld samples. A friend had come out from NE a while back and we had a fun day in the shop together, solving various probs.

He was complaining about his aluminum gas welding so I set him up and gave him a nudge and downhill he went. I went over to him and remarked that it sure looked rough, and he replied that it was just like back home. hmmm....

Attachment 34797

I then flipped his weld and pointed out the root side for his inspection:

Attachment 34798

(he is a failure-analysis engr for railroads, so he puts the breadcrumbs together very tidily.) ;)

So he says, "YOU have dirty gas, too!"
Yup, so I drags out another bottle, and he welds away, again.

Attachment 34799

When he got home his supplier replaced his bottle -
with another bottle just like the first one.

sigh,

So he got the inline filter and now reports, "clean welds!"
yeehaw