Hey Lawrence,
ahhh, as I guessed!
I really supposed that you may have experience with High Purity GTAW applications, as I really supposed that in particular Tommy (Aircraft Welding) and Henry (Master of Titanium-Welding), to name only two of many more appreciated colleagues, might have as well!
As for Tommy I was likewise right... :-)
Waiting now for Henry :-) and - hopefully - some more information from the post's initiator.
You know, I have a slightly different idea, since I can recall to have experienced somewhat in the past which has happened in a large German shipbuilding project.
The shielding gas Argon 4.6 (99.996%) has been delivered by - at that time the company has existed, but was meanwhile purchased by a large US-American Gas supplier - a highly esteemed German gas supplier.
I can remember the responsible gas supplier's welding engineer has called me on the phone to discuss the problem - which was porosity - or better the problem's solution, respectively.
Their client has assumed the shielding gas purity in regard to moisture was insufficient and had yield to even the porosity. As you can imagine, the gas supplier has disagreed with the customer and has searched for "multiple" support among experts on his argumentation at that time.
So far as I can say, it was not the gas purity, since as well as they have used Argon 5.0 (99.999%) they could not resolve the problem, what was the reason for my entire agreement with Miltons predications.
The final result whereas was an entirely different one, and this was extremely interesting and most impressive!
Finally and at the end of the day they used different gas hose materials which were more resistant against mositure or hydrogen diffusion(!!). The hoses, used within the hose packages and within the machine were exchanged by different ones. Please forgive me that I can't recall what kind of specific material it was at that time, but...
subsequent to these experiences there has been inquired a research project in Germany which was monetarily supported by a particular consortium of industrial companies.
Even this investigation has recently been carried out over a period of 2 years and the topic "gas hoses" to be used in GTAW has been investigated e x t e n s i v e l y. The results are concluded in a final report having a size of 204 pages(!). A tremendous number of measurements and calculations have been accomplished and - I must repeat - the results are very impressive.
This should - of course - not mean, that a purifying device used to dehydrate the shielding gas would not be the better solution. But as I have read what aerowelder has wrote, I was reminded immediately on these experiences. And additionally, I personally have - by now and quite comparable with what Tommy wrote (Never heard of a purifying device used in process before .....interesting.) - not seen any industrial application where a purifying device was used.
This is, why it was - once again - so interesting to having read what your extraordinary personal experience has shown here!
Thanks and best regards,
Stephan
P.S. Great link by Marty Sims...