A member on another forum recently suggested 35CFH was the "ideal" flow for a beginner weldor, since every weldor (15) in the shop in which he worked was using that pressure, at all times. I suggested that this was a waste of gas for the hobbyist, and that, there was no "ideal", and that gas flow should be set according to conditions, the type of joint, type of gas and size of filler, amperage, weld type, etc,
Also, I mentioned that flow can be can be "ideally" set, economically, by going to the lowest flow possible before encountering porosity, and increasing until porosity disappears, and, if production speed, or other factors made this impractical, 20CFH would cover most situations, where you are paying for the gas. All of this, of course, is based on the assumption that both the employer and the hobbyist would want to work as economically as possible ( although, this is obviously not the case for the previously quoted member's employer, and I realize many employers would simply charge more for the wasted gas, rather than "waste" production time in adjustment).
Is there anything any of you would correct or add to this?
A "hobbyist" is not gong to take into consideration conditions such as joint type, type of gas, size of filler, amperage or travel speed. So 35 CFH covers most all bases.
A hobbyist is not going to be spending great amounts of arc time, so being economical with shield gas is not a pressing issue. So again, they are not going to be making calculations that result in gas flow economy... 35 is a fine rule of thumb. You are an expert North, and think of these conditions and can wisely conserve due to your ability to judge what is necessary, and a hobbyist will never do that.
A "beginning welder" is going to have many changes in both gun angle and CTWD (stick-out) so being stingy on shield gas flow is just opening the door for trouble... 35 CFH would be my minimum recommendation for a beginning welder.
I have seen very few production GMAW WPS's for short circuit or spray transfer GMAW that called out less than 35 CFH... So if I were working with 15 welders *beginners* I would again run at least 35 CFH gas flow and then evaluate the welds. Excessive silicon deposits, grey puckering, smoky weld toes are all signs of insufficient gas flow that I would be looking for on the shop floor with these 15 welders.
If I'm responsible for a weld shop (and I am, for several) I don't want my WPS's to be running on the ragged edge of porosity and failure due to poor gas coverage, caused by a technique issue combined with economizing on shield gas... I want a robust procedure that will work for variations within WPS limits on gun angle, travel speed, fit-up, fans, exhaust, sneezes and coughs and anything else that can spoil a weld.
The cost of a single backcharge for back-gouge and reweld in the field or an erection site is typically more than the monthly savings of reducing shield gas in 15 workstations by 10 CFH.
Sorry to be oppositional... But I just don't see any value in this type of economizing outside of my own garage where *I'm* the expert and have complete control
Need a 'Recommend' button. Good post Lawrence.
Good question Ron but I do agree with Lawrence. Granted, if the welders are running over 45 or 50 we have a whole different discussion. But, trying to save/economize shielding gas to get below 35 for a production shop is not as good of an idea as it sounds on the surface. Under certain jobs you could probably get away with using 30 cfm as your base rate. But I sure would not try to get much lower and expect consistency.
A little breeze and there goes your shielding (sure, GMAW doesn't like much of a breeze anyway, but lower the flow and you are asking to multiply your troubles).
He Is In Control, Have a Great Day, Brent
Opposition is just what I was looking for, since I always like to know when I am wrong! Thanks to you and Brent for taking the time to answer.
I'm happy the debate is helpful...
Just to bring the point home :)
I would not call it opposition. A variety of opinions and personal procedures.
It is a good idea, just hard to implement into a practice that would be helpful in many cases.
And you know as well as I do, the average welder is going to run everything including the gas just as high as he can get away with. They don't care about the economics and savings that could be allowing the owner to give them a raise. To them its about making sure the owner doesn't have too much profit. The two don't go together for them.
Really, good question.
Brent
By Lawrence 
Date 05-04-2017 13:10
Edited 05-04-2017 13:18
Once upon a time, a long time ago and in a galaxy far far away.
A salesmen came into a weld factory and said "Buy this gas reducer and you can save save save"
The salesman showed impressive charts and graphs and even hooked his very costly digital electrically powered unit up to a welding machine and made a weld that looked wonderful. He said, I will take the 45 CFH you are currently using and reduce it to 12 CFH on every machine in your shop... You will impress the bean counters with your "out of the box" thinking and progressive attitude. No mention was made that a WPS was in place, and that operations should stay within the scope of the procedures.
So a large purchase was made, and digital flow controllers were placed on every welding machine, based on theoretical savings that were computed to pay for the equipment over several years.
The results were ... Well....
