I just have to throw in my 2 cents worth, I worked for many
years for Bath Iron works as a 1st class pipe fitter on the FFG CG
and DDG program and I believe that its more the person than the machine, with
the onset of MIG machines almost anyone can run a bead and make it look good
but fail a fracture test but you take an old experienced 1st class
man with a stinger and box of wire and it will be both nice looking and 100 %
and I have seen some very nice jobs done with automated MIG machines.
And one other thing to remember all the x ray joints and consumable
ring joints on pressure systems are done with TIG, I might add we just bought a
miller M350 MIG but it is for the aluminum on PRV2 and you need to be a
computer programmer to run it
Just bored in Haiti and thought I would read my mail but its in
the 80s and sunny water temp 89
Brian V. Ryder
brian@subatlantic.com
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From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Daniel Lance
Sent: Tuesday, March 02, 2010 6:47 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] MIG vs Arc
I
strongly disagree with Mr. Granato . It has been my experience on
numerous occaisions to see weld test coupons done with MIG break . On one
project alone I saw fifty welders have at least one out of four coupons fail (
as in snap in half ). Like I mentioned in a previous email my experiences are
supported in the professional literature. There are so many varibles that will
affect the outcome the only way to be sure is to do your own testing. That is
what industry does. If Mr. Granato is talking about sheet metal then he is
correct , it won't make a difference. In heavier thicknesses it most definately
does. I have thrity years of welding experience and an investment in welding
equipment worth tens of thousands of dollars. I have dedicated MIG welder but
the only wire feed type process I will use to build a pressure vessel is
Dual Shield Flux Core. MIG welding is fine for body work or building a
motorcycle but not a submarine. I would recommend to you to
fabricate a guided bend test jig , weld up some test coupons using
516Gr70 and bend in a side bend mode. ( not a root or face mode) .
-----
Original Message -----
Sent: 3/2/2010 10:01:06 AM
Subject: [PSUBS-MAILIST] MIG
vs Arc
I have been doing alot of reserach about
MIG vs Arc. I contacted Miller here is their response:
Scott,
If you have the same filler metal tensile strength and set the machines to have
the same heat input the end result should be the same. With the GMAW process
you can use different shielding gases to give different penetration profiles
but in the end with both processes you should be able to get the same results.
John Granato
Welding Engineer, Integrated Mig Systems
Miller Electric Mfg. Co. An ITW Company
1635 West Spencer St.
P.O. Box 1079
Appleton, WI 54912-1079
I am going to do a few pressure stress tests of my own, because of the wide
array of answers I am getting, just to be sure.
Thanks,
Scott Waters
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