Re: [PSUBS-MAILIST] Re: Mig welding a sub

Dan,

I somehow missed this message.....

I have a question........Wouldn't submerged series arc be the best method to seal a pressure vessel? It's totally one bead, has similar penetration to stick, and is easily controlled.

Although I'm not sure who would have a rig that could weld a round vessel, I'm sure it could be done.

I agree a backhoe bucket weld wouldn't do the trick, but also on the other hand the seam to seal a vessel designed to go 1000 feet, is not the same seam as a vessel only designed to go to 200. The variables are totally different.

James Long
Owner/Designer
Lil Brother LLC (Instrument Division)

----- Original Message -----

From: james kocourek

To: personal_submersibles@psubs.org

Sent: Wednesday, July 25, 2007 5:51 AM

Subject: Re: [PSUBS-MAILIST] Re: Mig welding a sub

Hi Dan,

I appreciate your input. I have done failure testing prior to welding on my sub with exceptional success. I think that some of the time flux core gets a bad rap because of the fact that the little buzz boxes use flux core. Mine is a 350 amp mig computer controlled pulse welder as speced by both lincoln tech specialists and my coach, an extremely experienced and active pressure vessel welder.

I concure that one cannot be too cautious.

I am interested in talking with you more at the convention about this subject and appreciate your feedback.

Rest assured that I did considerable homework prior to choosing the method that I am using now.

Thanks again & Best Regards,

Jim Kocourek

----- Original Message -----

From: Daniel Lance

To: personal_submersibles@psubs.org

Sent: Tuesday, July 24, 2007 7:50 PM

Subject: [PSUBS-MAILIST] Re: Mig welding a sub

James

I believe it would be in your best interest to strive for the highest possible weld integrity for the pressure hull of your submarine. A weld procedure that is acceptable for a backhoe bucket isn't necessarily adequate for Pressure Vessel Quality work. Typical Quality Control standards for PVQ require full penetration X-ray quality welds to acheive 100 % of the strength required for such a demanding applicaton. While there are many welding processes available to the average person, ( mig, tig, stick). Some are better suited than others in a given situation depending on a particular individuals skill and experience level. As an example , I have seen "side bend" Mig weld tests performed by highly skilled welders with ten's of thousands of hours of welding experience split apart in the weld bead zone. Mig has a tendency to exhibit very shallow penetration in certain circumstances. The trick is to know WHA! T circumstances. If you are going to perform your own welding I would recommend that you do what industry does. Take a weldor qualification test in the weld process and welding procedure you intend to implement in your build project. Get a copy of "The Procedure Handbook of Arc Welding" by the Lincoln Electric Co. of Cleveland Ohio. This an excellent reference book with a chapter devoted to weldor qualification tests. If you have a hydraulic press in your shop you can perform your own tests. If you plan to hire someone to do the welding for you insist that they pass an approved test administered by a qualified laboratory. Rework is expensive , do it right the first time. And of course,......what is your life worth?....... someone who says they can do it or someone who can prove that they can do it.

Happy sub building,

Daniel Lance

lanceind@earthlink.net