[PSUBS-MAILIST] Heads Question

Tue Sep 19 06:51:40 EDT 2017

 Since the topic has come up in this current thread I want to state for the
record that I would encourage anyone contemplating using the " Short Arc
MIG welding process " to weld their submarine's pressure hull to consult a
licensed qualified , experienced  Welding Engineer before doing so ( and
NOT the Welding machine manufacturers sales rep) . MIG ( short arc ) should
only be used on light gauge metals ( .1875" and below ) , when used on
heavier thickness steel it produces welds brittle in nature and ultimately
prone to cracking . This process is ill suited for building pressure
vessels especially ones intended for PVHO . Steel has an inherent tendency
to become brittle at low ambient temperatures ( think a northern latitude
lake where the bottom temperature could possibly be in the upper 30s , 40s
or 50 degrees F range ) add to that a welding process well documented to
produce brittle welds and then factor in a bottom pressure of hundreds
maybe even thousands of pounds per square inch. Chances are very good that
the hull won't fail on the first dive or hydro test but basically what you
have is the proverbial " one bullet in the revolver " situation  leading to
a false sense of security .    Like I mentioned earlier consult a
"Licensed" qualified , experienced Welding Engineer and heed his advice
before loading that spool of wire in your shiny new welding machine or
hiring the "expert welder from down the street . Like the old saying goes "
what you don't know can hurt you " .
Dan Lance

On Mon, Sep 18, 2017 at 2:57 PM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Alec,
> Yup, I have heard it all from the stick welding only crowd.  I hear all
> the time "I like to turn it up and burn it in"  or  " I like to crank er
> up"  LOL.
> The fact is, too much penetration is bad because you introduce parent
> metal into the filler metal, and that is bad.  You need sufficient
> penetration and I have no problem achieving that.  I mig welded Elementary
> 3000 and it is 1 inch thick, with no problem, and it has been to 1,250 psi.
> Hank
>
> On Monday, September 18, 2017, 10:13:50 AM MDT, Private via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Yep, I think you're probably right! My only concern would be using mig on
> a pressure vessel though. I'm not an expert, but what I've always heard
> from those who are is that it's for high-productivity jobs but not for jobs
> like full penetration where quality trumps speed.
>
> On Sep 18, 2017, at 7:56 AM, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Alec,
> I like a bevel on both sides, and I also do a mig pass on the inside then
> grind outside as you do.  When your welding such light material, the
> external grind job is creating the same shape weld grove as if you started
> with a bevel on both sides.  Same difference really.  The big difference is
> guys like Rick and Dan can do this all at ounce because they are
> professional welders.
> Hank
>
> On Sunday, September 17, 2017, 8:33:43 PM MDT, Alec Smyth via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Here's the method I used. The starting point is a bevel with the sharp end
> of course on the ID and the wide end of the wedge on the OD. An air gap of
> about 1/8" is left between the two parts.
>
> 1) TIG weld the root pass, from the *inside* of the hull, plugging the
> air gap.
> 2) Grind with an angle grinder from the outside into the root pass. Use a
> 1/4" wheel on the angle grinder. You need to get a clean shiny U shaped
> channel, pure like-new metal, with no visible discontinuities whatsoever.
> 3) Stick weld from the outside building up layers until meeting the plate
> thickness.
>
> Perhaps a double bevel would be needed for very thick material. The method
> I'm describing, I've used on material up to 1/2" with no problem.
>
> Dan, if I'm talking rubbish please set me straight!
>
>
>
> Best,
>
> Alec
>
> On Sun, Sep 17, 2017 at 9:52 PM, Rick Patton via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Definitely want to bevle both sides. If you don't, your wire/stick/Tig
> will short out way too soon becoming molten and not reaching the ID of the
> hull and you will have to do a lot of back gouging before reaching your
> first pass.
> Rick
>
> On Sun, Sep 17, 2017 at 3:54 PM Brian Cox via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
> I have found that I get a better weld if both sides are beveled .
>
> Brian
>
> --- personal_submersibles at psubs. org <personal_submersibles at psubs.org>
> wrote:
>
> From: Private via Personal_Submersibles <personal_submersibles at psubs. org
> <personal_submersibles at psubs.org>>
>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> Subject: Re: [PSUBS-MAILIST] Heads Question
> Date: Sat, 16 Sep 2017 19:30:01 -0400
>
> Hi David,
>
> Absolutely, you want it with the flange. Any impression otherwise was my
> "mind typo" that I was trying to clarify in the second email. If you can
> avoid beveling it yourself, however, it'll save quite a job. You only need
> one of the two edges beveled, either the head flange or the end of the
> cylinder it will mate to, and it doesn't matter which. Greg has a good
> point, but I suppose a key factor is whether you'll be welding yourself or
> contracting out. I learned to do my own, with an awful lot of help from Dan
> Lance.
>
> Best,
>
> Alec
>
> On Sep 16, 2017, at 12:50 PM, james cottrell via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
> Hi David,
>
> In my experience it was cheaper and faster to hire an ASME tank fabricator
> to produce a steel cylinder with the head (or heads) welded on. Mine came
> machine welded with an ASME code stamp.
> If your design will feature external frames, ask them for both heads
> welded on. If your design will feature internal frames (done later) ask
> them to weld one end only. This will be cheaper in the long run and better
> built. It's hard to beat pressure vessel code machine welding. Specify NO
> backing strips.
>
> Another tip- call it a "vacuum tank".
>
> Greg Cottrell
>
> ------------------------------
> *From:* David Colombo via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> *To:* Personal Submersibles General Discussion <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> *Sent:* Saturday, September 16, 2017 12:20 PM
> *Subject:* Re: [PSUBS-MAILIST] Heads Question
>
> Hi Alec,
> I just spoke with the company that Roberto mentioned here in California to
> place an order for dished head for the SeaQuestor. I will be using the
> 36"OD x .375 A516-70 steel what they call Elliptical 2:1 Ratio ASME Code
> Type. It comes with a 2" flange which is really a 36" od ring shape as part
> of the forming. This would mate up to the 36"OD first hull section. I'm
> thinking that this would give me the best welding condition with two
> matched surfaces that I would bevel for full pen welding. I'm curious why
> not to have the flange?   My cost here is $480.00 + $96 to have it shipped
> to northern California from southern California. even though its only a
> nine hour drive one way, I think my time would be worth more than $5 hr to
> pick it up. LOL Unless of course its cheaper in Canada (Hank), I might make
> the trip and could serve as support crew for the Gamma. Any thoughts out
> there from fellow Psubers would be appreciated.
>
> Best Regards,
> David Colombo
>
> 804 College Ave
> <https://maps.google.com/?q=804+College+Ave+Santa+Rosa,+CA.+95404+(707&entry=gmail&source=g>
> Santa Rosa, CA. 95404
> <https://maps.google.com/?q=804+College+Ave+Santa+Rosa,+CA.+95404+(707&entry=gmail&source=g>
> (707
> <https://maps.google.com/?q=804+College+Ave+Santa+Rosa,+CA.+95404+(707&entry=gmail&source=g>)
> 536-1424
> www.SeaQuestor.com <http://www.seaquestor.com/>
>
>
> On Fri, Sep 15, 2017 at 2:28 PM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
> Ugh, mental typo. I meant "un-beveled" and "bevel them yourself", not
> "un-flanged" and "flange them yourself".
>
> !!!!!!!
>
> On Fri, Sep 15, 2017 at 5:25 PM, Alec Smyth <alecsmyth at gmail.com> wrote:
>
> Hi Roberto,
>
> I believe the short description for what you need is flanged, beveled, and
> code. You could get them unflanged, but it takes quite a while to make a
> flange with an angle grinder. The flanges if I recall are 2". Do set up a
> project page or something so we can follow progress!
>
>
> Best,
>
> Alec
>
> On Fri, Sep 15, 2017 at 5:07 PM, roberto alvarez via Personal_Submersibles
> <personal_submersibles at psubs.o rg <personal_submersibles at psubs.org>>
> wrote:
>
> Hi, lost the plans cd for the k250, i am  interested in the  head
> selection, i found a seler in california and have
> flanged ,beveled ,code, non code,
>
> Will apreciate your support in this ( until i found the plans cd )
>
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