[PSUBS-MAILIST] Heads Question

Daniel Lance via Personal_Submersibles personal_submersibles at psubs.org
Tue Sep 19 16:25:51 EDT 2017


Thank you River !
Very well said !  This is why I suggest that a licensed experienced welding
engineer be consulted .
Hank,
Yes, It's possible to produce a very pretty ( appearance wise ) multi-pass
weld with a low end MIG welding machine . But there is a big difference
between what is pretty and will be structurally sound over the long term .
I will say it one more time , Yes it might be a very pretty weld but it is
brittle and given the right circumstances it will fail .
The next time I get out to the west coast I will stop by your place . We
will have you weld up a test coupon and I will show you how to
destructively test to ASME standards .  I am confident the results will
surprise you .
I was hesitant to respond originally to this MIG welding reference in this
thread because I knew there would be hurt feelings and possibly start a
flame war . I can assure you I have better things to do with my time then
argue about something like this . But I decided that if I can keep even one
person from being harmed then it would be worth it . If we don't look out
for the inexperienced people in the group the government will do it for us
and we definitely won't like what happens next .
Dan

On Tue, Sep 19, 2017 at 2:39 PM, River Dolfi via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> I'm sure Sean can also speak at length about this, but a single pressure
> test gives no information about fatigue life. The size of flaw in a
> weldment (and all welds have flaws) may not be constant over the service
> life of the vessel. Weld material with sufficiently low fracture toughness
> (aided by low temperatures) will have it's flaws elongate with each cycle,
> as predicted by the Paris Law of crack propogation, until eventually
> reaching a critical size and fracturing. This is compounded rather
> unpredictably by the corrosion typical of a marine environment.
>
> All I know is that I know nothing. But sometimes I think we should pool
> our money and buy an ultrasound machine...
>
> -River J. Dolfi
>
> 412-997-2526 <(412)%20997-2526>
> rdolfi7 at gmail.com
>
> On Tue, Sep 19, 2017 at 1:29 PM, via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
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>>    1. Re: Heads Question (hank pronk via Personal_Submersibles)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 19 Sep 2017 17:23:42 +0000 (UTC)
>> From: hank pronk via Personal_Submersibles
>>         <personal_submersibles at psubs.org>
>> To: Rick Patton via Personal_Submersibles
>>         <personal_submersibles at psubs.org>
>> Subject: Re: [PSUBS-MAILIST] Heads Question
>> Message-ID: <674133299.2545129.1505841822312 at mail.yahoo.com>
>> Content-Type: text/plain; charset="utf-8"
>>
>>  Dan, Rick,I would argue that you guys are indeed experts. ?I am
>> not,,,but,, I am an expert experimenter and tester . ?My welder has a 60%
>> duty cycle and I have welded and tried to destroy the weldments and
>> actually wrecked a jack trying . ?I test welded and bent and tortured
>> material and not once did a weld break. ?Again you guys are the experts but
>> Elementary 3000 had 392,500 lbs trying to push the hatch through the
>> opening with no issues at all. ?I can talk about my welding all day long
>> but it is the pressure test that says it all. ? I would have tested it a
>> lot higher but that was the limit of the chamber.How can you explain my
>> pretty welds holding ?6,500 lbs per inch? ?If my welder can only weld sheet
>> metal, why did it not fail? ? I am a pretty luck guy, maybe that is it
>> ;-)Hank
>>
>>     On Tuesday, September 19, 2017, 11:00:50 AM MDT, Rick Patton via
>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>
>>  Mig welds can be deceptive sometimes. I have seen very pretty factory
>> fellet mig welds come threw my doors in both aluminum and mild steel where
>> the weld had completely let go of one of the two sides due to lack of
>> penetration.? The prep or process wasn't done correctly but yet it still
>> looked good.?This is not the case with TIG or stick. There is a saying
>> amongst Welders that if a stick weld looks good, it probably is. If it is a
>> critical weld, you still want to X ray or UT it but you will always have
>> penetration on both sides unlike mig. Beginners and novice welders
>> sometimes gravitate towards Mig as it is easier than stick but a pressure
>> vessel that you are going to be in, then l would stick with stick "pun
>> intended " or if your insistent on Mig, have it done professionally or make
>> darn sure your using the correct equipment as Dan inferred.?Rick?
>> On Tue, Sep 19, 2017 at 9:08 AM Daniel Lance via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Hank,I do not in any manner consider myself an expert .? I am just
>> relying on what I learned during 36 years in the welding industry . My
>> motto is if a person keeps the right attitude he or she can learn something
>> new everyday ! ?:)Dan
>> On Tue, Sep 19, 2017 at 7:43 AM, hank pronk via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>  Dan,I could tell you all about the million tests I did after loading the
>> wire into my shiny welder and i could talk about the results, but, you are
>> the expert and we should take your advice.? No question about it, i would
>> not want to encourage anything else.Hank
>>     On Tuesday, September 19, 2017, 4:52:00 AM MDT, Daniel Lance via
>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>
>>  ?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 p!
>>  er 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> wrote:
>>
>> I have found that I get a better weld if both sides are beveled .?Brian
>>
>> --- personal_submersibles at psubs. org wrote:
>>
>> From: Private via Personal_Submersibles <personal_submersibles at psubs.
>> org>
>> To: Personal Submersibles General Discussion <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> 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>
>>  To: Personal Submersibles General Discussion
>> <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
>> Santa Rosa, CA. 95404
>> (707) 536-1424
>> www.SeaQuestor.com
>>
>>
>> On Fri, Sep 15, 2017 at 2:28 PM, Alec Smyth via Personal_Submersibles
>> <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> 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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