[PSUBS-MAILIST] Personal_Submersibles Digest, Vol 51, Issue 91

Rick Patton via Personal_Submersibles personal_submersibles at psubs.org
Wed Sep 20 10:43:30 EDT 2017 

Jerry,
Sean or Dan may be able to correct me but what little I know about that
process mainly only shows cracks that have made their way to the surface
and not all the way to the root.

Thought more costly, X ray and ultra sound which is more accurate than X
ray tell the whole story.
Rick

On Wed, Sep 20, 2017 at 7:18 AM Jerry Koontz via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Weld inspection can be done with Magnetic particle inspection. It is an
> inexpensive method that works really well. I use the dry power and a car
> battery. Works good.
>
> Here is some more information on that method.
>
> Magnetic particle Inspection (MPI) is a non-destructive testing (NDT)
> process for detecting surface and slightly subsurface discontinuities in
> ferromagnetic materials such as iron, nickel, cobalt, and some of their
> alloys. The process puts a magnetic field into the part. The piece can be
> magnetized by direct or indirect magnetization. Direct magnetization occurs
> when the electric current is passed through the test object and a magnetic
> field is formed in the material. Indirect magnetization occurs when no
> electric current is passed through the test object, but a magnetic field is
> applied from an outside source. The magnetic lines of force are
> perpendicular to the direction of the electric current, which may be either
> alternating current (AC) or some form of direct current (DC) (rectified AC).
>
> The presence of a surface or subsurface discontinuity in the material
> allows the magnetic flux to leak, since air cannot support as much magnetic
> field per unit volume as metals.
>
> To identify a leak, ferrous particles, either dry or in a wet suspension,
> are applied to a part. These are attracted to an area of flux leakage and
> form what is known as an indication, which is evaluated to determine its
> nature, cause, and course of action, if any.
> ----- Original Message -----
> From: "via Personal_Submersibles" <personal_submersibles at psubs.org>
> To: "personal submersibles" <personal_submersibles at psubs.org>
> Sent: Wednesday, September 20, 2017 7:17:31 AM
> Subject: Personal_Submersibles Digest, Vol 51, Issue 91
>
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> Today's Topics:
>
>    1. Re: Heads Question (Sean T. Stevenson via Personal_Submersibles)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 20 Sep 2017 06:17:51 -0600
> From: "Sean T. Stevenson via Personal_Submersibles"
>         <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion
>         <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] Heads Question
> Message-ID: <7356e0c7-9a7d-4f7e-8305-3c5de3918232 at email.android.com>
> Content-Type: text/plain; charset="utf-8"
>
> Fatigue issues in weldments typically arise as a result of the geometry of
> the weld, where fatigue sensitive details such as doubler plates, sharp
> interfaces, inherent "cracks" at the apexes of partial penetration welds,
> overlapping weld toes etc. cause local amplification of the service stress
> ranges. Pressure hulls are inherently resistant to fatigue as a result of
> the mandated geometries, CJP welds, and barring the high strength alloys,
> the generally tougher nature of e.g. ASTM A516 Gr. 70 steel. I might go as
> far as to say that a PSub is unlikely to see enough high stress cycles
> within its lifetime to justify worrying about fatigue at all. Indeed, ABS
> only requires a fatigue analysis under specific conditions:
>
> >From the ABS rules (2017):
> Section 6/9:
>
> Fatigue? (2002) A? fatigue analysis? is? to? be submitted? when? it is?
> anticipated? that the life time? full range pressure? cycles? N will
> exceed? that obtained? from? the following? equation:
>
> N = [1160(3000? ?? T)/(Kf?? ?? 14500)]^2
>
> where
>
> T = temperature? in? degrees? C? (degrees? F)? corresponding? to?
> application? of? the? cyclic? or repeated stress
> K? =? 5688 SI/MKS units (4? U.S.? units)
> f? = range? of? cyclic stress? kg/mm2? (lb/in2)
>
> Pressure cycles? of? less? than? full? pressure are to? be included? in?
> N? in? the ratio? p/P? where? p? is? the? actual pressure of? the? cycle?
> under? consideration? and? P? is? the design? pressure.
>
>
> Sean
>
>
>
> On September 19, 2017 12:39:42 PM MDT, 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
> >rdolfi7 at gmail.com
> >
> >On Tue, Sep 19, 2017 at 1:29 PM, via Personal_Submersibles <
> >personal_submersibles at psubs.org> wrote:
> >
> >> Send Personal_Submersibles mailing list submissions to
> >>         personal_submersibles at psubs.org
> >>
> >> To subscribe or unsubscribe via the World Wide Web, visit
> >>
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> >> or, via email, send a message with subject or body 'help' to
> >>         personal_submersibles-request at psubs.org
> >>
> >> You can reach the person managing the list at
> >>         personal_submersibles-owner at psubs.org
> >>
> >> When replying, please edit your Subject line so it is more specific
> >> than "Re: Contents of Personal_Submersibles digest..."
> >>
> >>
> >> Today's Topics:
> >>
> >>    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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> >>
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> >>
> >>
> >>
> >>
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