[PSUBS-MAILIST] Heads Question

Wed Sep 20 21:48:00 EDT 2017

Hank,
I would suggest that you take the hull section that was cut from your port
frame and send it to a Materials Test Lab . ( probably the same company
that is going to do your ultrasound can do it ) . Have them do a " Guided
Bend Test " on the coupons they cut from it .
  If you have it done professionally you will have unequivocal proof of
your weld integrity . The lab is well practised in this type of test and
has all the proper equipment . Without the coupon guide/bending jig that
fits in the hydraulic press it is difficult for an individual to get
reliable results .
  When you send your sample to the lab ask them to do " Side Bends " on the
coupons that they cut from your welded plate instead of  "Face" and  "Root"
bends . Performing side bends puts you solidly in the realm of the
rigorously high standards of ASME PVHO .
  With a design depth of 914 meters (3000fsw) you are  in the big leagues
now and the peace of mind that comes from a professionally  done test will
be priceless .
Dan

On Wed, Sep 20, 2017 at 12:58 PM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> River,
> I agree the pressure test is of little value determining  fatigue life.
> My goal was to establish if the engineering is good and if the welds would
> fail.  Mission accomplished.  Before the pressure test I was going to do an
> ultrasound test but decided to do a preliminary dye penetrant test.  I
> figure why spend 1,000 dollars on a test that needs to be repeated after
> the pressure test.  My next step is the ultrasound test and I have a hull
> section that was cut out for the port frame with the weld going through the
> middle.  I will cut that piece up and bend it to prove the weld quality.
> Hank
>
> On Wednesday, September 20, 2017, 6:18:15 AM MDT, Sean T. Stevenson via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> 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)/(Kfτ  –  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)
> fτ = 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 <(412)%20997-2526>
> rdolfi7 at gmail.com
>
> On Tue, Sep 19, 2017 at 1:29 PM, via Personal_Submersibles <
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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
> <personal_submersibles at psubs.org>>
> To: Rick Patton via Personal_Submersibles
>         <personal_submersibles at psubs. org
> <personal_submersibles at psubs.org>>
> Subject: Re: [PSUBS-MAILIST] Heads Question
> Message-ID: <674133299.2545129. 1505841822312 at mail.yahoo.com
> <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
> <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 <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 <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
> <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 t! housands 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 <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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