[PSUBS-MAILIST] Specifications when ordering shell

Tue Mar 24 18:36:18 EDT 2015

That`s a bit scary, not 100% sure you actually get the material you have
calculated for...

-André

2015-03-24 22:17 GMT+01:00 Emile van Essen via Personal_Submersibles <
personal_submersibles at psubs.org>:

>   The difference between 3.1 and 3.2 is that the material is stamped by a
> employee who is licensed to do that.
>
>
>
> With the 3.1 one certificate, it happens often that the material not
> belongs to the batch on the papers..
>
>
>
> 4 mm ovality is a bit high for your deep diver but within 0,5 %
>
>
>
> Regards, Emile
>
>
>
>
>  ------------------------------
>
> *Van:* Personal_Submersibles [mailto:
> personal_submersibles-bounces at psubs.org] *Namens *André Eriksen via
> Personal_Submersibles
> *Verzonden:* maandag 23 maart 2015 16:32
> *Aan:* Personal Submersibles General Discussion
> *Onderwerp:* Re: [PSUBS-MAILIST] Specifications when ordering shell
>
>
>
> Thanks for the info guys! Made things abit clearer. The company I`ve
> talked to is in Germany, and I live in Norway so I can`t go and measure the
> shell.
>
>
>
> This is the tolerances they gave me on a OD1000x1500 shell:
>
>
>
> OD +/- 2mm calculated out of >outside circumferential length and real wall
> thickness
> Ovality max 4 mm, measured at both ends
> Straightness 1mm/m max. 3 mm
> Length - 0 / + 5 mm
>
>
>
> Is the ovality tolerance good enough?
>
>
>
> Regards
>
> André
>
>
>
> 2015-03-23 14:54 GMT+01:00 James Frankland via Personal_Submersibles <
> personal_submersibles at psubs.org>:
>
> Thanks for the clarification Steve.
>
> Regards
>
> James
>
>
>
> On 23 March 2015 at 12:18, Stephen Fordyce via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi guys,
>
> The material certificate thing is all about quality control and
> traceability of exactly what is the composition of the elements in
> it.  Ie. when the steel gets smelted and poured into a block (or whatever)
> at the mill, that particular batch gets analysed for exact percentages
> of all elements, and all parts poured from that batch are given the "heat
> number" of the batch.  Since the certificate is meant to trace back to the
> original steel mill, it's often called a "Mill Certificate".
>
>
>
> Each time the steel goes through a process (ie. rolling into sheet, the
> sheet formed into pipe or endcaps) there is a chance the traceabilty to the
> original analysed composition could be lost, if the material gets mixed up
> - and there are varying levels of quality control that make sure of this,
> and these are reflected in different types of material certificates.
>
>
>
> The EN 3.1 cert is pretty high end (ie. good enough for the SS304/316
> cryogenic liquid ethane pressure vessels I'm currently involved with at
> work) and typical for most industrial applications at least.  I've not come
> across requirements for 3.2 (which is even more stringent), and we
> frequently work with lesser requirements than 3.1.
>
> Here's a good explanation of the difference:
> http://www.classicfilters.com/blog/materialcertificates/
>
>
>
> Tracing the material back to the mill is supposed to be important in case
> there is a failure in another part in the same batch, so it can prevent
> other failures.  I've always thought the whole certificate/traceability
> thing was just a PITA and that so long as you get steel or parts from
> reputable suppliers who's QC practises you trust, then that's just as
> effective.  Especially when you're building a big system with hundreds of
> welded parts.
>
>
>
> Cheers,
>
> Steve
>
> (Among other things - mechanical engineer in Melbourne, Australia)
>
>
>
> On Mon, Mar 23, 2015 at 10:55 PM, James Frankland via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> Hi Andre,
>
>
> I was in this position some years ago.  Not knowing what to specify on the
> order.
>
>
>
> I believe the EN number is a certificate of the material quality.  Mine
> was done to EN10204.3.1.B but i never specified it.  I just asked for the
> material type.
>
>
>
> So just ask for your dimensions of shell, material, percentage of round,
> bevel, weld.
>
>
>
>
>
> Example.
>
>
>
> Shell.  P355 Steel.  10mm Thick.
>
>
>
> OD 1000mm x 2000mm length.
>
> Shell to be within +\- 3mm on diameter.
>
> Welded seam.
>
> 35 degree external bevel with 2mm nose.
>
>
>
>
>
> Something like that should do it.  They will send you a quote and should
> tell you what material grade it what code they will be working to.
>
>
>
>
>
> Make sure you specify clearly the tolerance of roundness you want and say
> your not paying for it if its not right.  They will probably need to
> re-roll the cylinder.
>
>
>
> Ideally go to the factory with a wooden template and measure the cylinder
> before you accept it.
>
>
>
> Get the bevel put on, it will save you pain.  But. don't bother with grit
> blasting, you need to paint it straight away after that or it will start to
> oxidise again.  By the time you've finished your hull, it will be all rusty
> again.  Grit blast when you've finished working on the hull.
>
>
>
> Someone else may have some other suggestions.  Comments.
>
>
>
> Hope this helps.
>
>
>
> Kind Regards
>
> James
>
>
>
>
>
>
>
> On 21 March 2015 at 22:30, André Eriksen <personal_submersibles at psubs.org>
> wrote:
>
>   Hi,
>
>
>
> I`m in the process of ordering the shell and tower for my submarine.
>
> What specification should I ask for? (Europe)
>
>
>
>  I asked for EN10204 with 3.1 Sertificate (Not 100% sure of this, but this
> is what I got when I ordered the endcaps from another company. 3.2
> Sertificate was a bit too expensive)
>
> Told them I had no special requirements for the plates and needed no edge
> preperation.
>
>
>
> *They replied*: "this is not the normal enquiry type, but we will not ask
> any longer" (?)
>
> And said the plates was going to be EN10028-3 with certificate 3.2.
>
>
>
> I want to keep the cost down, but should I ask that they grit blast the
> shell after rolling?
>
> Also I didn`t ask for bevel on the edges. Again to keep cost down. But
> maybe I should, to spare me the extra work?
>
>
>
> May I ask what you tell your supplier when ordrering?
>
>
>
>
>
> -André
>
>
>
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>
> --
>
> Med Vennlig Hilsen / Regards
>
> *André Eriksen*
>
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>

-- 
Med Vennlig Hilsen / Regards
*André Eriksen*
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