<div dir="ltr"><div>Hi guys,</div><div>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".</div><div><br></div><div>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.</div><div><br></div><div>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.</div><div>Here's a good explanation of the difference: <a href="http://www.classicfilters.com/blog/materialcertificates/">http://www.classicfilters.com/blog/materialcertificates/</a></div><div><br></div><div>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.</div><div><br></div><div>Cheers,</div><div>Steve</div><div>(Among other things - mechanical engineer in Melbourne, Australia)</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Mar 23, 2015 at 10:55 PM, James Frankland via Personal_Submersibles <span dir="ltr"><<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hi Andre,</div><div><br>I was in this position some years ago. Not knowing what to specify on the order. </div><div> </div><div>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. </div><div> </div><div>So just ask for your dimensions of shell, material, percentage of round, bevel, weld.</div><div> </div><div> </div><div>Example.</div><div> </div><div>Shell. P355 Steel. 10mm Thick.</div><div> </div><div>OD 1000mm x 2000mm length.</div><div>Shell to be within +\- 3mm on diameter.</div><div>Welded seam.</div><div>35 degree external bevel with 2mm nose.</div><div> </div><div> </div><div><div>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. </div><div> </div></div><div> </div><div>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.</div><div> </div><div>Ideally go to the factory with a wooden template and measure the cylinder before you accept it.</div><div> </div><div>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. </div><div> </div><div>Someone else may have some other suggestions. Comments.</div><div> </div><div>Hope this helps. </div><div> </div><div>Kind Regards</div><div>James</div><div> </div><div> </div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On 21 March 2015 at 22:30, André Eriksen <span dir="ltr"><<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid"><div><div class="h5"><div dir="ltr">Hi,<div><br></div><div>I`m in the process of ordering the shell and tower for my submarine.</div><div>What specification should I ask for? (Europe) </div><div><br></div><div><span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px"> I asked for </span><span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px">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)</span><br></div><div><span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px">Told them I had no special requirements for the plates and needed no edge preperation.</span><br></div><div><span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px"><br></span></div><div><b>They replied</b>:<span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px"> "this is not the normal enquiry type, but we will not ask any longer" (?)</span></div><div>And said the plates was going to be <span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px">EN10028-3 with certificate 3.2.</span></div><div><span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px"><br></span></div><div><span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px">I want to keep the cost down, b</span><span style="color:rgb(0,0,0);font-family:Verdana,Arial,Helvetica;font-size:11px">ut should I ask that they grit blast the shell after rolling?</span></div><div>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?</div><div><br></div><div>May I ask what you tell your supplier when ordrering?</div><span><font color="#888888"><div><br></div><div><br></div><div>-André</div></font></span></div>
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