Which Is The Best Vendor To Purchase Marine Grade Aluminum From?

Discussion in 'Metal Boat Building' started by John Stream, Feb 28, 2014.

  1. John Stream
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    John Stream Junior Member

    This would be for enough marine grade plate and extrusion to build a 50 foot boat.

    Preferably the vendor is in North America or East Asia.

    Who has the best prices?

    Who has the best quality? The material should be certified marine grade I suppose.

    Is there any place to get scrap material?
  2. Ad Hoc
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    Ad Hoc Naval Architect

    There are plenty in North America. All you need to do is ensure that what you are supplied is LR/DNV/ABS approved marine grade. If you buy 5083 - O grade simple, if you but 5083 - H116, you'll need to ask for an ASSET cert (for proof of marine grade).

    But in asking for such documentation, guess what...yup, the price goes up from buying "off the shelf" bog standard aluminium.

    You only get what you pay for..
  3. NavalSArtichoke
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    NavalSArtichoke Senior Member

  4. Kevin Morin
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    Kevin Morin Junior Member

    Aluminum Mill Cert.s

    John Stream,

    I guess from your question you don't know enough about aluminum alloys to buy them! 99% of all vendors don't provide MTR's or material test reports for their inventory. And the industry or welded boats in the US has suffered because of this pure laziness and poor business practice.

    There was a huge scandal, accompanied by many bankruptcies and lots of very short lived boats in the Pacific Northwest a while back; because no one asked for or demanded the suppliers carry materials certifications from refining to builder.

    Just to give a reasonable comparison, the oil and gas industry won't purchase pipe, fittings or valves without MTR's for the steel involved when there are critical alloys or applications involved-neither should you.

    If you demand all bidders/vendors on your boat provide MTR's that will probably reduce by half the number of suppliers who will bother to reply, but it will insure you the metal provided is produced to 'spec.'

    Without these credentials, each stage of the supply chain can completely and totally AVOID their liability for the material's alloys that the sell!! Yes you read that right- if you don't require MTR's the supplier and his upstream supplier can avoid material efficiency claims by saying " I thought it was 5086 since that's what I ordered....."

    All you have to do is put one line in your purchase order or order contract:
    "No material is accepted for delivery in this contract unless accompanied by a Material Test Report and Certification for the metal products that traces the origin, alloying, milling and all stages of supply of these materials to be (describe alloys of plate/sheet and extrusion)."

    If and when the metal shows up without these documents, then just tell the supplier they're in breach of contract, and magically the papers appear.

    Most people just trust, and take what they get.

    "Trust but verify" (Ronald Reagan)

    best of luck on your project,

    Kevin Morin
    Kenai, AK
  5. John Stream
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    John Stream Junior Member

    Good advice

    What are the differences between:

    LR/DNV/ABS approved marine grade

    ASSET cert

    Material test reports

    I did hear about the bad alloy that was used in the Pac. NW. I certainly don't want that to happen.
  6. air1ck
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    air1ck New Member


    I sent you a PM.

  7. Stumble
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    Stumble Senior Member

    These are different certification bodies, and different certificates attesting to exactly what material what you hold in your hands is. A MTR is a document from the mill that certifies that batch of metal was made according to a specific recipe with certain alloying compounds in a specific ratio.

    Basically they are the only quality control paperwork that is worth looking at. Unless you are willing to pay for alloy testing post delivery.
  8. Ad Hoc
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    Ad Hoc Naval Architect

    Very little. If either has a proper Class certificate.

    This test method provides a reliable prediction of the exfoliation corrosion behavior of Al-Mg alloys in marine environments.5,6,7 The test is useful for alloy development studies and quality control of mill products such as sheet and plate.*


    That was because of a poor run of aluminium. The strain hardened aluminium should have been hot rolled but was cold rolled.

    If you want to read more, there is a good article in Professional Boatbuilder magazine, page 24, this month:
  9. John Stream
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    John Stream Junior Member

    Good article.

    Surprising that the strain hardening technique could make such a huge difference.
  10. BMcF
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    BMcF Senior Member

  11. Barry
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    Barry Senior Member

    Ad Hoc recommends the the current article in the Professional Boatbuilder Magazine.

    Often people will not take the time to look at some recommendations but to John Stream, if you are considering a 50 foot aluminum boat, the cost to get your hands on this article is immaterial but can be invaluable.

    Of the many technical articles written on aluminum as a boat building material that I have read and the Ibex seminars on the same, this is perhaps the clearest article on aluminum as a boat material that has surfaced.

    The article explains yield strength with respect to alloys, hardening processes and tempering. Additionally it goes into detail on loss of strength within the Heat Affected Zone, filler rod material and also includes issues of working the aluminum above its yield strength but below its ultimate tensile strength to produce a situation where the aluminum can be close to catastrophic failure due to work hardening and shows examples of the same.

    Though of interest to a few, it even shows some grain pictures of areas within the HAZ

    This is an exceptional read.

    For a supplier you just need to stay away from pure retailers and get to the distributors if possible, Ryerson is one of the best and if you go in and ask for a quote on the entire boat, you will usually get a much better price than buying a few sheets here or there or a partial order.
  12. Ad Hoc
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    Ad Hoc Naval Architect

    As with everything in design, one must understand the material properties that one is using and select accordingly. It seems that most "common knowledge" on aluminium is not common after all, despite many talking as if they know it all out of "years of working" with the metal, yet it is more often misunderstood, thus poor selection and probable failures occurs out of simple ignorance. The perception is the aluminium is like steel, i.e. it is a metal and thus easy to understand. That is where the misconceptions starts. Steel is very forgiving and one can abuse it without any serious deleterious effects. Not so aluminium.

  13. yofish

    yofish Previous Member

    Alaskan Copper & Brass = good.
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