The great aluminium debacle

Discussion in 'Materials' started by rwatson, Jan 23, 2011.

  1. rwatson
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    rwatson Senior Member

    The Feb.March issue of "Professional Boatbuilder" has a story about a boatbuilder sued for building boats in an alloy that was proved defective "and failed in more than 300 vessels"
    The 5083-H321 plate was made around 2007, and caused two years of litigation amongst boat owners and Alcan branches.
    Wow- when products like Aluminium can no longer be trusted, it makes you wonder if you need to personally test everything you put in a boat!
     
  2. rwatson
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    rwatson Senior Member

    That follows all of the story's main points. Your point about it not being that easy to detect is one that is really worrying. The article says that the first warning was when investigators were called in when a boat hull started showing excessive corrosion at the mooring.

    Aluminium may show up problems under welding, but what about the poor composite builders, who just 'pour and set'. How on earth would you know that in ... say 5,7 years the 'plastic' isnt going to crumble and fail. At least with plywood, you can boil it, and 'spot the holes', but how do you test one of the most expensive parts of a boat - the paintwork , for example ?
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

    This, as your date notes is very old news. It also highlights the lack of understanding and knowledge required when using materials for building boats. It also highlights how quickly mis-information spreads, based upon no facts and/or knowledge, which is sad. Just shows how much people are willing to believe Joe Blogs down the road, who's is an expert on..er...um....exactly! Just word of mouth.

    When reading articles like this or hearing from others, it is wise to ascertain the facts, the real facts.

    Real boats, and i stress real boats, boats that are used day in day out by ferry operators, work boats, crew boats patrol boats etc, they want their boats to be built to a minimum standard. They want to buy a boat that is expected to last, under normal service conditions.

    So, how is this achieved?...it is called Classification Society design/build.

    In a nut shell, every product/material must be tested and witnessed by the approving Classification Society. They check the material, how it was made, what methods are used to make it, where does their material, raw, come from, what paper trail is there, is there a proper QA system in place to ensure consistency of product etc etc...is it tested against the industry standards for compliance etc etc....you get the picture. This is why many products used for real boats, I'm not talking about your backyard builder, are not cheap. This is because of the rigorously tested and sourced and administered procedure that the product must undergo go to be acceptable by Class.

    So, back to the 5083 - H321.

    Firstly, this is not a marine grade alloy. To ensure the product is marine grade, the mill that produces it must make the alloy under very exacting procedures and the final product must conform and pass the ASSET 66 & 67 test, if memory serves. This ASSET test is basically to ensure that the alloy does not suffer from exfoliation, peeling away of the layers, once the alloy has been strain-hardened.

    Without getting in too deep on this, the mill (in Osego) cold rolled the alloy to get their final H321, when they should have hot rolled. Hot rolling in a nut shell ensure that the magnesium is evenly distributed in the alloy matrix. So when the final process of strain hardening is done, it does not cause or exacerbate exfoliation corrosion.

    This is why any temper of H321 is not classified as marine grade, it must under go additional tests to ensure it is fit for purpose.

    exfoliation-ASSET test.jpg
     
  4. hoytedow
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    hoytedow Carbon Based Life Form

    The more I learn about boat-building, the less I think I know.
     
  5. Ad Hoc
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    Ad Hoc Naval Architect

    It is like any subject. To scratch the surface (so to speak) is relatively easy. Everyone knows some thing or other about boats..even correct terminology for certain parts: bow, stern, port, starboard etc. But like most subjects, once you go beyond the surface, there is a wealth of information to digest. The "scratching the surface" approach is just a very quick summary for easy digestion. If our interest (or profession) has piqued a desire to know more, it is this that dictates how much we learn/understand by delving deeper into the subject.

    It is a bottomless pit of information...we never stop learning.
     
  6. hoytedow
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    hoytedow Carbon Based Life Form

    That is why we specialize in certain lines, techniques. Mind-boggling.
     
  7. Ad Hoc
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    Ad Hoc Naval Architect

    I have no idea what you are talking about...or is this just a personal rant against those that have more experience and knowledge on the subject than you?

    I simply haven't a clue what this statement is about. Care to elucidate?
     
  8. Ad Hoc
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    Ad Hoc Naval Architect

    The reason why i separated back garden builds to full on Class builds was precisely for this reason.

    In your back garden you can build whatever you like, fit it with whatever you like. But when a real boat, ie a commercial boat, it must comply with a strict set of minimum standards. These standards are often seen as over the top, waste of money etc etc by those that do not rely on their boat being a "workhorse" for the job and often cost well in excess of several million dollars.

    My own little fishing boat, i had cheap cleats on the gunwhales, so what..i know where they came from, and i inspect them regularly for wear tare etc.

    But commercial boats is a totally different world. The standards are very strict. Many amateur boaters do not appreciate this.

    That's ok, none taken.

    I don't blow my own trumpet, I'm not here for that. You can either accept what i say or not, doesn't bother me one bit.

    The point i was making about "not getting too deep on the subject", is that i would have start delving into rather heavy metallurgy theory and how alloys are formed etc. It is heavy stuff. Thus i simply made a quick one line statement about the difference between hot rolled and cold rolled. However, anyone out there is free to look up and either accept what i say or challenge as being rubbish, or find evidence to support the statement. Again, doesn't bother me. (I can provide references of tech data statements etc if required)

    But suffice to say, there is a big misunderstanding about H321 strain hardened temper.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    I find it hard to believe there are independent inspectors on hand during the production process, testing of finished product samples maybe, you can't circumvent the "**** happens" factor in any manufacturing process entirely.
     
  10. Ad Hoc
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    Ad Hoc Naval Architect

    Well, you may not believe it, which indicates that you are not in the commercial field.

    Here is DNV's minimum standards, for starters.

    2.4 Initial Survey of product and production facilities including witnessing of Type Tests. The objective of Initial Survey is to verify that the fabrication, quality control arrangement, product design, material composition and the product marking is according to the Type Approval documentation.

    The main elements of a DNV Initial Survey are to:
    — ensure that production and quality control arrangement are according to requirements as specified in section 4.3 and as stated in Type Approval documentation submitted by manufacturer
    — witness Type Tests, if relevant, as specified in section 4.4
    — ensure traceability between manufacturer’s product marking and the type designation as stated in the application for Type Approval.

    The objective of Type Tests is to verify the ability of the product
    to meet specified requirements by subjecting the test sample to physical, chemical, environmental or operational stresses.

    Type Tests as specified in section 4.4, are to be carried out and
    verified in one of the following ways:
    — at a DNV laboratory
    — at a recognised and independent laboratory accepted by DNV
    — at the manufacturer’s premises in the presence of a DNV surveyor.

    The Initial Survey report and Type Test results are to be submitted
    to DNV Approval Office for evaluation.


    As i said before, ".. commercial boats is a totally different world. The standards are very strict. Many amateur boaters do not appreciate this..."

    You have just proved my point.
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    Well, as I said you can't circumvent potential problems entirely, or this little kerfuffle wouldn't have happened, which proves my point ! You would need inspectors checking other inspectors to see they followed the book, and then further checkers checking the checkers, ah....forget it.
     
  12. Ad Hoc
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    Ad Hoc Naval Architect

    Well, yes and no.

    The yard did not hot roll, they cold rolled the alloy. So what QA procedures were in place?..was it a human error?...was the mill certified to produce Class approved material..and on it goes.

    But as i have noted above, you get what you pay for. When buying aluminium, you can buy it with or without a certificate. If you buy without, you get what you pay for...but, even if buying with a certificate, there is no guarantee, since this too is broken down further.

    If you wish to saves money, you get "just parts" of the boat approved by Class. It is not a full 100% approval, but many operators accept this as "good enough". Otherwise the costs are prohibited. On big tankers Ore carriers etc, this is standard MO, check everything. But on smaller boats, not so, only parts...like the aluminium, for example.

    So, the ally cert was it a "3.1" or a "3.2" type?..if indeed the ally was certified.

    Since 3.1 is a cert which simply declares that the final product has been made in compliance with the requirements. (No visual nor independent checking..ie you are trusting the mill)

    A 3.2, is the full monty, authorised inspection, independent verification etc etc..they look and witness everything. (No trusting just paper work, the inspector(s) look at everything for themselves to verify).

    So, what type of cert, if any, did the mill issue with the faulty H321 alloy?

    You can't just forget it....you are paying for this certification and quality product, you INSIST on it.!
     
  13. rxcomposite
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    rxcomposite Senior Member

    When Ad Hoc posts, it not only answers How but Why.
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    So what it gets down to is legalities, you get a certification that enables you to sue if the product didn't meet the specs guaranteed by the certificate, but in terms of absolute assurance, there is and can never be that ! I mean corruption does exist and you get dodgy inspectors signing off on things they never even bothered to check, that is as old as humanity, and there is no way to eliminate it.
     

  15. SamSam
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    SamSam Senior Member

    And so apparently the answer is yes, you have to personally test everything you put in your boat.
    http://www.professionalmariner.com/...91&tier=4&id=A8E43FA7CD2746F8AACD1DCF82781F6A
     
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