Some questions about ISO 12215-5: 2019

Discussion in 'Class Societies' started by TANSL, May 7, 2021.

  1. TANSL
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    TANSL Senior Member

    I don't know what you mean by "centralized" but there are entities, authorized by the administrations of each country, to deal with those ISO issues. You can talk with them, and ask them about all the issues related to it.
    My question only wanted to know what is done in other countries.
    I would like to know the opinion, the advice, of professionals who do know the ISO, about the convenience, advantages/disadvantages, of its use or its non-use.
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    I mean a central head quarters where one can argue the case.
    For example, the structural Dept of Class...is a centralised 'place, in that sense....and once accepted all regions, worldwide, accept this to be so.

    Have you ever had any success in dealing with "someone" who is authorised to approve ISO rules, on such matters?

    Don't we all..hence my point.
    I gave up long time ago trying to get a 'centralised' response from anyone/body in ISO..it is just nonsense...and replies tend to be..wait until the next update!!
    I can.. if I could be bothered...become one of such "centralised" bodies..it doesn't take much. But the point is..it is just here is the rule...take it or leave...it is binary in that sense....no debate!
    There is no way to apply for dispensations or to argue the point that said rule is not suitable..as once can do in Class rules.

    That's point of what I mean of - 'centralised.
     
  3. TANSL
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    TANSL Senior Member

    I don't know who can be "authorized to approve ISO rules", except the ISO itself. I have approached, if that is what you are asking, the ISO on a number of occasions and have received no response. As for an entity authorized to verify compliance with the ISO for small boats, I have also spoken with some of them and I can say that, in my experience, they are very accessible and open to dialogue.
    I don't need a "centralized" answer, but an answer to the question, centralized or not, that I ask. And what I was asking, to anyone who knows about the subject, is how he would solve the problem of presenting some calculations, which have been made according to what seems to be the correct procedure, and whose results do not coincide with those that would be obtained by applying the formula of the ISO.
    Everything else can be criticism or praise of the norm but they are not answers to my question. Thanks nonetheless for your attempt to help. Giving advice is cheap, but following bad advice can be very expensive. The ISO standards for small craft may have many shortcomings, to be sure, but they probably also have advantages. Therefore, in principle, there is no reason to advise not to follow them, quite the contrary. That is why I am more interested in the opinion of those who do know them and have used them in real cases.
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    And that's the whole point!

    Yet with Class... you can find "someone" to ask and you do get an answer!
    Since you are paying Class for a service...and thus they reply.

    Having worked in the background and knowing HOW they both work (ISO and Class)... I have made the comments noted above.
     
  5. TANSL
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    TANSL Senior Member

    Excuse me, but it seems to me, based on the comments you make, that you do not know the ISO we are talking about well, nor have you had the opportunity to work with the ISO Organization, at least in what we are discussing. It's just an opinion derived from your comments so if I'm wrong, please forgive me. On several other issues, I do respect your opinion, but in this case, I can't do it.
    Humans cannot know everything, humans have to limit their field of knowledge.
    Cheers.
     
  6. Alik
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    Alik Senior Member

    'Class' has another problem - they are heavy and not optimized for craft below 24m.

    Look at new DNV for instance, what scope of engineering is required there for a sandwich structure, including global strength.
    And the calcs for 10m boat will be assessed by guys in Oslo, from special and passenger ship department who have little (or no) clew on small boats.

    So yes, we dont know waht is better - either faulty standards but intended for small craft, or 'centralized dummies' checking your calcs ;)
     
  7. Alan Cattelliot
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    Alan Cattelliot Senior Member

    Yes, Alik, you are right. The graph does only consider the table A7 value, and the values of the shear strenght and of the compressive strenght required should be divided by the kAM factor, as recalled in the application form of the 12215:2019 (annex J). The values should be raised by a maximum of 10/9 when using the simplified method, that corresponds to a 11.11% raise of the value, to be taken into account.

    upload_2022-7-4_21-9-23.png

    Here is a recall of practical definitions of the different methods, established to clarify when each one can be used with profit.


    CHOOSING YOUR METHOD
    Structural analysis of the 12215 demands the user an additional effort to get confidence in the choice of the method. In cause, the “trial and error” approach.

    As the standard will reached his end of presumption of conformity the 1st of July, we have implemented several assessment procedure, until a consensus is attained together with official recommendations.


    Method 1 and Method 2 are proven methods with a high level of consensus among users. Compared with the old standard, they provide updated results from new coefficients formulas, also extending options for users(*). Their domain of validity is very well known.

    Method 3 is a more detailed method applicable to any bi-directional layered composite manufacture. It concerns most of the boat production, since the industry of Plaisance is essentially plastic-based. Using this method requires a lot of trustworthy data from the user(***). However, it has not been possible to find numerical tools to validate unbalanced material compositions with low fiber content, as it is in most of industrialized composition.

    Method 4 makes a link to other standards - ISO,ASTM -, which are specifically applicable to material testing. Habilitated test centers operate under ISO9001 rules are the most thrusted sources. However, local university laboratories or independent test centers may produce poor quality results, depending on their true experience in the industry field.

    Method 5 is used for a pair of decades in boat industry. Most naval engineering cabinets master FE analysis. From their theorical knowledge and practical experience of the manufacturing, they are capable of producing the more realistic results(**).

    Method 6 is the most marginal, but also the most undisputed, being optionally compatible with SOLAS examination. Services companies present on the market propose the drop test.

    (*) Strictly identical in nature to the formulas in the last 12215, the new formulas are more “strain-based”, to encourage users to perform material testing, as well as to go further in their quality insurance of their production.
    (**) The unification of their own method, together with the FE implementation in the standard, pose, in the end, un-solved questions to users. An attempt to propose solutions is under currently under validation study, through our collaboration with G. Dolto in the study of composite panels with the EF method.
    (***) The material composition accessible to users are, most of the time, the thickness, the fiber orientation, the moisture level and the temperature. “Pre-Preg” technologies gain material strength in the formulas, authorizing users to balance the calculated normative efforts inside the material.
     
  8. Ad Hoc
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    Ad Hoc Naval Architect

    They are heavy, if you compare them to a paper thin 5m bath tube - then yes!
    All will be considered heavy...in that sense.:(

    No one in Class is suggesting their rules are optimised for below 24m....you can use them, but like all prescriptive rules, when pushed to the ends of their parametric limitations, odd results pop out.

    And so, when those odd results pop out when using rules for a 10m, you can liaise and communicate with that same very guy you criticise in Oslo, and discuss what is or is not applicable.
    Which guy and where, can you do the same when using ISO? :oops:

    The "better" one in that sense is the one that provides a fit-for-purpose structure, and thus satisfies the SOR.
    Neither Class rules nor ISO will do that..that's the role of the designer, to make the structure fit-for-purpose.....since any set of rules, are just the bare minimum standards.

    Whichever set of prescriptive rules you select, is entirely your choice.
    Criticising or moaning about their applicability wont alter the result... only your blood pressure! :rolleyes:
     
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  9. Alik
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    Alik Senior Member

    In fact, since 2021 we are going the other way: developed our own method of structural calcs for composites (based on first principles, and looking to ISO, LR SSC, RS), making software for it. And get the method/software approved by Class.
    This is because in general quality of norms is going down, and many of them are written by those who are not involved in practical design.

    Regarding ISO12215-5:2019, I have noticed that HullScant2.0 - they are not using official text of standard only, but also some interpretations.
     
  10. Alik
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    Alik Senior Member

    This is something that I don't really understand. The foam is not produced by the boatbuilder, it is produced by foam manufacturer and tested independently. The designer is using msmv values for shear and compressive strength from the certificate of core - why would one apply kAM factor to the foam properties, which is tested? ;) I dont see much logic here.

    What I mean, the old standard was not referring exactly which properties of core to use. So there was a chance to use average values from the certificate/tests. The new 2019 requires to use 'msmv' values which are lower. We usually take properties of foam from certificate issued by the Class...
     
  11. Alan Cattelliot
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    Alan Cattelliot Senior Member

    And eventually the purse of the boatyard, in the case of an ISO review by a Control Authority who applies the standard, no matter what contradictions there is in it, and requires more and more additionnal calculations, to cover their butt.

    Standards, erroneous or not, are meant to be used with intelligence, and by an agent with a proper engineering background. Doing that, you are able to determine the minimum requirements, as prescribed by the standard, and discern between the requirements that are applicable, and those which are not.

    The Control Authority should be considered as in the best position in knowing how to determine the minimum requirements.
    The boat Builder should always be considered as in best position to discern the applicable requirements, among the minimum requirements.

    The Control Authority and the Boat Builder are to put their best efforts in maintaining their position.

    But that would be the better of the world, wouldn't it ?
     
    Last edited: Jul 5, 2022
  12. Ad Hoc
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    Ad Hoc Naval Architect

    Indeed.
    Life would/is always easy when there is seamless liaisons and common understanding between multi-parties.
    But in the case of prescriptive rules...this is only achieved by a shared history and common understanding of each others abilities and the end objective.

    I was lucky enough - many years ago - to have such with a Classification HQ structures Dept.
    They later told me they never bothered checking my work after a few years, when submitted, as I they saw, in their eyes, that I always did the 'right' thing..no matter what the rules said.

    In this day and age of press buttons and instant graphs and spreadsheets, proper communication and understanding of structures - both theory and practice - and its applicability, has been lost.
     
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  13. TANSL
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    TANSL Senior Member

    @Alik and @Alan Cattelliot, very interesting and useful your experiences, reflections and comments. Many thanks.
     
  14. Alan Cattelliot
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    Alan Cattelliot Senior Member

    You're welcome TANSL, even if what ve said does not really help in your practical cases. I'm very sorry.

    The situation regarding the ISO is different, depending on the point of view of the user. So is the answer at the question :"How can we manage a 12215 review in the context of the standard that do not correct ?". As AD HOC was saying, without a shared history and common understanding of each others abilities and the end objective, the fact that the 12215 rules are put in question, really force us to find " #TANSL#how he would solve the problem of presenting some calculations, which have been made according to what seems to be the correct procedure, and whose results do not coincide with those that would be obtained by applying the formula of the ISO."

    This is how I do it, as a reviewer.
    -Compute the minimum requirements according to the rule
    - Comment the minimum requirements and highlight the error in showing how the computed requirement does not fullfill the intended purpose.
    - Detail the correction, add any technical document, explaining how the corrected requirement fullfill the intended purpose
    - Compute the corrected requirement
    - Present all the results and analysis
    - add a note like :
    "Where these are adequate and relevant, some requirement of the standard have been explicitly adapted to the craft's particular with respect to their intended purpose, as defined in the standard. Additionnal requirements have been established, from the requirement of the standard, that have been adapted. Those additionnal requirements are also reviewed, together with the following reference documents. They shall not be considered, in any way, as replacing or correcting the reference ISO standard, and their use is limited to the execution of the present review. "

    Most of the time, it passes without question, sometimes, it triggers new requests from the control authority. But it has never be invalidated by no control authority in Europe.

    For the control authority, the question is somehow, more difficult. The use of the ISO standard is mandatory for any control authority in many countries, so none of them can skip a full application of all the requirements, even if the requirement is stupid.

    A approved standard - in the meaning of ADHOC -, represent a good insurance for any institution. In contrario, a standard that is not accepted exposes the institution to the risk of not being able to distinguish between the applicable requirements, whether they can rely on a sufficient level of expertise, or not. And even having an extra expertise on the suject raises their exposure to the risk of making a false distinction.

    As a consequence, I would say that the use of the ISO 12215 standard leads, in general, in spending more time and more money, than using other procedure, when available. I wouldn't say that I'm satisfied by this present situation.
     
    Last edited: Jul 5, 2022
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  15. Alan Cattelliot
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    Alan Cattelliot Senior Member

    I share your point of view, or, I may be a little more pessimist than you, because I see a very lazy but common confusion, in people's mind : . The result of a ruled review demonstrates that your REVIEW is correct, but not that your RESULTS are correct. In France, undergraduate's student are given the education of basic rules that applies in some matters, but no explanations of the meaning of the rules themselves. Sometimes, they are given explanations derived from the rules themselves, which brings nothing under the sun...
    Verifying that something is true is then reduced to repeat, till the end of the times, the same rules, the same procedures, without being able to question the rules, when needed.

    Human societies are more interested in having a consistent, eventually stupid, set of rules, instead of being aware of the truth. Understanding the theory can be seen as a waist of time, The truth is crude, with angles, without compromise, very unstable. Any reflexion about the applicability exposes at too much trouble. In that context, Ruled system are considered as better insurance than understanding ; you can always show that you followed the rules, but it may be hard to demonstrate your understanding.
     
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