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"But the concept of "alternate rules" causes misunderstanding with many engineers."

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I guess this is the real problem. Maybe you should give a better guidance regarding this Appendix P (and B31.3 as well).

While being obscure prevent beginers to perform calculations (in fact do not prevent it at all),it will also prevent clients to understand the real problems and to have basis in rejecting poor calculations. It is a matter of "who is the strongest stone".