Questions & Answers
Why is my multilayer M pipe with the highest SDRm not the weakest pipe in my dimension group?
It should be taken into consideration the SDRm rule in the ISO standard is only a rule of thumb for appointing the so called “weakest” pipe in your dimension group. In practice other dimensions with lower SDRm values can be “weaker” on hydrostatic extrapolated values due to dimensional aspects of the pipe construction. Before starting a hydrostatic strength evaluation on a metal multilayer dimension group, be sure which pipe construction is your “weakest” pipe and perform the full evaluation on this pipe dimension.
Marco Mekes