SnTMan & ggrindle, thanks for your help, however try this...
My equipment is not a 'pipe' as such (not part of a processing plant with piping supports etc), it is a downhole tool (oil industry) which is round in section with changes in wall section along it's length, etc, not a plain od/id pipe...
I use Lame' equations to calculate Int. Yield and Collapse,
on components which are round. The length of the sections are invariably relatively short (less than 2ft).
I am trying to qualify a statement in a calculation regarding length criteria in a thin walled shell. The formula is simply...