SHR,

I have dealt with re-analysis of large bore gas transmission piping, where the design temperature was 50 deg C and a stupid engineer thought it ok to ignore pressure elongation. It was thin wall, high yield pipe and the thermal equivalent of pressure was about 25 deg C. Consequently expansion and thrusts were grossly under-estimated. Clearly pressure elongation and thermal expansion are not the same, but ignore pressure effects at your peril.

Returning to your latest missive ... Deliberately introducing an error is ok provided it's not a huge one ? That is a bold judgement. How big is huge in that sense ? To paraphrase a famous WW2 air vice marshal, there are old stressmen and bold stressmen, but no old, bold stressmen. Think about it.