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P-Delta analysis has been a near-mandatory requirement in structural design codes for many years due to the importance of its effects in design calculations. In fact, ASCE 7 has over 100 mentions of P-delta (P-Δ). However, piping stress models have traditionally ignored P-Delta effects since most older generation piping stress software programs are incapable of P-Delta analysis.
As this Ansys article says regarding large deflection analysis (aka P-delta): “geometric nonlinearity involves a few different concepts and it is not always easy to identify when it is required.” and “If you don’t know if you need large deflection (P-delta) or not, you should turn it on. There is really no way to know for certain if it’s needed or not unless you perform a comparison study with and without it.”
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