Some Observations on the Analysis of High Temperature Steam Piping Systems

The effects on system stresses and terminal moments of some factors not normally considered in high temperature steam piping design have been assessed by analysing notional but representative pipe lines. The factors considered include bend flexibility, anchor stiffness, rotational restraint achieved during cold pulling, and extraneous loads introduced by hanger hysteresis. In addition, the influence of hanger lateral stiffness is quantified by evaluating the implications for thermal expansion stress/displacement ranges and cold pull design.Procedures are developed enabling cold pull distances to be calculated which either induce predetermined moments into the system or minimize the difference between moments at specified locations and a required set of values.It is established that certain of the factors considered can have an appreciable effect on terminal moments and system stresses. Consequently it is essential to include them in design analyses.