Can the oval pipe analysis be used at pipe bends where the ovality can be high compared to the rest of the pipework system?
A. Although “Haigh’s” analysis is strictly for straight pipe I know that it is often applied to pipe bends. You would have to give consideration to combining the results with other factors, e.g. the pipe bend stress intensification factor, in the assessment. • Q. Can the oval pipe analysis be used for external pressure or vacuum conditions? A. No. “Haigh’s” analysis is strictly for internal pressure systems. Although in principle there is only a sign change for external pressure the problem is more complex as cylinders subject to external pressure can collapse due to buckling, especially with increasing amounts of out-of-roundness. The major pressure vessel codes have rules for cylinders subjected to external pressure.