How do you know if a pipe failed due to excess pressure?

The approach for a pipe stress analysis is detailed in industry-standard codes such as ASME B31.3 and EN 13480. In such a pipe, stress analysis assessments are done for a range of failure mechanisms, one of the principal ones being the design against plastic collapse. This happens when the primary stress in the pipe wall exceeds the yield strength of the material.

The internal pressure within the pipe exerts a primary load on the pipe wall. Therefore, it is important to understand the effects of pressure on the behavior of the induced stress in the pipe. It can be seen by comparing the equations below that the hoop stress is always twice the magnitude of the longitudinal stress in pressurized piping.

If you are confronted by a failed piping as seen in the image below, the relationship between hoop and axial stresses allows you to immediately see if the burst in the pipe is due to excessive internal pressure. This can be concluded by looking at the direction of the crack in the material. The crack direction is always perpendicular to the direction of the stress that caused it, so a crack (or burst) caused by excessive internal pressure always runs in the longitudinal direction of the pipe.

Want to grow your skills in performing a pipe stress analysis conform ASME B31.3 or EN13480, consider our learning path “Pipe Stress Analysis according to ASME B31.3 and EN 13480”

To focus only on the failure mechanisms and loading types consider our short course "Failure Modes and Allowable Values for Piping Analysis."