Definition - What does Collapse Pressure mean?
Collapse Pressure is the pressure which is supplied from the outside of a pipe. When the Collapse Pressure is higher than the rated or designed Collapse Pressure of the pipe, then the pipe crushes or collapses. In other words, when the differential pressure from outside to inside the tube or vessel increases, the tube deforms catastrophically.
Petropedia explains Collapse Pressure
For a perfectly round-shaped pipe or tubing, the Collapse Pressure has to be relatively high. In case the tubing is not round but slightly oval, the Collapse Pressure at which pipe will break can be significantly less. It is treated as one of the important factors in finding the operating limits of coiled type tubing strings. This happens because the spooling action of the string hence inducing ovality in the tube. The pipe is subjected to both internal and external pressure and the equation can be written as:
Pe = Po –[1-2/(D/t)]x Pi = Delta P + (2/(D/t))x Pi
Po is equivalent external pressure
Pi is internal pressure
Delta P = Po-Pi