Many in safety may not recognize that the “burst pressure” of piping is NOT the same as the Maximum Allowable Working Pressure (MAWP). ASME B31.3 requires the facility to identify and work within the MAWP.
For those who may not know the difference and why it matters…
The MAWP is the safe operational limit of the piping system. It is the maximum pressure at which a pipe or component is permitted to operate. It is determined by applying design factors, material allowable stresses, and code-specified safety margins. It is the pressure used to establish the system’s “operating envelope.” We must never intentionally exceed the MAWP during normal operation.
The Burst Pressure is the failure threshold of the piping. It is the theoretical or actual pressure at which the piping (not the joinments such as welds, flanges, threads, etc.) will physically rupture or deform to the point of structural failure. It is NOT a value intended for operation or even for pressure/leak testing the piping. It serves as a benchmark for the structural integrity of the material and wall thickness.
The “burst pressure” is significantly higher than the MAWP. The difference between the two is defined by the Factor of Safety inherent in the design code.