What does the boiler MAWP determine?

The Maximum Allowable Working Pressure (MAWP) of a boiler is a critical measurement that indicates the maximum pressure at which the boiler is designed to operate safely. This value is essential in determining the structural strength requirements for the boiler's components, particularly the drum or shell. The drum or shell must be constructed to withstand the internal pressures exerted during operation, and the MAWP helps engineers and designers ensure that the materials and thickness of the construction are adequate for this purpose.

When the MAWP is established, it serves as a guideline for ensuring the integrity and safety of the boiler system under normal operational conditions. If the drum or shell cannot withstand the pressures outlined by the MAWP, it could lead to catastrophic failures, such as ruptures or explosions, posing serious risks to personnel and equipment.

Understanding the implication of MAWP sheds light on why it is not directly related to the type of pressure relief valve (PRV), the length of the tubes, or the type of burner. Those elements, while important in their own right, are governed by different design criteria and operational parameters that do not directly correspond to the pressures handled by the boiler's shell or drum.