A component is loaded by pressure and temperature. This introduces stresses in the material of the component which should stay below a certain allowable stress. The allowable stress of the material is depending on the calculation code, the temperature and the kind of calculation. All calculation codes contain tables or formulas that determine the allowable stress.

For a certain pressure and temperature combination (PT combination) the difference between the allowable stress and the introduced stress by the process will have a minimum. The pressure temperature combination where this difference is at its smallest value is called the 'Critical pressure temperature combination'. The PCC program performs also the detailed calculations to determine the final critical PT combination. Due to the non-linear equations of the branch calculations it is required to evaluate all PT combinations to find the critical combination. The designer can then identify the most critical combinations and needs therefore only to review the related calculations.

The PCC program calculates the critical PT combination based on the selected design pressure/temperatures, the material properties and the detail calculations.