PCC - ASME B31.3 special features
The ASME B31.3 states that fittings do not have to be calculated in case the fitting is listed in the Table 326.1. This table gives a list of standards with fittings having an established rating.
However, under special circumstances or when a fitting (such as a Tee) is custom build, the fitting needs to be calculated.
PCC has a special setting for the pipe classes which allows the calculation of custom fittings or also to calculate the rated fittings. The check mark as shown in above image allows the engineer to make the detail calculations for the rated or custom fittings.
The rating only of the fitting is checked against the pressure temperature combinations of the pipe class when the check mark is unchecked.