Required pipe run expansion is based on the thermal expansion coefficient of the pipe class. These coefficients are listed in the thermal-expansion-coefficient data table (see Appendix A - "Table: DPAR-THERMAL-EXPANSION-COEFFICIENTS (needed)") and are based on material type and temperature. Material is obtained by cross-referencing the ther-exp-mat-type found in the pipe-class-properties data table. The table lists coefficients at 100 degree increments (Fahrenheit for English projects, Celsius for metric projects) in the form of expansion per pipe length. Coefficients at line design temperature are obtained through linear interpolation of the table values. The coefficients are then multiplied by the length of the pipe run to obtain the required expansion.

For each pipe run, the expansion to be absorbed by loops is calculated by subtracting the expansion allowed at changes of direction from the total required expansion. (The expansion allowed at changes of direction is set as a project variable and is based on the pipe diameter.) The number of required loops is then calculated by dividing the expansion to be absorbed into loops by the allowable expansion per loop. (The expansion allowed per loop is also a project variable and is based on the pipe diameter.)