EngineerHub.orgWhat this calculator does
Calculates pressure design thickness, adds corrosion/mechanical allowance, and corrects for negative mill tolerance. It does not select a commercial schedule automatically.
Inputs
Results
t = PD / [2(SEW + PY)]. The entered allowance is then added, and the total is divided by 1 − mill tolerance to obtain a minimum nominal wall. Confirm that this equation and every factor apply to the selected piping code, material and temperature.
Background
Optional reading — open any section below.
The pressure term resists hoop stress from internal pressure. Allowances account for expected metal loss or mechanical requirements, while mill tolerance ensures the delivered pipe is not thinner than the required minimum.
Final piping design also considers external pressure, sustained and occasional loads, thermal expansion, branches, bends, threads, grooves, cyclic service, impact, brittle fracture, examination, testing and the selected commercial schedule.
Frequently Asked Questions
Practical questions about code factors and interpretation.
No. Use the allowable stress prescribed by the applicable code for the exact material and design temperature.
No. Select the next available nominal wall that meets all code and procurement requirements, then verify the actual dimensions.