Pressure thickness calculations are generally straightforward and employ simple hand calculations which effectively calculate hoop stress. Piping systems often require many other checks:
  • Code stress compliance to ASME B31.3 - longitudinal stress for sustained, occasional and displacement cases
  • Calculation of loads on equipment nozzles
  • Flange leakage assessment
  • Calculation of loads imposed by piping onto structural supports
These checks are usually done by performing a finite element analysis using beam elements to calculate forces and moments. These forces and moments are then used in code equations to calculate longitudinal stress. In ASME B31.3 these are equations (17) - (20) for displacement stress range and equations (23) for sustained stresses. The forces and moments at critical locations in the piping system (such as flanges, restraints and nozzles) are often required for other checks.
Pipe Stress