Our customer is positioned as world leader in cooling system. For a PTA plant, they were responsible for overall engineering tasks related to commissioning of cooling tower and its piping layout. There exist 6 pumps that pick water from cooling tower sump and supply into plant through a pipe network. The pipes may experience surge load when pumps are stopped, started, switched-over or tripped. The pipe support should withstand this surge load. Customer engaged Zeus Numerix to quantify surge load and to assess robustness of pipe supports.
For simulating transient surge phenomena, flow network was modeled in 1D. Reservoir, pumps, pipe sections, couplers, butterfly valves and non-return check valves were accounted in the study. The four identified scenarios were simulated to generate maximum surge pressure. ASME Boiler and Pressure Vessel Code, Section III was referred to calculate stresses at pipe bends and reaction forces on support locations. FE analysis utilized PIPE16 elements and under loads of internal fluid pressure, forces at bend and self weight, stress distribution was estimated.
Zeus Numerix accompanied the customer to end client for presentation of study and analysis of results. Downstream valve failure turned out to be worst scenario generating maximum surge pressure. Corresponding to it, maximum stresses were generated at bend on discharge side of pump; however, they were almost half of material yield strength. Thus layout was proven safe.