Stress Analysis and Design Evaluation of Centrifugal Pump Discharge Line Piping System Connected to a Heat exchanger

Abstract

Liquefied Petroleum Gas (LPG) is flowed from the cold fresh separator to the heat exchanger
via a centrifugal pump in a piping system at a temperature of −101°C and a pressure of 435 psig. This
path is classified as critical and is analyzed using stress analysis software to evaluate stress, nozzle
load, and natural frequency. The shortest pipe span of 22,5 feet was selected based on deflection limits
for safety considerations. Initial results showed sustained (24576,5 psi) and occasional (28811,2 psi)
stresses at Node 470 exceeded ASME B31.3 limits, while expansion stress at Node 850 (7865,9 psi)
remained within the allowable range. After support modification, sustained and occasional stresses
were reduced to 2108,4 psi and 4101,4 psi. Nozzle load on the pump remained within API 610 M limits,
while the heat exchanger initially exceeded API 662-2 limits; both became acceptable after support

adjustment. The initial natural frequency of 2,298 Hz was insufficient, but increased to 8,028 Hz post-
modification, meeting DNVGL-RP-D101 (2017) criteria.