On Line Design & Engineering Ltd. provides engineering expertise to the piping and process industry and works closely with leading owner operators in the petrochemical industry. The company was employed to search for possible solutions to maintain piping system operations within a major oil refinery after fitness for service measurements revealed potential problems.
During an inspection phase, a nozzle connection to a critical item of equipment (shell and tube heat exchanger) was found to be corroded. The plant owners were concerned that the remaining thickness to safely retain the fluid during operation was non-compliant with the site schedules and safety standards.
The owner operator wanted to avoid replacing the nozzle as this could be time-consuming and potentially very costly due to the necessary system downtime. To avoid a plant outage, On Line Design & Engineering needed to implement a fitness-for-service solution that enabled the heat exchanger and piping to safely remain in operation.
The main objective was to avoid any costly shutdowns and to have a better understanding of the current state of the piping system. The challenge was to accurately calculate the stiffness of critical components at and close to the nozzle. This was of most significance in calculating accurate loads and stresses.
On Line Design & Engineering implemented CAESAR II® for qualification of piping systems in accordance with appropriate design codes to ensure compliance with site and industry standards. NozzlePRO® supplemented the solution by carrying out local finite element analysis on pipe components, included on the pipe checks.
Using CAESAR II and NozzlePRO, On Line Design & Engineering found that the piping system in question was safe since the loads produced on the equipment nozzle using the more refined and accurate model were lower than the owner operator originally believed. The analysis showed that the nozzle connection was still compliant with site and industry standards, enabling the owner operator to avoid an unnecessary nozzle exchange and an unproductive and lengthy shutdown of the system.
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