Piping System Design & Relief Sizing for a Process Unit

Problem

A process unit required a new piping design package covering several hot process lines running between a reactor, heat exchangers, and downstream storage. The lines needed to satisfy ASME B31.3 requirements for thermal expansion, support loading, and equipment nozzle loads, and the associated relief devices needed to be sized for the governing overpressure scenarios.

Approach

• Developed the line list from the PFD/P&ID, capturing design temperature, pressure, and fluid service for each line.
• Performed a stress screening pass to identify lines requiring detailed flexibility analysis, then modeled the governing lines in CAESAR II to check code stress, displacement, and nozzle loads against allowable equipment limits.
• Identified governing overpressure scenarios (blocked outlet, fire, control valve failure) for each protected system and sized relief devices accordingly, then checked relief header sizing for the combined relief load case.
• Iterated pipe routing and support locations with the piping designer to resolve flexibility and interference issues before issuing for construction.

Outcome

Delivered a piping design package (stress reports, isometrics, line list, relief datasheets) that passed client engineering review with no code-compliance rework items, and confirmed nozzle loads were within vendor-allowable limits for all major equipment.