Project Synopsis

Evaluation of refinery pressure relief valves to determine relief valve capacities relative to current process throughput rates.

Project Summary


Process Engineering Associates, LLC (PROCESS) was contracted by the client to conduct a comprehensive evaluation of selected refinery pressure relief valves for the purpose of determining relief valve capacities relative to current process throughput rates.  Project elements included:

  • Refinery process information review
  • Heat and mass balance and vapor-liquid equilibrium calculations preparation
  • Relief valve relief requirements and capacities evaluation.

PROCESS reviewed the client’s engineering documentation to identify existing relief valve locations, applications, and sizes.  Existing heat and mass balance information was also reviewed and additional heat and mass balance and vapor-liquid equilibrium calculations were performed by PROCESS using commercial computer process simulation software to complete the refinery throughput information required for the relief valve evaluation.  The computer process simulation software was also used to determine relief stream detailed chemical/physical properties as required for input to PROCESS’ proprietary in-house relief valve capacity computer program.  This program was used to evaluate the vapor and liquid relief capacities of each relief valve as well as relief requirements for identified potential pressure relief scenarios, including:

  • Blocked liquid and/or vapor flow
  • External fire
  • Loss of cooling
  • Loss of power
  • Gas blowby
  • Malfunctioning control valve
  • Heat exchanger tube failure
  • Reverse/misdirected flow
  • All other pressure relief scenarios identified during the course of the evaluation.

The same computer technology was used to calculate the required size for relief valves determined to be undersized for the current applications.

Relief valve evaluations were performed for 100 valves not evaluated during previous PROCESS project for the following refinery process units:

  • Crude/vacuum
  • Hydrogen
  • FCC unsaturate gas
  • Fluid catalytic cracking
  • Saturate gas plant
  • Naphtha hydrotreater
  • Reformer
  • Naphtha splitter
  • Isomerization
  • Sulfur recovery
  • SCOT
  • Amine
  • Cat feed hydrotreater
  • HF alkylation.

In addition, PROCESS identified 20 heat exchangers that required relief paths to cooling towers to mitigate potential tube rupture overpressure scenarios.

Industry Type

  • Petroleum Refining

Utilized Skills

  • VLE calculations
  • Computer process simulation
  • Pressure relief valve (PRV) and pressure safety valve (PSV) sizing
  • Comprehensive relief valve evaluation

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