Overpressure Protection

We offer a complete overpressure protection systems analysis including the checking and verification of process safeguarding, relief devices and disposal systems.

Schedule-driven design projects, limitations on skills or resources and the consequent limited evaluation of complex overpressure issues can lead to safety risks.

Operating assets and lifecycle management-of-change carry a risk of external agency inspections identifying non-compliance and ordering shutdown.

We can help you be compliant.

PSE provides a straightforward, one-stop solution for overpressure analysis and design. We offer rapid analysis of potential external audit findings and we can apply rigorous simulation tools when required. With an experienced team dedicated to relief and blowdown analysis, PSE has the knowledge to provide the most cost-effective solutions.

Pressure relief stream verification and auditing

Relief stream verification checks all factors that affect the device capacity within the system of piping it is installed in. PSE performs audits on either representative sampling or full detailed checks of calculations, depending on the level of documentation existing for the facility.

  • Governing relief scenario correctly identified and calculated
  • Confirmation of relief device sizing and selection
  • Integrity of calculations and relief documentation
  • Rigorous simulations, fire survivability
  • Flare network capacity

Process safeguarding

Process safeguarding is the term applied to systematic evaluation and recording of a facility’s overpressure protection. PSE has wide experience in overpressure protection system design, including the analysis of relieving requirements and provision of relief devices.

Process safeguarding includes a written analysis of all potential causes of overpressure, the relevant features of all safety systems (including instrumented protective systems, relief devices, blowdown and sectionalisation) and a full record of safety devices on the Process Flow Diagrams (PFD) – illustrating at high level the scope and extent of pressure systems. These documents are an important record of all overpressure safety systems as designed, and should be embedded in company operating manuals and operator training plans. Many operating companies require this documentation, in addition to detailed safety device calculations and equipment datasheets.

In the American Petroleum Institute’s (API) review of equipment falures caused by overpressure, the overwhelming cause of vessel failures was an improperly sized relief device. For example, the catastrophic failure of the LP separator at the Grangemouth refinery in 1987 was a result of the relief valve not being sized for the breakthrough of HP gas from the upstream hydrocracker.

The API 521 code of practice defines most of the commonly encountered overpressure scenarios. While not an exhaustive list, it is typically used as the basis for a formal review aimed at evaluating the relieving rates and determining the scenario which requires the largest relieving area. In our overpressure protection design analysis, PSE reviews the credible causes of overpressure and establishes the required relieving rates to determine the governing scenario and sizing basis.

HIPPS, blowdown or relieving devices – new designs

  • Identifying potential for elimination or mitigation of relief loads
  • Applications for HIPPS
  • Requirement for blowdown valves and plant sectionalisation to protect assets
  • Sizing of orifices and analysis of flare disposal capacity
  • Mitigation of low temperature / brittle fracture risks