Overpressure Protection Assessment

Overpressure Protection by System Design

CANEIL houses a strong team of multidisciplinary Integrity Professionals with backgrounds in Process, Mechanical, Chemical, and Materials Engineering to provide clients with support on OPPSD.  Furthermore, CANEIL employs software professionals as part of our OPPSD team to automate data collection and filtration as well as semi-automating final report writing.  The use of in-house software allows CANEIL to deliver OPPSD Assessments with unrivaled efficiency while minimizing error.


Jurisdictions require detailed assessments and documentation to demonstrate that pressure equipment is protected against overpressure and loss of containment.  Overpressure protection can be provided by a pressure relieving device (PRD) such as a pressure safety valve (PSV), pressure relief valve (PRV), rupture disc, or pin device.

Alternatively, under specifically permitted cases, overpressure protection can also be provided by overpressure protection by system design (OPPSD). CANEIL’s OPPSD team is trained to determine if existing over-pressure protection is acceptable and make recommendations on necessary safeguards to ensure overpressure protection requirements are met.


OPPSD is broken into two categories:

Source: chemengonline.com

Self Limiting

Self-Limiting OPPSD applies to systems where all sources of pressure have an inherent maximum limit (e.g., the maximum impeller size on a centrifugal pump)

Non-Self Limiting

Non-self-limiting applies to systems where the source of pressure is not inherently self-limiting; where protection will be provided by some combination of safety instrumented systems, administrative controls, and PSVs.

Source: aiche.org

The Process

The OPPSD Assessment process begins with loop identification, including the identification of PRDs and the equipment they protect, equipment partially protected, and any equipment where pressure protection is vague.  Pressure equipment not fully protected by a PRD is assessed for all valid overpressure scenarios as described in API 521, as well as any specific scenarios described by the jurisdiction; to determine the maximum upset condition.

An overpressure risk assessment (ORA) is generated that documents any existing or required safeguards to satisfy the results of the overpressure assessment. CANEIL also ensures that the client’s integrity management system incorporates any OPPSD-specific requirements, according to the jurisdiction.

CANEIL's Approach

To ensure the best of services are provided to our clients, we partner and work with leading simulation software. The software our experts use are Aspentech’s Hysys, Aveva’s ProII and IPRSM by Curtiss-Wright. These software enable us to efficiently model vessel pipeline design and run a number of scenarios along with generation of highly accurate drawings.

Below are a few examples of the work where the software mentioned above were used to create accurate models: