Critical P & ID Reviews Using HAZOP/LOPA Methodology Overkill or Underrated?

  • Type:
    Conference Presentation
  • Conference Type:
    AIChE Spring Meeting and Global Congress on Process Safety
  • Presentation Date:
    May 1, 2013
  • Duration:
    30 minutes
  • Skill Level:
  • PDHs:

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Critical P&ID Reviews Using HAZOP/LOPA Methodology ? Overkill or Underrated?

Mr. John T. Perez, P.E.

Mr. Andrew Madewell

Cognascents Consulting Group, Inc.

11777-A Katy Fwy Ste 438

Houston, TX 77079

Keywords: Process Safety Management (PSM), HAZOP, LOPA, Process and Instrumentation Drawing (P&ID), Process Hazard Analysis (PHA), Inherently Safer Design (ISD).


Prior to moving from define phase to execution phase on a given project, the typical project protocol is to perform a critical process and instrumentation drawing (P&ID) review as a transition from ?issued for information or preliminary design? to ?issued for design or HAZOP?.

The objectives of a critical P&ID review are to (1) identify commercially-positive design changes early in the project lifecycle to reduce downstream implementation costs, (2) identify operational concerns to ensure optimal resolution and long-term operational effectiveness, and (3) identify safety vulnerabilities for early application of inherently safer design (ISD) principles where possible and early identification of safety integrity levels (SIL) for required safety-instrumented systems (SIS).

Companies perform critical P&ID reviews using various evaluation methods, including P&ID symbology/element checklists, process hazard analysis (e.g. Checklist, HAZID, and HAZOP), and ?cold-eyes? review. Each of these approaches provides structure to a critical P&ID review; however, each also provides opportunities for commercial, operability, and safety vulnerabilities to remain in the design when applied independently.

The author posit that use of a hybrid HAZOP/LOPA process hazard analysis methodology to conduct critical P&ID reviews results in a more rigorous evaluation and reduces the likelihood for commercial, operability, and safety vulnerabilities to persist into the design/execution phase of projects. In this paper, the authors present the advantages and disadvantages of using a hybrid HAZOP/LOPA approach for critical P&ID reviews. They also provide recommendations to enhance the effectiveness of the HAZOP/LOPA methodology when applied to critical P&ID reviews. Specifically, the authors provide examples of commercial benefits realized, enhanced operational insight, ISD successes, and application pitfalls when applying a hybrid HAZOP/LOPA PHA methodology to a critical P&ID review.

The target audience for this paper includes project managers, project engineers, EH&S managers, PSM coordinators, and operators; however, anyone involved with small or large capital projects may also benefit from this paper's content.




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