(112a) An Overview of PHA Templates and Checklists Developed for a Refining System and Lessons Learned

The Chevron Refining organization has completed a multi-year effort to create Process Hazard Analysis (PHA) templates and checklists in an effort to improve the consistency and quality of PHAs. The goal of this paper is to provide an overview of the content, development process, and lessons learned. The hope is other organizations can use the information provided to drive improvements in their PHAs and improve the management of process safety.

Template and Checklist Content

First, here is an overview of the HAZOP and LOPA templates and checklists and how they are utilized by PHA teams at the Refineries. The templates and checklists cover the following common processes:

Sulfuric Acid Alkylation, Amine and Sour Water processing, Cogeneration, Coker, Crude, Distillation, FCC, Hydrogen Reforming, Hydroprocessing, Isomerization and Reforming, and Sulfur Recovery,

and equipment:

Boilers, Compressors, Cooling Water Towers, Fired Heaters, Pumps, Relief and Flare Systems, Atmospheric Tankage and Pressurize Storage, and LPG and NH3 Loading.

For most templated scenarios resulting in loss of containment of a flammable or toxic material, teams are required to utilize release consequence modeling and ignition probability data from facility quantitative risk assessments (QRAs) to determine the consequence severity and modifiers for the specific process units. This provides a consistent and rigorous method to adjust templated scenarios for the differences in process unit pressures, temperatures, flow rates, volumes, population densities, etc. For templated scenarios that result in consequences such as shrapnel, thermal burns from hot materials, corrosive burns, etc. consequences and modifiers are fixed in the templates with PHA teams required to consult with subject matter experts (SMEs) prior to adjustment.

PHA teams are required to apply all applicable template scenarios and utilize standardized lists of safeguards and independent protection layers (IPLs). The templates require PHA teams to select specific safeguards or IPLs for scenarios or make a recommendation when required safeguards/IPLs are not present. When more than one potential safeguard/IPL may address a hazard selection guidance is provided to the teams. Prior to teams utilizing safeguards or IPLs other than those specified by the templates they are required to consult with the relevant SMEs.

PHA checklists supplement the HAZOP and LOPA templates for scenarios for which HAZOP and LOPA are not ideal methodologies (e.g., double jeopardy scenarios, escalation events, etc.). The PHA checklists create minimum requirements for safeguards with PHA teams required to make recommendations for gaps when identified. The checklists were created by process, equipment, and process safety SMEs. Again PHA teams must consult with SMEs to adjust the checklists for unique conditions.

Other materials produced and available to PHA teams include:

Technical bases, guidance documents, and safeguard / IPL design details for PHA teams to use to improve understanding,

Training webinars conducted with current PHA facilitators to allow for efficient referencing of topics during studies by PHA teams and for training of future facilitators,

Generic process flow diagrams (PFDs) of process units referencing the applicable portions of the templates and checklists.

Template and Checklist Development

Now that an overview of the template and checklist contents and use has been provided, an overview of how they were created will be given. The creation was led by a small core group of experienced facilitators working over a period of several years with the relevant process and equipment SMEs. The typical information used to create the templates and checklists included previous PHAs, process and instrument diagrams (P&IDs) from multiple similar units and equipment, incident histories, best practices, etc. Approximately 70 SMEs participated in the creation process with several years of Full Time Equivalents (FTEs) committed to the project. Each set of templates and checklists went through an endorsement process including refinery operations, technical, and PSM management as well central PSM management.

The reasons for creation of the templates and checklists are likely not unique to the Chevron refining system. The primary reason was an on-going effort to improve the quality and consistency of PHAs. Quality issues included:

Similar scenarios with similar losses of containments ranked with orders of magnitude differences in risk and a corresponding difference in listed or recommended safeguards and/or IPLs leading to the potential under or over management of risk.

PHAs missing process safety hazards such as backflow, furnace bogging, etc. even when hazards and incidents were available for teams to review within existing incident databases, best practices, etc.

A centralized templated approach was selected because:

The need to complete PHA studies in a reasonable timeframe and on a predicable schedule as well resource limitations for SMEs made it difficult to improve studies simply by bringing the SMEs into ongoing studies.

Changes in personnel performing the PHA facilitator role, whether from normal attrition or intentionally to build process safety organization capability, created a need for a means to rapidly build competency for new facilitators.

Template and Checklist Lessons Learned

Finally, an overview of some key lessons learned during the template and checklist development will be provided. Lessons learned included:

Members of PHA teams and SMEs have differing experiences and perspectives on the risk of losses of containment necessitating a standardized method for developing consequences and modifiers. The earliest attempts at template development relied on the teams of SMEs, including senior facilitators, to use their experience and judgement to qualitatively determine consequences, modifiers, and risk. When scenarios were compared between templates, inconsistencies remained with the differences in SME experience leading to variance. Simply improving the experience level of the teams performing the analysis did not result in improvements to the analysis to the desired degree. This learning resulted in the development of the technique to utilize QRA release consequence modeling and ignition probability data as a standardized method for consequence and modifiers within PHAs and LOPAs.

Typical PHA teams (e.g., facilitator, process and/or design engineer, and operator) cannot have the depth of engineering and operating experience to thoroughly understand the varied types of equipment and processes in a typical refining unit. This can be highlighted by the varied number of templates and checklists that may be required to be used by PHA teams for a typical Hydroprocessing unit. The teams will typically utilize over 100 required scenarios from the PHA and LOPA templates for equipment including pumps, compressors, relief systems, fired heaters, boilers, tankage, cooling water towers, distillation columns, as well as Hydroprocessing technology specific scenarios such as reactor temperature excursions, backflow, loss of flow through furnace tubes, etc. In addition PHA teams may need to apply up approximately 40 requirement checklists to supplement the analysis.

PHA teams cannot realistically bring in SMEs on an as needed basis to aid with the analysis.

Arranging for the availability of appropriate core team members (composition and experience level) for ongoing studies is a constant effort.

SME resources typically have limited availability, and “on-demand access” for all the ongoing PHAs impractical.

Even if PHA teams did call in SMEs on an as need basis, SMEs for the same process or equipment often have different perspectives on similar issues. During template and checklist development it often required substantial effort (up to several months) to educate a group of equipment or process SMEs on PHA methodologies, work to align the experts on a common understanding of process safety hazards and align on a standardized solution for a single issue for a single piece of equipment.

There was some concern that creating templated solutions might cause PHA teams to lose their creativity and focus only on the templates, and that templates might omit or incorrectly assess a hazard. While neither of these issues can be completely dismissed, feedback from PHA teams using the templates and checklists so far has been that the benefits of the templates outweigh these concerns. One of the unexpected benefits of PHA teams using the templates and checklists is when the templates do not appear to apply to a unique design or situation the teams are often contacting the SMEs for assistance. This has led to a shift in SMEs participation in ongoing studies from reviewing the common issues already integrated into the templates to the unique situations where their expertise can provide value added input. Also, when PHA teams have encountered areas within the templates in need of improvement the teams have frequently contacted SMEs for assistance.

This concludes an overview of content, development process, and lessons learned from the HAZOP and LOPA templates and checklists developed for the Chevron refining system. Hopefully others will find this information useful to drive improvement of PHAs and improve process safety management in their organizations.