Inspectioneering Journal

Risk-Based Inspection Case of Histories (Part 1 of 2): An Interview with Sean Johnson, Pressure Equipment Integrity Assurance Engineer for the Shell Martinez, CA Refinery.

By Greg Alvarado, Chief Editor at Inspectioneering. This article appears in the July/August 2006 issue of Inspectioneering Journal.

Refinery Background

The Shell Martinez Refinery has been in operation since 1915, and is located 30 miles northeast of San Francisco on about 1,000 acres of land. The refinery combines state-of-the-art facilities and equipment to convert approximately 165,000 barrels of crude oil a day into many products including automotive gasoline, jet fuel, diesel, petroleum coke, industrial fuel oils, liquefied petroleum gas, asphalt, sulfur, and lubricants.

The Shell Martinez Refinery has grown into a sprawling yet efficient assemblage of sophisticated processing equipment; modern control rooms; environmental protection facilities; shipping and receiving terminals for marine, rail, and truck cargoes; maintenance shops; office buildings; quality assurance laboratories; storage tanks; and warehouses. In some ways it resembles a small city with its own utilities, medical facilities, and fire department.

More than 700 men and women fill jobs encompassing a wide variety of activities. Most are highly skilled craftspersons and experienced operating personnel who work to make sure the refinery functions safely and efficiently day and night.

Please tell our readers about you, your position with Shell, how you arrived where you are.

Sean: I started at Shell in 1990 after graduating from Cal Poly San Luis Obispo with a degree in Metallurgical and Materials Engineering. I served as the corrosion engineer for 10 years then advanced to the Technical Assurance Engineer for the pressure equipment group. In this role, my primary responsibilities are to provide technical assurance for corrosion and materials engineering as well as pressure equipment engineering, fitness for service, the approval of all risk based inspection plans, and the selection and interpretation advanced NDE techniques. I serve on the Shell Pressure Equipment Integrity TechNet, the RBI Implementation Team, as well as the Equipment Integrity Global Process Network where we are globalizing many of the well established PEI related work processes worldwide.

Why did Shell decide to implement RBI?

Sean: Shell chose to implement RBI because it is a quantitative way to establish which pieces of equipment carry the highest risk so that our inspection resources could be better focused. RBI can also provide an additional benefit of optimizing turnaround work scopes and maintenance activities while helping to provide a safer workplace.

The philosophy of setting inspection intervals in the past mainly focused on condition based strategies that aligned with turnaround intervals. With the advent of risk based decision making, we determined that we weren’t as good as we would like to be at assessing and communicating risk. About the same time, the API was developing RBI into a usable work product and it was a good fit for many of our newly developing risk assessment work processes. As we globalize our business, risk based decision-making for setting inspection intervals has become a global standard within Shell.

Why did Shell decide to implement API RBI technology in the US?

Sean: API RBI technology was the best tool to implement for Shell refining in the US because it has the most features to quantify risk, and these risks can be calculated continuously overtime which affords us the ability to see not only the current risk, but also how risk changes over time. API RBI also carries with it several degradation modules and tracks each damage mechanisms’ contribution to the overall risk as time changes. It also has features that credit past inspection results, calculates damage rates for different mechanisms, and plots risk results in several different ways.

Additionally, numerous industry corrosion and materials experts have been involved in the development of the API RBI damage modules. This feature of “Corrosion Engineer in a box” will be useful to operating companies that may not have access
to historic damage rates as a function of process conditions. I know world class corrosion experts from Shell and other member companies have contributed significantly to the development of these damage modules.

As far as the consequence calculation, post equipment release, the NIST technology for dispersion modeling for a vast array of fluids used by the API RBI software is also a feature not found with many other risk assessment tools. Considering this and the other features, we feel that API RBI technology is the best way for us to quantify risk that is currently available.

How has Shell US tailored the API RBI process, reporting and data management?

Sean: At Shell, we have chosen to plan our inspection intervals based on certain criteria that involve the likelihood for personnel injury, financial risk in dollars, and a limit of the total amount of accumulated damage. Shell may be unique in this capacity as others typically plot relative risk as a function of, say, predicted square feet of damage or just a position on a risk matrix.

Depending on consequences, the API RBI model may allow the user to exceed the minimum required thickness specified in Code calculations. For the latter, we currently do not plan to operate equipment past Code calculated renewal thickness without further evaluations such as a API 579 fitness for service assessment. Either way gives a relative ranking of equipment from high to low risk. Based on these results, we apply our expert knowledge of NDE techniques as they relate to the primary damage mechanisms to evaluate which equipment needs to be inspected inside or outside of the turnaround.

Additionally, a team of people generates the models with expertise in operations, inspection, corrosion engineering, and maintenance that are intimately familiar with the process unit in question. Operating histories, inspection data, and operational variables are key to developing an accurate assessment of the risk. Once the initial risk assessment is complete, the information is reported to the Operating group and the inspection plans are approved. From there, it is an evergreen work process to keep the model up to date by including changes brought about by process changes, inspection results, process monitoring, or management of change (MOC’s).

Who sets the risk targets for RBI decision making at Shell Martinez?

Sean: Teams of people with experience in health and safety, pressure equipment inspection, risk assessment, statisticians, set risk targets. Personnel safety is of primary importance to Shell, and I believe that many of the risk thresholds for personnel safety were derived from insurance industry information. The initial drive was to set risk targets at ALARA levels, (as low as reasonably achievable). Using these criteria in inspection planning has given good results. As an example, we found that about 20% of our equipment inspection intervals were reduced by RBI analysis using the aforementioned inspection planning criteria.

What challenges that you believe may be specific to the state of California did Shell Martinez have to overcome?

Sean: We have worked diligently with the State of California in developing the philosophy and wording in the State Safety orders that would allow the use of RBI in refining facilities. The final wording that is in the law would limit the maximum inspection interval to 15 years, which is acceptable and should provide operating companies that choose to have their RBI inspection programs approved by the state enough leverage to benefit worker safety and provide alignment with business needs.

What changes are coming for the state of CA?

Sean: The State will have to face familiarization with the RBI processes, as many refining companies have chosen different RBI technologies and work processes to implement their RBI programs. With the State’s proposed guidelines for auditing RBI implementation records, they face a huge challenge to sort through thousands of records every year. This process will take significant resources as well as challenge the users of RBI in the State to maintain excellent records and management systems specifically for the RBI programs.

Who implements RBI at your refinery?

Sean: The Pressure Equipment Group implements RBI. Once the inventory group is established with Operations, the Unit Inspector is responsible for the gathering records and specifications required in the RBI model. The Materials Engineer generally reviews inspection histories, corrosion rates, and inspection strategies, and from there they work together to establish a model and agree on how the each equipment item is modeled in the API RBI software. Once this process is complete, on average, 500 components are modeled within a particular unit. The results are communicated to the Operating and maintenance groups. If all agree to the results, then the inspection plans are implemented. People who work here complete the entire work process at the Martinez refinery. The model is typically owned and updated by the unit inspector and the materials engineer.

What resources are required for implementation?

Sean: As we have implemented RBI entirely with our own resources, it typically takes 3-6 weeks for the inspector to gather inspection data and specifications. The materials engineer typically takes 2-3 weeks to review the inspection histories and to develop a modeling strategy based on inspection history. From there the planning phase of the RBI model will take the two of them roughly 1-2 weeks to complete. Review of the data with the operating department and set up of the inventory groups is 1- 2 days. All in all for an average size unit with 400 pieces of equipment including piping, we are looking at 6-11 man weeks to get it together.


Inspectioneering extends our sincere thanks to Sean for his time and contribution. This sets the stage for another interview where we begin discussing specific case histories, value achieved in the RBI process and lessons learned.

If you have any questions regarding this interview or questions you would like to ask Sean, please e-mail them to the Inspectioneering Journal at


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