A Functional System Approach to Criticality Analysis, Fsca

ABSTRACT

A Functional System Approach to Criticality Analysis, FSCA.

This paper will outline and discuss a new and unique approach to physical asset criticality analysis: Functional System Criticality Analysis (FSCA) and illustrate key results with two sample case studies.  This approach is applicable to any type of complex facility or process where process security and continuity are paramount.  It has consistently identified previously unknown significant risks that were missed by other methods and analyses such as HAZOPS, FMA, process reviews, and can quantify the risk potential in dollars.  A functional system based approach (FSCA) is more efficient than current methods through analyzing and ranking system risks via system failure scenarios rather than failure modes at the asset level.  It is an invaluable tool and approach when risk mitigation is important to assure overall success balanced against the reality of limited time, capital, maintenance, and staff budgets. 

The two case studies featured involve an Envirex ground water remediation facility, and an industrial RO water treatment system within a refinery.  Each study had a unique set of evaluation criteria determined by the client's values and the specific performance, contractual, and regulatory issues affecting the facilities.  Importantly, in each case study previously unknown significant system risks were identified, as well as highly effective mitigating steps. 

Approach:

Several key principles are foundational to the functional system based approach to criticality analysis, FSCA:

•             A deep and well structured hierarchy of the asset register, leading to a rigorous parent/child ratio

•             Inclusion of all valves and pipes (strive for 100 percent asset listing) in the hierarchy

•             Uniform asset levels (every pump is an asset no matter where it is or how big)

•             The grouping of assets into single-purpose functional systems

A very clear description of the mission statement/priorities is very important in this type of an analysis.  Whether it is defined as a level of service or a more numerical set of KPIs, the defined mission of the physical assets under review will determine the categories evaluated against: safety, environmental, up-time, product quality, maintenance cost, capital replacement, etc.  These in turn must also be clearly and uniquely defined from one another on a severity scale ranging from virtually ‘no impact' through to ‘worst case' in the client specific nomenclature.  The next step is to proportion or allocate a contribution ratio for combining categories into overall risk.  This will determine, for example, the relative importance or ranking of a worst case scenario compared against a scenario with 2 or 3 instances of a slightly lesser consequence.  These can be adjusted to suit a client philosophical approach. 

With these principles in place, a risk analysis is then performed at the functional system level derived from the hierarchy, prior to the asset level. Failure scenarios and their resulting consequences are evaluated per the evaluation criteria defined (not failure modes since those are at the asset level).  The failure scenarios for each functional system define a composite risk space for each system, and then each system is ranked against all others in terms of risk. 

Important to note is that assets within a parent system initially assume the risk ranking of the parent system.  Thus, systems with highest risk ranking (mission critical) are then further evaluated at the asset level, employing a suitable mix of evaluation tools (RCM, FMA, etc) to discern which of the contained assets pose the highest risks to the mission objective.  Systems with low risk ranking do not have assets that can significantly impact the mission, are thus not mission critical, and are thus relegated to a lesser priority for further evaluation.

In this approach mission critical assets are more rapidly identified with subsequent evaluations more efficiently utilizing complementary tools saving time, staff resources, and money.  We have also found that, due to the unique arrangement of the assets within the system level and overall integration, this approach captures risks that might otherwise be missed.

Base Case 1.  Envirex Ground water remediation system

In mid 2004 a sequence of unusual, but not extraordinary, events led to an extended shutdown of a key ground water remediation process consisting of extraction wells, a fluidized bed activated media treatment process with filtration, and internal re-use of the treated water.  The result of this was that the owner was at considerable risk of consent decree violations.  Excellent engineering, standard process reviews, HAZOPs, and an aggressive maintenance program had not correctly identified risk. The need to find the true risks in the system was paramount.

Response:

The owner requested assistance in the evaluation of the overall process to identify the as yet hidden risks and related potential issues in order to prevent future similar and unforeseen occurrences.  The Uberlytics criticality analysis approach and an early version of a software tool were brought in and applied in a workshop environment where the owner's system experts, including engineers and operators, were brought together with a criticality analysis expert facilitator.

Inclusion of 100% of the overall process units in this functional area of the refinery, and inclusion of pipes and valves as a separate group asset again proved essential.  Successful discovery depended on the aforementioned and what had previously not been done: leveraging the network system approach rather than a discrete assets approach.

Results:

While the owner's focus was primarily on preventing recurrence of the event that had occurred, a full analysis of the system revealed several key aspects that led to a more comprehensive understanding of the process and associated risks, as well as providing specific improvement opportunities that would immensely reduce risk with remarkable little effort and expense.  The networks systems approach to criticality analysis pinpointed the issues behind the major occurrence, and also found a number of other previously unidentified risks, including one previously thought to be insignificant.  Commensurate simple and cost effective solutions that immensely reduced the risk profile for the entire process in all risk areas were identified.

Base Case 2: Refinery boiler feed pretreatment RO system

Situation

A boiler feed water pretreatment system was due for an expansion and had undergone several design reviews, two HAZOP reviews, and several construction reviews. However, given the importance of this system within the refinery operation, as well as being a key part in the refinery overall water reuse initiative, the refinery elected to commission an analysis on the plant boiler feed water pretreatment system.  The decision to perform a criticality analysis was also based, in part, on the success of the previous review methodology.   However, since the system had also undergone some annual refurbishments and, after 18 years of operation, was thought to be fully ‘known', it was not expected that any previously unidentified issues would surface.  This assumption proved to be false.

Response

As in the previous example, the success of this analysis again hinged on the flexibility of the analysis to include not only areas such as safety, environmental, capacity, and up-time, but also commercial terms, liquidated damages, and contract terms.  This proved to be a truly unique analysis in comparison to the many previous ones that had been conducted on the process.  The results were reflective of more than just a process view, showing the unique position of this process's risk profile within the larger context of the client operation. 

The same steps were conducted as in the previous case, except in here an asset registry had previously been generated as part of a HAZOP review.  The database was imported for the analysis.  Again, a team comprising various client experts was assembled with a criticality analysis expert facilitator, and again the unique approach proved essential.

Results

While the analysis did clarify and further define the generally known critical areas central to the overall mission, the analysis brought to the surface as yet uncovered critical risks inherent to the system as well as a different than expected risk ranking. One system was a particular surprise to the investigating team as it could shut down the whole operation in a single shift, and two other systems were elevated to a higher criticality ranking than previously thought given the potential for overall system failure. The inclusion of contractual and commercial evaluation parameters highlighted the relationship between process and commercial risks that had previously gone unnoticed.  This provided the opportunity to monetize those risks for a more comprehensive business risk evaluation.

Conclusion

A sophisticated yet efficient approach is required to identify all risks, including hidden ones, in a cost effective way that also lends itself to solution identification.  Conventional analysis and evaluation often fail to identify some significant mission critical risks because they do not take context into account.  The functional systems approach to criticality analysis, FSCA, is a unique and proven approach that consistently meets and exceeds that objective. This approach to criticality analysis reliably identifies previously undiscovered system risks, means of mitigation, does so in a more efficient way than conventional means, and delivers verifiable and reproducible results.

Ignorance of risk it is not absence of risk.