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A hybrid approach to RBI methodologies with PCMS

Published by , Senior Editor
Hydrocarbon Engineering,

Implementing risk-based inspection (RBI) programs can be a challenging task for mechanical integrity personnel. Several decisions are required to implement an RBI approach such as inspection planning and risk identification/management.

The American Petroleum Institute (API) offers three approved methodologies. Most organisations choose only one of the three methodologies identified below:

  • Quantitative.
  • Qualitative.
  • Semi-quantitative.

Each methodology has its unique advantages and challenges, and deciding when, how, and which methodology to use can be overwhelming when trying to ensure compliance with industry regulations while also considering cost, feasibility, and on-going program success. Since facilities have a wide range of equipment types, process units, and criticality, just one methodology applied broadly across a facility or organisation may not lead to the most effective way of implementing and evergreening an RBI program.

A quantitative methodology, while thorough, is labour-intensive, far less intuitive for the average user, and requires detailed and extensive, statistically derived calculations for probability and consequence determinations. Quantitative implementations are usually not the most appropriate tool for risk-ranking entire equipment populations.

A semi-quantitative approach has proven to be an ideal middle-ground solution for the majority of an equipment population blending aspects of both quantitative and qualitative methodologies. While robust, a semi-quantitative approach should not be viewed as a one size fits all approach for all equipment in a facility. Semi-quantitative RBI assessments contain the best of both the fully quantitative and qualitative approaches with more statistical modeling than the qualitative approach but with less dependency on the subject matter exerts required for a fully quantitative approach. The majority of an equipment population may be best served using this approach.

Qualitative assessments are simple in comparison to the two methodologies identified above. Qualitative RBI assessments are usually based on questions and answers or other standardised criteria and provide for an efficient and intuitive approach to assigning risk rankings to low risk assets. Qualitative assessments, like the quantitative methodology, is heavily dependent on individual inputs and is probably the most subjective of all three API 580 approved approaches.

Since selecting only one methodology may prove counterproductive and not as value-added as a hybrid approach that combines all three, an optimised solution is moving the industry forward: MISTRAS Group (NYSE: MG) offers a hybrid approach to optimise RBI programs with its Plant Condition Monitoring Software (PCMS) solution.

PCMS offers a custom approach by combining all three methodologies into a single RBI program. The software allows quantitative calculations to determine a plan of action for the most critical assets while qualitative and semi-quantitative considerations are used to determine an appropriate probability and consequence of failure based on expertise for a well-rounded view.

PCMS, which also boasts the API-approved logo on its platform, is the only software available that allows all three methodologies to be performed in the same solution as part of a single program. The solution’s approach to RBI methodology meets all API 580 and API 581 requirements while optimising use of the methodologies based on criticality and facility experience.

MISTRAS allows full configuration to allow methodology to vary within a facility and across multiple facilities. PCMS also includes API 571 Damage Mechanism screenings as a major part of the RBI calculation and embeds the RBI calculators within the inspection database to allow for an evergreen program that addresses changing conditions and risk factors.

MISTRAS’ hybrid approach to RBI methodology with PCMS is a breakthrough solution for petrochemical professionals and the most effective method for implementing quantitative, qualitative, and semi-qualitative approaches to RBI.

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