MAH Critical Tasks (MCTs)
MAH (Major Accident Hazard) Critical Tasks (MCTs) are tasks, which prevent or limit the consequences of major accident hazard. This includes tasks required to maintain the integrity of MAH critical elements such that they perform their functions when required.
The objective of MAH Critical Tasks(MCTs)
- To identify all MAH Critical Tasks, which is associated in prevention of major accidents or mitigation of severity of consequences during occurrence of top event in MAH management.
- Gap analysis shall be carried out against comprehensive requirement of major critical tasks in line with international standards in terms of comprehensive task list for total compliance
- A workshop shall be conducted for validating recommendations as a result of gap analysis in terms of ALARP demonstration & CBA (Cost benefit analysis).
Structured methodology shall be used for identification of MAH Critical Tasks . The identification report shall be done comprehensively, which captures the outcome from Bow Tie development workshop where unit level / equipment specific MAH scenarios are covered.
Data shall be collected from all-relevant documents including plant-operating manuals that may be required for development of MCTs. The necessary data and other information required for the MCT development will be collected through HAZOP reports, SIL reports (LOPA), interactive observations, examination of documents (critical procedure), discussions, focused questions, interviews of Personnel and Management.
The inputs gathered will be organized into Bow Tie Diagrams that depict different scenarios of (MAHs) management in diverse locations. The outcomes from Bow Tie workshop for each individual facilities are captured in MCT list sourced from Bow Tie diagrams. Bow Tie diagrams shall be the final reference document regarding the role of each safety critical task in MAH management.
A task shall be defined as MCT, if failure to execute the task as defined would directly contribute to the occurrence or severity of a MAH. MCTs would typically be associated with, human intervention as a step in procedure, if not executed as defined would directly contribute to occurrence or severity of a MAH or an action that if not executed as defined could result in the failure of an MCE to function as and when required.
Assessment shall be done for identified MCTs by analyzing MAH critical tasks to determine the competency requirements and skill set matrix for MCTs. The MCT identification process shall encompass all critical tasks within production facilities / stations and operating units. Technical site survey will aid in gap analysis. Competency and experience criteria for personnel executing the MAH critical task shall be documented in the form of Performance Standard.
Human Factors Assessment (HFA) shall be executed for each MAH critical task, when required. HFA shall be used to confirm the feasibility of assigned personnel being able to execute MAH critical tasks in the expected conditions before or during a MAH. The assessment process shall be recorded in MCT report.
Analysis of Human Factor Assessment shall be done using performance indicating factor checklist. This checklist shall be used for interactive observations, discussions, focused questions and interviews of management
HFA carried out as part of MCT identification process, as minimum, shall consider the following factors:
- Potential Human Performance issues, such as long hours of work and multi-tasking
- Assessment of Human-Equipment interface
- Adequacy of Task definition and any associated procedures
- Requirement for decision making in high stress situations
- Potential for impaired escape or evacuation as consequence of executing the task
Verification scheme to be developed for identified MCT to confirm that each MCT are adequately defined, suitable to achieve the intent even in emergency scenarios, also defined competency requirements and are not reliant on a single individual.
Training sessions for individual operational sector shall be conducted for nominated personals. The training session will enumerate the importance of MCTs and its identification process prior to workshop.
Standalone register for Major Accident Hazard Critical Task shall be prepared for each production facilities / stations and operating units. The register comprises of the following,
- Personnel experience and competencies required to execute each task
- Performance Standards and supporting documentation
- Verification scheme
- Competence assurance scheme
- MAH critical task Audit Reports
MCT workshop is to present and discuss the draft list of identified MCTs for each of the production facilities/stations and operating units. MCT identification workshop team involves all stakeholders and is facilitated by an independent facilitator, along with a scribe.
The ALARP demonstration shall be done for all recommendations identified in MCTs workshop. In the context of risk tolerability criteria or ALARP (As Low As Reasonably Practicable), a hierarchical approach will be employed to identify additional risk reduction measures for recommendations that do not fall under the broadly acceptable region. This is necessary as part of the ALARP demonstration:
- Eliminate, to physically remove the hazard
- Substitution to replace the hazard with a less hazardous substitute
- Segregation from the hazard by distance or isolation
- Prevention by engineering
- Mitigation by engineering
- Prevention/mitigation by organization
- Mitigation by intervention
- Personal protective equipment.
The Cost Benefit Analysis is performed for all recommendations taken from MCT identification workshop, except for the recommendations that meet the below mentioned criteria.
- Basic Engineering study is required to estimate the Bill of Material, which in turn is required to carry out a cost benefit analysis.
- The implementation of high/low deviation alarms in current Distributed Control System (DCS), as well as the modification of control logic without the incorporation of any supplementary instruments, are proposed.
- The alteration of Emergency Shutdown (ESD) interlock logic without the addition of new instruments is suggested.
- Designating existing alarm as critical alarm
- SOP updation, addition of dead zones for corrosion monitoring, increase in preventive maintenance frequency
- P&ID and other document corrections
- Studies including alarm audits
- Low-cost provisions such as NRV and blinds are suggested
Identification of MCTs workshop report will be prepared comprehensive for each production facilities / stations / operating units/ equipment specific. The identified inadequacies and recommendation shall be captured in the report. The Identification of MCTs report of each individual facility covers the following
- Provides complete list of MCTs for each Facility
- Identification and Classification of MCTs
- Contain results of Gap analysis of obtained equipment data with respect to existing MCT management philosophy
- Determine the competency requirements (e.g. practical, technical and behavioral skills) and skill set matrix for MAH critical tasks
- Contain Human Factors Assessment for each MAH critical task
- Present the link between identified MAHs, identified MCTs and the task definition which defines the task and its requirements in the report
- Shall include clear linkage between MCT requirements and Competency Assurance System (CAS)
- Criticality ranking of all generated actions from a risk-based perspective.
- Perform mapping of recommendations against the relevant CCPS PSM element(s).
- CBA and ALARP demonstration studies for all recommendations with suggested execution strategy
For traceability, the outcomes from meetings, workshop sessions, group sessions, and agreements are recorded in minutes of meeting, which shall be finalized and signed by all parties. Excel based live action tracking workbook shall be prepared for all generated actions that can be periodically updated and log any discrepancy noted in Operations, Drawings / Technical Documents.