Schedule ‘What if ‘Analysis: Optimising to a realistic Turnaround duration.
The 'What-if' Schedule Analysis aims to determine the most favourable Turnaround duration by optimizing resources and costs while minimizing impacts on safety and quality based on a selected scope of work and execution methodology. It involves comparing various schedule alternatives and considering changes in conditions such as scope, priorities, constraints, resources, and execution methodologies, etc.
For Turnaround projects, 'What-If' analysis serves two primary purposes: first, developing the most feasible baseline execution schedule during the planning phase; and second, analysing and predicting the optimal turnaround outcome in response to changing conditions during execution.
A prerequisite for performing ‘What If’ analysis is a risk-mitigated, quality schedule. We have previously discussed about the Schedule Quality Check points that are necessary to ensure the schedule integrity, and the process of Schedule Risk Analysis (SRA) to mitigate uncertainties and risks.
Typically, instead of analysing the entire schedule, 'What If' analysis focuses on critical, near- critical, and major jobs that could potentially impact the Turnaround duration under various conditions. Once a suitable scenario is selected as the best outcome, the entire schedule must be levelled to assess overall resource loading and perform optimization of resources for maximum productivity, including reviewing and possibly removing low-priority jobs if necessary. Also, reaffirm its risk mitigations in light of changing conditions. Multiple iterations between ‘What If’ and SRA might be necessary to arrive at the most optimal schedule. Follow the below flowchart (Chart 1) for schedule optimization process.
Here we discuss an example of ‘What If’ Analysis.
During the turnaround, one of the significant jobs is the maintenance of a shell and tube heat exchanger with fixed tubes configuration. It has a length of 10 meters and a tube sheet diameter exceeding One meter, fitted with 5000 tubes of 20mm diameter. The scope of work includes opening, cleaning, inspecting, and hydro testing, which are critical activities potentially impacting the project's critical path.
The previous Turnaround data indicated that this job was initially planned for 17 days, with a long-duration tasks of hydro jet cleaning of tubes expected to take 8 days using a manual cleaning method and Tube NDT (IRIS) inspection for 4 days. However, during execution, this task was delayed to 4 days, extending the total duration to 21 days, and the Turnaround duration was consequently extended by an additional four days.
Given the substantial revenue loss caused by the four-day delay, Leadership requested the TA Core team to explore various options for optimizing the duration of the next Turnaround. After further brainstorming, the team identified the following scenarios to include in the 'What If' analysis, to determine the optimal duration while considering other impacting factors:
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1.??????? Risk-Mitigated Baseline Using Manual Cleaning Method: This scenario assumes the use of a manual cleaning method with baseline risk mitigation strategies. Total duration is 21 Days.
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2.??????? Semi-Auto Tube Cleaning Method with Single Lancing Machine: This method involves moderate risk, increased setup time, and additional costs for extended scaffolding and jetting machinery. Overall, it offers a 20% time saving in tube cleaning.
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3.??????? Semi-Auto Tube Cleaning Method with Double Lancing Machine: This method carries moderate to high risk, requires more setup time, and incurs additional costs for extended scaffolding and jetting machinery. It results in an overall 40% time saving.
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4.??????? Reliability Risk based Prorated Inspection Requirements: Perform a reliability risk analysis on equipment conditions. Based on this analysis, the inspection requirements for the tubes can be prorated, allowing for a reduction in the inspection test (IRIS) requirement to a percentage of the tubes inspected randomly, rather than inspecting 100% of all tubes. Considerations include moderate risk, lower cost impact, and an overall time saving of 25%.
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5.??????? Adding More Resources for Blinding and Opening of Exchangers: Adding more resources can reduce the time required for blinding and opening exchangers. Considerations include lower productivity, increased cost, and a 10-15% time saving.
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6.??????? Create Various Combinations of Scenarios: Develop various combinations of the above scenarios, taking into account all associated considerations.
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Plot the Safety impact, Quality Impact, Cost Impact against project durations for all scenarios in three scatter charts. (Ref. Charts 1, 2 &3).? Select a most favourable TA duration with an optimal impact on other KPI constraints.? From the below chart analysis, most favourable TA duration identified as15 Days.
To summarize, the 'What-If' Schedule Analysis is essential for optimizing Turnaround projects by examining various scenarios and their impacts on schedule, resources, and costs. It focuses on critical jobs and possible changes to create a solid baseline schedule and predict outcomes under different conditions. This analysis not only facilitates efficient planning but also ensures adaptability to changing circumstances, enhancing overall performance and risk management. By incorporating this approach, organizations can achieve more predictable and manageable turnaround outcomes, reducing disruptions and boosting operational efficiency.
Chart 1: Turnaround Schedule Optimization Process
Article has been authored by Anil Sasi , PMP ( Head Turnaround Excellence @ Maximl )
Read More in our series of articles on Turnaround Management: