A turnaround can be one of the most difficult events for an operating plant to conduct. Most continuous processes run without interruption, leaving little opportunity for routine maintenance on critical equipment, especially if entire systems need to be isolated to complete work. The combination of cyclical repairs, equipment inspections, product changeover and capital project tie-ins can have a resounding effect on a company’s bottom line.
by Lee Williamson, Senior Consultant at T.A. Cook
Although taking a plant or production unit out of service for a short period of time to optimize productivity in the long run may be inconvenient, it is necessary to maintain continuity and optimal productivity. These highly complex events require significant capital expenditure and, as any plant downtime represents a loss of revenue, the incentive to stay on schedule is very important. Having a streamlined scope will help minimize downtime and allow the plant to return to maximum production in the shortest time possible.
Only work that has a specific business purpose should be integrated into the turnaround (TA) scope. In order to bring about this desired result, you’ll need to remove any ambiguity when building a work list. Basically, there are two types of work list items: mandatory and non-mandatory. Mandatory items should include all inspections that are required for the plant to remain in compliance with local, state or federal regulatory requirements and relevant company policies during the premised frequency cycle. Non-mandatory work is all other activities that fall outside of mandatory. Mandatory work will be reviewed to determine if other mitigation options exist that may allow this work to be done while the unit is still operational. Likewise, if the inspection due date can be extended until the next turnaround, the item should not be included in the current TA scope. However, once validated as turnaround only, these work list items will be included in the (TA) scope. Non-mandatory scope will be vetted more thoroughly during the review or optimization process. These items must be “challenged into” the TA scope rather than challenged out. This challenge In methodology is a time saving measure that will scrutinize every work list item based upon an established criteria and risk-ranking.
Before the risk ranking begins, some work may be excluded from the TA scope if the worklist item doesn’t satisfy certain criteria. Does the item have a spare? Can the item be safely bypassed? If the answer to either one of these questions is “Yes,” the items should be excluded from the TA scope. Spared equipment or piping bypasses allow repair work to be done while the plant is operating. If the work list item does not have a spare and cannot be safely bypassed, risk-ranking will need to be performed. “Cannot be repaired while plant is running” does not automatically allow item inclusion into the TA scope. In this case, the risk-based assessment (Item 1) will serve as the guide to determine whether or not the item will be included or excluded. The severity of not performing the work during the current turnaround will be determined by a group of key stakeholders experienced in the work being done and familiarity of the equipment or item being repaired.
Additional work list items that are submitted after the scope has been frozen will need to be challenged in using the same principles. In fact, Best Practice dictates that the closer to execution the higher the threshold for acceptance. Considering work performed during a turnaround costs three to four times as much as work repaired using routine maintenance, each item needs to be thoroughly scrutinized and debated regardless of when the item was submitted. If not challenged, these additional work requests can increase the overall length of the event and threaten to knock off other essential tasks in order to stay on schedule. Ultimately, scope growth should be between 10 to 15% to avoid cost overrun and an extended schedule.
The challenge in methodology is a best practice process designed to eliminate items from the TA scope that are not required to achieve set plant availability and performance targets as defined in the Premise document. At the end of this process, the stakeholders confirm that the scope is accurate and complete. Items that have been excluded from the TA scope will be transferred to routine maintenance, deleted or postponed until the next turnaround. Without an effective scope definition and challenge methodology, it is very unlikely that your STO budget be met.