ABSTRACT
The refinery, petrochemical, chemical, and process industries comprise a very capital-intensive sector� Today the process plant equipments have become complex due to the complexity of the technology being employed in building process plants� Machines of all types are now installed in process plants� They are more numerous and more complex compared even to those in the 1960s� Maintenance has to take place at a process plant in order to assure its reliability� It is imperative to take the plant off-line (shutdown) to carry out maintenance of large-scale assets� During this shutdown period, critical inspection, equipment overhaul, repair, and plant modification take place� For a couple of months, a part of or the entire refinery is shut down in order to perform maintenance activities, inspections, and so on� This period will cost the refinery a few million dollars, due to lost production� So it is very important to prepare this shutdown period well�
Refineries’ petrochemical and chemical process plants operate round the clock during normal operations; therefore, periodic maintenance is required, along with occasional major overhauls� As in the case of any car, where maintenance and repairs vary significantly, the same is the case with refineries’ petrochemical and chemical process plants� For the car owner, major overhauls are highlighted in the new car owner’s manual under the preventive maintenance schedule, along with suggested times for more frequent minor maintenance, including fluid changes, belt tightening, mechanical adjustments, and parts or tire replacement� Such maintenance is required to ensure reliable transportation� The same is the case for process plant equipments like compressors, turbines, heat exchangers, and columns� When process plants perform maintenance, they usually need to stop processing raw materials and slow down or stop producing finished products�
The turnaround is a planned, periodic shutdown of a refinery’s processing unit (or possibly entire refinery) to perform maintenance, inspection,
and repair of equipments that have worn out or broken in order to ensure safe and efficient operations and to replace catalysts that have deteriorated� Often, improvements in equipment or the processing scheme can only be implemented during these turnaround or shutdown periods� Currently, routine turnarounds for refinery units are planned once every 3-5 years�
Maintenance activities during a planned turnaround might include
• Routine inspections for corrosion, equipment integrity or wear, deposit formation, integrity of electrical and piping systems
• Special inspections (often arising from anomalies in the prior operating period) of major vessels or rotating equipment or pumps to investigate for abnormal situations
• Installation of replacement equipment for parts of or entire pumps or of instruments that have worn out
• Replacement of catalysts or process materials that have been depleted during operations
Improvement activities could include
• Installation of new, upgraded equipment or technology to improve the refinery processing
• Installation of new, major capital equipment or systems that may significantly alter the refinery process and product output
Outage became more frequent as plants became older and hence accepting shutdown/turnaround became inevitable with so much revenue at stake� This strategy has necessitated changes in plant operating philosophy and inspection technique� Operating companies should use their technical expertise for setting intervals for inspection� So shutdown and turnaround planning and preparation should be carried out more carefully, by assessing plant deterioration and its impact on reliability, planning stocks and logistics, impact of supplies to customers, and checking availability of contractors for plant turnaround activity�
How Shutdown Is Different from Normal Plant Operation
A shutdown is temporary in nature, which means that it has a specific start and finish, while operations are ongoing� Operations involve work that is
continuous without an ending date and often repeat the same process� There will be a preferred sequence of execution for the shutdown tasks (the schedule)� The shutdown is a unique, one-time undertaking; it will never again be done exactly the same way, by the same people, and within the same environment� This is a noteworthy point, as it suggests that you will rarely have the benefit of a wealth of historical information when you start your project� You’ll have to launch your shutdown with limited information or, worse yet, misinformation�
Why Is Shutdown/Turnaround Management So Important?
