Procedure for shut down of a plant: A plant shutdown, or turnaround, is a temporary closure of a building to perform maintenance. The main activities should be preventative in nature with the focus on equipment inspections. This is the opportune time to replace wornout or broken process materials and equipment at their useful end-of-life. An effective plant shutdown should result in reduced unplanned downtime, reduced overtime, and greater operational efficiencies. Five distinct phases of a plant shutdown are scoping, planning, scheduling, execution, and wrap up.
Shutdown operation needs sequential steps like cooling and de-pressuring, pumping out, removal of residual content e.g. hydrocarbons, corrosive or toxic chemicals, water, oil, pyrophoric catalyst, disposal of effluents and sludge, drainage and blinding and isolation activities.
Heat source should be cut off, cooling may be continued till required, where vacuum is possible due to cooling, inert gas or air (if compatible) should be introduced to maintain atmospheric pressure, pumping out material after cooling and de- pressuring and pumped out hot oil should be cooled below its flash point. Residual hydrocarbons can be removed by purging with steam, water or water followed by steam. After purging, air should be allowed into the system. Residual water should be removed. Lastly running blinds should be removed and shutdown blinds should be installed.
If the shutdown is required due to any fault, the cause of the fault should be found, studied and removed before restarting the plant.