Hi Crazy,
Shut down planning is very major activities for Maintenance Dept. that can capture this process from Revision no.using in Maintenance order and Notification.
So, If you are using Revision No. that you can track the shut down activities like Component, service and Activities cost in future with using existing maintenance order type.
But you are not using Revision No. application that will unable to track this and further create separate order type for Shutdown maintenance.
Please read this link for more information.
Revision (SAP Library - Maintenance Planning)
Use Revision Work Area (SAP Library - Plant Maintenance (PM))