One way smart plant engineers use contractors is to “offload” onto them expensable small projects or small capital projects.
With a large capital project, the typical plant engineer (or other responsible party such as the plant electrical engineer) knows the details by dint of having designed the project. To get large capital approval, a great deal of information is obtained ahead of time. To properly chart the cash flows (to determine the Internal Rate of Return or similar quantity), corporate financial types also want to know the maintenance costs. To know the maintenance costs, you must identify the maintenance tasks.
There’s a different dynamic with smaller projects. The engineer (plant, electrical, etc.) will often specify the outcome but not the details. The contractor puts together an estimate based on meeting the specified outcome. Often, the project is completed without attention to the maintenance aspect. Rarely any sort of baseline testing performed. Some kind of generic preventive maintenance (PM) might be affixed when the asset is added to the computerized maintenance management system (CMMS).
With smaller projects, always task somebody with accurately determining what the maintenance requirements will be. If you’re offloading to a contractor, include this as part of the project.