Equipment field in Refurbishment work order

1.I enabled Equipment field as 'Req' in OIAN ( Field selection for header data (PM)). The field doesn't appear in the order header data. But when I want to save the order it throws error to input equipment number. I have to revert it.

2.Is there any way I can get the equipment field into the header? or Is there any other field I can use to enter my Equipment number just for reporting purpose?

Don't want to go Sterilization way.

Not looking to enable business functions.

Thank you!