What is the step before and during valuation class change?

Hi,

Basically i have problem to transfer goods from production line to inventrory. SAP consultant ask me to change the valuation class but before change the valuation class i need to ensure a few things such as no production order, purchase order and so on. Can somebody explain to me what should i do and look before and during change the valuation class.

Thank you.

Br. Hadi