Give an practical example of a real structure of cost management engineering department in a multi national companies ?

I was not part of such a department. I know that they get invovled at the project inception phase to give the first budgetary estimates. The get involved in contractors' bid evaluations. They alo get project progress reports and get involved in any change request issued either by the owner or by any of the contractors.

Sorry, this is not my expertise area

COST MANAGEMENT  AT ANY COMPANY AND ANY PROJECT IS THE CONTROL OF THE PARTELY ITEMS COST AS CONTROL IN CONCRET COST NOT INCREASE THAN ITS BADGET BY GIVEN IT TO SIBCONTRACTOR OR BY COMPANY LABORS

We must take two analysis in cost management:

1- Contingency reserve analysis realted to known unknowns

2- Management reserve analysis realted to unknown unknowns