PMC or PMS refers to the function provided by the engineering companies contracted as consultant.
This consultant supports the Oil & Gas and Petrochemical companies in supervising the good contract execution of the contracts awarded to the contractors for the engineering, procurement and construction of a project.
PMC may also be called EPCS for Engineering, Procurement and Construction Services or EPCM for Engineering, Procurement and Construction Management.
As expressed in the above definition, the PMC, or PMS or EPCM refers to very different role from the EPC where the engineering company having the EPCM contract, supports the End Users in supervising the good project execution by the EPC companies.
A PMC contract is solely a service contract, by contrast with the EPC contract.
It may be seen as an interface between the End User and the EPC companies, but the role of the PMC takes a major importance in case of multiple EPC involved in the same complex project and calling for a close co-ordination.
In some case the engineering company nominated as PMC may also act as EPC, but those roles will run according to different contracts.