How do you handle change request and changes in project scope?

We use a time-tested change management procedure for any changes in the project. For ongoing minor changes in the running project, the changes are communicated to the project manager concerned, who gets them executed. If the changes are significant and can greatly add to the work-load that has been estimated at the beginning of the project, then we scope creep the project again and submit the revised quote, for acceptance to the client.