WHEN to Manage Non-Conformance
Obviously, there cannot be any non-conformance process before the technical requirements have been defined, but it does need to start fairly early in a project.
After DG2 (during the FEED or define phase) the process needs to be defined, systems in place and resources assigned.
Before DG3 - during the tender phase negotiations with contractors - is when most of the deviation requests are generated, and they are quite often not easily identifiable as formal requests.
After DG3 (during the execution phase) is when the non-conformance process is usually at its busiest, and when the post-realisation non-conformance reports (NCRs) are submitted. This may be discovered during production by the contractor, or as a result of factory acceptance tests (FAT) or through audit or some other quality management check.