Commissioning of a project, whether large or small, essentially verifies that it's ready to be put into operation. This point in the project's timeline is reached only after a thorough period of precommissioning, during which a project is tested tested under real-world conditions and and certified. Some examples of projects which undergo exhaustive precommissioning programs before they're put into service are oil pipelines, buildings and naval vessels.
The bulk of the precommissioning work commences once the construction phase is largely completed. The precommissioning crew calibrates and tests all components of the project under conditions as close to operational as practical. Depending on the nature of the contract and the adjustments necessary, the precommissioning crew may make adjustments or modifications, or it may return the project to the construction crew for required work.
The final phase of a project's preparation, commissioning certifies that the project is ready for regular operations, and follows successful precommissioning. There's a good amount of behind-the-scenes work, with documents and punchlists being checked and doublechecked, because once commissioned and handed over to the client, any problems or issues arising from the project's operation are the property of the client. Depending on the project, commissioning may be the last stage of the precommissioning process, or it may be a separate phase entirely, during which the entire project, with all systems energized and operational, is tested under real-world conditions.
These precommissioning and commissioning activities ensure there are no glitches in the project. Most large projects, including building construction, manufacturing plants, sea vessels, oil pipelines and the like are time-, labor- and capital-intensive undertakings. Precommissioning and commissioning are safeguards that ensure the project is built to specifications and will operate and intended.