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In practice, the commissioning process comprises the integrated application of a set of engineering techniques and procedures to check, inspect and test every operational component of the project, from individual functions, such as instruments and equipment, up to complex amalgamations such as modules, subsystems and systems.
Commissioning activities, in the broader sense, are applicable to all phases of the project, from the basic and detailed design, procurement, construction and assembly, until the final handover of the unit to the owner, including sometimes an assisted operation phase.
Commissioning of large civil and industrial projects (such as chemical and petrochemical plants, oil and gas platforms and pipelines, metallurgical plants, paper and cellulose plants, thermoelectric and hydroelectric plants, buildings, bridges, highways and railroads) is a complex and sophisticated technical specialty, which may be considered as a specific and independent engineering discipline, as important as the more traditional ones (civil, naval, chemical, mechanical, electrical, electronic, instrumentation, automation and telecom).
Objective and impact
The main objective of commissioning is to effect the safe and orderly handover of the unit from the constructor to the owner, guaranteeing its operability in terms of performance, reliability, safety and information traceability. Additionally, when executed in a planned and effective way, commissioning normally represents an essential factor for the fulfillment of schedule, costs, safety and quality requirements of the project. 
Commissioning Management Systems
For complex projects, the large volume and complexity of commissioning data, together with the need to guarantee adequate information traceability, normally leads to the use of powerful IT tools, known as Commissioning Management Systems, to allow effective planning and monitoring of the commissioning activities.
- BENDIKSEN, T., YOUNG, G. Commissioning of Offshore Oil and Gas Projects: The Manager's Handbook, AuthorHouse Publishers, 2005.