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Subsea Pipeline Pre-Commissioning Activities

Subsea Pipeline

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Subsea Pipeline

Subsea Pipeline Pre-Commissioning Activities


Pre-commissioning is generally considered to include the preparation and integrity verification or structure upon completion of construction/installation and prior to commissioning.

Pre-commissioning includes all or the combination of operations to allow the pipeline or system to be cleaned, internally gauged pressure tested and dewatered and/or dried. Sometimes there can be a final operation to prepare the pipeline for product by introducing an ‘inert’ nitrogen blanket in preparation for hydrocarbon production. However, this is often considered to be a commissioning activity. De-commissioning can also be considered within the realms of the pre-commissioning discipline, allowing preparation of existing systems or infrastructure for maintenance, shut-down or preservation.

As per the rule of thumb in all areas of oil and gas industry, safety should always be highly regarded. Several pre-commissioning activities are conducted in high-risk environment, such as handling hazardous and highly flammable chemicals or gas. Risk assessments are expected to be carried out for all activities for pre-commissioning and operations must follow a procedural framework that has client’s approval.

Once a pipeline has been constructed, several tasks are generally undertaken for pre-commissioning and commissioning of the pipeline. Some of the tasks include flooding with water in preparation for the hydrotest, also known as pipeline flooding. Cleaning and gauging the line is also done to remove construction debris and prove that the line is within diameter tolerance and that no damage or buckling occurred during construction.


Some examples of pipeline pre-commissioning activities include:

  • Pipeline Flooding
  • Pipeline Gauging
  • Pipeline Cleaning
  • Hydrostatic Testing
  • Umbilical Flushing
  • Umbilical Testing
  • Fibre Optic Testing
  • Leak Testing
  • Dewatering
  • Air Drying
  • Nitrogen Drying
  • Vacuum Drying
  • Methanol Swabbing
  • Glycol Swabbing
  • Nitrogen Packing


Failure to perform one of these pre-commissioning tasks correctly may lead to problems later. For example, gas ingress into the water during flooding may make hydro testing difficult; inefficient dewatering of the pipeline may lead to hydrate formation in gas lines or corrosion problems during production.


Subsea Pipeline Pre-Commissioning Operations Management is a 4-day training course held on 22-25 April 2019 (Kuala Lumpur). This course will take the delegates through the pre-commissioning activities, from the detail design issues related to testing, mechanical completion of the pipeline construction and the preparation activities. Key issues such as risk assessments, environment protection, licences/permits, safety training, logistics and interfaces will be addressed. Workshops addressing pre-commissioning preparations, scopes of work and major issues will be interactive with the delegates.

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