The limits of the pipeline precommissioning activities are from pig launcher to pig receiver and include all in-line valves, flanges and fittings.
The different sequential precommissioning work phases are:
Filling using forced flooding or free-filling methods.
Cleaning using chemical or mechanical methods that removes deposits or debris to ensure optimum flow and efficient throughput.
Gauging that detects any internal restrictions and gives indicative results as to whether the pipeline is geometrically suitable for the progression to more aggressive cleaning pigs. Gauging is achieved by fitting a pig with an aluminum plate, sized to approximately 90% of internal pipeline diameter. This is carried out to prove the dimensional quality of the internal diameter of the pipeline
Hydro-testing is performed to expose defective materials that have missed prior detection, ensure that any remaining defects are insignificant enough to allow operation at design pressures, expose possible leaks and serve as a final validation of the integrity of the constructed system.
Dewatering and Swabbing using advanced compression and dewatering train designs to leave the minimal residual water.
Drying using forced air to lower the internal dew point of pipeline. This avoids hydrate formation when pipeline is put into service by using the blower.
Purging using nitrogen to effectively and completely purge the pipeline prior to commissioning, capping or abandonment. The mobile nitrogen unit is considered for this purpose.