Marine pipeline installation comprises all the activities following the fabrication of the pipe joints, bends and components trough the preparation of the pipeline for commissioning. The principal exercise is the joining of the individual pipe joints into a continuous pipe string which take place concurrently with the installation on the seabed (laybarge), or may be carried out onshore in preparation of installation by reeling, towing, pulling or directional drilling and end with offshore tie-ins. Tie-ins can be carried out above water or on the seabed.
Owing to installation deviations and sebed irregularities the actual distance for pipe laying is higher than the kilometre post (KP) designation measured along the theoretical route.
To avoid overstressing or excessive displacements, seabed intervention may be needed prior to or concurrent with the placement of pipe string.Subsequently, post-trenching or backfilling maybe required to ensure long-term hydrodynamic stability and global buckling resistance.
Once the installation is complete, the pipeline will undergo hydrostatic testing. Subsequently the pipeline is made ready for service by removal of the test water (sea water) and complete drying.