After-laying Trenching is the main means of protecting subsea pipelines and meeting pipeline stability requirements. The subsea trencher consists of water surface support system, trencher body, subsea monitoring system, umbilical cable winch etc. Trencher types include non-contact and cross riding trencher.

      Non-contact trencher is suspended directly above subsea pipeline. High flow axial pump is used to pump water flushing away the soil at bottom of pipelines, forming trench for subsea pipelines to sink. The soft sediment on both sides of trench is back filled under the action of sea wave to complete the burial of subsea pipelines.

      The cross riding type trencher is operated by a combination of high flow jet from the main jet arm and high-pressure jet from the auxiliary jet arm, which flush away sediment to form V-shaped trench. Then suction system (air pump, water pump or mud pump) discharges the mud and pipelines can sink to trench bottom.

      We have conducted theoretical and experimental research on soil breaking and mud discharge mechanisms, optimized the design of flushing and suction systems, achieved efficient burial of subsea pipelines. The maximum soil breaking capacity of the trencher is 120kPa and the maximum trenching depth is 12 meters.cross riding type trencher