Abstract: A method of lowering a discrete load from a pipelay vessel comprises holding a rigid rod on an upright launch axis where the rod extends through a hold-back system; coupling a lower end of the rod to the load; connecting a wire to the load either directly or indirectly via the rod; operating the hold-back system to advance the rod downwardly, hence submerging the load, while the weight of the load is suspended from the hold-back system via the rod; when the load is under mater and beneath the splash zone, transferring the weight of the load directly or indirectly from the hold-back system to the wire; and continuing to lower the load in the water, suspended directly or indirectly from the wire. The method may be reversed to recover a load from a subsea location, such as when lifting a wellhead or blowout preventer from the seabed.

Abstract: Lined pipelines with different inner diameters are spooled successively onto a reel while their constituent pipe stalks are cyclically pressurised internally to combat wrinkling of the liner. A first, variable diameter pig is advanced to a trailing end of a first pipeline. A transition joint is attached to the trailing end of the first pipeline to effect a transition from the inner diameter of the first pipeline to the different inner diameter of a second pipeline. A leading end of the second pipeline, containing a second pig, is attached to the transition joint. The first pig is driven through the transition joint into the second pipeline. The diameter of the first pig changes to match the inner diameter of the second pipeline. The first and second pigs are then driven along the second pipeline when assembling the second pipeline from a succession of pipe stalks.

Abstract: In a method of joining a structure to a water-filled pipeline aboard a reel-lay vessel, a trailing end portion of the pipeline is suspended upright on a reel-lay tower. Water is drained from the trailing end portion while being retained in an inclined portion of the pipeline extending from the tower to a reel of the vessel and in a spooled portion of the pipeline coiled on the reel. The structure is joined to a trailing end of the pipeline after inserting a pig into the trailing end portion through the trailing end. Pumping additional water into a leading end of the pipeline on the reel propels the pig from the trailing end portion into a conduit of the structure while flooding the trailing end portion. This expels air through a port of the structure that was trapped in the trailing end portion between the pig and the structure.

Abstract: Lined pipelines with different inner diameters are spooled successively onto a reel while their constituent pipe stalks are cyclically pressurised internally to combat wrinkling of the liner. A first, variable diameter pig is advanced to a trailing end of a first pipeline. A transition joint is attached to the trailing end of the first pipeline to effect a transition from the inner diameter of the first pipeline to the different inner diameter of a second pipeline. A leading end of the second pipeline, containing a second pig, is attached to the transition joint. The first pig is driven through the transition joint into the second pipeline. The diameter of the first pig changes to match the inner diameter of the second pipeline. The first and second pigs are then driven along the second pipeline when assembling the second pipeline from a succession of pipe stalks.

Abstract: In a method of joining a structure to a water-filled pipeline aboard a reel-lay vessel, a trailing end portion of the pipeline is suspended upright on a reel-lay tower. Water is drained from the trailing end portion while being retained in an inclined portion of the pipeline extending from the tower to a reel of the vessel and in a spooled portion of the pipeline coiled on the reel. The structure is joined to a trailing end of the pipeline after inserting a pig into the trailing end portion through the trailing end. Pumping additional water into a leading end of the pipeline on the reel propels the pig from the trailing end portion into a conduit of the structure while flooding the trailing end portion. This expels air through a port of the structure that was trapped in the trailing end portion between the pig and the structure.

Abstract: A method of lowering a discrete load (32) from a pipelay yessel comprises: holding a rigid rod (30) on an upright launch axis where the rod extends through a hold-back system (26); coupling a lower end of the rod to the load; connecting a wire (24) to the load either directly or indirectly via the rod; operating the hold-back system to advance the rod downwardly, hence submerging the load, while the weight of the load is suspended from the holdback system via the rod; when the load is underwater and beneath the splash zone, transferring the weight of the load directly or indirectly from the holdback system to the wire; and continuing to lower the load in the water, suspended directly or indirectly from the wire. The method may be reversed to recover a load from a subsea location, such as when lifting a wellhead or blowout preventer from the seabed.