Pipeline laying method
AssigneesThe British Petroleum Company p.l.c., Saipem S.P.A.
InventorJohn William Ells
Life of this patent
Estimating the term…
Abstract
The free ends of two pipelines lying on the sea bed are joined by raising both ends to above the surface and supporting them on a barge, bringing them into axial alignment and welding them together by inserting a spool piece if necessary. The welded line is then lowered back to the sea bed and the barge moved sideways.
Claims10
A method of joining together the ends of two pipelines having an internal diameter of from about 10 to about 60 inches into a continuous length at an offshore location wherein at the commencement of the method at least one of the pipeline ends is submerged in water from about 100 to about 1000 feet in depth, the method comprising:
- a. dewatering the submerged pipeline or pipelines over the length to be lifted;
- b. initially lifting the submerged end or ends above the surface of the water with at least one first lifting means;
- c. positioning buoyancy means along the submerged pipeline or pipelines adjacent the end or ends to be lifted to assist said initial lifting;
- d. gripping the ends of said pipelines to maintain them in axial alignment;
- e. lifting the thus aligned pipelines into engagement with a plurality of longitudinally spaced-apart supporting structures with a plurality of longitudinally spaced-apart second lifting means, said supporting structures being lockably movable along the vertical plane and pivotal along the horizontal plane and being positioned so that the pipeline ends are presented horizontally end to end in axial alignment for joining;
- f. interposing a spool piece between the horizontal, axially aligned ends of said pipelines and welding said spool piece to said ends to form a continuous fluid tight length;
- and
- g. lowering and laterally moving said continuous length of pipeline back to the sea bed to form a loop in a horizontal plane on the sea bed.
Dependencies are inferred from the claim text.