Anchoring Collar for Subsea Flowline Reeled Lay
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Solution Overview
Problem
The reeled lay method for subsea pipeline installation faces challenges in anchoring the flowline to the seabed without disrupting the continuous laying process, as existing buckle arrestors and collars interfere with reelability and can cause buckling due to their design, requiring additional steps like cutting and welding during installation.
Innovation Solution
A butt-welded anchoring collar with a radially outward fixture or shoulder that is designed to be clamped, allowing for anchoring without affecting reelability, and featuring a jacket that maintains a uniform outer diameter to prevent ovality and buckling, enabling continuous reeling and spooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a collar is welded to the pipe for anchoring, then the anchoring strength is improved, but the reelability deteriorates due to interference with the reeled lay method
Solution Approach 1:
The collar is pre-welded to the pipe sections at the manufacturing location before the pipe is spooled and transported to the installation site. This preliminary action allows the collar to be properly attached to provide anchoring strength without interfering with the reelability during transport and deployment, as the collar is already in place and does not need to be installed during the reeled lay process
2Adaptability or versatility
If a collar with radially outward fixture is added for anchoring, then the anchoring capability is improved, but the pipe uniformity deteriorates causing ovality and buckling
Solution Approach 1:
The radially outward fixture (protrusion or shoulder) is provided only on the collar at the specific anchoring location, not on the entire pipe. This local quality allows the collar to provide anchoring capability while the rest of the pipe maintains its uniform circular cross-section, preventing ovality and buckling during reeled lay. The fixture is localized to where it is needed for anchoring without affecting the overall pipe geometry
Data Source
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AI summary
A flowline for hydrocarbon is laid on the seabed using the reeled lay method Successive pipe sections have opposing ends which are joined by an anchor collar butt welded to the opposing ends The pipe sections have a exterior jacket Anchor collars are affixed by butt welding between the ends of adjacent pipe sections Each anchor collar has a fixture protrusing radially outward having an outer diameter less than or equal to the outer diameter of the jacket The flowline has the same inner diameter at the pipe sections and the collar, and the pipe has the same outer diameter as the collar, while the protrusion protrudes outward from the exterior of the collar The flowline is anchored by unreeling it, applying a clamp to the collar, and anchoring the clamp to the seabed The jacket may expose the Fixture or protrusion or may be removed to enable the clamping