Innovative Solutions to Address Stabilization Challenges of a 48-Year Old Subsea Pipeline

Subsea pipelines are externally concrete coated to provide vertical and lateral stability. The loss of concrete can lead to floatation or lateral movement on the seabed. If seabed is hard/rocky, then lateral rubbing may lead to wall thinning at 6 o'clock and can result in a leak or flattening at the bottom affecting ovality. This paper presents challenges faced during stabilization of an aging pipeline suffering from excessive concrete loss and subsequent lateral movement of 4m. This led to erosion scattered along pipeline length at several locations and flattening at bottom of pipeline. Concrete mattresses were initially used, but due to wall thinning of pipeline sections and significant weight to be compensated, concrete clump weights were subsequently used as an innovative solution. These stabilization measures compensated lost/damaged concrete weight coating by providing sufficient weight to avoid lateral movement, as well as eliminating the risk of pipeline damage in the future.
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Pipeline Technology Journal 2/2023
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