Pipelines may observe significant axial displacement or force at the ends that tie-in with connected equipment and/or facilities. These axial forces are mainly driven by pipe size, temperature, pressure, length and surrounding soils or supports, and can have devastating effects on connecting facilities if not properly accommodated in the design.
The most common approach to address this issue is deployment of concrete anchor blocks just before tie-in locations to achieve full isolation between pipelines and other connected systems. This leads to an increased cost of construction as well as handling and installation of massive concrete tonnage on a soil foundation of potentially high uncertainty, therefore proving to be economically unattractive. With the expansion of fields and processing facilities, including an anchor may also be physically challenging due to space restrictions.
This paper covers assessments of several pipeline case studies that range from 6” to 18” Nominal Pipe Size (NPS) interacting with the major soil categories clay and sand for design temperatures up to 250°C. The assessments show that for a significant number of cases the presence of an anchor is an over-design of the pipeline system, leading to unnecessary costs and potentially more complicated logistics.
Studied cases were analysed using the non-linear Finite Element Analysis (FEA) algorithm of the Abaqus software suite with controlled end displacements.
The work also establishes a case envelope to which the outcomes of this study will be applicable where pipeline conditions lie within the boundaries of the studied cases.