System design for buried high-pressure/high-temperature pipelines

Journal Article · Mon Jun 01 04:00:00 EDT 1998 · JPT, Journal of Petroleum Technology

OSTI ID:634621

A pipeline expands or contracts when temperatures or pressures vary from the conditions at the time the pipeline was installed. Buried pipelines operating at high temperatures and pressures experience extreme compressive loads. Because radial expansion is limited by soil restraint, buried pipelines expand axially. High axial forces combined with imperfections in the seabed may overstress the pipeline or result in upheaval buckling. Methods to control expansion and upheaval buckling were investigated for the design of a buried high-pressure/high temperature (HP/HT) sour-gas flowline in Mobile Bay, Alabama. After investigating conventional and unconventional methods, the decision was made to use expansion loops over the length of the pipeline to protect the risers and reduce axial force in the middle of the pipeline. Expansion loops and doglegs act as springs to absorb pipeline expansion. Methods were investigated to prevent soil from accumulating around the buried expansion loops. Commercially available concrete dog houses used to protect pipelines and expansion loops from dropped objects were not suitable for burial, and fabrication of custom concrete housing was expensive. Fabrication of a steel enclosure was the solution chosen. A mathematical model based on internal-design guidelines and ultimate soil friction was used to determine placement and size of the expansion loops.

• OSTI ID: 634621
• Journal Information: JPT, Journal of Petroleum Technology, Journal Name: JPT, Journal of Petroleum Technology Journal Issue: 6 Vol. 50; ISSN 0149-2136; ISSN JPTJAM
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
DESIGN
EXPANSION JOINTS
MATHEMATICAL MODELS
NATURAL GAS
PIPELINES
STRESS ANALYSIS