Key Challenges In The Mechanical And Thermal Design Of Insulated Pipelines

Proceedings Publication Date:

31 May 2018
Kai Bauerbach
Kai Bauerbach, Paschalis Grammenoudis
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Various pipeline systems depend on thermally insulated product pipes. Conflicting thermal conditions inside and outside of a pipeline commonly result in the need of thermal insulation. Environmental conditions may impede maintaining the aggregation state of the medium. Harsh ambient conditions or strictly defined thermal intervals of safe operation could lead to the additional need for temperature control systems. Thermal design and a proper selection of insulation components ensure safety and reliability. The operation scenarios of these systems include large temperature differences and steep thermal gradients between ambient and operation conditions outside and inside the pipeline. As temperature differences and gradients will result in thermal strains and stresses, structural measures assure management of these thermal loads. Thermally induced loading conditions pose demands on the material selection and must be considered in the mechanical design. The management of heat loss and thermal stresses during all stages of pipeline engineering, construction, and operation will eventually lead to contradicting priorities in mechanical and thermal design. Structural fixation (anchors) constitute potential thermal weak spots with inevitable heat loss. Thermal stresses will have to be balanced by the compressive resistance of lightweight insulation materials. Different approaches of above-ground and buried pipelines result in different sets of challenges. While thermal weak spots might not affect regular operation, less common scenarios such as start-up or shutdown could be heavily impacted by negligence in the thermal design. A holistic vantage point considers how the pipeline’s routing will exacerbate intricacies and impact different scenarios in the life cycle of a thermally insulated pipeline system. Using numerical models and analytical approaches we illustrate how to meet key challenges in the design of thermally insulated pipelines for selected representative scenarios derived from operation data. Our investigations include numerical models to validate heat loss in pre-commissioning scenarios and the effects of phase transition.

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