HotPipe JIP: HP/HT Buried Pipelines

The HotPipe Project is a Joint Industry Project, whose overall objective is to prepare a DNV Recommended Practice to be used in structural design of high temperature/high pressure pipelines. The developed design criteria are based on the application of structural reliability methods to calibrate the partial safety factors involved. One of the three scenarios covered in this DNV-RP is buried pipes subjected to upheaval buckling which is discussed in this paper. The most significant factor in this scenario is uncertainty in the pipeline configuration and uncertainty in the pipe-soil interaction. The paper presents the background of the proposed soil capacities and the associated uncertainties for both uplift resistance and downward resistance in cohesive and non-cohesive soil. The paper links these soil models with the design requirements to upheaval buckling including: - Functional requirements i.e. survey data accuracy, smoothing of survey data, modeling of the pipeline, design conditions, soil cover etc.; - Trenching technology; - Qualification of the minimum soil cover, natural or artificial, with the aim to guarantee pipeline stability; - Assessment of pipeline response; - Pipe integrity checks and design criteria. The internal confidential project guideline has been completed and is currently in the process of being converted into an official DNV-RP-F110, to be published later this year.