scope:

This recommended practice gives recommendations on how to evaluate pipe-soil interaction in various design situations or assessments relevant to exposed and buried submarine pipelines.

The recommendations are primarily related to the interaction between the pipeline and soil per unit length of the pipeline. The following topics are covered:

- required soil and pipeline properties for pipe-soil interaction assessments

- pipeline embedment

- pipe-soil interaction considerations for exposed and buried/covered pipelines

- treatment of uncertainties related to pipe-soil interaction assessments

This recommended practice does not consider the following topics:

- geohazards

- earthquake design and assessment of pipelines

- riser-soil interaction

- pipeline-soil-structure interaction.

Further, the full interaction between the pipe and soil, accounting for the stiffness of the pipe and the loads acting upon the pipe, is not covered in this recommended practice other than as brief discussions where relevant, with references to other relevant recommended practices.

Likewise, the integrated interaction between a pipeline or flowline, including spools and connected structures, is covered in respective standards or recommended practices for pipelines and structures. The recommendations given herein may be used as input for analysis of such integrated interaction.

Application

This recommended practice is applicable to the design and assessments of submarine pipelines. The document may be used for the design of new pipelines by engineering contractors and by engineers assessing the lifetime extension of existing pipelines.

The recommended practice can be used in different phases of a project, ranging from FEED, through detail design to operation. Important aspects and principles that are valid for pipe-soil interaction assessments of all types of pipelines and soil conditions are highlighted. Through site- and project-specific soil testing, the applicability range for the recommended practice is not limited to specific pipeline properties and/or soil conditions. However, validity ranges for empirical methods should always be carefully assessed and methods should be used with care if designers are not familiar with the background to the method.