Thanks to their exceptional thermal insulation capability, Pipe-in-Pipe (PIP) systems are well suited for the transportation of hydrocarbons at high pressure and high temperatures (HP/HT), preventing hydrate formation and ensuring high discharge temperatures at the arrival facility.

In this whitepaper resulting from a close interaction between Fugro GeoConsulting, Genesis Oil and Gas and different Universities, Filip Van den Abeele reviews and compares different numerical approaches to simulate the structural response of a pipe-in-pipe system. The fully bonded PIP system can be simulated using an equivalent diameter approach, replacing both pipes by a single pipe with an equivalent mass and bending stiffness. This approach has been pursued to evaluate the mechanical response of a PIP system in a free span. A formulation is presented to reconstruct the stress distributions in the inner and outer pipes based on the strains and bending moments calculated for the equivalent cross section. The results show that the equivalent pipe section methodology can be used for on-bottom roughness analysis and free span assessment of fully bonded Pipe-in-Pipe systems.

 Free Spanning Pipe in Pipe: Benchmark between SAGE Profile 3D and Abaqus

 >> Read more – 2014

Rock dumping of untrenched pipelines is generally undertaken to increase the lateral or upheaval resistance of the pipeline to buckling. While it is important to understand the increased resistance to lateral loading provided by the rock berm, it is also essential to capture the influence of the underlying soil on this resistance, which can be critical to the design sizing of the berm.

The latter point is illustrated in the paper presented by Jean-Christophe Ballard at the latest Offshore Pipeline Technology Conference (OPT 2014) in Amsterdam.  The paper presents soil structure interaction analyses performed to aid in the design of a rock berm to provide restraint to a surface laid pipeline in the case of full bore rupture of the line. The motivation behind this analysis was the planned removal of an unexploded World War II mine, which was located against a high pressure gas transmission pipeline. The purpose of the analysis was to identify the suitability of application of a rock berm restraint to stabilise the pipeline in the event of an explosion.

Since soil conditions at the location consisted principally of soft clay, the analyses highlighted the significant influence of the soft soil layer on rock berm stability under lateral pipeline loading. It has also been demonstrated that upheaval buckling problems can be conveniently modeled in Sage Profile 3D through inclusion of a backfill soil spring in addition to the three conventional pipe-soil interaction springs.

 >> Read more – 2014

SAGE Profile has been designed to assist the pipeline engineer during the entire lifecycle of an offshore pipeline. The software suite has been certified by Bureau Veritas for static applications like on-bottom stress analysis, out-of-straightness analysis, span assessment,… In a paper, recently presented at the 6th Pipeline Technology Conference, the use of SAGE Profile to simulate dynamic events like trawl gear interference was demonstrated.

In the paper, numerical models are presented to simulate the displacements and corresponding stresses during trawl gear pull-over. The finite element analyses are compared with simplified analytical approaches and results published in DNV-RP-F111. The results indicate that SAGE Profile can indeed predict the transient dynamic response of subsea pipelines subjected to trawl gear pull-over loading – provided the damping factors are judiciously chosen.

Based on these observations, we shall submit SAGE Profile for full dynamic certification and the development team is keen on introducing trawl gear interference (as per DNV-RP-F111) as a new load pattern in forthcoming versions of SAGE Profile.

 >> Read more – 2013

The pipeline engineering students at Cranfield University are using SAGE Profile to explore new frontiers for their group projects and master theses. Recently, a group of motivated students has successfully completed an assignment on the prediction of susceptibility to upheaval buckling for buried pipelines. In addition, master theses are on-going to investigate structural reliability of free spanning pipelines, dynamic loading in SAGE Profile and the simulation of pipe-in-pipe systems.

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