Strain-based design of spiral-welded pipes for demanding pipeline applications (SBD-Spipe) : final report

Driven by increasing interest of Oil&Gas companies towards the application of spiral-welded pipes in construction of steel pipelines for hydrocarbons transportation, the objective of the SBD-SPipe project is to generate specific know-how concerning the development and possible use of spiral welded pipes (HSAW) for onshore/offshore applications, when good performances under large imposed strains are required. For the achievement of the above mentioned objectives, a combined numerical and experimental program has been defined. The experimental activity was aimed at investigating most important pipe and girth welded joints limit states related to large plastic deformations. In particular the following activities have been performed: Small scale tests: a basic experimental testing program was carried out to characterize the pipes object of the investigation, and an extensive testing campaign was carried out to obtain relevant input for the numerical modelling activity; Large scale tests: a relevant fracture mechanics testing program was set up and carried out to investigate the tensile strain capacity of the welds; Full scale tests: four full scale bending tests and two full scale collapse tests were performed, to investigate the compressive strain capacity of the spiral welded products. The influence of spiral welded pipes manufacturing process on final process was also investigated. Finally development of suitable finite element models and sensitivity analysis was performed to investigate how relevant load/material parameters affect the behavior at failure. The outcome of this project can also be used as technical basis for O&G pipelines standards/guidelines improvement addressing design and safety of spiral-welded pipelines.