Design requirements for pipelines regarding both ultimate strength and flow assurance in ultra deepwater scenarios motivated the development of a new sandwich pipe which is able to combine high structural and thermal insulation properties. In this concept, the annulus is filled with low cost materials with adequate thermal insulation properties and good mechanical resistance. The aim of this research work is to perform small-scale laboratorial tests and to develop a finite element model to evaluate the structural performance of such sandwich pipes with two different options of core material. After calibrated in view of the experimental results, a three-dimensional finite element model incorporating nonlinear geometric and material behavior is employed to perform strength analyses of sandwich pipes under combined external pressure and longitudinal bending. Ultimate strength envelopes for sandwich pipes are compared with those generated for single-wall steel pipes with equivalent collapse pressures. The study shows that sandwich pipe systems with either cement or polypropylene cores are feasible options for ultra deepwater applications.

Subsea production systems (SPSs) have dominated the exploration of oil and gas resources in deep water; however, failure of SPSs can lead to enormous economic loss, serious environmental pollution and even severe casualties. Hence, the safety and reliability of SPSs have become a major concern. To guarantee the high integrity of SPSs, investment should be made in inspection and monitoring of SPSs (IMSPSs) in order to prevent failures of the subsea equipment, as much as possible. This paper reviews the current progress in technologies for IMSPSs using non-destructive testing (NDT). The basic principles and features of four common NDT techniques used for IMSPSs are reviewed. Based on these NDT techniques, the current development of IMSPSs, as well as the latest advanced technologies, is then discussed. Furthermore, capabilities and limitations of IMSPSs are discussed. Finally, suggestions for future development of IMSPSs are provided.