Modern pipelines need to operate safely in environments that present major challenges:
Sour gas (H2S) in an aqueous environment can lead to sulphide stress cracking or stress corrosion cracking. This type of cracking is heavily influenced by the specific environment experienced by the pipe and by the microstructure and metallurgical characteristics of the steel and welds. Consequently, qualification by physical testing of the steel is essential.
External arctic conditions or internal blow down conditions can result in very low temperatures being experienced by the pipe line (down to -40°C for example). Such low temperatures require the steel to be able to demonstrate resistance to fracture initiation and propagation at these extremities of service.
Seismic, geological and other high strain environments (including reeling installation) can also mean that the pipe line needs to have sufficient strain capacity to address concerns such as fault line crossing, frost heave or repeated bending during installation for example.
Some environments experienced by pipelines result in material loss due to classic corrosion or erosive effects; in these instances, it is imperative that sufficient design effort is applied to allow for these mechanisms.
External pressure (and other challenges) associated with deep/ultra deep applications are becoming more prevalent. The ability of the pipe to maintain structural integrity during such demanding installation and service environments relies on better understanding of the design aspects of this service, and of the material behaviour required to withstand such demands.
Finally, today’s pipe professionals need to consider the unknown; what is required of line pipe design, materials and manufacture when contemplating new fluids for transport, or new materials that offer the possibility of accessing resources in environments too extreme for more traditional pipe material.