The ever-increasing demand for natural gas will further influence the type of its transportation in the future, both from the strategic and economic point of view. Long-distance pipelines are a safe and economic means to transport the gas from production sites to end users. The energy scenario has been changing quickly in recent years. International studies forecast that the demand for natural gas will be nearly doubled by 2030. The distance between gas production sites and end users increases, implying the need for the construction of complex gas transportation pipeline networks, when the use of LNG tankers is impossible or uneconomical. This will make the high pressure natural gas transportation via pipelines increasingly interesting. The use of grade X 80 linepipe has already been shown to result in substantial cost savings. Results of tests on grade X 80 production pipe supplied for onshore and offshore projects are presented in this paper. But the economic transport of gas over very long distances requires additional cost cuts. The use of grade X100 and/or X120 could be a solution. Therefore, the benefits of using high-strength linepipe and the present-day technical limitations on its production are addressed. Laboratory and production results on high-strength large-diameter pipes are presented to describe the materials properties as well as the service behaviour. Girth welding procedures covering mechanised and manual methods have already been developed.
This paper gives an overview of the development of high-strength lowalloy linepipe grades. Some of the current projects for pipelines in grade X 80 and the benefits of using X 80 pipe are presented. Also, important aspects of the properties of base material and welds are discussed. The development of material grades up to X 100 or X 120 represents one of the big challenges and opportunities in the future.