Natural gas could become one of the most important and strategic energy sources. In the years to come the renewable sources growth will play a fundamental role, but natural gas has the chance to assure a continuous and reliable energy supply on an economically viable, long term base span. Potential routes from giant mid-continental fields to end user gas markets have been analyzed by the industry. These analyses included also material selection and definition of operating flow parameters. Several and independent technical-economical evaluations have proven that natural gas transportation systems based on semi-traditional construction techniques, high strength steel and high gas pressure (more than 10 MPa) are the only options for challenging projects aimed to exploit “stranded gas fields”.
X80 steel pipes spread worldwide and the amount of laid lines continuously increased, thus demonstrating a consolidated trend in adopting X80 steel pipes as a standard solution for high pressure gas transportation. The largest development in field application is in North America and in the United Kingdom, even if the overall figure (in term of installed km) is low compared to conventional steels as X65-X70. A rapid increase of long distance pipelines is expected in the next few years, as the rapid development of the Asiatic countries (especially China and India) is reflecting a higher energy demand.
However, the general lack of massive application of this technology pushed Majors to be engaged in filling the gaps to make available application over an industrial scale. eni launched its first project on High Pressure High Grade Strength Steel in the 90’, followed by a long series of others commitments (either proprietary and within cooperative projects). This paper describes specifically the project launched in 2008 and finished last year, furthermore an analysis of the results got in previous experience is provided. The topic is the missing link between high pressure and conventional transportation pressure of onshore netgrid system, specifically the adoption of API 5L X80 pipeline steels (UOE & Spiral welded) to be used in pipeline (for intermediate pressure application, i.e.up to 12 MPa) even for harsh environments.