In north-eastern Alberta/Canada, Canadian Natural Resources and others operate systems of steam transmission pipelines to deliver steam to hundreds of oil wells in Alberta. The delivered steam is injected into the well to stimulate the reservoir, enhancing the recovery of heavy oil. Due to changing stimulation techniques it was required to inject up to 3,000m3 per day per well of cold water equivalent steam at a wellhead pressure of 13 MPa. Up to ten wells can receive steam simultaneously. To facilitate the economic movement of this large volume of steam, the installation of a 24NPS steam pipeline was essential and required the innovative application of existing technology. Another requirement was that the pipes must be field-weldable without post-weld heat treatment — a requirement aimed at keeping installation costs low. Several linepipe steel grades including grade X-80 and GRS 550 steels, which are comparable to CSA Gr. 550 steel, were examined for their mechanical properties up to 400°C. Based on this knowledge Europipe delivered the pipes for a steam pipeline of 4,500 m. The line of 24NPS CSA Gr. 550 material operates at a temperature of 354°C and a pressure of 17.2 MPa. The elevated temperature tensile and CVN tests performed during the production of the 24NPS pipes confirmed the results of the preproduction tests of similar steels. Additionally, aging and creep tests with the original material were performed to determine a satisfactory lifetime at the given operating conditions. All tests established that the delivered material is suitable for the application. Also a field welding procedure was developed that did not require post weld heat treatment for the 24NPS CSA Gr. 550 pipes. The 4,500 m of 24NPS Gr. 550 linepipe were successfully installed and placed into service during the summer of 2001.

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