API 5L X80 ERW Pipes: TenarisConfab and Usiminas Development

The utilization of high strength steels can decrease, both, installation and operation costs of a new pipeline, since the increase of mechanical resistance can reduce the pipe wall thickness and, consequently, the weight of the pipe. For this purpose, the manufacture of electric resistance welding (ERW) pipes is recent, and it comes as an opportunity for gas pipelines, mainly onshore projects. As a function of their larger productivity, ERW pipes are more economically attractive than those produced by seamless and SAW processes. TenarisConfab and Usiminas, through studies and investments in manufacturing processes, have been working to increase their skills, in order to supply API 5L X80 ERW pipes. The steel elaborated by Usiminas is low C, high Mn, Nb, V and Ti microalloyed, and with additions of Cr and Mo, aiming to produce hot rolled coils with acicular microstructure, achieved as a combination between its chemical composition and higher cooling rates after hot rolling. The results in φ18” (457 mm) × 0,469” (11,91 mm) pipes are presented in this article. High toughness values reached at very low temperatures suggest that X80 ERW pipes developed by TenarisConfab and Usiminas may be an excellent option of choice for onshore projects that request pipes in diameters up to 20” (508 mm) and thickness up to 0.500” (12.7 mm).