The HTS (Helical Seam Two Step) manufacturing process is used for the production of HSAW-pipes for high pressure service since 1987. The production process is split into pipe forming combined with continuous tack welding followed by submerged arc welding. The process has been continuously developed further. Details of this modern technology are described and qualitative and economical advantages over the conventional process are explained. The benefits of the existing network with steel plant and hot rolling mill as well as the quality controls, process automatisation and new NDT-equipment used in the pipe production are highlighted. Statistics on mechanical, chemical and dimensional properties of HTS pipes are presented to furnish proof of the uniform and well balanced profile of this product. Results from hot and cold bending on site, field weldability trials and tests related to the safety of spiral pipes are discussed. Results and experiences with the application of three-layer coatings (especially HDPE-high density polyethylene) on spiral pipes are also presented. Actual examples for the use and application of spiral welded pipes in international gas and oil projects are presented and an outlook on future development trends is given.
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