A new concept within riser technology was considered by Norsk Hydro for use on the Visund field. The concept included catenary risers in titanium, transporting oil from 27 wells on 335 m depth, and up to a floating production unit. Four different suppliers delivered titanium test pipes of ASTM grades 23+Pd and 29 (Ti-6Al-4V ELI, alloyed either with palladium or ruthenium) with the requested dimensions, and Kvarner Energy produced TIG (titan inert gas) butt welds on pipes from all suppliers. Det Norske Veritas carried out a large test programm concerning the properties of both base material and weldments. On main consideration was the wish to accomplish extended lifetime compared to the alternative flexible risers. Special attention was therefore paid to the fatigue and corrosion properties of base materials and welds. Additionally, the mechanical properties, as well as the microstructural features of the materials were tested and evaluated. The oil and gas to be produced at the Visund field will hold temperatures as high as 100 deg C, and it was considered essential that the qualification programme should verify the material properties in realistic environments. This quite comprehensive test programme made it possible to draw the conclusion that titanium Grade 23+Pd and 29 was found suitable for use in the Visund risers.
Qualifying titanium risers for the Visund field
Qualifizierung von Titansteigleitungen für das Visund-Feld
Stainless Steel World ; 11 , 5 ; 53-59
1999
7 Seiten, 7 Bilder
Aufsatz (Zeitschrift)
Englisch
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