With respect to modern deep water pipeline installation techniques, the use of riser pipes under more severe cyclic stresses, and increased safety and environmental protection requirements a new high-strength line-pipe steel has been developed by Vallourec & Mannesmann Tubes to meet the necessary toughness of base material and HAZ (heat-effected zone) of the girth welds. The steel has been developed for use as seamless pipe in API material grades X60 to X70 by primarily focusing on the microstructure and method of manufacture. The higher strength was proved in a series of crack-tip opening displacement tests, which where used to test the toughness of the HAZ. Even in the critical test location of a single-bevel weld the HAZ of the steel show good toughness. The smallest individual impact energy value of the base material measured in Charpy V-notch tests is above 200 J. As a result of chemical composition, secondary metallurgy, and heat treatment the steel has excellent resistance to corrosion under sour gas conditions. The steel is optimal suited for applications where welds have to meet special toughness requirements.
New steel meets operator needs for high-strength line pipe, risers
Pipe Line and Gas Industry ; 84 , 7 ; 45-48
2001
4 Seiten, 3 Bilder, 5 Tabellen
Aufsatz (Zeitschrift)
Englisch
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