Development of Double Joint Welding Procedure for X90 Grade Seamless Pipes in Riser Applications

<jats:sec> <jats:title>Abstract</jats:title> <jats:p>With the increasing strong demand for the development of oil and gas fields in ultra-deepwater, offshore applications with higher strength are required for the reduction of construction costs. Riser system costs are particularly sensitive to increases in the depth of water. Ultra-high strength seamless pipes of X90 and X100 grades have been developed for deepwater or ultra-deepwater applications.</jats:p> <jats:p>Girth welding procedures need to be developed whilst considering the material properties of both the heat affected zone (HAZ) and the weld metal for ultra-high strength pipes. Double jointing with submerged arc welding (SAW) in particular is one of the most important process due to the high productivity and quality of the welding. However, there is little information about girth SAW joints in pipes above X90 grade.</jats:p> <jats:p>In addition, fatigue properties of parent pipe and welding joints are required for riser systems as cyclic stress is applied marine phenomena.</jats:p> <jats:p>This paper describes developed welding procedures and test results of material properties of X90-grade double joints by using SAW. Welds were made with typical welding parameters for riser productions. In order to assess the applicability of double joints for riser applications, high cycle fatigue testing and fatigue crack growth rate testing was conducted. This work was performed with Engineering Critical Assessment (ECA) for riser applications by using the material and fatigue properties of X90 parent pipe and welding joints.</jats:p> </jats:sec>