Grade 23 and/or 29 titanium alloy pipe and forgings are typically butt-welded together in the fabrication of offshore riser components such as tapered stress joints (TSJs) for top-tensioned risers and as hang-offs for dynamic catenary risers. Although Grade 29 titanium base metal in a relevant wrought/forged product form has already been evaluated in regards to sustained-load cracking (SLC) resistance, minimal data is available to ensure that the SLC resistance of typical GTA butt-welded joints in these thicker-wall titanium alloy components will also meet design requirements. As part of a TSJ production weld qualification, conservative fracture-mechanics based SLC tests were conducted at room temperature on 1G-position machine GTA butt-welded Grade 23 titanium pipe utilizing Grade 29 titanium filler metal. Test results revealed no significant SLC susceptibility in the weld and a minor effect in HAZ metal, producing KSLC values similar to KQ values. These values safely meet typical TSJ fracture mechanics requirements, and are consistent with published SLC information on this alloy system.

Volume Subject Area:
Materials Technology
Topics:
Cracking (Materials), Fracture (Process), Pipe joints, Stress, Titanium, Fracture mechanics, Pipeline risers, Pipes, Risers (Casting), Titanium alloys, Alloys, Base metals, Design, Filler metals, Forgings (Products), Machinery, Manufacturing, Metals, Ocean engineering, Temperature, Top-tensioned risers
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 by ASME
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