Recent changes in the design of steam turbine power plant have necessitated the replacement of bolted flanges with welded joints. The design process therefore requires a knowledge of the creep rupture strength of the weld metal consumed in the welding process. This paper presents a method which can be used to estimate the creep rupture strength of ferritic steel weld metals, from a knowledge of the creep strength of wrought plates. The method is validated using published data.

This paper was selected for presentation by the OTC Program Committee following review of information contained in an sbstract submitted by the author(s). Contsnts of the peper, as presented, have not been reviewed by the Offshore Technology Conference and sre subject to correction by the author(e). The material, ss presented, does not necessarily reflest anv oosition of the Offshore Technolorw Conference or its officers. Permissionto COPY Is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The ahstra-. ..-. ah6ild oentaln omwplcuous soknowl;dgment of whare and by whom the psper IS"presentad. ABSTRACTA unique process was developed to manufacture a titanium riser stress joint. The weld free 30 foot long TF64(ELI) component was produced so that the flanges were integrally extruded on the tube portion of the riser. The full size production part was extruded following a development program which included subscale trials and finite element modeling to determine metal flow. The amount of titanium required was minimized by the use of a bimetallic preform whereby part of the titanium was replaced by an insert made of a lower cost metal. The component was successfully manufactured to meet all of the customer's requirements. Elimination of weld qualification procedures and minimizing the amount of titanium made the cost of this approach competitive with the method of welding flanges or other available methods. References, tables and figures at end of paper.

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