Extruded outlet headers are furnished as special fittings to the various fittings specifications. These specifications provide the controls for materials and manufacturing necessary to produce the fittings. Some of these specifications are complete while others refer to ASTM (or CSA) standards for part of the control. The piping codes provide the rules for design of the outlets. Most of the codes have a special section covering the reinforcing rules for extruded outlets. These rules require control of dimensions and radii, and require that the reinforcing be integral with the body of the fitting and cover the complete circumference. The outlet radii must be produced by forming, rather than by machining of grinding. For qualified fittings, the amount of reinforcing required can be reduced for outlet diameters smaller than the run. Some of the piping codes require integral reinforcing for the more critical applications. The piping codes also provide Stress Intensification Factors (SIF’s) to be used for piping fatigue analyses. Although the codes give SIF’s for many types of outlets, they do not provide guidance for properly reinforced outlets made per the rules for extruded outlets. Taylor Forge (TF) has run tests over the years demonstrating that properly reinforced extruded outlets, will not only pass burst tests as required by fittings specifications, they also have SIF’s approaching those listed for tees. (B31.3 recently increased the SIF’s for tees with smaller crotch radii, and TF tests indicate that properly reinforced extruded outlets are better than indicated by the new rules for tees.) Reasons to consider extruded outlet headers for pipeline service are: • Versatility of size, spacing, number of outlets, etc.; • Low stress concentrations, fatigue resistant construction; • Radiographable butt weld connections; • Design and analysis rules are code qualified; • Field work is minimized.
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Extruded Outlet Headers for Pipeline Service
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Lankston, RJ. "Extruded Outlet Headers for Pipeline Service." Proceedings of the 2002 4th International Pipeline Conference. 4th International Pipeline Conference, Parts A and B. Calgary, Alberta, Canada. September 29–October 3, 2002. pp. 623-627. ASME. https://doi.org/10.1115/IPC2002-27387
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