Welds are ground during manufacturing to free them from offset edges and notches and thus to obtain a more favorable stress curve. Apart from the above, welds are also ground to prepare them for periodic testing and inspection by improving the conditions for these in-service inspection measures. The latter is one reason for a local decrease in wall thickness in the weld area at the connection between straight pipe and bend, so that there may be local deviations from the original design-based minimum required wall thickness. In order to fulfill the task of evaluating the strength of such material-loss regions, this paper determines appropriate stress indices for typical wall-thickness deviations and various wall-thickness/diameter ratios. For the beginning and the end of the bends, the factors B* and C* for common pipe bend dimensions have been determined. In , the factors B* and C* for 90°-bends are compared to the stress indices B and C given in the literature for the crown of the bend. These factors B and C are commonly used in piping calculations, which are based on the transverse beam theory. In this paper the factors B* and C* are presented for both ends of the bends with bend angles in the range of 0° to 90° degree. These factors for the beginning and the end of 0°–90°-bends will also be compared with factors given in the literature. The correct combination of both factors — wall-thickness reduction and B* or C* — allows to decide, whether a detected deviation from the minimum value is permissible.
- Pressure Vessels and Piping Division
Assessment of Local Decreases in Wall Thickness at the Connection Straight-Pipe to 0°–90°-Bends
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Kauer, R, & Holzer, W. "Assessment of Local Decreases in Wall Thickness at the Connection Straight-Pipe to 0°–90°-Bends." Proceedings of the ASME/JSME 2004 Pressure Vessels and Piping Conference. Design and Analysis of Pressure Vessels, Heat Exchangers and Piping Components. San Diego, California, USA. July 25–29, 2004. pp. 131-137. ASME. https://doi.org/10.1115/PVP2004-2607
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