| Abstract Scope |
Code compliant welding details for mitered elbows, often left up to pipe fabricators and ultimately the welder, may not be well understood by the engineering community. For example, AWS D1.1 indicates “a decrease in groove angle” constitutes an essential change. For mitered pipe elbows, this has specific implications as to weld joint geometry of complete joint penetration (CJP) butt joint welds, including groove angles and bevels in addition to root face and root openings.
Weld joint preparation for mitered elbows, to be code compliant, requires the weld groove angle remain constant to avoid welding difficulties. For example, a narrow groove angle may result in incomplete penetration (IP) and inability of the welder to adequately clean weld passes, thus trapping slag. Too wide a groove angle results in excessive weld metal, greater weld shrinkage and distortion.
Awareness of seemingly small details, including code welding geometry, can contribute to water project success. Most welders, not being Engineers are ill-equipped to fit pipe that requires complex calculations, so Engineers should make it easy for welders.
In addition to observations and recommendations, this paper will address code welding details required for mitered elbow compliance including example calculations of welding bevels and a chart showing bevel vs rotation angle for mitered elbows with 60-degree single vee groove welds, for various miter deflection angles from 0 to 60 degrees. The chart eliminates complex calculations, making code compliance easier for welders, which benefits the water industry and the public. |