A change of direction of the pipeline, in either the horizontal or the vertical planes, or in a combination of both. A bendA change of direction of the pipeline, in either the horizontal or the vertical planes, or in a combination of both. A bend is primarily defined by its angle (i… is primarily defined by its angle (in degrees), and radius (in a multiple of the pipe diameter). It can also be defined by the plane of change of direction (horizontal, vertical, combination of both).