Slow bend (45 degree, 90 degree)

A slow bend is a long radius pipe fitting used in drainage and waste systems to change direction with reduced turbulence and lower risk of blockage compared with a tight elbow. The most common configurations are 45 degree and 90 degree, with the 90 degree form usually built up from two 45 degree bends or supplied as a single moulded sweep. UK Building Regulations Part H1 and BS EN 12056 recommend slow bends or rest bends at the foot of soil stacks to dissipate energy from falling flows and reduce splashing. Slow bends are particularly important on long horizontal runs to maintain self-cleansing velocity. Modern PVC-U and HDPE systems include standard slow bend fittings in a range of angles, all designed to be rodded through without removing the pipe.