A full range of butt weld long radius 180-degree return bends to ASME B16.9:2018 is available to purchase here on our website, they're supplied directly from stock in sizes between 1/2" and 8".
These seamless return bends are all manufactured using black (self-colour) carbon steel to ASTM A234 WPB, they're also standard (Sch40) weight/wall thickness and supplied with 3.1 test certification. Fittings to this standard were previously known as BS 1640 welding fittings.