Red-Bag has calculated many pipe class flanges. The pipe class consists of various piping components, ranging from pipe, all sorts of fittings up to flanges. The flanges are usually the limiting factor, since the flange rating is used as the design condition for the pipe class. The strength limitation of the flange is therefor covered, however the leak tightness of the flange assembly (flanges, bolts, gasket) is not further determined. The bolt load will to a large extend determine the overall quality of the flange assembly. Red-Bag does the flange calculations for example according the EN 1591-1 to obtain the required bolt load for the design conditions and the required leak tightness. The bolt load table and assembly requiremnts are added to the pipe class and is therefor consistent with the quatlity requirements for the welding work. (work done for Borealis and Vopak)