 Although flange fittings are bulky, they perform well in demanding applications such as large water supply networks and hydroelectric systems.Flanges are rated at 150, 300, 400, 600, 900, 1500 and 2500 lbs or 10, 15, 25, 40, 64, 100 and 150 bars of pressure.Various types of flanges are available, depending on construction.