This specification covers the requirements for materials, workmanship, performance, and dimensions of circular contact-molded "fiberglass" (glass fiber reinforced thermosetting resin) flanges for use in pipe systems and tank nozzles. This specification does not address flange design or gasket selection. Flanges may be produced as integral flanges (Type A) or flange-on-pipe (Type B). They may be made of either epoxy resin (Grade 1), polyester resin (Grade 2), phenolic resin (Grade 3), vinylester resin (Grade 4), or furan resin (Grade 5). Flanges are also grouped into classes according to pressure and thrust capability as Class I (hoop and axial pressure) and Class II (hoop pressure only). Specimens shall undergo tests for which performance requirements must be met for sealing, short-term rupture strength, and maximum bolt torque.