Learn from a series of frequently asked questions about various types of plastic pipe and fittings, including how green building systems use plastic pipe and fittings. PRESS FITTINGS FOR STEEL PIPE • FASTLOCK™ fittings provide the quickest and easiest way to connect schedules 10 through 40 black and galvanized ASTM A53 compliant steel pipe. • FASTLOCK™ fittings are available in ½" – 2" sizes. • ™FASTLOCK fittings install without the use of. HDPE Pipe, Polyethylene (PE Pipe) are sorted by strength classified according to the intensity of the earlier technological nevery.info Pipe pressure classes that can be made between Pn4-Pn32 and the production of the desired diameter and size of HDPE pressure pipe system has undergone many tests in , particularly in the carriage of .