ASME B16.5: Pipe Flanges and Flanged Fittings What is the purpose of ASME B16.5 Pipe Flanges and Flanged Fittings? ASME B16.5 specifies Dimensions Materials Pressure-temperature ratings Tolerances Marking Testing for pipe flanges and flanged fittings. Where ASME B16.5 applicable (Materials And Units)? It applies to flanges with nominal pipe sizes (NPS) ranging from ½ inch