Flanges are available in standard sizes from ½ inch (DN15) up to 24 inch (DN600) under ASME B16.5, with larger sizes (NPS 26–60 / DN650–1500) covered by ASME B16.47. Common materials include carbon steel (e.g., ASTM A105), stainless steel (SS304, SS316), and cast/ductile iron, each selected based on the system’s pressure, temperature, and corrosion requirements. Flanges are supplied in multiple pressure classes such as Class 150, 300, 400, 600, 900, 1500, and 2500 (ANSI/ASME) or PN6, PN10, PN16, PN25, PN40 (EN/DIN), which define their maximum allowable working pressure at different temperatures for each material group.