• All dimensions are in inches.

• Dimensions to ASME B16.5 - Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard

• Bolt circle diameters are 1/8 inch larger than bolt diameter.

Weld Neck Flanges are drilled with the wall thickness of the Flange having equal dimensions to the matching pipe. The lighter the pipe is the larger the bore is in the Weld Neck Flange. And conversely the heavier the pipe is the smaller the bore is in the Weld Neck Flange. Weld Neck Flanges are usually used in high pressure systems and are suitable for cold or hot temperatures. This Standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. Included are: flanges with rating class designations 150, 300, 400, 600, 900, and 1500 in sizes NPS 1/2 through NPS 24 and flanges with rating class designation 2500 in sizes NPS 1/2 through NPS 12, with requirements given in both metric and U.S. Customary units with diameter of bolts and flange bolt holes expressed in inch units; flanged fittings with rating class designation 150 and 300 in sizes NPS 1/2 through NPS 24, with requirements given in both metric and U.S. Customary units with diameter of bolts and flange bolt holes expressed in inch units; and flanged fittings with rating class designation 400, 600, 900, and 1500 in sizes NPS 1/2 through NPS 24 and flanged fittings with rating class designation 2500 in sizes NPS 1/2 through NPS 12 that are acknowledged in Non-Mandatory Appendix E in which only U.S. Customary units are provided.