How Many Bolt Holes Does a 6-Inch ASME Flange Have?

by | Nov 11, 2026 | Mechanical engineering

A 6-inch (NPS 6) ASME B16.5 flange has 8 bolt holes in Class 150 and 12 in Class 300. Both classes use 3/4 in bolts. The class stamped on the flange decides the drilling, so check it before you order bolts or draw the flange.NPS 6 is the nominal pipe size for a 150 mm...