... -on collarsInner diameter: 2", 2 1/2", 3", 4", 5", 6"Outer diameter: 3.06", 3.45", 4.18", 5.18 ... ", 6.18", 7.20", 8.20" We can also supply according ... .3 Seaworthy packing, according to the customer demand. Concrete pipe flanges , Weld-on collars