O-Ring Flange - SAE J518
The SAE Code 61 and Code 62 4-Bolt Split Flange is used worldwide, usually as a connection on pumps and motors. There are three exceptions.
    1. The -10 size, which is common outside of
        North America, is not an SAE Standard size.
    2. Caterpillar flanges, which are the same flange
        O.D. as SAE Code 62, have a thicker flange
        head ("C" dimension in Table).
    3. Poclain flanges, which are completely different
        from SAE flanges. SAE Code 61 and Code 62

SAE Code 61 and Code 62