Also known as a slip on flange. A flange that fits over a valve body flow connection. It is generally held in place by means of a retaining ring. This style of flange connection conforms to ANSI / SA 275.20 and allows for the use of different body and flange material.
Example: A valve with a stainless steel construction could use carbon steel flanges. This type of valve is very popular in the chemical and petrochemical plants because it allows the use of exotic body materials and low cost flanges.