Blind Flange is a flange with no bore or outlet, designed to close off an outlet or end connection. While Test Flange is a Blind Flange, with a tapped test port in its center or side to allow application of pressure or the attachment of a gauge.
The blind flange serves a function similar to that of a plug or cap. It is used to terminate the end of a piping system. The blind flange is basically a flange that does not have a hub or a bored center.
Blind flanges have the face thickness of a flange, a matching face type, and similar bolting pattern. Blind flanges can also be used to seal a nozzle opening on a pressure vessel. Because it is bolted, the blind flange provides easy access to the interior of a vessel or pipe, unlike a cap that is welded. Figure 4.24 represents the drawing symbol for the blind flange.
|2-1/16"||5M, 10M, & 15M|
|3-1/16"||5M, 10M, & 15M|
|4-1/16"||5M, 10M, & 15M|
|7-1/16"||5M, 10M, & 15M|
|11"||5M, 10M, & 15M|
|13-5/8"||2M, 3M, 5M, 10M, & 15M|
|18-3/4"||10M, & 15M|
|21-1/4"||2M, 3M, 5M & 10M|
|26-3/4"||2M & 3M|