Blind flanges, abbreviated as BF, are commonly used in any industries that utilize piping. They are available in all face types (RTJ, Raised and Flat Face) at all pressure ratings. A blind can be inserted between two flanges to block flow but this isn’t good practice in most piping. When trying to block flow temporarily in a pipe, the designer should use a spectacle blind instead.

Blind Flange Standards

ASME Standards

• ASME B16.5 - Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
• ASME B16.47 - Large Diameter Steel Flanges: NPS 26 Through NPS 60 Metric/Inch Standard
  • Series A / MSS SP-44
    • For general use
    • Bolt circle diameter is larger than Series B
    • NOT interchangeable
  • Series B / API Std 605 (cancelled)
    • For compact use
    • Bolt circle diameter is smaller than Series A
    • NOT interchangeable

Blind Flange Sizes - 1/2" through 24"
	Raised Face & Flat Face ANSI Class 150, B16.5, RF (in) ANSI Class 300, B16.5, RF (in) ANSI Class 400, B16.5, RF (in) ANSI Class 600, B16.5, RF (in) ANSI Class 900, B16.5, RF (in) ANSI Class 1500, B16.5, RF (in) ANSI Class 2500, B16.5, RF (in)		Ring Type Joint ANSI Class 150, B16.5, RTJ (in) ANSI Class 300, B16.5, RTJ (in) ANSI Class 400, B16.5, RTJ (in) ANSI Class 600, B16.5, RTJ (in) ANSI Class 900, B16.5, RTJ (in) ANSI Class 1500, B16.5, RTJ (in) ANSI Class 2500, B16.5, RTJ (in)

Blind Flange Sizes 26" through 60"
	Series A ANSI Class 150, B16.47 Series A (in) ANSI Class 300, B16.47 Series A (in) ANSI Class 400, B16.47 Series A (in) ANSI Class 600, B16.47 Series A (in) ANSI Class 900, B16.47 Series A (in)		Series B ANSI Class 150, B16.47 Series B (in) ANSI Class 300, B16.47 Series B (in)

Blind Flange - Industry Standard
	ANSI Class 75, Industry Standard (For SOF) (in) ANSI Class 75, Industry Standard (For WNF) (in) ANSI Class 250, Industry Standard (in) ANSI Class 350, Industry Standard (in)