General flange standards

All flanges are manufactured in accordance with industry-accepted standards.

Flange - ASME B16.36, Orifice Flange (1/2"-24")

Flange - Industry Standard Flange (also called Large Diameter Flange) (26"-larger)

• Slip-on Flange: Class 300, Class 400, Class 600, Class 900, Class 1500
• Threaded Flange: Class 300, Class 400, Class 600, Class 900, Class 1500
• Weld Neck Flange: Class 300, Class 400, Class 600, Class 900, Class 1500, Class 2500

Industry Standard Flanges have no national standard code or are they covered by any governing body.

A blind flange is a solid disk used to block off a pipeline or to create a stop.

• Blind Flange: Class 75, Class 125, Class 175, Class 250, Class 350
• Welding Neck Flanges: Class 75, Class 125LW, Class 125, Class 175, Class 250, Class 350
• Slip-on Flanges: Class 75, Class 125LW, Class 125, Class 175, Class 250, Class 350

Flange - AWWA Standard Flange

AWWA C207

• Steel Ring Flange: Class B, Class D, Class E, Class F
• Steel Hub Flange: Class D, Class E
• Blind Flange: Class B, Class D, Class E, Class F
  

AWWA C207

• Steel Ring Flange: Class B, Class D, Class E, Class F
• Steel Hub Flange: Class D, Class E
• Blind Flange: Class B, Class D, Class E, Class F

ASME STANDARDS

• ASME B16.1 - Gray Iron Pipe Flanges and Flanged Fittings: Classes 25, 125, and 250
• ASME B16.5 - Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
• ASME B16.24 - Cast Copper Alloy Pipe Flanges and Flanged Fittings: Classes 150, 300, 600, 900, 1500, and 2500
• ASME B16.36 - Orifice Flanges
• ASME B16.42 - Ductile Iron Pipe Flanges and Flanged Fittings: Classes 150 and 300
• ASME B16.47 - Large Diameter Steel Flanges, NPS 26 Through NPS 60

ASTM STANDARDS

• ASTM A105 / A105M - Specification for Carbon Steel Forgings for Piping Applications

AWWA STANDARDS

• AWWA C115 - Standard for Flanged Ductile Iron Pipe with Ductile-Iron or Gray-Iron Threaded Flanges

• MSS SP-9 - Spot Facing for Bronze, Iron and Steel Flanges
• MSS SP-25 - Standard Marking Systems for Valves, Fittings, Flanges, and Unions
• MSS SP-44 - Steel Pipeline Flanges
• MSS SP-106 - Cast Copper Alloy Flanges and Flanged Fittings Class 125,150, and 300

ANSI & ASME B16.5 Pipe Flanges

What's the difference between ANSI B16.5 and ASME B16.5 standards?

ASME B16.5 and ASME B16.47 cover pipe flanges up to NPS 60 (B16.5 from 1/2" to 24" and B16.47 from 26" to 60"). ANSI B16.47 covers two series of flanges, Series A is equal to MSS SP-44-44, and Series B is equal to API 605 (API 605 has been canclled).

The B16.5 standard was first published by ANSI in 1973.  Prior to that it was an ASA standard.  In 1996 the standard changed to ASME B16.5.   For 10 years prior to the change, the standard included both and was listed as ANSI/ASME B16.5.  

So what's the difference?  The answer is there is no difference.  The ASA, ANSI and ASME have continually refined and broadened the B16.5 standard.  I'm sure there is a committee working on future enhancements right now.  

The current and correct standard is ASME B16.5.  ANSI B16.5 is common industry lingo and is still referred to extensively by architects, engineers, manufacturers and suppliers.  And although the ANSI B16.5 standard does not technically exist, it its understood as another way to say ASME B16.5.  

The B16.5 Standard defines the following:

1. Dimensions
2. Tolerances
3. Materials
4. Markings
5. Pressure/Temperature Ratings
6. Pressure Testing