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ANSI and ASME Valve Standards

Updated on September 1, 2017
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Tamara Wilhite is a technical writer, engineer, mother of 2, and a published sci-fi and horror author.

Using valves in piping assemblies allows you to shut off fluid flow when a leak is found, preventing damage like this.
Using valves in piping assemblies allows you to shut off fluid flow when a leak is found, preventing damage like this. | Source


ANSI and ASME standards exist to ensure standard dimensions and performance requirements. For example, standard dimensions for valves and fittings ensure that they are interchangeable, regardless of length, material and manufacturer.

ASME and ANSI standards for valves and pipe fittings are based on the piping application, type of material and performance criteria. The American National Standards Institute, ANSI International, B16 series outlines design and performance specifications for fittings and valves. ANSI shares many valve and fitting standards with the ASME.

ASME and ANSI Flange and Gasket Standards

ASME B16.5 covers pipe flanges and flanged fittings nominal pipe size or NPS ½ through 24. At this diameter, the nominal pipe size is greater than the outside diameter or OD. ASME B16.20 covers metallic gaskets used with pipe flanges if they are used with flat face and raised face flanges. These gaskets help prevent leakage where the flat faced flanges meet.

ASME standard B16.21 applies to nonmetallic flat gaskets. ANSI/ASME B16.36 covers orifice flanges. A flow meter can be placed within the orifice flange.

ASME B16.47 applies to very large steel flanges with a nominal pipe size of 26 through 60; these flanges are between two and five feet in diameter. At this diameter, the nominal pipe size equals the outside diameter. ASME B16.48 addresses operating line blanks for pipes between NSP ½ and 24 when used with flanges covered by ASME standard B16.5.

Valves and Fittings for Gas Pipes

ASME B16.40 covers manual gas shut off valves used with underground gas tanks and buried gas lines. ANSI/ASME B16.33 applies to manual gas valves used in gas piping under pressure up to 125 pounds per square inch gauge.

ANSI/ASME Standard B16.38 covers very large metal valves used in gas distribution pipelines. ANSI/ASME B16.44 applies to manual valves used with inside gas piping systems, such as within a building.

Gray Iron Valve and Fitting Standards

ASME B16.1 covers gray iron pipe flanges. This standard includes specifications for marking iron pipes and their fittings, how the flanges are to be bolted together and pressure testing the connection. ASME B16.4 addresses gray iron threaded fittings that are class 125 and 250.

Malleable Iron Valve and Fitting Standards

ASME B16.3 covers malleable iron threaded fittings that are class 150 and class 300. ASME B16.39 applies to malleable iron threaded unions for classes 150, 250 and 300. ASME B16.42 covers ductile iron pipe fittings and flanges for classes 150 and 300.

Ferrous and Cast Iron Pipe and Valve Standards

ASME B16.12 covers cast iron drainage fittings that are threaded. ANSI/ASME B16.14 covers ferrous or iron based pipe plugs, bushings and lock nuts that have pipe threads. ANSI/ASME B16.45 applies to cast iron fittings in Sovent drainage systems, a type of single stack drainage system.

Copper and Copper Alloy Valve and Fitting Standards

ASME B16.15 applies to cast copper alloy fittings that are class 125 and class 250. ASME B16.23 covers cast copper alloy drainage fittings. ASME B16.26 covers cast copper alloy fittings when they are used with copper tubes. ANSI/ASME B16.22 addresses copper and copper alloy pressure fittings that are soldered together.

ANSI/ASME B16.24 applies to cast copper alloy pipe flanges. ANSI/ASME B16.29 applies to wrought copper drainage fittings. ANSI/ASME B16.50 covers wrought copper braze-joint pressure fittings. The brazed joint is created by melting a filler metal that will act as a glue, holding the copper or copper alloy fittings together.

Forged Fitting Standards

ASME B16.11 sets the standard for socked welding and threaded forged fittings on valves. Forged fittings can be made from carbon steel, nickel alloys and chromium and molybdenum alloy, also called chrome moly.

Butt Welded Joint Standards

ASME B16.25 addresses butt-welding ends, joints created using weld plate. ASME B16.49 covers butt welding induction bends for distribution systems. ANSI/ASME B16.9 covers butt welding fittings that are made in the factory, not at the construction site. ANSI/ASME B16.28 covers steel butt-welded elbows and pipe returns that have a short radius.

Related Valve Standards

ANSI/ASME B16.10 gives the face to face and end to end dimensions of straight way valves. For angle valves, ASME standard B16.10 gives center to face and center to end dimensions. ANSI/ASME B16.34 covers flanged, threaded and welded valves.


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