The American National Standards Institute (ANSI) Class 150 is a system of dimensional standards for weld neck, threaded, slip-on, lap joint, socket weld and blind flanges. Dimensions for facing, bolts and studs are also included in ANSI Class 150.

ANSI Class 150 establishes measures for pipe sizes.


ANSI Class 150 considers characteristics of flanges, such as wall thickness, diameter, length and weight for global manufacturing and engineering.

Relation to ASME

In conjunction with ANSI, the American Society of Mechanical Engineers (ASME) provides specifications for protruding edges of pipeshafts in cast, forged or plated materials. ASME B16.5-1996 Class 150 is the standard for engineering and applications of flanges. This standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking and testing for operating line blanks in nominal pipe sizes (NPS).


Polypropylene Class 150 ANSI flanges are offered in threaded and blind types on These one-piece flanges have a maximum operating pressure of 150 pounds per square inch (PSI), with their glass reinforcement contributing to their strength and durability.