ANSI B16.5 is a standard developed by the American National Standards Institute (ANSI) that defines the dimensions, pressure ratings, material specifications, and testing methods for pipe flanges. It specifically applies to flanges from 1/2" to 24" in nominal size.

ANSI B16.5 covers several types of flanges, including Weld Neck, Slip-on, Blind, Threaded, and Socket Weld flanges, among others.

The pressure rating (e.g., 150, 300) indicates the maximum pressure a flange can withstand at a given temperature. Higher ratings are used for applications involving higher pressures or temperatures.

ANSI B16.5 flanges must meet rigorous testing and quality standards, including visual inspections, pressure testing, and dimensional checks, as well as material certification to ensure the flange meets the required mechanical properties and safety standards.