ANSI 150 Class Pressure Rating Flexible Pipe Connector: Heavy-Duty Reinforced Bellows Coupler for High-Stress Piping The American Standard Workhorse for High-Stress Piping Applications. The ANSI 150 Class Pressure Rating Flexible Pipe Connector is a heavy-duty, engineered bellows coupler built to meet the rigorous demands of industrial piping systems designed to ASME/ANSI B16.5 Class 150 standards. High-stress piping networks—such as those found in power generation,