ASME B16.36-2015 standard covers flanges(similar to those covered in ASME B16.5) that have orifice pressure differential connections.Coverage is limited to the following:

• (a) welding neck flanges Classes 300, 400,600,900,1500,and 2500
• (b) slip-on and threaded Class 300
• Orifice,Nozzle and Venturi Flow Rate Meters