SS 316/316L Dual Certified Flanges

What’s SS 316/316L Dual Certification?

The stainless steel 316/316L dual certification refers to the austenitic stainless steel that meets all of the requirements of both stainless steel 316 and stainless steel 316L. These requirements include chemical composition requirements, tensile testing requirements, hardness requirements, as well as other requirements stated by relative standard specifications. For a dual-certified 316/316L flange made in accordance with ASME B16.5 or ASME B16.47, it may be made from forging which meets all requirements of both ASTM A182 F316 and F316L, or it may be made from plate which meet all requirements of both ASTM A240 TP316 and TP316L.

Determination of Pressure-Temperature Ratings

According to ASME Boiler & Pressure Vessel Code Section II Part D Mandatory Appendiex 7, dual certification 316/316L is the multiple marking of flange materials permitted by the Code. The dual-certified stainless steel 316/316L takes the merit of higher strength of SS 316 and the merit of low carbon content and excellent welding performance of SS 316L. The pressure-temperature ratings and allowable stresses shall be determined on the basis of SS 316, which has higher strength. Thus, the P-T ratings shall be in accordance with ASME B16.5 Table 2-2.2 (metric unit) or Table II-2-2.2 (US Customary unit).