What is Dual Grade Stainless Steel Pipe:
According to ASME BPVC Section II states that control the material characteristics such as mechanical properties (Mechanical Properties), chemical (Chemical, COMPOSITION), the Heat Treatment Through the provision of Grade supplies more than one Grade will be identified as Dual or Multiple Grade.
For example, Dual Grade Stainless Steel Pipe, ASME SA-213 TP316 / 316L:
Looking at the ASME SA-213 spec, you can see that 316L Low-Carbon Grade is defined to have the Carbon content lower than 316 Standard Grade, and at the same time requires that 316L have Min. Tensile Strength and Min. Yield Strength be lower.
(Steel in general, if having less Carbon, will also have low Tensile Strength)
This means that the Dual Grade Pipe TP316 / 316L must have less carbon content equal to 0.035%, as well as having more Tensile Strength equal to 75,000 psi and Yield Strength greater than or equal to 30,000 psi.
With the properties of Overlap materials of both Grade 316 and 316L specifications, this Dual Grade Pipe can be used in both Grade 316 and 316L pipe systems.