Sprung Disc Check Valve RD40. The 316 stainless steel sprung disc check valve is suitable for ANSI and EN flanges. Features and Benefits. Low pressure drop Simple and compact design Overall lengths according to DIN 3202 part 3-K4 Horizontal or vertical installation. Materials. Body – CF8M/1.4408 Disc – AISI316/1.4401 Spring – AISI302/1.4300 Star – AISI316/1.4401