The 28 series with size up to and including 2" (DN50) is capable of operation under full Class 2500 differential pressure, providing smooth and trouble free functionality. For sizes 2½" (DN65) and above the 28 series with hybrid seats can handle differential pressure of up to 255 bar (3700 psi).
The pressure containing parts are in compliance with ASME B16.34, for wall thickness, the design successfully passed burst testing according to DNV rules, i.e. holding four times the pressure rating for 5 minutes. A one-size-up stem made of high tensile material complies with ASME B16.34 and API 6D for drive train requirements provides sufficient safety factor during operation. A special hybrid seat design is comprised of a metal housing and polymer insert machined as a single unit. This provides higher metal seat stiffness and bubble tight shut-off (Rate A) combined with lower operating torque compared to any equivalent valve solution.