500 Series Wafer and 522 Series Lug style cast iron bodies are offered. The Lug bodies are drilled and tapped to meet ANSI Class 125/150 flanges. The disc is spherically machined and hand polished to provide a bubble tight shut-off, with minimum torque and extended life. The stem to disc connection features a taper pin design for high pressure requirements. Unique “tongue and groove” seat design is designed to seal with slip-on or weld-neck flanges. Seat totally encases the valve interior to isolate the body from the line media. In addition, all 500 Series seats are bonded for increased pressure rating. Molded seat O-ring provides seal between valve and pipe flanges. Flange gaskets should not be used with this valve. Primary and secondary seals are interference fits between seat and disc hub, and stem and seat stem hole respectively. A corrosion resistant, heavy duty acetal bushing absorbs side thrusts. The stem packing gland is a self-adjusting double “U” cup design and gives positive sealing in both directions, preventing external substances from entering the stem bore. The mounting flange meets ISO 5211 and allows direct mounting of Ultraflo manual operators and power actuators.