Long service life and high functional reliability. Hard-faced body seat made of wear-resistant and corrosion-resistant 13 % chrome steel or Stellite. Additional features ensure safe sealing to atmosphere. Fully confined cover gasket with controlled compression ensures leak-proof joint. Welded body/cover joint provides added safety at high operating pressures and operating temperatures. Reliable, tight shut-off. Zero leakage thanks to perfect contact at seat/disc interface.