The first design is the Bolted Bonnet, with male-female joint,
spiral wound gasket, made in F304L/graphite. Ring joint gasket are also available on request. The second design is the welded bonnet, with a threaded and seal welded joint.On request a full penetration strength welded joint is available. The third design is the pressure seal bonnet, with a threaded and pressure seal bonnet joint. The check valves are also available in three different design configurations. These are piston check, ball check, or swing check designs.
Size range(s)

1/2 - 2'' (15 - 50 mm)
ASME class(es) 
150 - 800 
Standard connections 
SW,RF,NPT,BW