SUYAN valves are available in three bonnet designs. The first design is the Bolted Bonnet, with male-female joint, spiral would gasket, made in F304+flexible 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.