Union bonnet is the market standard design for bronze valves up to 2” size. A type of valve construction in which the bonnet is held on by a union nut with threads on the body. The nut is optimum sized hexagon shaped with high tensile properties to provide a leak-tight joint for maximum security under pressure. A union bonnet is appropriate for appliances that require regular inspection and maintenance and offers added reliability. Designed for rugged service applications, with maximum resistance to distortion produced by internal pressure.