Cast steel Swing Check valve The swing cast steel check valve is a one-piece body, top entry design for reliable operation and extended seat seal life. Description The swing check valve is a one-piece body, top entry design for reliable operation and extended seat seal life. Top entry construction allows field service and in-line maintenance if necessary. All major components of the check valve are normally made from cast and wrought forms, allowing the use of a variety of widely accepted materials. Swing Check Valves are full bore. The full bore to API-6D assures unrestricted flow and allows pigging and hot tapping.