Malleable iron union

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The Georg Fischer malleable iron union 342a (ISO/EN U11) provides a robust, three-piece detachable connection engineered for demanding industrial piping systems requiring reliable metallic sealing and effortless maintenance access. Manufactured from premium decarburised annealed whiteheart malleable cast iron grade EN-GJMW-400-5 conforming to Design Symbol A, the union features precision-machined bronze seating rings integrated into both mating faces to deliver a spherical-to-taper bronze-to-bronze seal. Tightening the heavy-duty union nut—threaded with parallel mechanical fastening threads according to EN ISO 228-1 (thread symbol G)—draws the spherical and conical bronze seating surfaces together, achieving outstanding metallic sealing efficiency through direct micro-contact without requiring elastomer gaskets or O-rings. Connection ends are engineered with parallel internal threads (Rp) according to EN 10226-1 and ISO 7-1, ensuring exact thread engagement, balanced load distribution, and pressure tightness along the jointing threads. Rated for maximum operating pressures up to 25 bar across temperatures ranging from -20 degrees Celsius to 120 degrees Celsius, with an allowable threshold of 20 bar at elevated temperatures up to 210 degrees Celsius, the fitting demonstrates exceptional structural strength under tensile and compressive stresses. Available in both black protective finish and hot-dip galvanised execution, with robust hexagonal or octagonal wrench profiles, this union is ideally suited for closed heating systems, thermal circuits, steam lines, industrial oils, compressed air networks, and process piping installations.