The leading cause of tube fitting leakage is under-tightening of the fittings, according to Sanjeev Moghe, an engineer and product manager at Swagelok Co. "Users often assemble tube fittings by what feels tight and not by the recommended 11/4 turns."
Swagelok's new tube fitting has a patented back ferrule design that hinges during installation and provides greater sealing pressure for preventing leaks. As the tube fitting is tightened, the front ferrule is driven into the body of the fitting and the tube, which creates the primary seal. Simultaneously, the back ferrule hinges inward, creating a strong grip on the tube. The hinging action translates forward motion into radial swaging of the tube, yet requires less torque. The back ferrule has a unique boot-shaped geometry that is patented.
The company also received a patent for a new method for surface-hardening ferrules called case carburization. This hardening process elevates the temperature of the steel to allow free carbon diffusion into its surface, which results in a uniform hard layer on the metal. Swagelok is the only manufacturer of tube fittings that independently developed and received a patent for commercial-scale processes to produce case carburization of ferrules on tube fittings. The tube fitting works with new alloys used in modern instrumentation, industrial, and hydraulic applications.
Additional details. . . Mike Valentine, Market Specialist, Swagelok Co., 31400 Aurora Rd., Solon, OH 44139; Tel: (440) 349-5934; www.swagelok.com ,
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