Straight Coupling (24° Cone)

A straight coupling is a tube-to-tube intermediate connection that joins two tubes of the same outside diameter on a single axis. The 24° cone ferrule type is commonly known in the field as an "Ermeto-type" fitting. Each end has a 24° cone, a ferrule and a nut; as the nut is tightened, the ferrule bites into the tube in a controlled manner and a metal-to-metal seal forms on the cone. This allows the line to be extended without welding, and a damaged tube section to be removed and replaced.

It is used in hydraulic power lines in ship engine rooms, in the supply piping of deck cranes, and on the fixed tube runs of rolling mill and board machines. In lines exposed to saltwater, humidity and washdown chemicals, the AISI 316L body eliminates the coating wear and rusting seen with plated carbon steel fittings.

• Tube OD and series (L light / S heavy) must be verified together; for the same tube OD, L and S series nuts have different threads.
• Tube wall thickness is selected according to the working pressure; thin-walled tubes may require a reinforcing sleeve.
• Ferrules and bodies from different manufacturers must not be intermixed.

Installation note: Cut the tube square and deburr it, and fit the nut and ferrule in the correct orientation. To prevent galling on stainless steel threads, apply a suitable assembly lubricant to the thread and cone, and tighten by the number of turns given in the manufacturer's instructions.