In underground mines, traditional staple-lock hydraulic couplings take a beating. They often get abused and damaged, and that makes them difficult to disconnect and service. At this year’s MINExpo show in Las Vegas, experts from Gates Corp., Denver, explained how their iLok coupling addresses the shortcomings of traditional staple-type connections, providing sizeable savings in assembly and maintenance costs.
According to the company, hydraulic hose assemblies in mines often operate at pressures of 5,000 psi or higher, see pressure impulses and spikes, and generally face wet and rugged conditions, abrasive dust and dirt, and impact loads. After months in this environment, staples can get bent or corroded and fuse to the grooves in the fitting. To service a coupling, workers often resort to time-consuming and dangerous practices to pry loose the staples and free the couplings using screwdrivers, hammers and crowbars. The result can be cracked ferrules or damaged hose, leading to leaks or a catastrophic burst when lines are repressurized.
In contrast, the Gates iLok coupling is reportedly simple to connect and disconnect by hand without tools. The coupling is based on a screw-on design with coarse, ﬂattened threads that permits hand-tightening in seconds. Then, when fully tightened, holes in the iLok nut align with a groove in the female ﬁtting to accommodate a cable lock and prevent the nut from backing off. The cable won’t pass through the grooves unless the nut is completely tightened, providing positive proof of a secure connection. The protruding cable lock provides a visual indication that “ﬂags” workers that a connection has been fully assembled.
Disengaging the connection is straightforward, too, according to the company. With the line depressurized, a worker need only cut and remove the cable lock and turn the swivel nut counterclockwise 2.5 turns by hand. Slots on the swivel nut accommodate a spanner wrench in case extra force is needed to loosen the connection.
The iLok nut provides positive contact along the entire coupling circumference, while a staple contacts only one-quarter to one-third of the mating groove. This spreads the load evenly, preventing fitting deformation and greater resistance to decoupling forces. And the iLok O-ring seal and back-up ring are housed inside the female end, where they are less prone to accidental damage. The sealing surface on the male end is protected within the swivel nut.
Compared to standard staple-lock couplings, the iLok coupling is more compact and has a smooth exterior that helps prevent abrading or snagging other hoses or adjacent equipment.
The coupling is impulse tested to 133% of operating pressure at 250°F (121°C) for one-million impulse cycles. And it exceeds Code 62 of SAE J518 flange specifications for 6,000 psi lines. Gates TuffCoat Xtreme plating provides red-rust protection that exceeds the 72-hour SAE standard by 1,000%. And it is MSHA-approved for underground mining applications.
The iLok is part of the Gates GlobalSpiral family of couplings.