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Hydraulic hose fittings and connections

Safety Alert
1 February 2014

A worker was injured when struck in the head by a hydraulic hose and fitting that had suddenly separated from its connection point to a 50-tonne hydraulic jack while operating under pressure during a lifting procedure.

Hydraulic jacks and cylinders (or actuators) are used on plant and equipment for many different applications. Hydraulic systems utilise high pressure fluid to transmit power (force).

Fittings, couplings and other connectors can be located in close proximity to the people operating the plant or equipment. Some applications or processes may require the frequent connection/disengagement of couplings while the hydraulic hoses are under residual internal pressure.

Hydraulic hose connection

Probable causes

  • incorrect thread tape used on the male thread of the snap hose fitting to the jack housing
  • the male thread of the fitting being misaligned during installation into the jack housing due to the hose and fittings remaining connected
  • threads were worn, stripped or damaged preventing full thread depth engagement into the housing
  • an excessive high torque applied causing potential over- tightening of the snap hose fitting into the housing
  • system hydraulic pressure exceeded design limit of the threaded connection
  • snap hose fitting physically damaged due to impact with another object.

Action required

  • hydraulic equipment should be visually inspected prior to use for any sign of fluid leakage at each connection and fitting, where practicable
  • hoses attached to snap on fittings should be removed when not in use, coiled and suitably stored to prevent damage or deterioration
  • threaded fittings should be installed by a competent person and be subject to regular maintenance, inspection and testing where the device and fittings are exposed to fluctuating pressures and varying environmental conditions
  • jacks and fittings where used in mobile service vehicles should be secured during transport to prevent damage from unintended movement.