FACEValue: Millwright killed disassembling hydraulic accumulator

Case report: #OR 2011-16-1*
Issued by: Oregon State Fatality Assessment and Control Evaluation Program
Date of incident: May 2011

A 61-year-old millwright with more than 30 years of experience was killed, and two others were injured, when trying to disassemble a hydraulic accumulator to rebuild it. The victim was viewed by everyone, including managers, as an expert at the task. Warning labels on the accumulator and in the rebuild kit instructions stated that all gas pressure must be released before disassembly. However, this step was skipped, and pressurized nitrogen gas remained in the accumulator. While the victim was removing a cap from the accumulator, it violently exploded off the cylinder and struck the victim in the abdomen and pelvis, killing him. Co-workers were injured by the cap and debris.

To prevent future occurrences:

• Employers should ensure employees follow the manufacturer’s recommendations and confirm all pressure is released prior to performing any maintenance work.
• Install a “dump valve” in hydraulic systems to ensure hydraulic energy is released.
• Train employees to recognize the hazards of stored energy.
• Empower employees to stop work whenever potentially hazardous methods are used.
• Ensure all warning labels remain visible while removing caps.
• Warning labels are a necessary form of safety communication, but label messages should be reinforced in the workplace through additional person-to-person communication.