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Millwright fatality involving a hydraulic accumulator.

Oregon Department of Human Services
Morgantown, WV: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, FACE 11OR016, 2013 Nov; :1-7
A 61-year-old senior millwright with over 32 years of experience was killed, and 2 other millwrights were injured, while trying to disassemble a hydraulic accumulator to rebuild it. The victim had previously rebuilt at least one other accumulator salvaged from another part of the mill. He was viewed by everyone, including managers, as the expert in this task. Warning labels on the accumulator and in the rebuild kit instructions stated that all gas pressure must be released prior to disassembly. However, this step was skipped in the disassembly process and pressurized nitrogen gas remained in the accumulator. While the victim was slowly removing an 8-inch diameter cap from the end of the accumulator, the cap violently exploded off the cylinder and hit the victim in the abdomen and pelvis. The flying cap killed the victim. His co-workers were injured by the cap and related debris. RECOMMENDATIONS: 1) Employers should ensure employees follow manufacturer's recommendations and confirm all pressure is released prior to performing any maintenance work on pressurized systems and components (in this case both hydraulic and gas). 2) Install a "dump valve" in hydraulic systems to ensure hydraulic energy is released from the system when the equipment is shut down. 3) Employers should ensure that all employees are trained to recognize the potential hazard of stored energy and how to eliminate or control it. 4) Employees should be empowered to stop work and re-evaluate a situation whenever potentially hazardous or unusual methods are being used to accomplish a task. 5) Manufacturers or employers should consider altering the placement of warning labels, or applying additional labels or seals, on the cap area of accumulators to ensure they remain visible while removing the caps. 6) Warning labels are a necessary form of safety communication, but label messages should be reinforced in the workplace through additional person-to-person communication.
Region-10; Accident-analysis; Accident-prevention; Accidents; Injuries; Injury-prevention; Traumatic-injuries; Warning-signs; Hydraulic-equipment; Compressed-gases; Milling-industry; Training; Safety-measures; Safety-valves
Oregon Fatality Assessment and Control Evaluation (OR-FACE/CROET) L606, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239-3098
Publication Date
Document Type
Field Studies; Fatality Assessment and Control Evaluation
Email Address
Funding Type
Cooperative Agreement
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
FACE-11OR016; Cooperative-Agreement-Number-U60-OH-008472
SIC Code
Source Name
National Institute for Occupational Safety and Health
Performing Organization
Public Health Services, Portland, Oregon
Page last reviewed: December 11, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division