|How the accident occurred:
|The millwright noticed oil leaking from an overhead hydraulic oil transmission line that transported oil from a power unit to a production machine.
|He used a stepladder so he could gain access to the leaking overhead transmission line.
|After a brief inspection, he determined that the leak was coming from a threaded connector.
|He returned to his toolbox to collect the appropriate wrenches he needed to tighten the connector.
|He DID NOT turn the machine off, or lock it out!
|While he was tightening the connector, it unexpectedly broke, allowing high-pressure oil to discharge from the damaged transmission line at high velocity.
|An eyewitness said that the force of the oil discharging to atmosphere literally "blew" the victim off the ladder.
Evidence gathered during the investigation, showed that the contributing factors to the accident are as follows:
|The machine design did not facilitate safe and verifiable de-energization.
|The victim did not seek help to determine how to de-energize the system and/or how to verify de-energization.
|Damage to the connector was caused by overtightening.
|Tightening connectors while they are under pressure is a routine practice at this plant.
|If the hydraulic system had been brought to "zero energy state" prior to his tightening the connector, the accident would probably not have occurred.
Don't be lured by logic -
This is a hydraulic accident that will lure even the most adept and alert person. The lure being nothing more and nothing less than good old logic.
Here's why! A hydraulic connector is leaking. If the pressure is left in the system, you will see if and when you have tightened it enough to stop the leak. However, if you turn the power off, and de-energize the system (remove the pressure), which is the safe way to do it, how will you know if and when the leak stops?
In fact, the task becomes tedious because you have to continually lockout and de-energize, and then re-start and re-energize to accomplish, what appears to be, the simple task of tightening a leaking connector.
Let safety prevail - assume that the reason why a connector is leaking in the first place is because it is damaged. Regardless of how much you tighten it, it is NOT going to stop the leak.
In the case of a tapered-pipe connector, caution is critical. The tapered design encourages failure when it is over-tightened. It is always best to error on the side of safety - lock it out, de-energize and verify, and proceed with caution.
We have several similar accident reports, which proves that accidents of this nature are quite common. However, evidence shows that the vast majority of these accidents go unreported.
Suggestions on how to prevent this type of accident:
|Training - All people who work on and around hydraulic systems MUST be properly trained. Hydraulic training must include safety.
|Accident or Mishap? - Hydraulics is already at a disadvantage - it is not a recognized occupational hazard. The majority of "certified" safety professionals cannot identify hydraulic hazards. Consequently, the vast majority of legitimate hydraulic accidents are written off as "mishaps".
All altercations with hydraulics SHOULD and MUST be investigated. If not, sooner or later they will out of necessity - when someone is either injured or killed.
|Job Safety Breakdown (JSB) - The majority of people who work on and around hydraulics are not properly trained. Consequently, written communication is critical to protect them from unforeseen hazards.
Write a job safety breakdown for this task. Make everyone aware of the potential hazard.
|Safety Training - Discuss hydraulic safety in your safety meetings. Even though hydraulics is not currently a defined occupational hazard, it is in many respects more hazardous than electricity. Make hydraulic safety a part of your corporate safety culture.
|Torque Specifications - There are recommended torque specifications for all hydraulic connectors. Make these specifications available to all maintenance personnel.
|The safe method of tightening a leaking hydraulic connector:
|Lockout and tagout the prime mover.
|De-energize the hydraulic system and verify.
|Refer to the connector manufacturers specifications for correct torque values, and/or tightening sequence. For example, there is a recommended tightening sequence for JIC 37º connectors. If it is a tapered pipe connector you may have to apply a sealant to the threads.
|Tighten the connector(s).
|Remove the locks, and start the machine.
|Visually check for leakage. WARNING! DO NOT USE YOUR HANDS TO "FEEL" FOR A LEAK.
|If, after tightening a connector in accordance with the manufacturers specifications, the leak persists, it is probably damaged and must be replaced. DO NOT attempt to tighten it further. Over-tightening can weaken a connector, and cause it to fail.
Never tighten a hydraulic connector, or any hardware associated with a hydraulic system while it is under pressure - lock and tag, de-energize and verify, and proceed with caution!