FLUID POWER SAFETY INSTITUTE™

Description of the accident:

A millwright with no previous hydraulic training was fatally injured in an accident at a steel plant.

He was standing on a stepladder tightening a leaking hydraulic connector in a steel hydraulic transmission line that was affixed to a wall approximately 12 feet above the floor.

He purposely left the power unit on because he wanted the hydraulic system to be at maximum pressure so he could see if and when the leak stopped as he was tightening the connector.

However, while he was tightening the connector it unexpectedly failed. High-pressure hydraulic oil burst from the broken connector, striking him in the face and chest. He lost his grip on the ladder, and fell to the concrete floor below.

He died as a result of the injuries he sustained from the fall.

How the accident occurred:

a.
The millwright noticed oil leaking from an overhead hydraulic oil transmission line that transported oil from a power unit to a production machine.

b.
He used a stepladder so he could gain access to the leaking overhead transmission line.

c.
After a brief inspection, he determined that the leak was coming from a threaded connector.

d.
He returned to his toolbox to collect the appropriate wrenches he needed to tighten the connector.

e.
He DID NOT turn the machine off, or lock it out!

f.
While he was tightening the connector, it unexpectedly broke, allowing high-pressure oil to discharge from the damaged transmission line at high velocity.

g.
An eyewitness said that the force of the oil discharging to atmosphere literally "blew" the victim off the ladder.

Contributing factors:

Evidence gathered during the investigation, showed that the contributing factors to the accident are as follows:

a.
The machine design did not facilitate safe and verifiable de-energization.

b.
The victim did not seek help to determine how to de-energize the system and/or how to verify de-energization.

c.
Damage to the connector was caused by overtightening.

d.
Tightening connectors while they are under pressure is a routine practice at this plant.

e.
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:

A. Training - All people who work on and around hydraulic systems MUST be properly trained. Hydraulic training must include safety.

B. 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.

C. 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.

D. 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.

E. Torque Specifications - There are recommended torque specifications for all hydraulic connectors. Make these specifications available to all maintenance personnel.

F. The safe method of tightening a leaking hydraulic connector:

1.
Lockout and tagout the prime mover.

2.
De-energize the hydraulic system and verify.

3.
Refer to the connector manufacturer’s 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.

4.
Tighten the connector(s).

5.
Remove the locks, and start the machine.

6.
Visually check for leakage. WARNING! DO NOT USE YOUR HANDS TO "FEEL" FOR A LEAK.

7.
If, after tightening a connector in accordance with the manufacturer’s 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.

Conclusion -

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!

The accidents we report are real, and the victims are real. The safety guidelines we provide are to help companies and individuals work safely with hydraulics. All guidelines we provide are general, and are not intended for one specific hydraulic system or machine.

WHEN YOU PURCHASE HYDRAULIC-POWERED MACHINERY AND/OR EQUIPMENT, WE HIGHLY RECOMMEND THAT ONCE YOU DETERMINE THAT IT CAN DO THE WORK YOU WANT IT TO DO, YOU THEN DETERMINE HOW MUCH SAFETY HAS BEEN BUILT INTO IT BY THE MANUFACTURER. IN ADDITION, WE RECOMMEND THAT YOU, WITH THE INPUT FROM YOUR OPERATORS, MECHANICS, ENGINEERS, PRODUCTION PERSONNEL, AND SAFETY DEPARTMENT, FORMULATE A LIST OF MINIMUM SAFETY STANDARDS FOR THE EQUIPMENT YOU PURCHASE. ALTHOUGH WE LIKE TO BELIEVE THAT MOST MANUFACTURERS ARE CONCEREND ABOUT SAFETY, SOME BELIEVE THAT CERTAIN SAFETY MEASURES ARE AN UNNECESSARY EXPENSE. WE FURTHER RECOMMEND THAT ALL THE SAFETY STANDARDS AND RECOMMENDATIONS THAT YOU DEVELOP SHOULD BE REVIEWED BY YOUR SAFETY DEPARTMENT, ENGINEERING DEPARTMENT, AND BY THE RESPECTIVE MACHINE OR EQUIPMENT MANUFACTURER PRIOR TO MAKING THEM POLICY - TOTAL SAFETY CAN ONLY BE ACHIEVED WITH A TEAM EFFORT.

CAUTION!

The Fluid Power Safety Institute™ does everything possible to insure that the information and drawings contained in these documents is accurate, and the procedures are deemed safe and reliable. However, these are general recommendations only and might not be applicable to all situations.

You MUST have your engineering department and service department read these recommendations and make the necessary changes for your specific application.

The Fluid Power Safety Institute™ is not responsible for actions taken by untrained and/or unauthorized persons. ALL hydraulic system service, repair, and troubleshooting should be done by trained, authorized persons ONLY.