Saturday, February 28, 2015

FATALITY INVESTIGATION: A WELDER DIES WHEN HE IS STRUCK BY A PROJECTILE FROM A TRUCK’S HYDRAULIC TANK HE WAS TESTING FOR LEAKS









A welder died when struck by a piece of a hydraulic tank that came apart after being pressurized with air and water to check for leaks. 

The employer of the victim was a waste collection and recycling company that had been in business for over 50 years and had approximately 1,300 employees.  The facility where the incident occurred was the company’s main transfer station and maintenance yard for their vehicles and equipment.  There were 45 employees at this facility at the time of the incident.

The victim was a 38-year-old Hispanic male welder who had been working for the company for 10 years. The victim’s primary job task was to repair and fabricate trash bins. He was born in Mexico, had been in the United States for 18 years, and had a 12th grade education.

On the day before the incident, the victim was assigned the task of repairing a leak in an aluminum hydraulic tank from a waste collection vehicle. He had performed this task in the past on several occasions. 

The victim removed the 55-gallon hydraulic tank from the truck, then emptied and disassembled it, welded the leak, and reassembled the tank. On the day of the incident, the victim filled the tank with water and pressurized it with air from the shop air compressor to check for additional leaks. 

The airline used to pressurize the tank did not have a regulator or gauge, and it is not known how much air pressure was used. As the victim was leaning over the tank checking for leaks with a flashlight, the rear end plate of the tank blew off under pressure and struck the victim in the head. 

Other welders in the shop ran to the victim’s aid and called 911. Emergency responders transported the victim to the local hospital where he was pronounced dead from his injuries.  The cause of death according to the death certificate was blunt force injuries to the head.

In order to prevent future incidents, welding companies should ensure that:
1.   Hydraulic tanks are not internally pressurized to check for leaks.  Rather than the use of both water and air to pressurize tanks such as this, an alternative method would have been to fill the tank from an elevated water column. Using this method, excess pressure could not occur inside the tank. Had the victim used this alternate method, the tank could not have been pressurized, causing an explosion.
2.   Welders receive training on approved procedures for repair of hydraulic tanks.  When repairing hydraulic tanks, welders should undergo specialized training that includes proper procedures for leak testing. In this incident, the victim occasionally repaired hydraulic tanks but did not have specific experience or training in tank welding. He likely did not recognize the explosion hazard when he pressurized this type of hydraulic tank. Had the victim been specially trained in hydraulic tank repair, he probably would not have used hydro-pneumatic pressure testing to check for leaks.

References:
Division of Occupational Safety and Health - Title 8 regulations, Subchapter 1. Unfired Pressure Vessel Safety Orders Article 10. Safe Practices - §560. Safe Practices.

Subchapter 7 - General Industry Safety Orders, Group 2. Safe Practices and Personal Protection, Article 7. Miscellaneous Safe Practices - §3301. Use of Compressed Air or Gases.