On January 15, 2008, a pressure vessel at a New Jersey foundry exploded, killing one 60-year-old worker instantly while injuring eight other workers with shrapnel.
The pressure vessel in question was used to pressurize/depressurize molten aluminum to prevent/eliminate porosity from the metal.
The incident occurred while two (2) workers, including the one who was killed, were testing a new O-ring gasket that had just been installed for leaks.
The procedure is one person stands beside the vessel and operates the controls, while the other one stands in front and observes for signs of leaks.
The first sign of a leak occurred at 80 psi on the day in question.
Then, in an attempt to force the O-ring into place, they increased the pressure to 112 psi, at which point the explosion occurred, propelling the worker 38 feet and the vessel’s hatch 35 feet.
It is important to note here that this vessel was rated for a maximum pressure of 100 psi.
Lessons Learned
- Recommendation #1: Employers should ensure that pressure vessels are not pressurized above allowable limits, all pressure relief valves are properly functioning, and that any
repairs to this type or similar pressure vessels be conducted by a certified worker.
Discussion: Several factors likely contributed to the explosion of the pressure vessel. First, the vessel ruptured due to overpressurization. In an attempt to correct a leak, the workers pressurized the vessel to 112 psi, which is greater than 3% of the maximum allowable working pressure of the unit (100 psi). Second, it was discovered that the pressure relief valves were clogged with aluminum production material and were inoperative. According to the American Petroleum Institute (API) 510, 8th Edition, Addendum #4, August 2003, Sections 6 and 7, all pressure vessels and pressure-relieving devices shall be inspected at specific intervals to ensure vessel integrity. Third, repairs and welds were performed on the vessel by a worker who was not certified by the American Society of Mechanical Engineers (ASME), or the National Board. - Recommendation #2: Employers should ensure that workers are properly trained on the safe operation of pressure vessels and are knowledgeable about the associated hazards.
Discussion: All vessel operators should be properly trained in the safe use of the equipment. Employers should provide classroom and hands-on training to the operators, and training must be specific to the worksite and equipment used. Training on safe operation and the associated hazards must be taught by a competent person, and workers should be certified as having passed the training. - Recommendation #3: A safety and health plan based on a job hazard analysis should be developed and followed.
Source http://www.cdc.gov/niosh/face/stateface/NJ/08NJ003.html