Early Sunday morning an operator was struck by a piece of a pressure gauge, on the 1700 psig steam system, when it blew apart, he then fell and bumped his head. Fortunately he was not seriously injured and returned to work the next day. The PowerPoint document shows pictures of this unusual event.

Although the NOx project is just starting the incident review, we do know the following about the circumstances leading up to this equipment failure. The gauge that failed is what is known as a "receiver" gauge. It receives a 3 to 15 psi signal from a pressure transmitter, yet its face is scaled to 2000 psig. The gauge is rated for 25 psig max.

When the NOx project rebuilt the furnaces, evidently all the gauges were collected and then reinstalled. When the gauges were reinstalled some low pressure rated receiver gauge were mistakenly put in 1700 psig service. As can be seen from the photos the 25 psig rated receiver gauge looks almost identical to the 2000 psig rated gauge it was mistaken for, with cautionary information is obscured by the dial indicator and mounting screws.

The mistake was easy to make, so we have banned the use and eliminated the stock of receiver gauges that resemble the 1/2" fitting, 4.5" face pressure gauge. Instead receiver gauges will be the more common 1/4" fitting, 3.5" or smaller face, gauge (see picture). The incident investigation should generate other lessons learned as well.