The Himeji acrylic acid tank explosion and rebuilding safety management (2012)

The blank space behind efficiency

At the centre of this accident is a paradox: the very arrangements that produced success were also the soil in which safety was eaten away. The バラコン method — dispensing with a general contractor so that the plant floor handled detailed design through to ordering — had long been described as a strength of the Himeji works. But that same discretion on the floor also led to small accumulated “improvements”: stopping the cooling unit on a tank’s top plate to reduce how often sludge had to be cleaned, and then removing the temperature controller altogether. The more efficiency was layered on, the more the equipment’s original purpose faded from the awareness of the people running it. The longer a plant had gone without an accident, the harder that blank space was to notice.

The timing also tells you something about the character of the accident: one departure from routine — maintenance work — was immediately followed by another, a capacity-improvement test. It is precisely when procedures leave their normal course that accumulated hands-on instinct stops working, and that appears to be what happened at Himeji. From the explosion in 2012 to indictment in 2015 and judgment in 2018, establishing criminal responsibility took close to six years. The underlying structure — acrylic acid and SAP, and the concentration of production at Himeji — was not changed by the accident itself, and the question of how to keep a safety management system permanently renewed remained with Nippon Shokubai after the verdict was final.