Violent explosion after inadvertent mixing of nitric acid and isopropanol – Review 15years later finds basic accident data corrupted, no evidence of broad learning

•Clean-in-place (CIP) chemicals present serious chemical incompatibility hazards.•Inadvertent mixing produced a violent explosion with multiple fatality potential.•The accident company took effective precautions to prevent recurrence.•There is no evidence of broader learning, indeed the accident has disappeared from open sources.•It appears critical to provide institutional support and to set up systems that facilitate learning. At a brewery in 1997, an operator confused filling nozzles for two commonly used acid cleaning agents and transferred nitric acid into a tank with P3, a proprietary phosphoric acid based cleaner that also contained 5–15% isopropanol. 10–15min later the mixture exploded violently. The stainless steel tank disintegrated with such force that fragments lodged in walls of concrete. The explosion ravaged the cellar, destroyed equipment, blew out a masonry wall and released large amounts of nitrous oxide fumes. Likely, 62% nitric acid (CAS 7697-37-2) and isopropanol (2-propanol, CAS 67-63-0) reacted to produce isopropyl nitrate (nitric acid 1-methylethyl ester, CAS 1712-64-7), a rocket propellant. It is argued that the accident has broad learning potential because of the widespread usage of the two chemicals across industries, the innocent nature of the human error and the severity of the consequence. A review 15years later of lessons learned finds that information dissemination has followed a tradition of informal meetings in small industry sector associations but impact is unclear. There is no useful mention of the accident in open sources. Although the Danish Working Environment Authority took the brewery to court for negligence, they did not report or investigate the accident, or attempt to disseminate information available to them. Today, the general literature is silent on the explosion hazards of mixing the two chemicals. The paper argues that without institutional support, learning opportunities are missed and broader cross-sector learning is limited or non-existent.