Inspection Detail

Inspection: 308059088 - Valmont Coatings-Oklahoma Galvanizing

Inspection Information - Office: Oklahoma City Area Office

Investigation Summary

At approximately 9:08 a.m. on August 30, 2004, employees responded to an emergency situation. A storage tank containing 93 percent sulfuric acid ruptured and its contents were released to the environment. Employees responded to the acid spill by constructing a dike, using gravel, lime and sand. Forklift drivers removed galvanized poles from the spill. The acid reacted with the lime, and released a white "cloud" with irritating properties which enveloped many of the responding employees. The employer called the Claremore Fire Department HAZMAT Team who responded to the scene. When the HAZMAT Team arrived employees were ordered to cease activities. This facility used sulfuric acid in the galvanizing process. The horizontal tank that ruptured had a storage capacity of 3,770 gallons of sulfuric acid and was located outside the facility in containment. It was used to replenish the sulfuric acid dip tanks. It was not designed and manufactured as a pressure vessel. The tank ruptured during the transfer of acid from the storage tank to dip tank(s) located inside the plant. Acid was transferred from the storage tank to dip tank(s) by pressurizing the storage tank with compressed plant air. The compressed plant air line went through an in-line air dryer which had not been maintained according to the manufacturer's instructions. The compressed air pressure to the storage tank was normally reduced from 120 psig by a regulator down to 30 psig. However, engineering design criteria specified that the regulator be set at 10-15 psig. After the accident, the regulator was found to be set at 90 psig. In addition, the regulator had recently been replaced and did not meet the engineering design specifications of the original regulator. An accident investigation concluded that the tank ruptured due to over-pressurization within the tank. After their exposure, employees reported burning faces, throats, headaches, and chest pain. Many of the employees coughed and choked, and had difficulty in breathing. The Claremore Fire Department HAZMAT Team decontaminated 18 employees and sent them all to Claremore Regional Hospital where they were treated for their exposure. Fourteen employees were hospitalized overnight.

Keywords: BURN, THROAT, INHALATION, STORAGE TANK, RUPTURE, EXPLOSION, CHEMICAL REACTION, HIGH PRESSURE, SKIN, SULFURIC ACID