Employees Chemically Burned by Leaking Dimethyl Sulfate Pipe (leak caused by thermal expansion of pipeline)

At 11:30 a.m. on June 20, 2007, Employees #1, #2, #3, and #4, who worked for Scaffolding Company, and Employees #5, and #6, who worked for Plant Services Company, and Employees #7 and #8, who worked for a chemical manufacturer, were hospitalized after being exposed to dimethyl sulfate (DMS) in the ethoxylation area where it was used in reactors 4 and 5. Employee #7 was an operator who moved bags containing chemicals into the area in order to add it to reactor 4. Employee #8 was a mechanic that worked unplugging an auger at reactor 4. 

Employees #7 and #8 started working at 7 a.m. at reactor 4. Employees #1, #2, #3, and #4 dismantled a scaffold at a platform at the reactors. Employees #5 and #6 removed and installed new insulation on piping at a platform at the reactors. The host employer did not become aware that employees were exposed to DMS until about 2 p.m., when workers were discovered having chemical burns. Employees worked on a raised platform around the two reactors. In order to enter and leave the area, they walked along a path between two the reactors that was only 30 inches wide, and a pipe that contained DMS which ran overhead between the reactors. The piping system normally operated at 5 psi, but thermal expansion of DMS caused pressures over 300 psi and caused a valve on the overhead pipe to leak this extremely hazardous compound down onto employees that worked beneath the pipe. 

Source:OSHA.gov