Abstract: On January 9, 2010, at least four Employees of Enbridge G & P (East Texas) working under the supervision of the plant manager were involved in relighting a waste heat boiler/reaction furnace. The process to restart the waste heat boiler/reaction furnace required the employees to stand close the sight glass valve, remove the sight glass, slide the igniter into the valve, open valve, slide igniter into the burner, ignite, pull igniter partially out, close valve and replace sight glass. However, it was discovered that the sight glass valve had seized and needed to be replaced. Without completing a safe work permit, locking and tagging out the system, or purging it of any toxic or flammable substances, the employees began replacing the valve when the hydrogen sulfide release occurred. Employee #1 died from hydrogen sulfide poisoning, Employee #2 was hospitalized from hydrogen sulfide poisoning, and Employees #3, 4, 5, 6, and 7 suffered symptoms of hydrogen sulfide poisoning but did not require hospitalization.