Michael York was a millwright for the United States Steel Corporation (USX). USX operated a steel-making furnace that was 32 feet deep. Union Carbide Corporation (Union Carbide) (defendant) supplied argon gas to the furnace through a main supply pipe. Union Carbide was not involved in the design, installation, or operation of the piping. In March 1986, USX shut down the furnace to make repairs. The argon pipelines were disconnected for the repairs but were reconnected two days before the repairs were completed. During these two days, argon gas flowed to the furnace chamber undetected. A USX technician tested the oxygen levels in the chamber and found that there was no oxygen deficiency. However, the USX technician mistakenly tested the air too high above the vessel floor. York and a coworker subsequently went to work at the bottom of the vessel and died from asphyxiation caused by the presence of argon gas in the lower part of the vessel. York’s wife (plaintiff), as the administrator of York’s estate, sued Union Carbide under a products-liability cause of action. The trial court granted summary judgment in favor of Union Carbide. York’s wife appealed, arguing that the products-liability cause of action was not preempted by federal law and that Union Carbide had failed to fulfill its duty to warn York of the hazards associated with argon gas.