GONZALES, La. (AP) — State and federal officials investigating the cause of the deadly blast June 13 at the Williams Companies Inc. plant near Gonzales plan to inspect a key element of the facility this week that one federal investigator said "failed catastrophically."
Investigators tell The Advocate  they hoped to get a close look at a heat exchanger in the Ascension Parish facility's propylene fractionation unit, an area company officials have already identified as being near the explosion and fire.
One worker remained hospitalized at the Baton Rouge General Medical Center's burn unit while another is being treated at Our Lady of the Lake Regional Medical Center.
The U.S. Chemical Safety Board, the U.S. Occupational Safety and Health Administration and the Louisiana State Fire Marshal's Office are among the agencies trying to determine the cause of the fatal blast that sent a fireball a few hundred feet in the air.
In the heat exchanger, hydrocarbons are mixed and heated to react chemically and then are cooled before being separated. Propane and propylene, which are both highly flammable, are involved in the processes, authorities said.
Daniel Horowitz, the Chemical Safety Board's managing director, said Friday this heat exchanger "failed catastrophically."
Don Holmstrom, the chemical board's investigator, said officials have been working with structural engineers to evaluate overhanging hazards near the heat exchanger and develop a safety plan so investigators can get their first up-close look. The heat exchanger is also known as a reboiler or thermal conversion unit.
"There is a lot of safety work that needs to be done to make it safe to go in there," Holmstrom said Friday. "Late next week, we hope to go in there and hope to have more information."
The Chemical Safety Board, which makes recommendations to prevent future incidents, was conducting interviews last week.
Tom Droege, a Williams spokesman, said the company is cooperating with investigators.
Information from: The Advocate, http://theadvocate.com 
State and federal officials investigating the cause of the deadly blast June 13 at the Williams Companies Inc. plant near Gonzales plan to inspect a key element of the facility this week that one federal investigator said "failed catastrophically."