Wichita ? A pipe fitting that split suddenly while workers were trying to drain anhydrous ammonia from refrigeration equipment was responsible for the Oct. 31 death of a worker at the Tyson Foods plant in South Hutchinson, the lead federal investigator said Wednesday.

At the time of the accident, two maintenance workers were installing a temporary vacuum hose on a drain pipe to remove the ammonia from the unit so they could replace a leaking cooling coil, said John Vorderbrueggen, lead investigator for the U.S. Chemical Safety Board, the federal agency that investigates chemical accidents.

“Because this involved a fatality, the board decided this was an opportunity to look at industry and identify if in fact there are improvements that can be made in operation of these refrigeration systems,” he said.

Also independently investigating is the Occupational Safety and Health Administration.

The rupture sprayed anhydrous ammonia on the face of Mike Wiebe, 51. He died after he breathed in the ammonia, Vorderbrueggen said. Bill Mumford, 55, is recovering at home from chemical burns to his left arm and torso.

The men were wearing safety glasses and rubber gloves, but not face shields or chemical goggles, he said.

It will be a year before the agency completes its full report, but a case study and safety bulletin with its recommendations to the company and refrigeration industry may come sooner.

“Certainly the situation would have been different if they had been wearing face shields for this activity,” Vorderbrueggen said. “If nothing else we would encourage the industry to look closer at the augmented personal protective equipment that workers should be using when they are opening ammonia piping systems.”

The pipe was probably 20 years old, and original to the equipment.

“Part of the reason the Chemical Safety Board is here … is because ammonia releases in ammonia refrigeration systems happen frequently throughout industry,” Vorderbrueggen said, adding that virtually every other incident involved minor exposure.

The South Hutchinson Tyson plant produces pizza toppings for food-service customers.