Cascading failures involving a corroded steam pipe and a defective natural gas fitting caused a powerful explosion in 2023 at a Pennsylvania chocolate factory, killing seven workers when the company failed to evacuate,

The National Transportation Safety Board met Tuesday to discuss last year’s deadly factory explosion in West Reading. But they did not vote to adopt the final report quite yet. The NTSB board said it wants to incorporate necessary changes to the final report before voting to adopt it at a later date.

That steam heated the ground, investigators said, which helped contribute to cracks forming in the service tee. In all, three leaks were discovered. That allowed natural gas to seep into the basement. The gas was then ignited by an unknown source.

NTSB holds a public hearing aimed at determining what the probable cause of the fatal explosion at the R.M. Palmer Co. chocolate plant was in March 2023.

A federal safety board says a corroded steam pipe and a defective natural gas fitting caused a powerful explosion at a Pennsylvania chocolate factory, killing seven.