The video above is from a previous ABC13 report.
According to the CSB, two contract workers at the refinery partially opened a flanged connection on piping containing hydrogen sulfide gas, which caused the release.
One of those workers was killed.
Two other contract workers from a separate company, who were working on equipment less than 250 feet away and downwind from the release, were also affected, with one dying from the hydrogen sulfide exposure.
Approximately 27,000 pounds of toxic hydrogen sulfide gas were released, the CSB said.
ORIGINAL STORY: 2 dead, at least 35 injured after chemical release reported at refinery in Deer Park, officials say
A lawsuit has been filed for one of the contractors, identified as 28-year-old Jose Perez.
His family, who is suing Pemex and two other companies, said his death was preventable.
The 30-page lawsuit was filed in Harris County alleging Pemex, Shell USA, and PMI Services of North America were negligent.
"(The families) can't get their loved ones back. What they want is changes so that this never happens again. This was an absolutely preventable event if folks would have followed procedure and safety rules," Managing Partner at Abraham Watkins Law Firm, Benny Agosto Jr., said.
Attorney Benny Agosto Jr. is representing the Perez family. He says Perez was in an adjacent unit when the release happened. He tried to escape but passed out before he could get out.
Agosto says they've investigated the Pemex site with their engineers.
"There was a work order that was not done properly. When you do work permits, you have to walk contractors out there. Contractors that started working on this pipe, that was not isolated. (It) was opened up, and poisonous gas came out," Agosto said.
The lawsuit accuses Pemex, PMI Services, and Shell USA of a laundry list of violations, including failure to implement safe evacuation procedures and improper maintenance of equipment.
The CSB said its investigation is ongoing and focuses on several key areas, including permit-to-work practices, energy isolation procedures, contractor management systems, emergency preparedness, communication, and response systems, hazard analyses and risk assessments, maintenance procedures, training programs, respiratory protection, and remote isolation capability.
The board doesn't issue citations or fines, but makes safety recommendations.