TORRANCE (CBSLA.com) — A federal safety board blamed Exxon-Mobil for a Torrance oil refinery explosion that injured four people and threatened to release thousands of pounds of acid into nearby neighborhoods more than two years ago.

According to a report released Wednesday by the U.S. Chemical Safety and Hazard Investigation Board, the blast on Feb. 18, 2015 could have been prevented and could have been catastrophic.

An 80,000-pound piece of flying debris came just a few feet from a huge tank containing highly toxic hydrofluoric acid that could form a vapor cloud and travel for miles. Even small amounts can be lethal.

ExxonMobil disputed that there was ever a threat of a hydroflouric acid release “or risk of harm to the community.”

The lead investigator said ExxonMobil refused to provide to the board the information it needed to conclude whether or not the facility is safe.

“To date, ExxonMobil has not provided the CSB the requested documents about safeguards to prevent or mitigate hydroflouric acid release,” CSB investigator Mark Wingard said Wednesday.

State regulators had issued 19 citations against the company.

Investigators concluded that the explosion was caused by the failure of a valve that had eroded, Exxon operated the equipment “beyond its predicted safe operating life…did not establish…safe operating limits” or “perform a sufficient hazard analysis. ”

The board also made a list of recommendations for improving safety at the facility.

Exxon-Mobil and the new refinery owners, PBF Energy, declined to be interviewed but released statements.

“ExxonMobil deeply regrets the Feb. 18, 2015, incident at the Torrance refinery. We are thankful that no one was seriously hurt and wish to express our appreciation to city officials and community partners, the Torrance Fire Department and the Torrance Police Department for their dedication in ensuring the safety of the community.

“We are confident that we understand the cause of the Feb. 18 incident and have worked cooperatively with the Chemical Safety Board and staff to fully understand their findings and recommendations to improve the safety of operations,” according to ExxonMobil.

PBF Energy spokesman Michael Karlovich said the company has already implemented several of the safety measures recommended in the report and will complete two studies this year addressing others.

“In addition, as part of our commitment to operating safely, reliably and in an environmentally responsible manner, we are investing more than $100 million in a maintenance turnaround at Torrance to improve the refinery’s operational reliability,” he said. “We are also pursuing an electrical power reliability project with Southern California Edison that will benefit both the refinery and community.”