The 90-year-old Wynnewood refinery employs about 265 workers.
A widow of the one of the workers killed in the blast said she found the company's decision to appeal the fines and citations troubling.
“They took two lives,” said Kari Smith, of Pauls Valley. “I know that's their right to contest it, but my kids no longer have their stepdad, my youngest no longer has a father and I no longer have my husband. It's just not right.”