Four ironworkers are suing Sunoco, alleging they suffered injuries that could have been prevented while working at a South Philadelphia refinery during an incident in March 2009. The workers were in a part of the Sunoco refinery where protective gear is usually worn. They said they were told by refinery supervisors that since the unit was shut down and depressurized, they would be safe without additional equipment. Lawyer Brian Fritz said his clients were injured from a hydrofluoric acid leak he says Sunoco could have prevented. “In terms of physical problems, the clients have experienced burning sensations in their nasal throat airways, without respect to their respiratory systems – a shortness of breath, cardiac problems,” he said. A Sunoco spokesman said the company invested $200 million in improving the safety and reliability of the equipment involved in the use and storage of hydrofluoric acid. During the incident in question, he said a very small amount of the acid was released. He did not directly address the allegations in the suit.