Nitrogen poses one of the most serious safety threats to tank cleaning rack workers, and it’s being used more than ever in tank trailers. All too often, workers who unexpectedly encounter nitrogen in a tank trailer suffer serious injury or death.
This was the warning delivered by panelists and members of the audience during the National Tank Truck Carriers Tank Cleaning Council Seminar April 9 and 10 in San Antonio, Texas. They also cautioned that the federal government is likely to take action if tank truck carriers and their customers don’t become more proactive in addressing the problem.
In the one of the most recent nitrogen accidents, a wash rack worker died on the job at a tank cleaning facility in Ohio in late March. Two people were injured in a nitrogen accident that occurred in August 2000. Exact figures on annual injuries and deaths due to nitrogen asphyxiation haven’t been released. However, statistics indicate that as many as 60% of deaths are would-be rescuers who enter a tank without taking appropriate precautions.
“This is not a new issue,” said Travis O’Banion, Trimac Transportation Services. “Nitrogen use in tank trailers affects everyone in this industry, and we have to do more than just care. If we don’t take the right action, and soon, we’re going to see OSHA (Occupational Safety and Health Administration)jump into the issue.”
Cliff Harvison, NTTC president, cautioned that all indications suggest that OSHA is very close to taking action. “Following the Ohio incident, an OSHA official indicated that the agency is ready to move,” he said. “We want to keep OSHA out of this if at all possible. If a federal regulation is required, we would prefer that it come from DOT (Department of Transportation).”
DOT has authority to write a nitrogen regulation, according to Harvison. Precedent of the action comes from the DOT rule on fumigants in agricultural shipments. It also fits with DOT’s oversight of loading and unloading activities.
Nitrogen, a component of the air we breathe, poses a serious threat because it is an odorless, tasteless gas that completely displaces oxygen. Nitrogen has a low heat transfer capability, and does not flow very fast. The result is that is tends to stay in a place in a cloud. It takes a breeze higher than 5 mph to make the cloud dissipate.
Nitrogen displaces oxygen very well. Death comes with no warning. When the oxygen content is less than 4% (a level that is quite possible in a tank trailer), unconsciousness occurs after one or two breaths. Respiration ceases.
Characteristics, such as no odor or taste and the oxygen displacement capability, make it ideal as a blanketing gas to protect against contamination during the shipment of various chemicals and edibles. It’s used to lower the flammability of some products.
More shippers also are using nitrogen to purge moisture from tank trailers prior to loading, according to Peter Nativo, Transport Service Co. If a trailer is subsequently rejected, it goes back to the wash rack or tank fleet terminal for rework.
In most cases, wash rack and terminal workers have no warning that nitrogen is in the tank. “A worker climbs up on the tank to see why it was rejected by the customer,” Nativo explains. “He leans over the manhole opening. He may get a just puff of nitrogen or maybe there is a small plume over the opening. That’s all it takes for the worker to fall down face first into the manway.”
Panelists stress over and over the need for strict company policies on confined space entry. Training must be rigorous and frequent. Discipline must be aggressive and certain. Most of all, management must be fully committed to preventing nitrogen-related accidents.
“We must make sure that everyone hears the message,” said O’Banion. “When a tragedy occurs, we all pay the price. We all suffer.”