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 one of the most recent nitrogen accidents, a wash rack worker died on the job earlier this year in Ohio. 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.”

Government Action

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 for 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 it tends to stay in a place in a cloud. A breeze higher than five miles per hour is required to make the cloud dissipate.

Nitrogen displaces oxygen so well that injury or death occurs with little warning. When oxygen content falls to 10% to 12%, a worker experiences irregular breathing, giddiness, poor judgement, and blue lips, according to Fred C Clark, ECS Risk Control Inc. An oxygen level of 8% to 10% brings nausea, an ashen face, and unconsciousness.

At 6% to 8% oxygen content, a worker dies within eight minutes. Fifty percent are dead within six minutes. When oxygen content is only four percent, a worker immediately falls into a coma and experiences convulsions. Respiration ceases, and the person dies.

Blanketing Gas

Characteristics, such as no odor or taste and the oxygen displacement capability, make nitrogen ideal for use as a blanketing gas to protect against contamination during the shipment of various chemicals and edibles. Even some plastic pellets are shipped with nitrogen blankets. Also, it is used to lower the flammability of some products.

More shippers 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 just a 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.”

Tag Programs

While everyone agrees on the need for more preventive action, they disagree on the form. One possible solution would be to require warning tags on any cargo tank that might contain any level of nitrogen atmosphere.

This is the approach taken by Trimac Transportation, according to O'Banion. Tanks containing nitrogen are triple tagged. The tags are color-coded green, which is the industry standard for nitrogen.

Others contend that tags create a false sense of security. Wash rack and terminal workers will assume that any tank without a tag is free of a nitrogen atmosphere. The problem is that tagging is voluntary, and tags can be lost in-transit.

“Tagging scares me to death,” says Ed Matlage, Miller Transporters Inc. “From a safety standpoint, we have to treat every trailer as if it contains nitrogen.”

Panelists stressed 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.”