Ferry Transporting Propane Has Scare off New England Coast
Cape Cod Times, Hyannis, Mass. (January 12, 2004)

Jan. 12--As a recipe for disaster, this one had real potential.

A tanker truck fully loaded with 10,000 gallons of liquid propane tips over to its side when the ferry Katama hits rough seas off Nantucket Thursday morning.

No one is injured, none of the flammable fuel is spilled and the Katama returns to Hyannis without further incident.

But if the tank had ripped open and spilled its contents, all it might have taken to trigger a fire was a car door being opened on the ferry, according to an expert with the Quincy-based National Fire Protection Association.

To make propane more economical to transport, it is converted to a liquid by chilling it to 40 degrees below zero Fahrenheit. It then takes up just one-270th the volume as a liquid than as a gas.

But liquid propane changes back to a gas when exposed to air at any temperature above minus 40 degrees and immediately becomes flammable.

"It's not the liquid that burns, it's the vapors," said Ted Lemoff, the association's principal gases engineer. "People buy propane because it burns real good. That's the good and bad of it."

Opening a car door sets off a tiny electric spark for the car's interior lights, Lemoff said. Near a tank venting propane, that could be enough to light the gas and start a fire.

"Certainly on a ship there are going to be plenty of sources of ignition," he said.

To prevent such a scenario, the Coast Guard forbids passengers from sitting in their vehicles on ferries carrying trucks filled with fuel oil, gasoline or propane, said Coast Guard Lt. John Winter, senior investigating officer with the Marine Safety Office in Providence, R.I.

The Coast Guard also limits passengers to 16 on these vessels, not including the crew, Winter said. Such conditions must be met for the vessel to receive its inspection certificate from the Coast Guard.

The captain and all six crew members of the Katama were tested for drugs and alcohol at a doctor's office in Bourne midafternoon Thursday, said Steamship Authority spokeswoman Paula Peters.

All passed the alcohol portion of the test, Peters said, but the results of the drug testing weren't available. All of the crew returned to work that day, she said.

Since Thursday's incident involved no fatalities, injuries or spilled fuel, it did not trigger a Coast Guard mandate for the crew to be tested, Winter said. The testing was done at the behest of the Steamship Authority, he said.

Gasoline, heating oil and propane are ferried to the islands on a daily basis, according to Steamship Authority records.

In 2003, excluding the last 10 days of the year, 910 "vehicle movements" -- or 455 round trips -- were tallied for heating oil and gasoline to Nantucket, according to boat line vice president Robert Davis.

Each leg of the trip is counted because the vehicles are considered to be carrying hazardous material even when they are empty of all but fumes, Davis said. Only if certified as "degassed" could the vehicle be transported and not be deemed hazardous cargo.

The figures for propane heading to Nantucket last year were comparable, with 898 vehicle movements. Another 49 were for liquefied oxygen and other hazardous materials.

While propane-fueled gas grills have become common, propane's main use locally is for heating and cooking, Lemoff said. Some tradesmen use portable propane heaters when working outdoors on the chilly days of midwinter.

Restrictions on vessels carrying fuel and other dangerous cargo tightened after the Exxon Valdez oil spill off Alaska in 1989, according to Capt. Tim Brady, an instructor at Massachusetts Maritime Academy who worked on sea-going vessels for 12 years.

"The Exxon Valdez changed everything," Brady said.

The new restrictions had the desired effect, based on a sharp decrease in oil spills from vessels.

In 1990, approximately 1.7 billion barrels of oil were hauled across U.S. waters and about 23,000 barrels (roughly 1 million gallons) were lost in spills and other accidents, according to the Coast Guard and Army Corps of Engineers.

By 2000, the amount of fuel transported was nearly the same, but only 3,180 barrels -- or 135,000 gallons -- were spilled.

Contrary to what is often depicted in movies and TV shows, the risk of a tanker truck with propane or another fuel exploding is not great, said Massachusetts Maritime Academy instructor Craig Dalton, who worked on tankers and other vessels for 24 years.

For this to happen, a fire outside the tank would heat its contents -- assuming the relief valve was damaged, thereby preventing the valve from venting the tank.

Pressure within the tank would increase to the point it would explode, much like a popcorn kernel, but with immense force.

Such an explosion, capable of inflicting damage over a wide area, is known by the acronym BLEVE -- boiling liquid evaporating vapor explosion.

"If a fire develops and the gas can't escape fast enough, the tank can explode and it can be a major explosion," Dalton said.