For decades, innovation in flammable liquid fire fighting has struggled to match the ambitions of the engineers designing ever expanding storage tanks. Today, the size of tanks being built in the Middle East far outstrips the ability of firefighters to protect them.
David White, a fire protection expert and president of Industrial Fire World, addressed the topic as a keynote speaker at the 4th Society of Fire Protection Engineers – Saudi Arabian Chapter Conference and Exhibition in Dammam, Saudi Arabia, in November.
“The evolution of fire fighting equipment has not kept pace with the challenge of how big the tanks are, how much product they contain and what the consequences of a fire can be,” White said.
In the beginning, the word crude applied to the contents and the tanks themselves, White said. Slowly, refineries transitioned from wooden tanks to the steel ones.
“And they were small,” White said. “A 10-meter tank was considered big. Fire protection? Nothing existed that could put one out.”
Natural causes such as lightning and human error regarding welding and other hazardous activities guaranteed a multitude of tank fires, he said. Firefighters arrived on the scene, used large quantities of foam but still managed to burn the tank to the ground.
“Other than selling a lot of foam, the results were negative,” White said.
Then came the advent of the self-educting nozzle as championed by Les Williams of Williams Fire & Hazard Control. To deal with larger tanks, Williams F&HC expanded the size of nozzle available from 500 gallons per minute to 2,000 gpm and bigger.
“We had tanks that required 10,000 to 15,000 gallons per minute application rates,” White said. “Then the engineers decided we could build tanks cheaper if we could build them bigger. When I say bigger, they weren’t kidding.”
In times past, the best fire protection available was adequate spacing between storage tanks, he said.
“We used to have the tanks at least one tank diameter apart, maybe even two tank diameters apart,” White said. “If one of them caught fire, unless there was a lot of wind, we could put the fire out. If it burnt out, we only lost one tank.”
The problem today is a large number of tanks crowded into a small area. White illustrated the point with a photograph of a major tank farm crushed onto a small island, offering firefighters limited approaches in event of a fire.
“I can’t image having a major tank fire on an island where you have to bring everything over by boat,” he said. “But that is the real world we live in.”
As a worst case scenario, White showed a battery of 328-foot diameter storage tanks located on top of a mountain.
“That’s a real challenge when you’re dragging hose up the hill,” he said. “These tanks are packed together like sardines, taking up every square inch.”
The issue of space is particularly critical with crude oil storage tanks due to the phenomenon known as a boilover. Water stratified throughout the contents eventually settles to the bottom of the tank. As a surface fire slowly heats the crude beneath it, that water turns to steam in a nearly volcanic reaction.
“If one of these tanks boils over, it’s not going to take out just one tank, or stop at just two tanks,” White said. “If a tank on top of a hill boils over, that burning oil is going to take out everything between the tank and the bottom of the hill.”
In too many cases, a refinery might need days, not hours, to collect and position the equipment necessary to address a fire in a mega sized storage tank containing crude oil, he said. A boilover is all but certain.
“When I show you what a boilover does, I want you to go back to your fire stations and say, ‘We need to look into this,’” White said.
Any fire department that pre-plans emergency response in terms of one tank at a time is going to be immediately overwhelmed. As an example, White referred to the December 2005 Buncefield oil storage depot fire near London that involved nearly 20 burning storage tanks.
“The local fire brigade knew exactly what it was going to do if it had one tank on fire,” White said. “When they had 12, 15 or 20 tanks on fire, they didn’t have an idea in the world what to do.”
Resources to battle such a blaze were far beyond anything immediately available to local fire brigades. The government ultimately provided 14 2,000 gpm pumps and miles of six-inch hose to relay water to the fire.
“So you say, ‘What’s the problem with that?’” White said. “It took three days to lay that much hose.” In a potential boilover situation “that’s not going to cut it.”
As far as battling a single burning tank, White was on hand in June 2001 when Williams F&HC extinguished a 270-foot diameter storage tank in Norco, LA, the largest successful tank fire extinguishment on record with product saved.
“Lightning ignited the tank and it burned about a third of the way through the contents before it was extinguished,” White said. “The good news was that it contained gasoline, not crude oil. It took about 14 hours from ignition to extinguishment. If you’ve got a boilover potential, you don’t have 14 hours to wait.”
Any crude oil storage tank that has burned more than four hours should probably be abandoned, he said. After that, moving personnel and equipment into the dike area to gain access to the flames becomes an unacceptable risk.
“You’d better get bulldozers and build up the dikes to channel it where you want it to go, not where it wants to go,” White said. “A boilover in a 150-meter tank is going to be a nightmare. If you can’t get it put out in three or four hours, the safest position is to back up and watch it.”
That assessment is not something most refinery managers agree with, White said.
“The problem is this is crude oil and all the rules change,” he said.
Some refinery fire brigades are ready to meet the challenge. In Azerbaijan, 300-meter tanks are becoming more common by the day, White said.
“At one terminal, their firefighters, who we helped train, had two miles of 12-inch hose, a 25,000 gpm water supply and plenty of foam logistics,” White said. “They bet me that they could set up their equipment and have foam flowing in less than an hour. I said, ‘No way.’ They did it in 55 minutes flat.”
The only way to gain that proficiency is practice, practice and more practice.
“Go out and lay the hose in the street,” White said. “Next year do it again, and again the year after that. You’ll have new obstacles come up each time. New people join the fire department and the people with experience leave.”
Of course, plant management will complain about the time lost that could go toward production, particularly if there has not been a tank fire in recent memory.
“Are you going to tell me that lightning can’t strike or that you can’t overfill a tank?” White said. “I’ve been around this game for a long time and have never had to search that hard to find an industrial disaster for the cover of Industrial Fire World.”
White urged the audience to keep the theme of the Saudi Arabian conference in mind – prevent, manage and control.
“And I’ll add practice, practice and practice for your worst possible nightmares and most frequent responses to always be ready.”