By Hans van Rooij, Managing Director, SMIT Salvage B.V.
What ship type is involved? Is it a cargo fire? Or an engine room/machinery fire? These are the key questions as the salvor prepares to respond to a fire emergency at sea. While the salvage team is hardened to such situations, it is a different story for the crew. Fire at sea can be a terrifying experience. Circumstances may have forced the crew to abandon. The salvor will want to know if they have left the ship. If they remain on board and the casualty still has power and can manoeuvre, it can be positioned in a way that minimises the spread of fire.
If there is fire at the bow, the correct protective action is to keep the stern into wind. If, on the other hand, there is a stern fire, the bow should be kept into wind to prevent the flames spreading along the vessel. If the vessel has been abandoned, the protective positioning of the casualty will be a priority task for the first tug to arrive at the scene.
The salvor’s fire-fighting tactics are shaped by ship type, cargo type and, of course, the specific circumstances. It is dangerous to generalise, but fires involving tankers, containerships and other specific types do require particular approaches. Certain cargoes also have special characteristics in fire situations. Cotton is an example. A cotton bale can be taken from a burning hold and immersed in water for half an hour, only to re-ignite almost immediately when exposed to the air once again. Smouldering fires are always a problem. Fires in cargoes such as coal and cocoa are extraordinarily difficult to extinguish, as these materials carry enough air to sustain a smouldering fire for long periods.
Fires in passenger vessels
There are likely to be hundreds (possibly thousands) of people on board a passenger vessel. Inevitably, there will be confusion, at the very least, in a fire situation. There are also likely to be variations in the quality of the crew’s fire-fighting and emergency response training. These are important concerns for the salvor.
Passenger ship fires ending in total losses over the past 25 years include the PRINSENDAM incident, in Alaskan waters in 1980 and the ACHILLE LAURO off Somalia in 1995. Both were engine room fires. Both capsized before salvors had a chance to intervene in a decisive manner. All too often, a list develops, portholes fail in the fire, the rate of water ingress increases and the vessel eventually rolls over.
Passenger ships are also vulnerable to flooding with fire-fighting water. This was a causal factor in the losses of the LEONARDO DA VINCI (La Spezia, 1980) and FIESTA (Piraeus, 1992). These ships also capsized; fire-fighting activities robbed them of stability. In the case of FIESTA, the local fire brigade arrived at the quay and began fire-fighting. They jetted a vast quantity of water over FIESTA. The vessel developed a list and water entered open portholes. FIESTA rolled over and sank in 30 metres of water, within an hour or so of the fire brigade’s arrival. They certainly put the fire out! Salvors performed the subsequent wreck removal. It goes without saying that a ship is not a building. Marine fire-fighting is different!
Tanker fires require a major response
It is crucial to deploy sufficient fire-fighting resources. Big tanker fires may require several days of boundary cooling before foam can be used with any chance of success. Hot steelwork vaporises foam as soon as it is applied. Even if a fire is extinguished, hot steelwork will almost certainly mean rapid re-ignition or, even worse, an explosion.
The aim of a “foam attack” is to smother and kill the fire. Foam is often used, however, as a defensive tool to prevent the spread of fire, rather than extinguish it.
It requires courage to board a burning tanker. There may be no choice if a tug is to connect up and prevent a laden tanker going aground. In this situation, the boarding party will make the most of the opportunity to reduce the flow of fuel to the fire, by closing every valve that will move. As they progress along the deck, it may be essential to shield them from the intense thermal radiation by jetting a “water curtain” over them.
There are three components to every fire: oxygen, fuel and a source of ignition. The salvor, of course, will seek to eliminate oxygen or fuel, in order to destroy the “fire triangle”. An internal fire, such as fire in the engine room, is in an enclosed space which can be evacuated, sealed and flooded with CO2, so excluding oxygen. In contrast, the only option in an open fire is to remove or reduce the fuel component.
In a major tanker fire involving bunkers or cargo, the priorities are to gain control by boundary cooling and reducing or, better still, eliminating the fuel source, by isolating it from the fire.
Collisions involving laden tankers may involve a large-scale initial outflow of oil. If this ignites, the resulting conflagration will destroy the ship unless it is kept moving. The casualty must not be allowed to sit in a lake of burning cargo.
There are many specific risks associated with crude oil fires. They include the “boil over”. This can happen when a crust forms on the surface of crude oil within a burning tank. The crust becomes increasingly heavy as the lighter fractions are consumed. Eventually, the crust will sink into the cooler oil below, so “renewing” the fire. If the crust sinks very deep it may reach a water layer. The water is vaporised in an instant and the boil over occurs. Flames and boiling oil will spurt from all vents and place lives at risk. An experienced salvage master may detect the early warning signs of a boil over. Equally, it could happen with little or no warning.
Challenging containership fires
There may be specific problems associated with a particular cargo. One recent example involved calcium hypochlorite (UN No. 2880, IMDG Class 5.1 – oxidising substances). During the late 1990s a series of major containership fires occurred. They had one thing in common: the carriage of calcium hypochlorite (used for treating drinking water and swimming pools). This is an unstable product and can decompose and generate extreme heat. The risk is influenced by ambient temperature and size of packaging. Uncontrollable self-heating may occur, for example, if hold temperatures rise due to the heating of bunkers in the double bottom.
One of the golden rules of salvage is to prevent the situation deteriorating. The correct choices must be made. It may well be better to commit resources to cooling, rather than make any immediate attempt to put out the fire. In a containership fire, the cooling water volumes will be extremely high. In the 1990s, for example, the severe fire on board the EVER DECENT, following a collision with the cruise vessel NORWEGIAN DREAM, required over 100,000 cubic metres of cooling water.
Containership fires present special problems. An open fire is relatively straightforward, but fires in containers are very different. Unfortunately, many of the packaging materials still in use are highly combustible and produce toxic smoke and fumes. Access will be difficult due to modern close stowage practices. Fire deep within a stack is a major headache. A massive cooling programme is essential, as containers transmit heat very efficiently. Indeed, the entire stack may well behave as one “entity”, with fire spreading in all directions unless subjected to constant high volume deluge. The situation may be aggravated if the force of the collision compresses the stack or a pronounced list encourages the fire to spread “upwards”.
Furthermore, most modern container vessels have no discharge capability. The salvor must have access to floating cranes with the height and reach to discharge containers. Given the sheer size of the latest generation of containerships, this means deploying very large sheerlegs. This problem can only get worse as containerships continue to grow in size.
Dealing with hazardous chemicals
Access to such equipment is essential when responding to casualties such as the ro-ro JOLLY RUBINO. Fire broke out on board this vessel in September 2002, forcing the crew to abandon. Two days later JOLLY RUBINO grounded very close to a World Heritage Site on the South African coast. On grounding, this casualty suffered several explosions, filling the air with dense smoke and chemical fumes. Full chemical suits and breathing apparatus were essential during the fire-fighting and subsequent removal of all pollutants.
There are several hazardous chemicals databases providing information on physical properties and health and environmental data. CHEMDATA holds information on some 20,000 chemical substances and appropriate response/PPE precautions. ISIS is a toxicological database, while VOICE focuses on techniques for monitoring hazardous chemical concentrations.
Prudent work regimes must continue after the fire has been extinguished. At that stage a wide variety of dangerous materials may need to be removed and decontamination performed. In some instances, the hazardous chemicals are categorised into several groups, according to degree of hazard. The prescribed PPE may range from rubber boots and gloves, goggles and a disposable suit for low hazard substances to positive pressure chemical resistant gas suits for more dangerous hazardous chemicals.
These agents are not fire-fighting foams, in the traditional sense. They work by attacking the fire’s heat component, as opposed to the oxygen component. The cooling effect much reduces the risk of re-ignition. In essence, these cooling agents arrest the molecular process of combustion. In one early Pyrocool trial, the temperature of a magnesium fire was reduced from 1,700°C to 33°C within 30 seconds. There have been subsequent trials involving every class of fire (Class A, solid combustibles; Class B, flammable liquids; Class C, flammable gases; and Class D, metal fires). Dramatic temperature reductions were achieved in all cases. Pyrocool has also been used successfully to kill fires on containerships – including the EVER DECENT.
The availability of high efficiency cooling agents has influenced fire-fighting tactics. Fire teams, in appropriate circumstances, can now adopt more aggressive fire-fighting tactics and remain safe. This includes close-quarters fire-fighting at ranges which would otherwise prove fatal due to the intense thermal radiation. Furthermore, these new cooling agents use less water and this is a major advantage in situations where stability is a matter of concern. In addition, early extinguishment is a key issue in accommodation, liquid hydrocarbon and container fires. The prevention of heat transfer in a large container stack is a critical success factor in some cases.
Other new fire-fighting technologies being developed include telescopic masts allowing fire-fighters to work above a burning container stack. Work is also under way on a remote-operated fire-fighting system able to drill into containers and inject foam/water mix.
Extreme environmental awareness has led to new restrictions over the disposal of wastewaters arising from salvage. Large volumes of contaminated wastewater may be generated during fire-fighting. It is now very difficult to obtain approvals for the discharge of any wastewaters, even when contaminants in the waste stream are close to zero. Due to the lack of suitable high flow-rate portable wastewater systems, LDS, the Legal Discharge System, has been developed. It provides for containment, a range of physical, chemical and biological treatments, together with data demonstrating compliance with effluent contamination limits.