UNDERSTANDING SCRAP FIRES

Published: 31 January 2023

CARRIAGE OF SCRAPS

Recently the Club has seen several incidents involving scrap showing signs of self-heating during voyages. As these incidents were well managed by the crew, they did not result in immediate risks to the ships involved. However, these incidents do highlight the hazards surrounding the transport of scrap and the importance of knowing the right precautions to mitigate these risks.

Scraps carried onboard vessels often consist of recyclable materials mainly left over from product manufacturing and consumption, such as auto parts, building supplies, metals, sheets, coils, strips, cutting wastes etc, which are being transported to recycling or scrap yards. Unlike waste, these scraps have monetary value, particularly recoverable metals and non-metallic materials[1].

 

INTERNATIONAL MARITIME SOLID BULK CARGOES (IMSBC) CODE

Metal scraps are typically transported on board in one of two forms: mixed scrap, which comes in a variety of sizes and may include car body parts and metal shavings the size of coins, or ferrous metal borings, shavings, turnings, or cuttings, which are produced by drilling, turning, and cutting steel.

According to the IMSBC Code[2], scrapped iron or steel intended for recycling:

• should be scheduled under Group C, known not to liquefy or possess hazards of any kind
• should be kept as dry as practicable before loading, during loading and during voyages
• should not be loaded during precipitation
• should only be loaded when all non-working hatches of the cargo spaces to which this cargo is loaded, or to be loaded, are closed.
• should only be carried when the bilges in the cargo spaces carrying this cargo are not being pumped overboard unless necessary
• should only be surface ventilated, either naturally or mechanically, when transported.

On the other hand, when cargo contains ferrous materials in the form of iron swarf, steel swarf, borings, shavings, or cuttings, these are categorised as materials susceptible to spontaneous fire and self-heating. If swarf (fine metal turnings) is included in the cargo, then the IMSBC Code Group B “ferrous metals borings, shavings, turnings, or cuttings UN 2793[3]” which comes with a totally different set of requirements[4] should be referred to. UN 2793 is assigned to substances with characteristics that are liable to spontaneous combustion.

Iron or steel will naturally oxidise (rust). This is an exothermic (chemical) reaction that produces and releases heat to the environment. When these iron scraps have been finely separated, they will oxidise more rapidly and produce heat faster. When material contains moisture, oily rags or combustible matter like military scraps, live shells, rubber, plastics, fabric, or even if contaminated with oils, then the oxidation process is further accelerated.

This heat will be dissipated to the environment in a shallow level mass of turnings but will be significantly retained if carried in huge, tightly packed quantities (bulk). As a result, the temperature of the mass will rise.

For transporting these types of consignment in bulk:

• the shipper has to declare in writing or certify that cargoes do not have properties that encourage self-heating[5]
• stowage should be separated from foodstuffs
• the carrier must realise cutting oils used in production operations may contaminate turnings and borings or these loads may contain flammable materials like oily rags
• loads should be protected against moisture before and after loading
• cargo bilges of each cargo hold should be kept as dry as possible both during loading and the voyage
• the temperature of the ferrous materials should not be higher than 55°C (Celsius) prior to loading
• loaded items should also be trimmed and compacted as much as possible in the cargo space using a bulldozer or other tools. This will create a denser mass to keep air out of the stow and less area will be exposed to oxidation
• if surface temperature exceed 90°C during loading, then loading should be ceased and should not restart until the temperature has fallen below 85°C. The ship should not depart unless the temperature is below 65°C and has shown a steady or significant downward trend in temperature for at least last eight hours
• the surface temperature should then be measured daily during the transportation without accessing the cargo hold before, during and after loading. However, if entry is required, breathing apparatus should be given in addition to the safety equipment required by company and local regulations
• cargo holds should not be ventilated during the voyage
• It should be noted that self-heating may cause the dangerous depletion of oxygen in the stowage spaces.

Any rise in the surface temperature of the material indicates a self-heating issue and a potential fire situation could develop if the temperature rises to 80°C. However, firefighting using water should not be undertaken when a vessel is still at sea. In this situation, the ship should advise the Club with the view of seeking further assistance from a technical expert which may involve diverting to the nearest port of refuge. In port, lots of water can be used but consideration should be given to the ship’s stability.

 

ROOT CAUSES OF SCRAP FIRES

What starts scrap fires on ships?

Scrap fires on board can result from several factors, such as spontaneous combustion, electrical problems and human error.

The inappropriate handling and storage of scrap metals is one of the main causes of scrap fires on ships. Scrap metal is often stored in large piles in the holds of ships where it is exposed to the elements. Then when oxidation takes place it makes the loads more combustible and susceptible to ignition. Sometimes the temperature can reach hundreds of degrees Celsius in a matter of minutes without apparently producing flames, while smouldering fire may have been developing under the surface of the cargo.

At times, spontaneous combustion occurs when a non-metallic substance, such as oil-soaked rags or paper, spontaneously ignites without an external ignition source. This occurs when the material reaches its ignition temperature through a chemical reaction. If sea water and salt crystals are present in the cargo holds, this can lead to  rapid oxidation resulting in rising temperature and setting the contaminants on fire.

Sometimes the wrong equipment that is not designed for the job is used to handle scrap metals, such as forklifts and cranes. This can also cause the metal to be damaged and at the same time create sparks or frictional heat, which then may ignite the scrap.

Another potential source of fire is from electrical malfunctions, such as faulty circuits or poor wiring. These malfunctions can ignite flammable materials, such as paper, tyres or rubber, to fuel the fire in the cargo spaces.

Human error, such as careless disposal of cigarette butts or improper handling of flammable materials, can also cause scrap fires on board vessels. While the danger may not be spotted during initial loading, these actions could cause a smouldering fire which might lead to the onset of a major fire incident.

 

ENVIRONMENTAL POLLUTION AND MISDECLARATION RISKS

Scrap fires on board vessels can release marine pollutants, such as fuel liquids and gasses into the water and air, posing a risk to the environment. When pumping the bilge wells, the master should be aware that a certain amount of dirt and oil can be expected from old machinery.

Another effective firefighting method when a vessel is in port is to use large amounts of water to extinguish scrap fires. However, the master should take prudent action to consider the stability of the vessel and proactively discuss with local port authorities the disposal of wash water used in the firefighting.

The wash water could be considered harmful to the marine environment and should be disposed of separately. This may require the vessel needing to consider diverting to another port to carry out this operation if the facility is not available. Member should advise the Club if any delay or deviation is expected.

In one instance a Panama-registered vessel caught fire while in Hong Kong waters in June 2021[6] sending billows of acrid smoke towards many  local residents. Scrap fires can release toxic fumes and pose a risk to the health and safety of crew members. In extreme cases, scrap fires can result in injury or death.

On 23 September 2021 a shipping agency processed an export declaration on behalf of a scrap metal exporter for ten containers of “polymers and ethylene”, but later the shipper was charged and pleaded guilty for making a false declaration to customs[7].

Therefore, the carrier should have in place a comprehensive set of due diligence and know your customer (KYC) procedures to mitigate the risk of accepting cargo which is mis-declared or undeclared.

 

RECOMMENDATIONS AND CONCLUSION

In case of loading scraps in bulk, including metal scraps, the bulkheads and flooring in the cargo holds should be protected by plywood dunnaging or similar arrangements. These arrangements will depend on the particular nature and/or shape of the scraps. Thereafter, deck coamings in the way of the loading and discharging paths, like cargo hatches, railings and hatch coamings, should be protected.

A layer of the cargo should be carefully soft-landed over the tank top to cushion any fall out of bigger pieces. The loads should not be released too high above the pile and every effort must be made to distribute the weight to avoid high load density on the tank top.

Furthermore, heavy pieces can easily penetrate the tank top and side hoppers when loading from height. As a result, ballast or the fuel oil tank may rupture or start to leak, affecting the vessel’s seaworthiness. This can be difficult to notice when the cargo holds are full so the tank levels should be checked after closing the cargo hatches.

How can scrap fires on board vessels be prevented or mitigated?

• appointing the expertise of a qualified cargo surveyor to support the master during loading and discharging to identify the presence of radioactive and/or combustible materials
• scrap cargoes should be classified by the shipper to comply with local and international regulations in force
• the shipper should provide in writing that the scrap metal cargo does not contain any borings, shavings, turnings, or cuttings that promote self-heating and that the cargo is free from radioactivity
• cargo holds should be prepared as per the shipper’s requirements and standard loading procedures as per the IMSBC Code
• scrap metals, including ferrous materials, should be loaded under dry conditions and should be kept dry during the voyage
• the shipper should specify the cargo’s ventilation needs, if any is required, including whether surface ventilation is to be by mechanical or natural means. Mechanical ventilation equipment should be intrinsically safe
• combustible goods, such as oil-soaked rags and paper, should be stowed separately in designated places to reduce the risk of fire
• items containing pressurized gases, fuel, oils, combustible engines, radioactive and flammable material should not be loaded
• all liquids like oil, fuel and water from used combustion engine parts should be drained off
• electrical systems should be regularly inspected and maintained to prevent short circuits and/or other malfunctions that can cause sparks
• crew members should be trained in the proper handling and storage of flammable materials, as well as the use of firefighting equipment
• regular fire drills should be conducted to help crew identify potential fire hazards and prepare them to respond to a fire
• if the crew has to enter the cargo hold, special breathing apparatus should be worn, as there can be oxygen depletion with hydrogen build up within cargo spaces.
• bilge wells should not be pumped unless absolutely necessary, as a certain amount of dirt and/or oil can be expected, which can result in an oil pollution claim
• it should be ensured that there is no smoking on board near the cargo spaces.

In short, scrap fires can cause significant harm to ships, cargo, the environment and can even result in the loss of life. To prevent and mitigate scrap fires on ships, it is important to collaborate with the charterer and/or shipper to understand the nature of the cargo and plan the stowage.

Furthermore, the ship’s crew should have regular firefighting training, including the use of fire detection and typical extinguishing methods for scrap fires. The ship’s cargo spaces should be regularly inspected for signs of corrosion, deterioration of the electrical systems and other factors that could increase the risk of a scrap fire.

The Club has also produced an article on “Containerised scrap metal – potential dangers” in our Risk Watch publication which is available to Members.

[1] https://en.wikipedia.org/wiki/Scrap

[2] International maritime Solid Bulk Cargoes (IMSBC) Code, 2019, Appendix 1 : Individual Schedules of Solid Bulk Cargoes – “Scrap Metal”

[3] International Maritime Dangerous Goods Code, 2022, Chapter 3.2 : Dangerous Goods List, UN 2793

[4] International maritime Solid Bulk Cargoes (IMSBC) Code, 2019, Appendix 1 : Individual Schedules of Solid Bulk Cargoes – “Ferrous Metal Borings, Shavings, Turnings or Cuttings UN 2793”

[5] https://www.bimco.org/Cargo/Solid-bulk-cargo/Solid-bulk-cargo-database/Solid_cargo_database-0621/Scrap_metal

[6] Stench from burning metal-waste ship blows across Hong Kong, https://www.thestandard.com.hk/section-news/section/11/230923/Stench-from-burning-metal-waste-ship-blows-across-HK

[7] https://www.sars.gov.za/businesses-and-employers/government/government-connect-issue-3-march-2022/

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