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This document delves into the safe storage and handling of ammonium nitrate, a widely used fertilizer, during offshore transit. It analyzes the m/v cheshire incident, highlighting the dangers of mishandling and contamination. The physico-chemical properties of ammonium nitrate, emphasizing the importance of temperature, pressure, and humidity control. It provides practical solutions for storage design and conditions to mitigate potential hazards, including the use of non-conductive materials, tight sealing, and proper ventilation. The document also discusses the decomposition process of ammonium nitrate and its relation to temperature, pressure, and particle size.
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School of Engineering Department of Chemical Engineering How Do You Store Ammonium Nitrate While in Transit Offshore? In Partial Fulfillment of the Requirements in CHE 3107 Physical Chemistry for Engineers 2 M 3:30 PM - 5:30 PM Submitted by: Buca, Ian Kenneth A. Capiral, Matthieu R. Montegrande, Michelle P. Submitted to: Engr. May V. Tampus Professor December 24 , 2022
How do you store ammonium nitrate while in transit offshore? II. Definition of the Problem Ammonium nitrate, which is a salt-like, white, crystalline solid, can occur naturally but these past decades, it is also manufactured in large quantities by the acid-base reaction of ammonia with nitric acid (see Figure 1), with its main use being as a fertilizer (Cargo Handbook, 2022). In addition, it is also utilized in pyrotechnics, herbicides, insecticides, an oxidizer for rocket propellants, and explosives. There have been instances of the materials being incorporated into illegal acts. 𝐻𝑁𝑂 3 + 𝑁𝐻 3 → 𝑁𝐻 4 𝑁𝑂 3 Figure 1. Acid-Base Reaction of Ammonia with Nitric Acid to form Ammonium Nitrate. Ammonium nitrate in pure form is stable, such that it will not explode due to commonly experienced friction or impact. However, heat and confinement or a severe shock can lead to detonation. For example, in a fire, molten ammonium nitrate may become confined (e.g., in drains or machinery) and it could explode if it becomes contaminated. Typically, an initiating explosion is required with ammonium nitrate already sensitized by heat and/or contaminants. It is hygroscopic, which means it readily absorbs moisture from the air, which can cause it to clump together. When heated, decomposition products are oxides of nitrogen and water but, provided there is adequate space, this combustion will not result in the material catching fire. However, if confined the gasses cannot escape and the heat will increase. The major risk posed by long term storage of ammonium nitrate while in transit offshore is due to contamination. Ammonium nitrate will react violently with various materials, particularly organics such as fuel oil. While the thermal decomposition temperature of ammonium nitrate is 200°C, the presence of contaminants can significantly reduce this. Solid ammonium nitrate-based fertilizers can pose a similar threat. Depending on their concentration, specifically blends containing 60% or more, or 40% or more ammonium nitrate mixed with ammonium sulfate. Percentages are by weight. We recommend applying the same guidance to such fertilizers as you do to pure ammonium nitrate (Swiss Re, 2020). Over 70 large accidents related to ammonium nitrate have occurred in the last century including one in Oppau, Germany, in 1921, in Texas City, USA, in 1947 and in Toulouse, France in 2001 (Babrauskas, 2016). These have caused tragedies with devastating human and infrastructure loss, disturbing all functional aspects of affected communities (Laboureur, 2016). Indeed, a recent explosion in Beirut, Lebanon last August of 2020 linked to ammonium nitrate fertilizers resulted in the death of over 200 (Al-Hajj et al., 2021). Among the ammonium nitrate-related accidents recorded recently, fifteen occurred during transport on a bulk carrier. Explosions in the early twentieth century, such as at Oppau, were due to the practice of using explosives to break up caked stockpiles of ammonium nitrate. The Texas City disaster started as a fire in a ship that was docked at port; the fire led to a detonation event that killed more than 580 people. The ship had 2,100 metric tons of ammonium nitrate storage on-board in the form of prills that had been coated in wax to prevent caking (Ettouney & El-Rifai, 2012). It is now known that contamination with organics, such as wax, and heating until molten, particularly in a fire, will sensitize ammonium nitrate to the point that an initiating explosion can detonate it. With regards to contamination, it is now understood that contamination with many materials, such as organics, chlorides, metals and acids will also sensitize ammonium nitrate and contamination of any form (debris, litter, etc.) should be avoided. Heating ammonium nitrate to melting point will sensitize it, reducing the energy required for it to
IV. Analysis and Solution Analysis The network diagram created in this study demonstrates the factors causing the explosion of ammonium nitrated and the relationships among these factors. Users of the network can understand the occurrence of AN explosion and predict the risk of explosion when several factors are present in the environment. While considering the Physico-chemical properties of Ammonium Nitrate, the analysis done on each node revealed the following: Cargo Declaration - Before anything else, the ammonium nitrate type must be carefully evaluated during loading as to declare whether or not it is a hazardous type of AN. In the M/V Cheshire incident,Investigations revealed that the cargo was loaded with ammonium nitrate declared by the shipper as being “Non-hazardous” and not liable to self-sustaining decomposition. Since it is a non-hazardous ammonium nitrate, it was designated by the IMSBC Code as a group C cargo. These are cargoes that do not liquefy (group A) nor possess chemical hazards (group B). Due to this, there was insufficient information on the behavior, risks, and carriage of the cargo, leading to the decomposition of the ammonium nitrate. Thus, there should be adequate IMO-stipulated tests for assessment of self-sustaining decomposition properties of an ammonium nitrate and correct designation and description of a cargo within the IMSBC Code should be done properly for safer carriage of cargoes and safer voyages. Heat Source - Because the cargo was classified as 'non-hazardous,' the crew neglected to follow the instructions for disconnecting all heat sources before loading. The judgment states that a light by a ladder in cargo hold 4 had probably been left on from the time of loading and, most likely, had not been disconnected until four days after that – by which time the heat around the lamp had started the chemical reaction. In this case, the size of the heat source to which the cargo is exposed, the exposure time of the cargo, and the tendency of the cargo to be under SSD must be assessed. Decomposition - When heated, decomposition products are oxides of nitrogen and water and since it is confined, the gasses cannot escape and the heat will increase. Decomposition of ammonium nitrate may occur via two ways: Thermal decomposition and self-sustaining decomposition (SSD). In the case of thermal decomposition, removing the heat source from the environment may be sufficient to prohibit further decomposition. However, even if the heat source causing thermal decomposition is removed, sufficient heat may remain in the material because of chemical reactions, giving rise to SSD, which is the case for the M/V Cheshire accident. Also, the decomposition tendency of the load is determined by the trough test specified in the IMSBC code. At atmospheric pressure, the risk of cargo degradation is significant at temperatures exceeding 200 °C. Thus, internal heat sources (welding, naked flame, electrical equipment etc.) must be kept away from the cargo. The temperature inside the hold may also increase due to the heat of the area in which the ship is located so temperature should be frequently monitored. Furthermore, accident investigation reports reveal a lack of understanding of the signs of decomposition during the transport of cargo, as well as incorrect action due to the lack of information. When the accident was examined, strain due to pressure, effluvium, and water accumulation were observed when the hatch cover drains were opened within the first days of sailing. However, these signs were ignored by the ship’s crew. Subsequent interventions were thus insufficient, and the ensuing accident resulted in the complete loss of the ship. Given this, all crew members must have detailed information on the need to hold cleanliness, cargo hazards, stowage and segregation, loading, weather, carriage precautions, and discharge on ships carrying ammonium nitrate- based products. Contamination - The day after departure the required information on the cargo holds was being completed daily. However, this information did not appear to be trended anywhere, otherwise it may have been recognised the oxygen level in the cargo in M/V Cheshire incident hold was falling, the percentage flammable gas was rising, and the carbon monoxide level was off scale since the vessel was loaded. These unusual readings may be due to some admixture/contamination which must be from the residue of previous cargoes. The major risk posed by long term storage of AN while in transit offshore is due to contamination. Ammonium nitrate will react violently with various materials, particularly organics such as fuel oil. While the thermal decomposition temperature of ammonium nitrate is
Solution Base from the analysis of the M/V Cheshire incident and considering the physico-chemical properties of Ammonium Nitrate found in Research section, the following summary of ammonium nitrate storage design and conditions should be strictly followed: a. The ammonium nitrate storage container should be a non-conductor of heat At atmospheric pressure, ammonium nitrate can only decompose on its own if its temperature is rapidly raised to 4000 F or t approximately 204^0 C (Gibbens, 2020). Because of this it is of utmost importance to store ammonium nitrate in a non-conductor of heat type of material, most especially in cargo where open heat from the sunlight is available. b. The ammonium nitrate containers should be tightly sealed and be placed in a close yet well-ventilated area in the cargo Hygroscopicity is one problem induced in storing ammonium nitrate while in transit offshore. Thus, to avoid moisture accumulation in the ammonium nitrate, containers used must be closed and sealed properly. Furthermore, to limit heating of the ammonium nitrate and lower the chance of an decomposition, the storage area should have a proper ventilation system that removes hot gases from the storage tanks and prevents the accumulation of highly harmful off- gas products, such as nitrogen oxides. c. Covering sheets and sheet-wrapping can be used to protect the storage area from heat and rain. The storage of ammonium nitrate in storage tanks will be much improved using cover sheets made of aramid fibers since aramid fibers are naturally heat- and flame-resistant and maintain these capabilities at high temperatures. These fibers not only have excellent thermal stability but also excellent mechanical properties. Several waterproof fabrics are also manufactured from aramid fibers, which gives them the ability to withstand heat as well as repel water. Meta-aramid and Para-aramid are the two different forms of aramid fibers. Heat and radiation are repelled by meta-aramid fibers. Since they don't melt or catch fire, they form effective fire-retardant materials. Although stronger, para-amid fibers are employed to reinforce polymers in stress skin panels, civil engineering constructions, and other uses that call for high tensile strength. Meta-aramid fibers are recommended for this case study to give the ammonium nitrate further protection from heat-related problems. d. The storage tanks should be elevated from the cargo ground. Because ammonium nitrate is highly hygroscopic, potential caking or clumping together of the ammonium nitrate particles might result from absorbing moisture from the air or directly absorbing water from the rain. An elevation is needed when storing ammonium nitrate to have a separation between the ammonium nitrate and the floor of the cargo ship. Pieces of metals or wood can be made as an elevation to these. e. The ammonium nitrate should be stored at least with a meter of surrounding free space Any sources of fire, incompatible materials, and sources of contaminations could be anywhere in the cargo ship. Thus, the ammonium nitrate should not be stored any closer than 1 meter to the walls, roof, or any electrical wiring or lighting when keeping it in an insulated shipping container. It is best to take note of the fire hazards and possible contaminants in a cargo ship.
V. Conclusion and Recommendation Several factors should be considered when transporting AN-based goods because of their risks. The network obtained in this study contributes to the literature by providing a means to understand decomposition, fire, and worst explosion accidents caused by ammonium nitrate. Since ammonium nitrate decomposes at approximately when temperature is raised to 204 o^ C (Gibbens, 2020), it is best to store ammonium nitrate in a non-conductor of heat containers. In addition, to prevent heat trapping, the storage area should be well-ventilated. Fire hazards in a cargo ship should be known and by this, ammonium nitrate should be stored away from these areas. Furthermore, since ammonium nitrate is hygroscopic, it is best to store ammonium nitrate with covering sheets preferably aramid fibers for this does not only have a good thermal resistance but might as well protect the ammonium nitrate storage area from moisture from the sea and rain. Also, the ammonium nitrate should be elevated from the floor when storing to protect it from possible water accumulation when it rains. Lastly, to avoid fire sources and cross contaminations, ammonium nitrate should be stored at least a meter away from walls, roofs, human activities and in general should be stored at least with a meter of surrounding free space. VI. Research A. Potential Hazards The three main potential hazards of relevance to ammonium nitrate (AN)-based products, such as fertilizers as declared by European Fertilizer Manufacturers’ Association (2004) are: a. Fire - Although ammonium nitrate does not burn on its own, it can support combustion because it is an oxidizer. As a result, the presence of combustible material is necessary for an ammonium nitrate fire to occur. The AN will break down and release oxygen when an AN-based fertilizer is exposed to fire or is heated to a certain degree, increasing the fire hazard. If the product, and spillage in particular, is polluted with flammable substances like coal, grain, sawdust, or oil spills, the decomposition threat may increase. In the event of a fire, the fertilizer will break down and release noxious chemicals such nitric acid, ammonia, hydrogen chloride, and NOx vapors. b. Decomposition - Chemical breakdown of fertilizers based on ammonium nitrate (AN) under the influence of heat is referred to as decomposition. Decomposition can occur without the presence of a flammable material. The type of product, the heat source's temperature, the amount of time the product is exposed to the heat source, and the fertilizer's containment all affect the decomposition risk. There are some compound fertilizer compositions that have the potential to decompose in a self-sustaining manner, meaning that once a hot source—such as a hot electric lightbulb or hot welding material—has started the process, the reaction in the fertilizer is sufficiently thermally energetic to continue without the need for additional heat from any outside source. These fertilizers are referred to as "cigar-burners" or Self- Sustaining Decomposition (SSD) type. They are categorized as dangerous items for marine transit due to their substantially higher potential hazard. They are classified as Type B fertilizers and belong to UN Class 9. For the purpose of identifying this behavior, the UN Trough Test has been created. The presence of sensitizing substances, such as chromates, chlorinated chemicals, and various metals, such as zinc and copper and their salts, will determine the decomposition hazard in straight-N fertilizers, such as AN, CAN, and ASN, as well as in non-SSD type compound fertilizers (NPK, NP, and NK). The generation of poisonous gases such NOx, ammonia, hydrogen chloride, and nitric acid vapors is typically followed with decomposition. c. Explosion/Detonation - Under specific circumstances, ammonium nitrate can explode, necessitating a powerful source of initiation. According to the official UN Resistance to Detonation Test, standard, high-quality AN-based goods have a strong resistance to denotation. This resistance, however, can be adversely affected by a number of factors, such as: a. Substantially smaller particle size,
VI. References Al Jazeera. (2022, August 4). Infographic: How big was the Beirut explosion? Al Jazeera. https://www.aljazeera.com/news/2022/8/4/infographic-how-big-was-the-beirut-explosion Al-Hajj, S., Dhaini, H. R., Mondello, S., Kaafarani, H., Kobeissy, F., & DePalma, R. G. (2021). Beirut Ammonium Nitrate Blast: Analysis, Review, and Recommendations. Frontiers in Public Health, 9. https://doi.org/10.3389/fpubh.2021. Babrauskas, V. (2016). Explosions of ammonium nitrate fertilizer in storage or transportation are preventable accidents. Journal of Hazardous Materials, 304, 134-149. Cargo Handbook. (2022) Ammonium Nitrate. Cargohandbook.com. https://cargohandbook.com/Ammonium_Nitrate Ertekin, M. (2017). Fiber Technology for Fiber-Reinforced Composites. Sciencedirect.com. https://www.sciencedirect.com/topics/materials-science/aramid-fiber Ettouney, R.S. and El-Rifai, M. A. (2012). Explosion of ammonium nitrate solutions, two case studies. Process Safety and Environmental Protection, 90, 1-7. Gibbens. (2020). The deadly history of ammonium nitrate, the explosive linked to the Beirut blast. Science. Guidance on the Ammonium Nitrate Storage Requirements in 29 CFR 1910.109(i) | Occupational Safety and Health Administration. (n.d.). Www.osha.gov. https://www.osha.gov/laws-regs/standardinterpretations/2014- 12 - 03 Grantham, A. (2021) AMAT INSIGHTS: Reducing Risks Associated with Ammonium Nitrate. https://www.gichd.org/fileadmin/GICHD-resources/rec- documents/AMAT_Insights_Issue_1_Reducing_Risks_Associated_with_Ammonium_Nitrate IMDG Code. (2020). International Maritime Organization. https://www.imo.org/en/publications/Pages/IMDG%20Code.aspx Laboureur, DM et al. (2016) Case study and lessons learned from the ammonium nitrate explosion at the West Fertilizer facility. J Hazard Mater, 308,164– 72. doi: 10.1016/j.jhazmat.2016.01. Swiss Re. (2020, October 13). Ammonium Nitrate Storage. Swiss Re Corporate Solutions. https://corporatesolutions.swissre.com/insights/knowledge/ammonium-nitrate-storage.html The Editorial Team. (2019, September 23). Fire risks in cargo areas. SAFETY4SEA. https://safety4sea.com/cm-fire- risks-in-cargo-areas/ Tyc, A., Nieweś, D., Pankalla, E., Huculak-Mączka, M., Hoffmann, K., & Hoffmann, J. (2021). Anti-Caking Coatings for Improving the Useful Properties of Ammonium Nitrate Fertilizers with Composition Modeling Using Box– Behnken Design - PMC. PubMed Central (PMC).