Uncontrolled and Controlled Destruction of Acetylene Pressure Cylinders

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1		Vojtech Jankuj	--	2267	2022-05-26 11:57:58	\|
2	format	Jason Zhu	-64 word(s)	2203	2022-05-27 03:39:06	\|

This entry is adapted from the peer-reviewed paper 10.3390/app12073577

The risk of physical destruction of a pressure cylinder increases with increasing temperature load. Acetylene is a significant hazardous gas in cylinders. If the destruction pressure is reached, the cylinder is torn into two or more pieces, followed by the gas release to the environment. The presence of ignition sources could lead to the formation of the fireball phenomenon. This phenomenon generally reaches approximately ten meters in diameter and can be accompanied by a blast wave and a spread of the cylinder’s fragments or surrounding objects. The consequences of this type of fire could be fatal. Shooting through the cylinder shell may lead to the mitigation, if not elimination, of the effects of the uncontrolled destruction mentioned above. As a result of the review of relevant publications, several states commonly use this method as a standard procedure. Internal gas is released through the resulting hole, the pressure drops down and the gas creates a fire jet or disperses to surroundings. This study is based on a large-scale experiment where acetylene cylinders were placed inside a prepared woodpile and exposed to fire. In the fire condition, the cylinders exploded and created fireballs, or were penetrated via shooting and created fire jets.

safety acetylene explosions

1. Introduction

Flammable gases are present almost in all industry sectors. Currently, gases are connected with transport or heavy industry. Flammable gases are used for fire cutting or welding but also for heating via flame, especially in households. Gases are stored inside pressure cylinders for better manipulation and transport inside houses, small workrooms, or in construction. Pressure cylinders present great advantages in connection with manipulation, but also risks connected with using flammable gases. Pressure cylinders are exposed to higher temperatures during a fire, and these conditions change the properties of the cylinders. Cylinders are over-dimensioned to resist higher temperatures but only to a certain limit. If this limit is exceeded, cylinder material loses key properties, bursts, and the content (gas) is released. When the gas is flammable, the fireball phenomenon is observed after ignition by surrounding flames.

This physical destruction presents dangerous risks and direct threats to people, animals, ambient infrastructure and last but not least rescue services. The early detection of a pressure cylinder in a fire and its immediate cooling is necessary for ensuring safety. Methodological instruction for the fire brigade determines the options for how to intervene in the case of a pressure cylinder in a fire. Cooling of the cylinder’s shell is performed by a stream of water or placement in a water bath. This prevention is very effective, but there is a limitation connected, especially with acetylene pressure cylinders. The pressure and temperature inside the cylinder increase as an effect of physiochemical processes which are initiated via flames, and these processes can continue even after extinguishing the fire. If the limit of the cylinder is achieved, the pressure cylinder is torn into two or more pieces and content is released. Due to the risk of destruction still being present after the fire is extinguished, acetylene pressure cylinders have to be checked for 24 h. These restrictions of lengthy periods of cooling and closing of safety areas could be limiting especially for an industrial complex, built-up areas or transport infrastructure. There exist several types of pressure release valves or fuses which can reduce increasing pressure and release inside overpressure. These safety systems can malfunction or be damaged by flames, and therefore the risk of destruction is still possible.

There is a solution used in several countries that seems very effective: shooting through the cylinder releases overpressure and there is no risk of physiochemical destruction. Although it is effective, shooting brings additional risk; therefore, it is necessary to carry it out with sufficient respect and know all risks and understand all situations.

This problem is well-known in the Czech Republic, where the Methodological Regulations for Firefighters are developed. The Battle order for firefighters—tactical procedure of intervention: Fires with a presence of acetylene pressure cylinders ^[1] was prepared in the Czech as Methodological List no. 33. For other technical gases in the pressure cylinders, Methodological List no. 32 ^[2] is used. In these regulations, all necessary information is mentioned step by step, to describe how to effectively and safely lead the fire intervention with attention given to existing risks and unexpected situations. In these Methodological Lists, shooting through the cylinders is mentioned as an option in extreme situations where it is not possible to stop uncontrolled destruction. The shooting can only be carried out by specialists of the police department, but it is not further written how to perform it, the specification of intervention, who is responsible or other options and unknown situations. Shooting through the cylinders is not a new trend in the Czech Republic. Kratochvíl ^[3] focused their dissertation thesis on the thermal stress of the pressure cylinders during a fire. The pressure cylinders were exposed to a fire and left to physically destruct, or the risk of destruction was eliminated via shooting. The safety zones and distances for the fire brigade and other forces were determined as a result of these experiments. These safety distances are listed in the Methodological List. Another experimental measurement between the years 2012 and 2014 was performed in Kaznějov. During these tests, the appropriate ammunition was chosen and the results of pressure cylinders in fire conditions were described by Hora et al. ^[4].

The concept of shooting through the pressure cylinder as a prevention of physiochemical destruction in Sweden is used as a standard procedure. The Sweden Gas Association examined the tests on how to use heated cylinders. The destruction of non-cooled acetylene pressure cylinders was delayed by 18 h. The requirement from the industry was to find the method and shorten the time of interruption of operating time. The ammunition selection by Lamnevik ^[5] in 1996 is described. Currently, this prevention is used in Sweden, and the procedure by Björnström and Setterwall ^[6] is described. In this book, the conditions, process, permission and other details are mentioned. In Sweden, the tracking ammunition, which is able to ignite releasing gas, was developed. A similar approach can be assumed for northern countries. At least in Norway, this procedure is normally used as a standard method for the elimination of acetylene pressure cylinder destruction. During a 14-day period this method was used twice. During a barn fire, the acetylene pressure cylinder was detected. The cylinder was in a fire, and it was not possible to find out the condition of the cylinder ^[7]. The risk of destruction was eliminated via shooting. In a second incident, safety zones of 1000 m were enacted and several houses were evacuated. After shooting through the cylinders, traffic was restored ^[8]. In the United Kingdom, Operational Guidance Incidents Involving Hazardous Material ^[9] was written in connection with pressure cylinder differences in the form of the use of a pressure relief valve. However, this effective relief of the pressure may fail. After opening the relief valve the gas is released through a small hole. The option of shooting is also not mentioned in Fire and Rescue Authorities Operational Guidance: Incidents involving acetylene ^[10]. However, an extensive study focusing on acetylene safety during and after a fire by the Department for Communities and Local Government ^[11] was performed. The document summarized existing knowledge, research, risk quantification and comparison on the current state in the European Union and the United Kingdom. In Germany, several experiments focusing on acetylene pressure cylinders were performed at BAM—a senior scientific and technical federal institute. In 1995, a large experiment that focused on exothermic decomposition ignited by recoil or cylinder wall heating was conducted ^[12]. During these tests, basic knowledge regarding pressure and temperature was determined. The investigation was focused on extinguishing, interruption of extinguishing and the behavior during these steps. In addition, the bundles were exposed to fire conditions. In Germany, shooting was tried as a prevention before acetylene pressure cylinder destruction, but this option is not used as a standard procedure ^[13]. BAM tested acetylene cylinders again in the project Acetylene cylinders in the fire for British Compressed Gas Association in 2009 ^[14]. This project aimed to find a new procedure when acetylene cylinders are exposed to fire. The project consists of three phases, laboratory experiments, mathematical model heat transfer and large-scale tests. If the single acetylene cylinder is cooled for one hour and controlled for another hour without any signs of internal process, the destruction of the cylinder has not occurred. Results are described in the detail by Ferrero et al. ^[15]^[16]. Attention has also been dedicated to the acetylene pressure cylinder in Poland. Case studies were carried out with acetylene cylinders ^[17]^[18] or with oxygen ^[19], and performed by the University of Wroclaw. Except for ignition with a bonfire, the local heating was tested, where a gas burner was used. Large-scale experiments within the project BLOW ^[20] were conducted in 2014. Although the knowledge seems to be sufficient, experimental tests were performed and the data are available, and in many countries the standard procedure based on the EIGA recommendation is used during a fire of acetylene cylinders ^[21]. Even though shooting the cylinders as prevention is effective, the standard procedure of cooling the cylinder shell is still primary.

2. Current Studies

The shooting through the acetylene cylinder shell as a prevention of physical destruction is effective. Measurements provided renewal of theoretical knowledge and practical experience. Shooting is very effective but represents a secondary risk. For this reason, it is necessary to have the procedure, operation and other requirements precisely specified. Penetration of cylinder shells is quick and more or less predictable. These facts can contribute to the effectiveness of fire intervention, safe time and also water, which would be normally used for cooling or water bath.

As it was mentioned, in the Czech Republic Methodological List no. 33 ^[1] for fire with the presence of acetylene cylinders in fire condition is used. All essential knowledge and procedures for fire with acetylene cylinders is described. Shooting is mentioned in point no. 39 as an extreme solution in the case when it is not possible to stop cylinder destruction. It is necessary to consider that flammable gas will be ignited, and the resultant fire jet may reach up to ten meters. The cylinder can explode due to the inside pressure. Shooting can be performed only by specialists from the police department.

The fact of lacking a description of procedures, conditions and specifications for shooting was the impetus for the study. Using this technique is necessary to prepare an extension in a certain way that follows Methodological List no. 33. This list is still primary, and after detection of an acetylene cylinder it is necessary to cool the cylinder shell. The time of the cylinder exposure to fire is not always clear, as well as the temperature and heat flux density and the amount of the gas inside. From the start, it is important to answer several questions. The method of shooting could be used only for acetylene pressure cylinders. According to evaluation of the conditions, this method could be used, and the acetylene pressure cylinder penetrated via shooting. It is necessary to consider potential risks in the case of unsuccessful shooting, used ammunition, the position of shooters and the accuracy.

More shots ensure the faster gas release and have to be distributed along the entire length. The most advantageous is a combination of two shots at once into the lower part of the cylinder. This method can be used only for acetylene cylinders. For use with other gases, it is necessary to consider different working pressures, construction of cylinders, material, hardness, etc. Called shooters should have sufficient knowledge and training for this situation, as the shooter always decides on the position and other specifications. The shooter is responsible for the action itself. Emphasis should be placed on the communication among intervening forces.

After successful shooting, the gas is released and initiated with the result of the fire jet. Immediately after releasing, outflow gas reaches a distance of about 10 m and then burns with approximate distance of fire of about 3 m. With decreasing amount of gas, the size of the flame decreases until it burns out. The releasing gas can accumulate if it is not initiated. Accumulation in a closed space can create explosive concentration.

The next step in this problem can be addressed at the training: an option for the shooting of the other pressure cylinders, for example, an oxygen pressure cylinder or a combination of acetylene with oxygen pressure cylinder. For another experiment, other ignition sources can be used, such as a pool fire. With the increasing use of this method in the Czech Republic, knowledge and experience will be accrued. In connection with the current state of knowledge, it is necessary to count on ammunition that will be able to ignite releasing gas. What could be really interesting is the modeling of these situations and an option to predict the behavior of the acetylene cylinders. Modeling and computer animations are popular and can be helpful in the case of extraordinary events. Another point to be discussed might be the distances from the cylinders of presenting special forces or specialists able to perform this prevention. In this methodological procedure, shooting is understood as speeding up the lengthy cooling of the acetylene cylinder and quick elimination of the uncontrolled destruction.

References

Methodological Regulations for Firefighters, Battle Order for Firefighters—Tactical Procedure of Intervention: Fires with a Presence of Acetylene Pressure Cylinders. Available online: http://metodika.cahd.cz/bojovy_rad/P_33_Acetylen.pdf (accessed on 18 November 2020).
Methodological Regulation for Firefighters, Battle Order for Firefighters—Tactical Procedure of Intervention: Fires with a Presence of Pressure Cylinders with Technical Compressed and Liquified Gases. Available online: http://metodika.cahd.cz/bojovy_rad/P_32_Technicke_plyny.pdf (accessed on 18 November 2020).
Kratochvíl, V. Heat Stress of the Steel Pressure Cylinders during a Fire. Ph.D. Thesis, Technical University of Ostrava, Ostrava, Czech Republic, 2004.
Hora, J.; Karl, J.; Suchý, O. Pressure cylinders under fire condition. Perspect. Sci. 2016, 7, 208–221.
Lamnevik, S. Beskjutning av Acetylengaseflaskor Inomhus 2: Beskjutning av Acetylentuber Med AK 4 och 7.62 mm Ammunition. 1996. Available online: https://rib.msb.se/Filer/pdf/6784.pdf (accessed on 22 November 2020).
Björnsröm, H.; Setterwall, T. Beskjutning av acetylengasflaskor. Sjuhäradsbygdens tryckeri AB. 2002. Available online: https://www.msb.se/RibData/Filer/pdf/18393.pdf (accessed on 22 November 2020).
Fear of Gas Explosion in Kvinnherad. Available online: https://norwaytoday.info/news/fear-gas-kvinnherad/ (accessed on 12 February 2021).
The Police in Control of Gas Cylinder Fires. Available online: https://norwaytoday.info/news/gas-cylinder-fires/ (accessed on 12 February 2021).
Chief Fire & Rescue Adviser. Fire and Rescue Service Operational Guidance: Incidents Involving Hazardous Materials; The Stationery Office: London, UK, 2012.
Chief Fire & Rescue Adviser. Fire and Rescue Authorities Operational Guidance: Incidents Involving Acetylene; The Stationery Office: London, UK, 2014.
Department for Communities & Local Government. Safety of Acetylene Containing Cylinders During and After Involment in a Fire: Fire Research Technical Report; Department for Communities & Local Government: London, UK, 2017.
Explosionsgefaren Beim Umgang Mit Acetylenflaschen Und-Bündeln Nach der Einleitung Eines Acetylenzerfalls: Abschlußbericht Zum Forschungsvorhaben 13 RG 9001. BAM. 1995. Internally report. Available online: https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/36243 (accessed on 18 November 2020).
Rönnfeldt, L.; Voss, S. Beschuß von zerknallgefährdeten Acetylengasflaschen. BrandSchutz—Dtsch. Feuerwehr-Ztg. 1999, 2, 121–124.
Research Report “Acetylene cylinders in a fire, phase 3: Experiments, observations, and conclusions”. BAM R&D Project Vh 2514. 2010; Internally report.
Ferrero, F.; Beckmann-Kluge, M.; Schmidtchen, U.; Holtappels, K. Modelling the heat transfer in acetylene cylinders during and after the exposure to fire. J. Loss Prev. Process Ind. 2010, 23, 654–661.
Ferrero, F.; Beckmann-Kluge, M.; Kreißig, M.; Hensel, C.; Schmidtchen, U.; Holtappels, K. Preventing the explosion of acetylene cylinders involved in fire with help of numerical modeling. J. Loss Prev. Process Ind. 2012, 25, 364–372.
Półka, M.; Salamonowicz, Z.; Batko, P. The explosion of acetylene cylinders—Case study. In Proceedings of the 9th International Symposion on Hazards, Prevention, Mitigation of Industrial Explosion, Cracow, Poland, 22–27 July 2012.
Półka, M.; Kukfisz, B. Butle i wiązki acetylenowe w warunkach pożaru. Przegląd Nauk.-Inżynieria Kształtowanie Sr. 2018, 27, 516–523.
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Ejsmont, J.; Świeczko-Źurek, B.; Ronowski, G. Shooting Gas Cylinders to Prevent Their Explosion in Fire. In Proceedings of the Conference of Word Academy Of Science: Engineering And Technology Conference, Venice, Italy, 14–15 August 2017.
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Vojtech Jankuj

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1. Introduction

2. Current Studies

References