THE CAUSES OF IBC (INTERMEDIATE BULK CONTAINER) LEAKS AT CHEMICAL PLANTS AN ANALYSIS OF OPERATING EXPERIENCE Christopher J. Beae (FIChemE) Ciba Expert Services, Charter Way, Maccesfied, Cheshire, SK10 2NX, UK Intermediate buk containers are in widespread use in industry for handing hazardous and non-hazardous materias. As the use of IBCs has increased, so the number of chemica eaks and fires from IBCs has increased. This paper anayses the causes of IBC eaks at a arge Ciba UK manufacturing site. The anaysis is based on incident reports, near miss reports, interviews with site staff and interviews with site emergency response staff. Common causes of eaks are identified. Generic eak frequencies are then cacuated for IBC eaks. The anaysis incudes different types of operations invoving IBCs incuding transport, temporary storage, warehouse storage, waste product storage and process appications. Keywords: Intermediate Buk Container, Learning From Incidents. INTRODUCTION THE USE OF INTERMEDIATE BULK CONTAINERS IN INDUSTRY IBCs are in common use in industry as they aow reativey sma quantities of chemicas to be transported between suppiers, manufacturers and customers and around site areas efficienty. IBCs are produced in a wide range of different sizes, shapes, materias of construction and designs to suit specific user requirements. They can be purchased as standard designs as a commodity product or they can be custom buit for specific uses. Custom buit designs are more expensive. They tend to be used for reguar shipments of product within a site or between different sites. Standard designs tend to be used for singe or medium use duty and are often used for deivering products to customers. Suppiers wi often operate a recycing scheme, picking up used IBCs when new deiveries are made. Recyced IBCs are then ceaned and checked prior to re-use. This paper is based on a study of 1,000 itre IBCs, with a variety of different designs. IBC Design Principes The integrity of an IBC depends on three critica components (see Figure 1): 1. A paet which aows the IBC to be moved easiy by fork ift trucks. Paets are commony made of heat treated timber, pastic or stee. Timber paets are more susceptibe to mechanica damage. Pastic and meta paets have a onger design ife but have ow surface friction resistance. This can cause sippage when handed by fork ift trucks.
Figure 1. Typica IBC design features Meta paets can aso cause sparks when they contact hard surfaces ike concrete. The paets are normay stamped, indicating the manufacturer and date of manufacture. 2. A container which hods the chemica. It is often made of transucent pastic, which is ight, strong and easy to manufacture. Cooured pastics are aso used for specific appications such as differentiating between different categories of chemica. Back pastic is used for reducing the risk of photo-initiation of monomers. White pastic is used for reducing heat input when containers are transported in hot countries. The container normay has a top screw cap which is used for fiing operations. Sma bore connections are normay provided, with arger bore connections for viscous iquids. An outet vave is provided at the base of the container. This is normay recessed into the container to prevent the vave from being damaged when in transit. The vave is 2
normay fitted with a screw cap for additiona eak integrity. Screw caps often have a tamper proof sea. Some IBCs are fitted with simpe pressure reief devices which are attached at the fi point. IBCs are normay specified with an uage space above the iquid eve. If the uage space is correcty cacuated, a pressure reief device wi not be required to meet norma transport requirements. For exampe, a 1,000 itre IBC wi typicay have a brimfu capacity of 1.050 itres. Mistakes can be made by not cacuating the uage voume correcty or by faiing to aow for the specific gravity of the product in the uage cacuation. 3. A meta cage which surrounds the container and is attached to the paet. The cage can be manufactured with weded tubes, mesh rods or meta sides. Namepates are attached to the cage so that the contents can be identified. The cage can be designed to provide static protection to the IBC. The combination of paet, container and cage provide mechanica integrity for the IBC. The mounting which hods the cage onto the paet has to be strongy fixed. IBCs which are used for transporting hazardous chemicas often have additiona and/or stronger fixings to improve integrity. Risk Drivers The foowing factors infuence the risk of chemica eaks from IBCs: Safe operation is argey determined by the way that peope hande IBCs. They are moved between different sites and reiance is paced on different companies in the suppy chain. They are often re-used. Checks are required to ensure that the containers are cean and have not been damaged. Large numbers of IBCs are handed on chemica sites, often by reativey unskied staff. There is a perception that they have imited hazard potentia due to their reativey sma size. They are often stored in groups in remote or unmanned site areas. Research has shown that this can aow fire incidents to spread rapidy, reeasing arge fammabe/combustibe inventories into uncontained site areas (Atkinson & Riey, 2006). FRAMEWORK FOR ANALYSING IBC FAILURE MODES Four consequence categories for IBC faiures have been identified: 1. Offsite chemica reeases during transport by truck, in port or on ships. These incidents are often imited to the reease of reativey sma inventories of chemica from one or a sma number of IBCs. Reeases tend to occur from poor packing/stacking, road traffic accidents or chemica reactions. These reeases can cause significant nuisance and shipping deays because chemicas may be dispersed in sma quantities over a wide geographic area. Particuar probems occur when eaks invove toxic, sticky, odorous or environmentay sensitive chemicas.
2. Chemica reeases which do not ignite. These reeases occur frequenty on sites which hande arge voumes of IBCs. The consequences of reease are often ocaised because of a combination of the reativey sma inventories feeding the reease, the fact that reeases normay invove singe or sma numbers of containers and the reativey ow hazard potentia of many of the chemicas which are handed in IBCs. This type of reease is typicay seen as a ow priority process safety issue at many sites. 3. Chemica reeases which ignite. These are very rare events based on data from UK Ciba sites. IBCs are essentiay sma chemica storage tanks which can easiy be manipuated by peope and which have very imited hardware safety features. The containers may be handed where ignition sources exist; they may be stored in remote areas of the site which have imited fire detection and protection systems; and they may be stored cose to other fammabe or combustibe containers, producing a scenario which aows rapid fire escaation. 4. Fue sources, causing fires in other areas of the site to escaate. IBCs are often stored in reativey arge groups in site areas such as waste storage areas, temporary container hoding areas and warehouses. Research has shown that this can ead to rapid fire escaation, fed by arge fammabe/combustibe inventories and imited poo containment systems (Atkinson & Riey, 2006). Data about fires and fire escaations is rare. Data about unignited reeases can, however, be found through staff interviews and an anaysis of near miss records. The Ciba Bradford site has used a database near miss reporting system since 2001 (Beae, 2004). Database records from between 1/1/2005 and 30/9/2007 (a period of two and three quarter years) have therefore been anaysed to identify reported chemica reeases and near miss incidents invoving IBCs. This provides a detaied profie of IBC reeases over the period 2005 2007. Incidents which occurred before 2004 woud ony have been recorded if they were significant. These significant reeases were identified from incident reports and from discussions with ine managers and emergency response speciaists. A of these reported and recorded incidents have been anaysed to identify IBC faiure mechanisms eading to oss of containment and the reative frequency of occurrence of each type of faiure mechanism. FAILURE MODES IBC incidents are amost aways caused by peope mistreating or mishanding IBCs. They are rarey caused by mechanica or structura faiure. This is how an experienced ine manager summarised his experience of faiures and near misses at his site. Interviews with ine managers and emergency response staff show that the foowing faiure mechanisms have occurred: Transport Incidents 1. IBCs are bady stacked inside trucks or the oads are bady secured. This aows movement in transit, causing IBCs to be damaged or toppe. 4
2. Trucks are invoved in road traffic accidents. IBCs are damaged and may eak inside the truck, onto roads and into drains. Warehouse Incidents 3. Poor stacking causes IBCs at the top of a stack to fa onto other IBCs or onto the ground. 4. IBCs which are not stacked carefuy into a warehouse compartment can protrude into the area where fork ift trucks operate. The next time that a fork ift truck accesses the area, it catches the protruding IBC, disodging the IBC. This can cause the IBC to fa to the ground and can aso cause the IBC to snag the warehouse racking, causing structura racking faiure. Structura racking faiure is most ikey when ta and narrow warehouse aises are used. Figure 2 shows an exampe of the aftermath of a racking faiure. Onsite Handing Incidents 5. IBCs fa off or unbaance a fork ift truck because they are not oaded carefuy onto the forks, because the fork ift truck is not driven carefuy or because the fork ift truck strikes an object or a pothoe. The IBC is then dropped onto the ground. 6. An IBC is pierced with the fork ift truck ifting arms, puncturing the IBC and reeasing it s contents. Figure 3 shows an exampe of a pierced IBC. 7. Fork ift trucks crash into static objects when moving IBCs. Static objects coud be trucks, other fork ift trucks, stacks of IBCs, warehouse racking and warehouse was. 8. IBCs jam or are misaigned on conveyor handing systems, causing deformation or topping onto the ground. Chemica Reactions 9. Containers are incorrecty abeed, often because they hod waste materia, byproducts or intermediate products. This can resut in chemica storage in the wrong Figure 2. Racking coapse incident 5
Figure 3. IBC pierced by fork ift truck ocation or chemicas may be eft in storage accidentay for ong time periods, increasing the risk of an undesired reaction inside the container. 10. Fork ift truck operators eave IBCs in the wrong area of site. If they are stored cose to incompatibe chemicas, this coud ead to a chemica reaction. 11. Waste materia is run-off into IBCs, where it is accidentay mixed with incompatibe materia or it generates an unstabe mixture. 12. Reactive chemicas, such as monomers, are eft in IBCs and a poymerisation reaction is initiated. Typica causes woud be inadequate quantities of inhibitor, contact with an impurity, ack of circuation and aged stock. IBCs are generay not fitted with pressure reief devices, so these faiures tend to cause container sweing or faiure. Figure 4 shows the aftermath of an IBC chemica decomposition reaction. Figure 4. Chemica decomposition incident 6
Process Operations 13. IBCs are normay fied under operator contro. They fi reativey quicky. If the operator is not concentrating or is distracted, containers can be overfied. 14. The container is pumped out with the top cap in pace, causing the IBC to be sucked in. 15. The contents of the IBC are charged to the wrong vesse or tank. This coud cause an uncontroed reaction in downstream process pant. Mechanica Faiures 16. The paet at the base of the IBC is broken causing the container to sump. These faiures are most ikey with wooden paets and rarey cause chemica eaks. 17. The outet vave eaks. Most IBCs are fitted with externa caps with tamper proof seas, thus providing an additiona barrier against vave eaks. 18. Outet vave connection eaks. This is normay caused by mechanica pressure on the top side of the vave mechanism. This causes the mechanism to bend with a faiure at the connection point to the main IBC body. These faiures can be prevented by fitting supports under the vave connection. 19. Deiberate tampering with the outet cap and vave during transit or in a process area. Many IBCs have tamperproof seas to minimise this type of scenario. 20. Outet vave eft open in error causing the contents to eak to ground. Damage To Safety Systems 21. In rack warehouse sprinker systems are damaged when IBCs are not stored carefuy. This shoud cause the system to operate, causing a reveaed faiure. This scenario is most ikey when sprinker heads are poory ocated or when operators try to pace mutipe or arge containers into a bay which is sized for a smaer container. 22. Fork ift trucks damage fire hydrants when manoeuvring around the site. Tabe summarises the reported causes of incidents and near misses invoving IBCs for one arge manufacturing site over the 33 month period. This data is based on empoyee generated reports using the site near miss reporting system. 107 reports for IBCs were raised in this time period. Tabe 2 summarises the type of site operation which was occurring when each report was made. Tabe 4 summarises the significant IBC incidents which were recorded in the period 1990 2003 based on incident reports and staff interviews. FAILURE FREQUENCIES Tabe 3 summarises the generic eak frequencies per year for the arge manufacturing site based on incident records over the 33 month period where oss of containment was known to have occurred. It is not possibe to determine the size of the eak from the reports and events coud range from pinhoe reeases (1 mm equivaent hoe diameter) to arger 75 mm hoe diameter reeases. Most of the reeases are known to have been associated with ow hazard products. 7
Tabe 1. IBC near miss and incident summary 2005 2007 Fork Lift Trucks (FLT) Paet overturned in transit 9 FLT coision with racking 5 IBC punctured (spiered) by FLT 5 FLT coision with IBC 4 FLT coision with wa 4 FLT coision with process equipment 2 FLT coision with FLT 2 Tried to stack 2 IBCs in 1 warehouse bay 2 FLT damage to fire sprinker system 1 Container sipped off racking 1 FLT mechanica faiure 1 FLT overbaanced 1 Process Leak during fiing 6 Waste product poymerises 3 Leak during emptying 2 Overfi 1 Hose hit by operator 1 Leak during IBC switchover 1 Suppy Chain Contamination in container 3 Lid not fastened tighty 3 Load incorrecty packed in HGV 2 HGV coision with IBC 2 Driver offoaded himsef with paet truck 1 Fied hot, capped, cooed, impoded 1 Operationa Errors Stored in too high a bay in warehouse 8 Incorrect or no abeing 7 Stored in wrong area of site 5 Wrong chemica deivered to works 3 Inappropriate container used 1 Integrity Container eak 11 Paet eak 2 Sea too big for container 2 Loose outet vave 1 Warehouse support beam coapse 1 Automated Packing Machines Snagged on packing machine 1 Fe off packing machine 1 Set to reverse not forward 1 Note: Number of reported oss of containment events over a 33 month period, 2005 2007. CONCLUSIONS 22 IBC faiure and error mechanisms have been identified based on the experience of ine managers and emergency response staff who work with IBCs. A detaied anaysis of reported near misses and incidents over a 33 month period between 2005 and 2007 identified 107 records reating to IBCs. Fork ift truck movements inside warehouse areas, warehouse storage and fork ift truck movements in site areas each accounted for about 20% of the faiure reports. Fiing/emptying operations and process incidents each accounted for about 13% of the faiure reports. 13% of the faiure reports were caused by errors in the suppy chain with site deiveries. 8
Tabe 2. IBC near miss and incident summary 2005 2007 by operation Operation Number of events % Receipt at goods inwards 14 13 Fork ift truck movement in warehouse 19 18 Storage in warehouse area 20 18 Fork ift truck movement around site 22 21 Fiing/emptying 14 13 Process use 16 15 Packing in warehouse 2 2 TOTAL 107 100 Note: Based on reported oss of containment events over a 33 month period, 2005 2007. Tabe 3. IBC eak frequency anaysis Cause of oss of containment Number % Frequency/site/yr Container eak 11 35 4.0 Leak during fiing 6 20 2.2 Spiered by fork ift truck 5 17 1.8 Uncontroed poymerisation 3 10 1.1 Leak during emptying 2 6 0.7 Container overfied 1 3 0.4 Loose outet vave 1 3 0.4 Spi during IBC switchover 1 3 0.4 Operator contact with hose 1 3 0.4 TOTAL 28 100 11.3 Note: Based on reported oss of containment events over a 33 month period, 2005 2007. The reports suggest that the arge site suffers about 11 IBC oss of containment incidents per year. These range from sma pinhoe eaks, such as nai penetration through base to catastrophic faiures, such as poymerisation reactions. 35% of the eaks are from the container. This wi incude brand new containers and re-used containers. 20% are caused by eaks during fiing. 17% are caused when fork ift trucks puncture the IBC with their forks. 10% are caused by uncontroed reactions inside the IBC. This anaysis coud be used to identify IBC faiure modes for a risk anaysis and as a source of generic frequency data for base events which coud be used in a faut tree or Layer Of Protection Anaysis (LOPA) study for a major accident hazard scenario. Athough 9
Tabe 4. IBC incident summary 1990 2003 Date Type Cause Consequence 1993 Warehouse IBC exposion at Goods In 1994 Fork ift truck faiure 1996 Warehouse fork ift truck faiure 1996 Warehouse racking coapse 1997 Fork ift truck faiure 1998 Warehouse fork ift truck coided with racking. 1998 Warehouse racking coapse 1998 Transport accident at major port 1999 Fork ift truck faiure Truck container fu of IBCs from the USA being offoaded. IBCs shoud have contained ow hazard product but it was contaminated with hydrogen peroxide which then decomposed. Securing pin on fork ift truck faied when an IBC was being ifted. Hydrauic faiure. Paets not centered on racking support rais. Paet fe dragging other containers with it. Beed pug expeed. Loss of hydrauic pressure on fork ift truck used for accessing high eves. Driver steering error. Fork ift truck crashed into racking. Paet not stacked accuratey in storage bay. Tug driver puing two containers which he beieved were both empty. One was actuay fu. Load was unbaanced. Container topped over at roundabout inside port area. Lifting chain on fork ift truck coapsed. 10 IBC expoded iberating 200 kg of product. Evidence of deformation and interna pressure buid up in remaining IBCs in the container. IBC fe to foor. No oss of containment. Damage to warehouse racking affecting ow hazard product. 16 IBCs fe, 12 from high eve. Sma spi of ow hazard product. Truck cab fe rapidy from height and then sowed. No injury. Locaised racking coapse affecting ow hazard product. Locaised racking coapse when paet moved. Container hed 18 IBCs. IBC eaked ow hazard iquid into container. Container had to be ceaned out. IBC fe to foor. No oss of containment. (Continued)
Tabe 4. Continued Date Type Cause Consequence 1999 Fork ift truck faiure 2000 Road traffic accident on major motorway 2003 Warehouse fork ift truck coided with racking. Lifting chain on fork ift truck faied. Empty IBCs had just been moved. HGV passed too cose to transit van and traier causing traier to jack knife. Traier contained IBC. Driver drove down narrow aise with forks protruding about 300 mm. The forks hit the main structura frame of the warehouse racking, weakening the structure. No impact. Viscous materia spit on motorway. Motorway cosed for ong period. Locaised racking coapse affecting 4 tiers of racking containing ow hazard product. the eak data from 2005 2007 is considered to be comprehensive for the site, care shoud be exercised because the data covers a reativey short 33 month anaysis period and it is difficut to ascertain the size of the eaks which underpin the anaysis. REFERENCES (Atkinson & Riey, 2006) Controing the fire risks from composite IBCs, G. Atkinson and N. Riey, IChemE Hazards XIX Symposium Series No. 151, 28 30 March 2006. (Beae, 2004) Deveoping a major hazards earning cuture interpreting information from the Ciba Speciaty Chemicas, Bradford near miss reporting system, C.J. Beae, IChemE Hazards XVIII Symposium Series No. 150, 23 25 November 2004. 11