This article is designed to provide emergency response personnel with background information, general procedures, and response guidelines for operating at incidents involving intermodal containers. Part 1 dealt with intermodal freight containers; here, we are discussing tank containers.

The use of portable tank containers, also referred to as “tank containers” or “iso-tanks,” has increased greatly during the past decade. Factors contributing to their popularity include improved safety, portability, lower transportation costs, and the advantages of a multimodal transport system. Like cargo tank trucks and railroad tank cars, different types of intermodal tanks are built to many domestic and international standards. They are being used to transport a varied and diverse range of commodities, including an increasing number of hazardous materials. It is projected that by the year 2000, the total number of intermodal portable tank containers will exceed 90,000.


An intermodal portable tank usually consists of a single, noncompartmentalized vessel held within a sturdy, metal-supporting frame that allows the unit to be lifted by appropriately designed handling cranes. The framing allows securement of the portable tanks on both vessels and surface vehicles.

Key construction features include the following:

Tank container. The tank itself is generally built as a cylinder enclosed at the ends by ellipsoidal, hemispherical, or flanged and dished tank heads. Although rare, rectangular tanks and tube tanks may also be found. The portable tank is usually a single, noncompartmentalized vessel with a capacity that does not exceed 6,340 gallons (24,000 liters). Multicompartment intermodal tanks are rare; however, when found, each compartment is constructed as a separate tank. There are typically no internal baffles on intermodal portable tanks.

Tank containers may be equipped with various features, including the following:

–Linings to protect the tank from its contents. Linings can be rubber, glass, or other coverings applied to the inside of the tank after it is built.

–Refrigeration units. Most tanks with refrigeration units are not provided with their own power source; an external supply source is required. Depending on the mode of transportation, options may include a ship`s power system, a plug-in at a fixed facility, a chassis-mounted generator for highway use, a freight car generator, or a generator container.

–Heating units for handling very viscous products. Options include electrical or steam heating. Electrical heater coil units are commonly found where the product must be heated during transportation and may be installed on the interior or exterior of the tank container. They operate on 200-240 volt or 340-480 volt, three-phase electrical supply. Steam heating is provided by pumping steam through external heater coils on the lower half of the tank.

–Insulation. It moderates the effects of the ambient temperature on the contents. Insulating materials include polyurethane foam, polystyrene foam, mineral wool, and fiberglass. Insulation is usually three to four inches thick and is always covered with a jacket with flashing to make it weathertight. Jackets are made of metal, at least one millimeter thick or an equivalent thickness of plastic reinforced with glass or fiber. Remember that the tank is attached to the container framing; the insulation is not an integral part of the tank.

–Electrical controls. The electrical control box is mounted on the tank frame at the rear of the tank container (i.e., the end at which the discharge valve is located). The control box will contain fuses or circuit breakers, temperature controls, the main switch to isolate the tank container from the power supply, and a method of selecting the correct circuit for the available main power supply.

Materials of construction. Because of its strength and excellent properties in cold temperatures, more than 90 percent of intermodal tanks are constructed of stainless steel. The remainder are constructed of mild steel. Aluminum and magnesium alloy tanks may also be found, but they cannot be used in marine transportation.

Shell thickness is measured in terms of “equivalent thickness in mild steel” after forming. Shell thickness requirements can be summarized as follows:

If you see external rings on an intermodal tank, it is most likely a single-shell, stainless-steel tank. Most tanks are constructed to the pressure-vessel standards of the American Society of Mechanical Engineers (ASME). Welds are x-rayed; the welds on carbon steel tanks are post-weld, stress-relieved.

Size and supporting frame. The supporting frame of a tank container protects the tank and provides for stacking, lifting, and securing the container. It also supports the walkways and ladders.

The most common size supporting frame for tank containers is length: 20 feet, width: 8 feet, and height: 8 to 912 feet. Very few tank containers used within the United States are longer than 20 feet. An exception is the Sea-Land Company`s half-height tank containers, which have a length of 35 feet. However, 30-foot-long tanks may be found in other countries.

Two basic types of supporting frames can be found: the “box type,” which encloses the tank in a cage-like framework with continuous side rails, and the “beam type,” which uses frame structures only at the ends of the tank. The “beam type” relies on the inherent strength of the tank as a beam.

Portable tank containers are usually described in relation to the end of the tank fitted with the discharge valve, referred to as the “rear end of the tank.” The right and left sides are determined when facing the rear end.

Corner castings. Like freight containers, supporting frames for tank containers are built with corner fittings, commonly referred to as “corner castings.” They are used to secure the tank and lift it with standard container-handling equipment. Cast-iron corner castings are prohibited. In the event of an accident, the corner castings may be used for lifting or moving the tank, but only after consultation with the tank`s owner or manufacturer.


A number of markings on tank containers can be used to gain knowledge about the tank design and construction features. These markings include the following:

Reporting marks and number. Tank containers are registered with the International Container Bureau in France. They must be marked with reporting marks and a tank number. The initials indicate ownership of the tank; the tank number identifies the specific tank. These markings are generally found on the right-hand side of the tank (as you face it from either side) and on both ends (see below). They may be displayed on the tank itself or the tank frame.

Specification marking. The specification marking indicates the standards to which a portable tank was built. Tank containers must meet U.S. Department of Transportation (DOT) design, construction, and safety standards. These markings will be on both sides of the tank, generally near the tank`s reporting marks and number.

Examples of specification markings are:

* IM-101

* IM-102

* Spec. 51

DOT exemption marking. Exemptions from DOT regulations are sometimes authorized. In these cases, the outside of each package/container must be plainly and durably marked “DOT-E” followed by the exemption number assigned (e.g., DOT-E8623). On intermodal tanks, these markings must be in two-inch letters.

AAR-600 marking. For interchange purposes in rail transportation, intermodal tank containers should conform to the requirements of Section 600, “Specification for Acceptability of Tank Containers,” of the Association of American Railroads (AAR) Specifications for Tank Cars. Tanks meeting these requirements will display the “AAR 600” marking in two-inch letters on both sides near the tank`s reporting marks and number. The “AAR 600” marking indicates tanks that can be used for regulated materials; the “AAR-600NR” marking indicates tanks that cannot be used for regulated materials.

Country, size, and type markings. The country code (two or three letters) indicates the tank`s country of registry. The tank will display a size/type code (LR-2276 in the photo on page 62 bottom).

The four-digit size/type code follows the country code. The first two numbers jointly indicate the container`s length and height. The second pair of numbers is the type code, which indicates the pressure range of the tank.

Common Size Codes

20 = 20 feet (8 feet high)

22 = 20 feet (8 feet 6 inches high)

24 = 20 feet. (> 8 feet 6 inches high)

Common Type Codes–Maximum Allowable Working Pressure

Nonhazardous Commodities

70 = < 0.44 (6.4 psig) bar* test pressure

71 = 0.44 (6.4 psig) to 1.47 (21.3 psig) bar test pressure

72 = 1.47 (21.3 psig) to 2.94 (42.6 psig) bar test pressure

73 = spare

Hazardous Commodities

74 = < 1.47 (21.3 psig) bar test pressure

75 = 1.47 (21.3 psig) to 2.58 (37.4 psig) bar test pressure

76 = 2.58 (37.4 psig) to 2.94 (42.6 psig) bar test pressure

77 = 2.94 (42.6 psig) to 3.93 (57.0 psig) bar test pressure

78 = > 3.93 (57.0 psig) bar test pressure

79 = spare

* 1 bar = 14.5 psi

Dataplate. Additional technical, approval, and operational data can be found on the dataplate, which is permanently attached to the tank or frame.

A tube that contains the tank`s shipping documents or a material safety data sheet (MSDS) may also be found in proximity to the dataplate. Constructed of metal or plastic, these tubes are normally at or near the rear end in proximity to the discharge valve.

Tank and valve test dates. If installed, tank and safety valves must have a retest interval no greater than five years. Retest and test due dates must be marked or stenciled on the tank or dataplate.

Markings and placards. Tank containers containing regulated materials must be marked and placarded. The four-digit identification number must be displayed. For domestic shipments within the United States, DOT regulations require that the proper shipping name be printed in two-inch letters on two opposing sides of the container shell. On international shipments, foreign placards, in addition to those required by the United States, are sometimes found. European shipments may carry the ADR/RID markings.

Some specific situations of which responders should be aware regarding the placarding of international shipments are as follows:

–Tanks loaded with a regulated commodity must display the appropriate DOT placard to correspond with the classification of the commodity. In addition to the required DOT placard, any additional placard authorized by the International Maritime Dangerous Goods Code (IMDG) should be found [see 49 CFR 172.502(c)(1)].

–The required placard must meet the DOT placard design specifications. For example, an INFLAMMABLE placard would not be legal in lieu of a Flammable Liquid placard, even though they are identical in size, color, and intent.


Tank containers are classified according to the specification of the portable tank and its fittings. The tank container class determines which products may be transported. The general classes of tank containers include nonpressurized, pressurized, and specialized. The Intermodal Tank Table found in 49 CFR Part 173 provides a list of hazardous materials approved by the DOT for transport in portable tank containers.

The three most widely used specification tank containers permitted to transport hazardous materials in North America are the IM-101, the IM-102, and the Spec. 51 containers. These portable tanks generally correspond to the design specifications set forth for international transportation by the International Maritime Organization (IMO) for the IMO Type 1, IMO Type 2, and IMO Type 5 tanks.

Nonpressure Tank Containers

Although classified as nonpressurized, these containers can have a working pressure up to 100 psig. Nonpressure tank containers comprise more than 90 percent of the total number of tank containers; the most common are the IM-101 and IM-102 portable tank containers. The only clue to distinguishing an IM-101 from an IM-102 container is to physically inspect the dataplate or container markings.

Nonpressure tank containers can transport both liquid and solid materials at maximum allowable working pressures (MAWP) of up to 100 psig. Tanks are tested to at least 1.5 times the MAWP.

IM-101 portable tanks (International IMO Type 1). These tanks are built to withstand MAWPs ranging from 25.4 psig (1.75 bar) to 100 psig (6.8 bar). DOT specifications for the design and construction of IM-101 tanks can be referenced in 49 CFR 178.270 and 178.271.1. An ASME certification or stamp is not required.

IM-101 tanks are used for transporting hazardous and nonhazardous materials, including toxins, corrosives, and flammables with flash points below 327F (07C). Capacities are normally in the range of 5,000 to 6,300 gallons.

IM-102 portable tanks (International IMO Type 2). These tanks are built to withstand lower MAWPs, ranging from 14.5 psig (1.0 bar) to 24.4 psig (1.75 bar). DOT specifications for the design and construction of IM-102 tanks can be referenced in 49 CFR 178.270 and 178.272. An ASME certification or stamp is not required.

IM-102 tanks transport materials such as whiskey, alcohols, some corrosives, pesticides, insecticides, resins, industrial solvents, and flammables with flash points ranging from 327F (07C) to 1407F (607C). These containers are also commonly used for the transport of nonregulated materials such as food-grade commodities. Capacities are normally in the range of 5,000 to 6,300 gallons.

–Dataplates. Each tank must have a corrosion-resistant dataplate permanently affixed to the portable tank in a location that is readily accessible for inspection. If the information is provided in metric, responders may have some initial difficulty with conversions. The following information is required:

U.S. DOT Specification Number (e.g., IM-101 or IM-102);

country of manufacture;

date of manufacture;

manufacturer`s name;

manufacturer`s serial number;

identification of USA/DOT approval agency and approval number;

maximum allowable working pressure–MAWP (psig or bar);

test pressure (psig or bar);

total measured water capacity at 687F (207C) in gallons or liters;

maximum allowable gross weight (lbs. or kg.);

equivalent minimum shell thickness in mild steel (inches or mm);

tank material and specification number;

metallurgical design temperature range (7F or 7C);

lining material, if applicable;

heating coil maximum allowable working pressure (psig or bar), if applicable; and

corrosion resistance (inches or mm), if applicable.

–Tank container fittings. The following fittings can be found on the IM-101 and IM-102 tank containers to make them both safe and functional. Although many of these fittings are similar to those found on a cargo tank truck, container fittings and threads are normally British Standard Pipe (BSP) or metric.

Access to top fittings is normally via a ladder and walkway installed on the container. Tank container ladders may be loose or weakened. During emergency situations, emergency responders should consider the use of portable ladders for access to the top of the container. Do not walk on the tank shell.

Tank container fittings include the following:

* Spillbox. On most nonpressure tanks, the top fittings are surrounded by a spillbox, which protects the shell of the tank from product spillage. Spilled materials, as well as rainwater in the spillbox, are drained away to the ground through one or more small open pipes.

* Manhole, cover, and dipstick. An 18- to 22-inch manway is located on top of the tank at the center. It is enclosed by a hinged or bolted lid fitted with six or eight large wing nuts. A replacement gasket is used with the manhole; neoprene (food quality) is standard. Other gasket materials may include Viton© and Teflon©.

A dipstick may be inside the manhole or lying within the spillbox. It is used in conjunction with a calibration chart, also known as a “strapping chart,” to measure the amount of product in the tank. Tanks must be loaded to at least 80 percent of capacity to avoid sloshing. For liquids, a minimum outage of two percent of the total capacity of the tank must be provided in rail transportation.

* Top-loading valves. Top-loading valves are attached to a removable eduction pipe (e.g., dip leg, dip tube, or siphon tube) running into the tank. They can range from 112 to four inches in diameter, although they are typically three-inch-diameter balls or butterfly valves with a four-bolt flange.

* Bottom outlet valves. They can range from 112 to four inches in diameter. When a tank container is intended to transport hazardous materials, two externally operated, bottom-outlet valves are required. Typical designs are for a three-inch internal foot valve, a three-inch external butterfly valve, and a three-inch BSP thread screw cap. They are connected in series with a replaceable gasket between them. Some containers may also have electrical sensor connections adjoining or as part of the bottom outlet valve to provide product identification and product overfill protection. This is similar to the sensor connection commonly found on gasoline tank trucks to prevent product overfills at loading racks.

Also required is a liquid-tight closure on the external valve. It may be a blind flange, a screw cap, or a cam-lock cap attached to the external valve. Blind flanges are required for international shipments. AAR 600-12 requires a positive lock on the external bottom valve to lock in the closed position.

Emergency response experience shows that most leaks occur at the blind flange as compared with the valve itself. Flange leaks can be easily controlled by tightening down on the flange bolts.

* Airline connection. An airline connection can be used for pressure unloading, vapor return, and blanketing the contents with an inert gas. It is normally a 112-inch line. In some instances, a 112-inch ball valve and pressure gauge may be found. This connection can be found on the tank`s top, normally within the spillbox.

* Thermometer. Some tanks have a built-in thermometer to measure the temperature of the lading. If a tank is equipped with an electrical or a steam-heating system, it will most likely be provided with a thermometer. The thermometer may be an immersion sensor or a surface, which is connected to a temperature gauge. Temperature gauges will usually read both in Fahrenheit and Centigrade.

Tank container safety devices. The following safety devices can be found on the IM-101 and IM-102 tank containers.

* Pressure/vacuum relief valves. They are generally found in pairs on nonpressure tank containers. Typically, two three-inch- spring-loaded devices are installed on top of the portable tank near the manway.

A combination pressure/vacuum relief device protects the tank from overpressure and a vacuum of more than 0.75 psig negative pressure. The valve will be marked to indicate its settings. In many cases, the relief valve will also have a rupture disk (i.e., burst disc) located between the safety relief valve spring and the commodity to protect the spring from the commodity.

This fitting may also have a gauge to determine if the disk is ruptured. The pressure gauge normally reads in both psi and bars; the gauge should always read zero.

Responders may find situations where the burst disc has failed but the relief valve has not actuated. Among some of the reasons for this may include container overfilling, product expansion due to ambient heating, and hydraulic surge effects.

* Emergency remote shutoff device. This emergency device can close the internal bottom outlet valve (foot valve) from a remote location. As one faces the discharge end of the tank, the emergency shutoff can be on the right-hand or the left-hand side, near the far end. It is usually a cable-actuated device, although hydraulic or pneumatic devices may be found.

* Fusible links and nuts. Fusible links or nuts may be found on cable-actuated remote shutoff devices. Should there be a spill fire under or around the tank container, the fusible device will melt, releasing cable tension. Fusible links are required to actuate at temperatures not greater than 2507F (1217C).

Pressure Tank Containers

Pressure tank containers, commonly known as “DOT Spec. 51 Portable” (International – IMO Type 5) containers, are less common in transport. They are pressure tank containers designed to handle internal pressures ranging from 100 to 500 psig. They must be designed for product lading in excess of 1,000 pounds water capacity and have a minimum shell and head thickness of .1875 inches.

DOT specifications for the design and construction of Spec. 51 containers can be referenced in 49 CFR 178.245 and 178.245.7. The DOT requires that Spec. 51 containers be designed and built to the ASME Code and bear an ASME “11” stamp.

Spec. 51 containers are used to transport liquefied gases, such as LPG, chlorine, and anhydrous ammonia; pyrophoric liquids such as aluminum alkyls; and other highly regulated materials, including those products in UN Packing Group 1. Spec. 51 containers will be in the range of 4,500 to 5,500 gallons, although containers as small as 50 gallons can be found (e.g., pyrophoric liquids).

*Dataplates. Each Spec. 51 tank must have a nameplate affixed to either head of the portable tank by soldering, welding, or brazing around the entire perimeter of the plate. The following information is required:

–manufacturer`s name,

–serial number,

–manufacturer`s serial number,

–U.S. DOT Specification Number (e.g., Spec. 51),

–water capacity (pounds),

–tare weight (pounds),

–design pressure (psig),

–design specific gravity,

–original test date, and

–tank retested at ____ psig on _____ .

*Tank container fittings. The following fittings can be found on Spec. 51 tank containers to make them safe and functional. These fittings may be on the top, at the end, or on the bottom. Generally, the fittings are enclosed with a cover or recessed to protect them from mechanical damage.

* Loading/unloading valves. Liquid and vapor valves are used for filling and emptying the tank. The liquid valve extends into the lading by means of an eduction pipe that may also be fitted with an excess flow check valve. Vapor valves, which also may have an excess flow check valve, are used to remove vapors from the tank or to pressurize the tank for unloading.

All tank outlets must be marked to designate vapor or liquid discharge potential when the tank is filled to the maximum level permitted. They may be threaded or flanged valves. Remember that valve threads may be BSP or metric threads.

* Gauging devices. Gauging devices to measure how much liquid is in the tank may be installed. Various types are found, including the rotary gauge and open and closed gauging devices such as those found on some pressurized railroad tank cars.

* Sample lines. They are used for sampling the lading without opening the tank. Sample lines can develop leaks at the handle or around the plugs.

* Thermometer wells. The thermometer well is used for measuring the lading temperature. Temperature readings can assist responders in determining if a product is expanding and increasing the internal tank pressure. If a thermometer well tube breaks inside the tank container, leaks can develop.

Tank container safety devices. The following safety devices can be found on the Spec. 51 tank containers:

* Safety relief devices. These devices are mounted on top of the container to protect the tank from overpressure under abnormal conditions, such as fire impingement or an internal chemical reaction. These devices may be found inside an unhinged compartment that protects them from the elements.

* Excess flow valves. Excess flow valves may be found on liquid and vapor piping. Mounted inside the tank under the liquid and vapor valves, excess flow valves will stop the product flow if a valve is sheared off. Excess flow valves are operated by gravity or pressure differential.

Specialized Tank Containers

Several specialized tank containers may be encountered, including cryogenic tank containers and tube modules.

* Cryogenic tank containers. They are built to the IMO Type 7 tank container specifications. Cryogenic containers transport cryogenic liquids and refrigerated gases, including argon, oxygen, and helium.

* Tube modules. Tube modules transport pressurized gases in high-pressure 3T cylinders tested to 3,000 or 5,000 psi and permanently mounted within an ISO frame. Examples include oxygen, nitrogen, helium, and hydrogen.


Basic factors must be evaluated in all incidents involving tank containers, regardless of their location or the mode of transportation involved. If the container is involved in a rollover or derailment, the risks associated with the incident can rise dramatically. As part of the size-up process, emergency responders must evaluate the following:

Type of intermodal tank involved. Specific factors include the DOT or IM designation (e.g., IM-101, IM-102, DOT Spec. 51), whether the container is pressurized or nonpressurized, the number of compartments, the type of tank metal (e.g., aluminum, stainless steel), and so on.

Nature of the emergency. Scenarios could include leaking attachments, derailment, rollover, being struck by an object, and so on.

Container stress applied to the container tank. It could be mechanical, chemical, thermal, or a combination. Specific evaluation factors can include stress to the container jacket (i.e., insulation), mechanical damage to the tank frame, and corrosion to the container and/or frame.

Jacketed and insulated containers can pose certain issues. If the jacket is damaged and the damage is limited to the outer jacket, the strength of the container may not be compromised. If liquid product is found escaping from the jacket, the actual source of the leak on the container may be at another location remote from the visible point of release.

When dealing with Spec. 51 containers, assessing container damage is critical due to the high container pressures involved. Remember, the higher the internal pressure, the farther the container and product will travel when breached. Also, liquefied gases commonly transported in Spec. 51 containers have tremendous liquid-to-vapor expansion ratios. Special attention must be given to dents with sharp edges or gouges that cross over welds or remove the upper bead of the weld. In these situations, consult the shipper for guidance and advice before moving the tank container.

Type and nature of tank damage. Examples would be a puncture, leaking manway, and bottom valve failure. If the container hasn`t opened up or breached, responders should review the likely types of container breach and consider where the hazardous material will go once it escapes. This is an integral element of the size-up process. Again, the shipper will usually be the best source of technical information regarding the container and likely breach and release scenarios.

Amount of product released and that remaining in the container. The maximum amount of product contained in an intermodal tank container is approximately 6,300 gallons. Responders must evaluate where the incident is now and where the incident will be once tactical operations are implemented. Experience shows that the most common releases from tank containers involve the valves and fittings. When safely possible to do so, you can often control these releases by tightening the valve flange or bolts.


Emergency response concerns at an intermodal terminal facility are a hybrid of the problems and concerns found within each mode of transportation. Specific issues and concerns include the following:

Major ports and terminal areas are extremely busy, with a significant amount of traffic and container movement. Failure to pay attention to one`s surroundings and daydreaming can easily get one injured or killed. Remember to stay alert!

Emergencies at port and terminal facilities can have significant economic and operational impacts on the facility. If an intermodal container is involved in a haz-mat emergency, terminal personnel may attempt to move the involved container to a preidentified isolated location where the problem can be handled without disrupting other terminal operations.

As part of preincident planning activities, responders should identify these locations and evaluate site safety conditions, including surrounding exposures, ground contours, spill control, and overall site safety.

The security and safety departments will typically be key players in the management of any emergency situation at seaports and rail terminals. When dealing with haz-mat emergencies, get a copy of the terminal`s Hazardous Cargo Manifest. This document is similar to the Dangerous Cargo Manifest carried on the container ship. However, the Hazardous Cargo Manifest is a complete computerized printout of each container in the terminal. The manifest will provide the following information:

–proper shipping name of the hazardous material,

–emergency contact (e.g., CHEMTREC(TM)),

–hazard class and UN number,

–packing group,

–trailer number, and

–quantity and weight of the container.

At marine terminals, the U.S. Coast Guard Captain of the Port (COTP) or his designated representative will coordinate all USCG operations. Personnel from the USCG Marine Safety Office (MSO) will be key players in any haz-mat emergency. Remember, the COTP has the authority to regulate and control the movement of vessels and personnel within its area of responsibility, including denying vessels entry into port, prohibiting departure, placing specific operating requirements on vessels, and establishing restricted areas. The authority of the COTP also extends over the land-side areas of all waterfront facilities, such as terminals, piers, and wharves.

Locating and identifying containers holding hazardous materials at terminals can be difficult. While some shipments may not be placarded under DOT regulations, international shipments can be marked and placarded in accordance with IMDG regulations from the point of origin to the final destination, provided the trip is by an ocean carrier.

For example, a container is loaded in Cleveland, Ohio, with drums of “methyl ethyl badstuff.” The container`s ultimate destination is a chemical plant outside Bremen, Germany. The container will be trucked from Cleveland to the Port of Baltimore and loaded on a container ship. In Bremen, the container will be discharged from the vessel and trucked to its final destination. The container is legally marked and placarded in accordance with the IMDG in Cleveland.

By nature of their operations, terminal facilities are also great candidates for technical rescue operations, including high-angle and confined-space situations.


Temporary storage. Portable tank containers are commonly used as “temporary bulk storage containers” at fixed facilities. Examples include the use of glycol solutions at airports for aircraft de-icing operations; solvents and adhesives at highway and bridge construction sites; and corrosive liquids, oxidizers, and poisons as intermediates for chemical processing operations.

Building and process construction operations are among the greatest potential emergency response problems. Experience shows that since construction projects are temporary and usually unoccupied by the general public, they may not receive the same level of code inspection and enforcement that a fixed facility would receive (e.g. tank farm or chemical storage area). Consequently, portable tank containers often “show up” on the job site and remain for the duration without meeting model fire code provisions for separation and diking.

Permanent and semipermanent storage. There is growing interest in using portable tank containers for fixed-facility permanent storage. In this scenario, the owner intends to incorporate the tank container as a permanent part of the facility`s storage or process area. The advantage of this arrangement is that the owner can lease the tank container or obtain the container as part of a package deal with the supplier (i.e., you buy the product from us, and we`ll supply the tank and install it). If the tank is damaged or requires cleaning, the facility calls the tank owner for a replacement. Be aware that local fire codes must be consulted when these tanks are used for permanent and semipermanent storage.

In some cases, tank containers may be incorporated into the process operation. If the tank container can be directly tied into the process unit, it eliminates the time, effort, and risks associated with product-transfer operations. This arrangement is especially popular among research and development laboratories, where several chemical storage tanks may be required during the life of a special project. When the project is completed, the process is shut down and the tank container is removed.

Loading and offloading methods. Loading and offloading methods for portable tank containers will vary depending on the type of product and container (i.e., liquid vs. gas) and the nature of the hazardous material. In general, open systems may be used for high-flash-point, low vapor pressure materials, whereas closed systems will be used for hazardous materials with low flash points and high vapor pressures.

If a tank container has been breached and cannot be repaired, transferring product or offloading some or all of the product into another compatible tank container may be required. In some situations, it may be possible to immediately use the product as part of a facility`s process operation. Emergency responders should be familiar with the loading and offloading techniques for various types of intermodal tanks.

* * *

Tank containers are classified according to the specification of the portable tank and its fittings. The tank container class determines which products may be transported. The three most widely used specification tank containers permitted to transport hazardous materials in North America are:

IM-101. Used for maximum allowable working pressures from 25.4 psig (1.75 bar) to 100 psig (6.8 bar). Products include nonregulated products and toxic liquids, oxidizers, and flammable liquids with flash points below 327F (1007C).

IM-102. Used for maximum allowable working pressures ranging from 14.5 psig (1.0 bar) to 24.4 psig (1.75 bar). Products include moderate- to low-hazard products such as alcohol, some corrosives, pesticides, resins, solvents, and flammable liquids with flash points between 327F (07C) and 1407F (607C).

Spec. 51. Pressure tank containers designed to handle internal pressures ranging from 100 to 500 psig.

Material of Regulated Nonregulated

Construction Commodities Commodities

Stainless-steel tanks .1875 inches .125 inches Steel tanks .375 inches .25 inches

(Top) Box-type tank container. (Bottom) Beam-type tank container. (Photos by author.)

Intermodal portable tank markings.

Examples of bottom outlet valves.

Tank car fittings section. Examples of container spillboxes and fitting arrangements.

End view of a DOT Spec. 51 pressure tank container showing the valve compartment.

Profile of damage sustained from the derailment of an IM-102 box frame tank container on a flat car.

Leak Control Considerations

Intermodal tank containers are tough and hold up well in high-impact crashes such as truck rollovers and derailments. The majority of the spill and leak situations encountered involve loading and unloading accidents. Common scenarios include loose fittings and valves, overfills caused by product expansion, and “mystery leaks” through the tank shell.

Overfills can be caused when a tank container is overfilled with product without room for expansion. Once the container is subjected to ambient heating after sitting in the hot sun for awhile, product will begin to overflow through the dome, or relief devices may actuate. In this situation, the container must be cooled to reduce the internal pressure and the effects of the ambient heating. As appropriate, product may have to be transferred from the container to reduce the potential for the problem to happen again, and burst discs may need to be replaced.

Another common scenario with tank containers is a “mystery leak” through the tank shell. For example, someone notices liquid dripping from an opening or crack through the insulating jacket in the lower half of the tank. If the tank has not been involved in an accident, the source of the leak is often water that has formed from condensation on the tank. If the outer jacket has been torn from a previous bump or scrape, the inner tank shell is exposed to warm air and sweats. The insulation between the inner tank and outer jacket becomes saturated with water and eventually drips out through openings in the outer jacket. If it is a warm day, the tank has an opening in the outer jacket, and the container has not been involved in an accident, you probably have water on the ground. Good identification procedures and monitoring will usually take the mystery out of the situation.

If product is leaking from the bottom outlet valve cap or blind flange, make sure that the cap or flange is tight. Do not remove the cap without checking the position of the valves! The valve handle should be in the closed position–horizontal to the valve. If the valve handle is in the open position–in line with the valve, activate the remote emergency shutdown handle to close the internal foot valve.

If the bottom outlet valve is leaking and the valve is in the open position, you can activate the remote emergency shutoff on the right side of the tank by pulling the handle. Some emergency shutoffs require that the wire cable running along the side of the tank be pulled.

If a tank container is damaged and the inner tank has been breached, the insulating jacket will make leak control tactics extremely difficult to implement. In this regard, jacketed tank containers share the same problems as jacketed MC-307/DOT-407 and MC-312/DOT-412 cargo tank trucks.

If the tank container is a single-shell container, standard leak control tactics and techniques can usually slow the leak. Critical factors in successful patching and plugging operations will include the pressure of the leak (i.gif>., higher pressures = less effective leak control operations), size and contour of the breach, and compatibility between the chemical and the patching/plugging device.

In rollover situations, the top-side manway may leak because the wing nuts were not properly tightened. These leaks are sometimes caused when the manway wing nuts are tightened sequentially in a clockwise fashion rather than in an alternating fashion (e.g., the way you tighten lug nuts on your automobile`s wheel so the rim and tire are straight). When this situation is encountered, the leak can sometimes be stopped by alternately tightening down the dome clamps.

Remember that Mr. Murphy usually rides shotgun to most haz-mat emergencies. Don`t expect everything to work just the way it was discussed in training. Remember the basics. Look for the quickest, easiest, and best leak-control option that provides safety for the responder. Go with your best option, but always have Plans B and C in your hip pocket. One of the techniques may eventually work.

GREGORY G. NOLL, C.S.P., is a senior partner with Hildebrand & Noll Associates, an emergency planning and response consulting firm. He is also a member of the Lancaster Township (PA) Fire Department and of the Fire Engineering editorial advisory board. The information in this article is taken from the textbook Hazardous Materials Emergencies Involving Intermodal Containers by Gregory Noll and Michael Hildebrand (Fire Protection Publications, 1995).




Intermodal freight and tank containers are becoming a common sight in all modes of transportation. Although similar to traditional types of freight and tank containers, they present several differences that can pose unique challenges to public safety and industrial responders.


The basic principle of an intermodal container is to have a transport vehicle that can be physically moved on more than one mode of transportation–e.g., from ships to trucks to railcars to fixed facilities. Intermodal containers are constructed to standard international designs. Common designs include freight or box containers and portable tank containers.

Use of intermodal containers in North America increased during the 1970s, when the United States began to be used as a “land bridge” for international traffic between the Atlantic and Pacific oceans. Under this service offered by the railroads to various ocean shipping companies, a container initially loaded in Europe and en route to the Far East would travel via container ship to the U.S. East Coast, be loaded on a train for the trip across the continental United States, and then be reloaded on another container ship on the U.S. West Coast for its ultimate destination in Asia.

In the 1980s, the use of intermodal containers became more prevalent for domestic transportation, particularly for box containers and their cousin, the piggyback trailer. Today, more than four million intermodal containers are routinely used to ship hazardous and nonhazardous materials throughout the world. This increasing use of intermodal containers has also created new problems for public safety and industrial emergency response personnel.

Freight containers are used to transport hazardous and nonhazardous nonbulk packages. Configurations include dry vans, refrigerated units, open-top containers, and flat containers. They can be found on marine vessels, as containers on flatcars (COFCs) in railroad transportation, and attached to the trailer chassis during highway transportation. In addition, they may also be found at fixed facilities, where they are used for short-term storage.


The most common intermodal freight container is the dry van, which is used for transporting a wide range of regulated and nonregulated materials. From an emergency response perspective, they share many of the same concerns presented by vans and tractor trailers.

Key construction features of intermodal freight containers include the following:

Container. Freight containers are commonly found in two lengths–20 and 40 feet, although containers as long as 45, 48, and 56 feet may also be found. In some countries, however, containers may also include 10- and 30-foot lengths. All ISO containers are eight feet wide. In addition to the standardized length and width, ISO also specifies standardized heights ranging from eight to 912 feet.

The 8 2 8 2 20 intermodal freight container is used as the basic measuring stick in many statistical comparisons. This container is referred to as a “TEU,” meaning that it is a 20-foot equivalent unit. The term “FEU”–which refers to 40-foot equivalent units–may also be used.

Door designs and the number of locking assemblies on intermodal freight containers vary widely. Doors may have two-, three-, or four-latch bar assemblies. Although fairly common in Europe, side doors are typically not found on containers in North America.

Materials of construction. Freight container designs are either smooth-side containers, external-post containers, or corrugated-side containers.

Smooth-side containers are generally made of aluminum or fiberglass-reinforced plywood (FRP). Aluminum smooth-side containers are constructed of a number of panels with interior posts riveted to them, whereas the FRP containers have no visible rivets or corrugations. Most of these containers are unvented. Vented smooth-side containers can be identified by a series of small holes along the top or bottom of the side panels.

External post containers have a number of posts riveted to the outside of the container. They are typically constructed of steel or aluminum. Vented external-post containers can be identified by the small rectangular panels usually found near the corners of the container sides.

The corrugated container, which has become the most common, is usually constructed of steel with sides consisting of a number of welded corrugated panels. These external corrugations may be a flat, square design or beveled with the corrugations angled or nearly rounded. Most of these containers are vented; the vents appear as small rectangular panels and are near the corners of the container`s sides or as the filler between the corrugations.

Corner castings. Supporting frames for all intermodal containers (freight containers and portable tanks) are built with corner fittings commonly referred to as corner castings. They are used to secure the container and lift it with standard container-handling equipment. Corner castings must conform to ISO Standard 1161, Specifications of Corner Fittings for Series Freight Containers. Cast-iron corner castings are prohibited.


Refrigerated containers. “Reefers” are very similar to dry freight containers, but they have a refrigeration unit mounted on the container`s nose or front end. The refrigeration units may be flush-mounted or exposed. Some insulated containers may also have clip-on refrigerated units attached to the container`s front face so that the container can be used for dry or “chill frozen” cargo. Cryogenic liquids, such as liquid nitrogen, are commonly used as the refrigerant (see photo on page 66, left).

Most refrigerated freight containers are not provided with their own power source. External power source options include a ship`s power source, a plug-in at a fixed facility, a chassis-mounted generator for highway use, a freight-car generator, a generator container, or a temporary clip-on generator. It is not uncommon to find 220- or 440-volt power supply cords being used to supply refrigerated COFCs when being transported by train.

The most common design for reefers is the smooth-side container constructed of aluminum or FRP. Insulation materials include polyurethane or polystyrene foam, mineral wool, and fiberglass. The insulation and refrigeration unit decrease the reefer`s internal cubic capacity in comparison with that of dry freight containers.

Flat containers. These containers are used for transporting heavy machinery, large containers, and other special equipment not capable of being transported in a box intermodal or other enclosed container. Flat containers may be a straight platform with no bulkheads or may have a fixed or collapsible bulkhead.

Open-top containers. These freight containers consist of four sides; are generally constructed of steel or aluminum; and have an open top, which is enclosed by a canvas-like tarp. Open-top containers are used for transporting loose or granular materials and items that are too large for fully enclosed containers.


Box container markings and placards are critical elements in (1) identifying the hazardous materials involved and (2) evaluating the hazards and risks. Container markings can include the following:

Reporting marks and number. All containers must be marked with reporting marks and a container number. The initials indicate ownership of the tank, and the number identifies the specific container. These markings are generally found on the right-hand side of the tank (as you face it from either side) and on both ends.

Country, size, and type markings. The container will display a country, size, and type code. The country code (two letters) indicates the tank`s country of registry. The following four digits indicate the ISO size/type code.

The ISO country code indicates the country of registry for the container. However, responders should note the following disclaimers. First, the country of registration can vary within a company`s container fleet. For example, Evergreen Marine has containers registered in the United States and Panama. Second, the country code may not always appear on the container.

The ISO size/type code indicates the container`s size and other specific container features. The first two digits indicate the container`s length and height; specific sizes are assigned specific numbers. The second pair of digits is the ISO type code. Specific types of containers are assigned specific numbers, such as “00” for a closed dry van container, “10” for a vented dry-van closed container, “20” for an insulated container, “32” for a refrigerated container, “51” for open tops, and so forth.

Markings and placards. Freight containers and trailers must be placarded in accordance with DOT and IMO regulations. Which placard is used depends on the hazard class, the quantities of hazardous materials being transported, and the mode of transportation.

Some specific situations responders should be aware of regarding the placarding of international shipments include the following:

–Containers loaded with regulated commodities that exceed regulatory thresholds must display the appropriate DOT placard to correspond with the commodity`s classification. Any additional placard authorized by the International Maritime Dangerous Goods Code (IMDG) should also be found [see 49 CFR 172.502(c)(1)].

–The required placard must meet the DOT placard design specifications. For example, an INFLAMMABLE placard would not be legal in lieu of a Flammable Liquid placard, even though they are identical in size, color, and intent.

— It is not uncommon to find hazard class terms (e.g., Flammable Liquid) written in a foreign language.

ADR/RID marking system. The European Agreement Concerning Transport of Dangerous Goods by Truck (ADR) and European Agreement Concerning Transport of Dangerous Goods by Rail (RID) are used within Europe for the movement of portable tank containers. These regulations are in line with the IMDG requirements and are used to assist emergency responders in safely identifying the contents of a hazardous-materials transportation container or vehicle. Intermodal tanks and containers shipped into the United States and North America may contain these markings. (See sidebar on page 65.)


Although listed under highway transportation, a number of the issues listed below pertain to all modes of transportation.

Emergency responders have encountered numerous problems in dealing with intermodal freight containers and tractor trailers containing hazardous and nonhazardous materials that do not require placarding (remember the 1,000-pound rule!). Shipping documents may refer to these shipments as “freight of all kinds” (FAK) and may not accurately reflect what is inside of the container.

Hazardous materials shipments originating outside of the United States can sometimes create problems in clearly identifying (1) who the shipper is and (2) who the emergency response point-of-notification is within the United States. Although this situation has improved with the DOT Emergency Response Communication regulations, responders still can encounter problems in quickly accessing a knowledgeable individual who can provide accurate information on what is inside a freight container. In some instances, the U.S. point-of-contact has been a shipping broker who has little or no knowledge of the container`s contents. If in doubt, start with CHEMTREC.

While the majority of shippers and intermodal carrier companies are very reputable, there are also those who “live on the edge”–both operationally and financially. Haz-mat enforcement and motor carrier inspections have consistently found problems with the mechanical integrity of equipment as well as inadequate vehicle and trailer maintenance (e.g., brakes, connectors, and so on).

Improper loading procedures–which can range from poor blocking and bracing to improper load separations between reactive chemical families and hazard classes–sometimes cause haz-mat emergencies. It is not uncommon to find that the last row of containers was “wedged” or pushed by a forklift into the freight container so that the container doors can be closed. Normal movement and vibration during transportation can place mechanical stress and eventually cause container leaks and spills. (Of course, the container that is leaking will never be at the back of the container!)

Intermodal carriers, particularly those operating in port and terminal areas, will typically make multiple runs during a one- to four-week period. Several public safety HMRTs have experienced incidents in which the driver had copies of the shipping papers in the truck cab for all runs during the preceding month. If the driver is seriously injured or hospitalized, it may take an extended period of time for emergency responders to gather, review, and determine which are the proper shipping documents.

The ADR/RID marking system assists European emergency responders in identifying the contents of a hazardous-materials transportation container or vehicle. Since intermodal tanks and containers shipped into the United States and North America may contain these markings, emergency responders should have a basic understanding of this system.

Some emergency responders refer to incidents involving intermodal freight containers as “surprise packages,” because you`re never quite sure what you will have until you open the doors. In this regard, freight containers pose the same concerns as vans and tractor trailers. Remember the following safety practices:

–NEVER stand in front of freight container doors when opening the container. Unlock the door. Using ropes or pike poles, stand off to the side as the container doors are opened. If anything goes wrong, responders will be off to the side and out of the high-hazard area. For example, loads may shift and come rolling out as the doors are opened. A 55-gallon drum of water weighs approximately 465 pounds, and most corrosives and other chemicals weigh in excess of 500 pounds. Insulated freight containers can be very tight. Opening the container doors and allowing the outside air to mix with the inside reactive environment may result in an explosion.

–If the freight container or trailer is completely loaded, it may be extremely difficult to identify which container is leaking and the source of the problem. In this case, responders will have to perform “container triage”– inspecting, removing, and separating the containers one by one until the leaker can be identified.

–Forklift trucks or other container-handling equipment may be required to perform the container triage process. If the container or trailer is intact, evaluate the hazards and risks involved in moving the vehicle to another location where it will be easier to manage the problem (e.g., off the highway onto an adjoining road, to an isolated area of a truckstop, to a state highway maintenance area, and so on).

–If a freight container has been involved in an overturn situation, forcible entry may be required. When dealing with noninsulated containers, the easiest entry points will be through the (1) doors (sliding vs. swinging), (2) roof, (3) walls, and (4) floor. Remember that the walls may have metal or wood sheeting on the interior and that the floor is the strongest structural element of the trailer.


Containers on flatcars (COFCs) and trailers on flatcars (TOFCs) are the two most common railroad shipments found today in the United States. COFCs can be found on trains in various configurations, including single and double stacks. The containers are attached to the flatcar through twist-lock attachments (i.e., corner castings), similar to those used with truck chassis. Stacking cranes and container lifters are the most common methods of placing COFCs on trains at rail terminals.

TOFCs are normally loaded on a flatcar by a stacking crane–a spreader is attached to the container`s top corners, and the trailer is lowered onto the flatcar. Container forklifts and container lifters can also be used to lift a trailer onto a flatcar; however, not all trailers are designed to be picked up in this manner, and there are specific lifting points on the trailers. Although not as common, ramps (i.e., “circus ramps”) may be available for driving the trailer onto the flatcar. The trailer is attached to the flatcar by locking the trailer`s kingpin to a fifth wheel assembly built on the flatcar.

There are no Federal Railroad Administration (FRA) restrictions specifying which regulated materials may be shipped in COFCs and TOFCs, although there may be individual railroad restrictions. Cargo tanks cannot be shipped as a TOFC on a flatcar.

1. Remember the basic clues and their priority for identifying intermodal containers:

container shapes,

markings and colors,


shipping papers and related documents, and


The consist will be the primary shipping document for railroad transportation and will be in the possession of the train crew. When dealing with TOFCs and COFCs, the consist will provide the following:

Number of the flatcar.

Number of each trailer or container being transported on the flatcar.

Description of each hazardous material being transported within the trailer or flatcar. For example, the consist description for a single UPS trailer on a flatcar may be several pages long, with the required shipping paper entries for each hazardous material.

2. The latest generation of deep-well flatcars allows up to four 20-foot containers to be double-stacked. While these flatcars allow for the movement of more containers, they also create potential problems for emergency responders, including the following:

If the COFCs on the bottom tier are placarded, the placards may be covered by the flatcar framing and not be readily visible to emergency responders.

Depending on how the COFCs are loaded, it is often not possible to open the container doors without removing the container from the train. Upper-tier containers may be loaded “back-to-back” and be approximately 25 feet high, whereas the doors on the lower-tier containers will be inaccessible due to the flatcar`s deep-well framing.

3. Flatcars containing COFCs may be connected in a series of three to five cars, sometimes referred to as “three-packs” or “five- packs.” One central generator supplies electricity to support refrigerated or heated containers on these flatcars. The generator is usually fueled by approximately 500 gallons of No. 1 or No. 2 diesel fuel oil. Electrical power is then supplied to the flatcars by 220- or 440-volt lines running within the flatcars.

4. Haz-mat releases in COFCs and TOFCs may pose a number of challenges for emergency responders, including the following:

Trailers with swinging doors and loaded back-to-back will be difficult to open without removing the trailer from the flatcar. Even if the trailer has a rear rolling door, limited space will make egress extremely difficult.

Even if the doors are accessible from the rear of the flatcar, the door will be approximately seven feet abovegrade. A ground ladder will then be required to unlock the doors. As already stated, NEVER stand in front of the doors when opening the container. Once the doors are unlocked, ropes or pike poles should be used while standing off to the side as the container doors are opened. If anything goes wrong, responders will be off to the side and out of the high-hazard area.

If the TOFC is involved in a derailment or rollover situation, the fifth wheel attachment on the flatcar may fail. Even if it doesn`t fail, the lightweight construction of modern trailers may likely cause the trailer roof or sidewall to fail.

If forcible entry into a TOFC is required, the easiest access points will be through the (1) doors, (2) roof, (3) walls, and (4) floor. Remember that the walls may have metal or wood sheeting on the interior and that the floor is the strongest structural element of the trailer.

* * *

An intermodal container can be physically moved on more than one mode of transportation (e.g., from ship to truck to railcar). These containers not only are intermodal but also are constructed to standard international designs. Because intermodal containers are easily moved from one location to another, they are gaining acceptance as the container of choice for moving bulk products from one country to another.

The most common intermodal freight container is the dry van or “box” container. As the workhorses of the intermodal industry, they are used for transporting a wide range of regulated and nonregulated materials. From an emergency response perspective, they present responders with the same problems as vans and tractor trailers.

In Part 2, we will review intermodal portable tank containers. n

Intermodal freight and tank containers are becoming increasingly common. This container ship is being off-loaded at the Port of Baltimore. (Photos by author.)

A 40-foot corrugated freight container is loaded on a railroad flatcar in a container on flatcar (COFC) configuration.

(Left) An example of a smooth-side refrigerated container with clip-on liquid nitrogen refrigeration unit. (Right) A flat container with fixed-end racks transporting uranium hexafluoride.

An example of freight container markings. The initials identify the tank`s owner; the number, the specific container.

(Top) An example of a trailer on flatcar (TOFC). (Bottom) COFCs can present unique forcible entry challenges for responders.


Intermodal containers are designed, constructed, and handled in accordance with a number of codes, regulations, and standards, including United States, international, and foreign domestic standards. In North America, the most notable include the following:

International Maritime Organization (IMO). Sponsored by the United Nations, IMO is the major maritime organization for establishing safety standards for ships, their cargo, and operating systems. The primary IMO reference document for the transportation of hazardous materials and intermodal containers is the International Maritime Dangerous Goods Code (IMDG). Section 13 of the IMDG pertains to “Portable Tanks and Road Tank Vehicles” and defines the types of portable tanks, design and construction requirements, special product-related features, and inspection requirements.

Although the IMDG does not have the force of law, it was the first detailed specification developed by major international trading countries, and many countries have adopted it into their national standards and regulations. In addition, ocean carriers have adopted IMDG as the minimum requirements for marine transportation of hazardous materials.

U.S. Department of Transportation (DOT). Title 49 of the Code of Federal Regulations (49 CFR) covers the transportation of hazardous materials. Parts 170 through 179 define the types of portable tanks, design and construction requirements, special product-related features, and inspection requirements.

Any deviations from the DOT requirements require an exemption or special approval. If a portable tank container is issued an exemption, the exemption number will be stenciled on the side of the container (e.g., DOT-E34567).

There are some differences between the DOT and IMDG requirements, including shell thickness calculations and relief valve settings.

Transport Canada (TC). TC has promulgated the Transportation of Dangerous Goods Regulations, which governs the transportation and use of intermodal containers for haz-mat transportation in Canada. The respective Canadian provinces have either adopted these regulations directly or have adopted similar regulations of their own.

Association of American Railroads (AAR). AAR is a U.S. trade association for the railroad industry that also develops industry standards and guidelines. All portable tank containers accepted for transport on the railroad must meet the requirements of AAR 600, Specification for Acceptability of Tank Containers. All tank containers that meet these requirements are stenciled with “AAR 600” on each side of the container. AAR 600 is not law.

International Standards Organization (ISO). ISO standards cover the structural design of intermodal containers, thereby allowing for worldwide intermodal movement. ISO standards cover the corner casting design; dimensional design; racking and stacking requirements; and markings relative to size, strength, and identification. Although ISO is not law, it establishes the standards ships, trailers and chassis, and railcars use for intermodal transportation requirements.

Convention for Safe Containers (CSC). CSC is an international convention primarily intended to ensure that all intermodal containers (i.e., freight, tank, and so on) undergo regular inspections for structural integrity. Certain strengths, testings, and markings are included in the convention. CSC is referenced by DOT in 49 CFR Parts 450 through 453, and compliance is required by 49 CFR Part 173.32 b (c). n


Also referred to as the “Kimmler System,” the marking system consists of two orange panels with black printing. The upper box contains a Hazard Identification Number; the lower box contains the four-digit United Nations identification number.

The Hazard Identification Number (upper panel) consists of two or three figures. The first figure indicates the primary hazard. In general, the figures indicate the following hazards:

1 Explosive

2 Emission of gas due to pressure or chemical reaction

3 Flammability (vapors) and gases or self-heating liquid

4 Flammable or self-heating solid

5 Oxidizing (fire intensifying) effect

6 Toxicity

7 Radioactivity

8 Corrosivity

9 Miscellaneous dangerous substance

X Reacts dangerously with water


* Doubling of a figure indicates an intensification of that particular hazard (e.g., 33).

* Where the hazard associated with a substance can be adequately indicated by a single figure, the figure will be followed by a zero (e.g., 30).

The second and third figures indicate the secondary or tertiary hazards. In general, the figures indicate the following hazards:

1 Explosive risk

2 Gas produced in contact with water

3 Flammable risk

4 Molten state (elevated temperature)

5 Oxidizing agent

6 Toxic risk

7 Open

8 Corrosive

9 Self-polymerization, risk of spontaneous violent reaction

X Reacts dangerously with water


23 Flammable gas

236 Flammable gas, toxic

33 Highly flammable liquid (flash point below 21ºC)

X338 Highly flammable liquid, corrosive which reacts dangerously with water

40 Flammable or self-heating solid

55 Strongly oxidizing substance

559 Strongly oxidizing substance that can spontaneously lead to violent reaction

63 Toxic or harmful substance, flammable (flash point between 21ºC and 55ºC)

663 Highly toxic substance, flammable (flash point not above 55ºC)

90 Miscellaneous dangerous substance n


Intermodal freight containers can transport various types of regulated and nonregulated materials. Hazardous materials may be found in nonbulk packages such as drums, pails, bags, or cylinders, as well as in bulk containers such as intermediate bulk containers (IBCs) or “totes.” If there is evidence of a leak or the interior contents need to be inspected for damage, open the box container. Obviously, the best way to gain entry is to open the door using safe entry procedures. However, when box containers are involved in an accident or rollover, the container can be crushed or collapsed to the point that its doors have become jammed.

When the container cannot be accessed through normal means, forcible entry is required. Unlike the smooth-side aluminum or fiberglass containers, the corrugated container can be very difficult to open if it is heavily damaged. The exterior walls are made from corrugated welded steel panels, and the interior structural members are well-braced. In short, corrugated steel containers are tough!

One of the fastest ways to gain entry to a damaged corrugated steel container is to cut through the side or roof with a power saw using a carbide-tip blade. However, saws cannot be used most times because sparks may cause a fire or an explosion. Remember that even if the risk of explosion is not present, saws can throw sparks into the interior space through the saw cut and ignite combustible packing materials. As a general rule, saws are not a good forcible entry choice for steel containers because of the risk from fire. Saws may be appropriate for cutting access holes into the sides or roofs of containers when a fire is involved. For example, when the container is loaded with Class A combustible materials (e.g., cardboard) and a smoldering fire needs to be extinguished, you can cut a triangular-shaped hole and place a handline through the hole to smother the fire before opening the container doors.

Hydraulically powered rescue tools are a good choice for forcible entry, because they minimize the risk of fire. Remember, however, that the rescue tool`s power plant is a potential ignition source when flammable liquids or gases are involved. When flammable liquids or gases are involved, place the power unit as far away from the container as possible to minimize the risk of fire or explosion. Standard hazard and risk assessment and site-safety procedures must be followed (e.g., monitoring, control zones, protective clothing, and so on).

Field tests and practical experience with hydraulic rescue tools have shown the following:

–Tools equipped with the typical automotive tips are often ineffective in forcing entry through the box doors. The wedge-shaped automotive tip is too large to spread the cargo doors open. When used to force the door`s locking rod open, the wedge tip either pulls the entire rod assembly from the box or rams the door further into the box.

–Tools equipped with a power cutter attachment have often proven to be the most effective method of forcing entry.

When forcing doors, secure them. Case containers may be resting against the inside of the doors. Options include chains or web straps with seatbelt-locking buckles. Once the lock mechanism is freed, the doors could swing open and the load could fall on the forcible entry crew. If the doors cannot be secured, brace or shore them up until forcible entry operations are completed and all personnel are clear of the rear doors. n

Entry operations into freight containers can pose physical and chemical hazards for responders.