Tricky Segregation Your Software May Not Catch

Your staff are trained, you've installed some expensive hazmat software, and operations are rolling along. Out of the blue, a load that your software told you was valid gets rejected due to invalid segregation. The shipment is put on hold, delays abound, and there is wailing and gnashing of teeth.

Want to avoid this? Put your software through the paces by applying these tricky segregation examples, and solve the problem in advance.

NOTE: This article addresses segregation according to the IMDG Code, which governs the transport of dangerous goods internationally by vessel, and 49 CFR, which governs the transport of dangerous goods domestically in the United States. While the article is focused on vessel-specific requirements, the principles can be applied to other modes and in other jurisdictions.

Examples below are meant to illustrate common situations where mistakes easily can be made. These examples are for illustration only and should not be taken as legal advice or as definitive methods for compliance with hazmat regulations.

Hazmat regulations are complex. They should be: the hazardous they are meant to mitigate are complex, and methods employed for mitigation are many. The regulations also change regularly to address new technologies and to correct previous regulations. As a result, there are a number of circumstances where compliance with the regulations is hard to quantify.

Software eases much of the work required to produce a hazmat shipping paper, but often such software is little more than a form-filling tool. Most software is simply not designed to determine if the load is in fact compliant, and a majority of the software that makes an attempt to determine compliance doesn’t finish the job.

Below are four examples of rather commonplace shipments that introduce a few tricky situations.

Example 1: Multiple Jurisdiction

Before software can determine if a shipment complies with the regulations, it must determine which regulations are applicable. Our company deals with ocean-going shipments exclusively, so the field of potentially applicable regulations is narrowed significantly. Since we are in the United States, and since almost all of the shipments we deal with are for import or export, we end up with two bodies of regulations: the IMDG Code when the shipment is in international waters, and 49 CFR (which contains the US domestic hazmat regulations) when the shipment is in US waters.

Consider the following consolidated load:

UN 3469, Paint Related Material, Flammable, Corrosive, Cl. 3 (8), PG III
NA 1993, Combustible Liquid NOS, PG III

UN 3469 is listed in the IMDG Code with two different proper shipping names; Paint, Flammable, Corrosive or Paint Related Material, Flammable, Corrosive. 49 CFR, however, only lists Paint, Flammable, Corrosive, so a shipment of Paint Related Material that is also flammable and corrosive (such as certain paint thinners), wouldn’t necessarily be subject to 49 CFR. For all intents and purposes, UN 3469 as described above is regulated by the IMDG Code only.

By contrast, NA 1993 is regulated by 49 CFR only, and not by the IMDG Code. 49 CFR adds an additional class of liquids, termed “Combustible,” with a flash point above 60° C (140° F) and below 93° C (200° F). These are not regulated by the IMDG Code because only liquids with a flash point below 60° C (140° F) can be classed as Flammable Liquids.

The tricky situation this presents is that most software will apply the requirements of one jurisdiction at a time; the user would be required to pick either 49 CFR or the IMDG Code, but not both. If the user picks 49 CFR, then UN 3469 would not exist as described above. If the user picks the IMDG Code, then NA 1993 simply wouldn’t exist.

The reality is that both jurisdictions are applicable, and the segregation between these substances is as for class 3 and a sub-risk of class 8 with another class 3. There are no additional segregation requirements in column 16 of the IMDG’s Dangerous Goods List, nor in column 10B of 49 CFR’s 101 table.

This load is valid for both IMDG and 49 CFR; but how would the software show it?

Example 2: Segregation Requirements in Column 16

It’s easy to get in the habit of only going as far as the segregation table in IMDG (or its corollary in 49 CFR §176.83(b)) and not checking for additional segregation requirements in column 16 of the IMDG’s DGL (or column 10B of 49 CFR’s 101 table). This pair illustrates the difference column 16 makes:

UN 1744, Bromine, Cl. 8 (6.1), PG I
NA 1993, Combustible Liquid NOS, PG III

UN 1744, Bromine, is listed as a class 8 with a sub-risk of class 6.1. NA 1993, Combustible Liquid NOS, is to be treated like class 3, as we saw above. The segregation table shows no conflict between the primary classes of 8 and 3, and no conflict between Bromine’s sub-risk of 6.1 with the class 3 liquid. If we were to consider only the segregation table and stop here, we would show no segregation required between this pair.

However, the entry for Bromine says in column 16, “…Segregation as for class 5.1…” So labeling, marking, and placarding for Bromine will only consider classes 8 and 6.1, but when Bromine is stowed in the same container with other hazmat, it is to be treated as a 5.1 (oxidizer). Class 5.1 is incompatible with class 3; the segregation table shows that class 5.1 must be ‘separated from’ class 3.

This load, then, is invalid.

Example 3: Packaging Requirements

Even if just one dangerous good is packed in a container by itself with no other dangerous goods to trigger a segregation requirement, it must be packaged properly. Column 8 in the IMDG Code’s DGL (and its corollary in columns 8B and 8C in 49 CFR’s 101 table) list specific packaging requirements applicable to the entry. These requirements can specify—among other things—which types of packaging can be used (e.g. Plastic jerrycans with a removable head), and net weight and capacity limits for that kind of packaging (e.g. no more than 60 liters).

To see this in action, let’s consider a load with only the following:

UN 1789, Hydrochloric Acid, Cl. 8, PG III, 10x Plastic Jerrycans (3H2), 709 kg, 601 L

UN 1789 is the only dangerous good present in the container, so there are no segregation requirements to deal with. The cargo is packed in 10 plastic jerrycans with removable heads (indicated by the UN packaging code “3H2”). All 10 jerrycans together contain 709 kilograms of Hydrochloric Acid which amounts to 601 liters. These numbers will fit very nicely into just about any hazmat software, but they need to be validated against the packaging requirements for UN 1789 if the load is to be considered valid.

Under the entry for UN1789, Column 8 references packing instruction P001, which can be found in IMDG It specifies that each plastic jerrycan containing a PG III liquid may contain a maximum of 60 L. There are 10 jerrycans in the container, and there is a total of 601 L of cargo between them. That means that each jerrycan most likely contains 60.1 L of cargo, which exceeds the maximum of 60 L.

This load is invalid because the maximum net capacity of 60 L per package was exceeded.

Example 4: Special Provisions for Segregation

The previous two examples highlighted situations where software may indicate a load is valid when it is in fact invalid. This example highlights an opposite situation:

UN 1789, Hydrochloric Acid, Cl. 8, PG III, 10x Plastic Jerrycans (3H2), 348 kg, 295 L
UN 1791, Hypochlorite Solution, Cl. 8, PG III, 10x Plastic Jerrycans (3H2), 326 kg, 295 L

Both substances are in class 8, but belong to different segregation groups. UN 1789 is a Strong Acid and UN 1791 is a Hypochlorite. Column 16 in the entry for UN 1791 specifies that stowage must be ‘away from’ acids, and UN 1789 is an acid, so it would seem this load is invalid.

However, an exception is provided in IMDG for loads such as this one. It states:

…substances of class 8, packing group II or III, that would otherwise be required to be segregated from one another due to the provisions pertaining to segregation groups as identified by an entry in column 16 of the dangerous goods list indicating “Away from” or “Separated from” “acids” or “Away from” or “Separated from” “alkalis”, may be transported in the same cargo transport unit, whether in the same packaging or not, provided:

  1. .1 the substances comply with the provisions of;
  2. .2 the package does not contain more than 30 litres for liquids or 30 kg for solids;
  3. .3 the transport document includes the statement required by; and
  4. .4 a copy of the test report that verifies that the substances do not react dangerously with each other shall be provided if requested by the competent authority.


So this load may be valid if four conditions are met:

  1. The substances do not react dangerously with each other and cause combustion and/or evolution of considerable heat; evolution of flammable, toxic or asphyxiant gases; the formation of corrosive substances; or the formation of unstable substances
  2. Each package does not contain more than 30 liters (since the cargo is liquid)
  3. The shipping paper includes the statement, “Transport in accordance with of the IMDG Code”
  4. A test report is available (i.e. a copy has been provided) to verify that the substances do not react dangerously with each other

Software may have packaging data readily available to verify condition 2 is met. If the software is assisting the preparation of the shipping paper, it may have some control over meeting condition 3. Meeting condition 4 implies compliance with condition 1: in order for such a test report to exist, a test must have been performed and compliance with condition 1 confirmed. Since condition 4 relies on a test report, which only the most bespoke software would track, the software may simply ask the user to confirm compliance with condition 4 (and, by implication, condition 1).

This load is valid if a test report is available to verify that the substances do not react dangerously with each other.


Software can ease much of the work required to determine if a load complies with hazmat regulations, just as technology can ease much of the work required for an accountant to prepare a tax return. The accountant’s job is made easier with the use of a calculator; the accountant is capable of doing the math, but the calculator makes it faster. The job is made easier still by tax software that accurately applies rules to data, and can reliably determine how closely tax law has been followed.

Just as a calculator or tax software does not create an accountant out of just anyone, hazmat software (be it simple or sophisticated) does not create a qualified hazmat employee out of just anyone. Software certainly can’t replace the hazmat employee (nor the accountant) entirely; human judgement is integral. Appropriate training is necessary—and mandatory—before one can be considered qualified to do the job, and before their judgement is trustworthy.

Once trained, however, software can quicken the pace at which a hazmat employee is able to produce accurate and correct documentation. A form-filling tool will quicken the pace somewhat, perhaps saving some typing and ensuring that required fields contain some type of information. Sophisticated software that can correctly resolve all four of the examples above will quicken the pace all the more, and avoid mistakes that could cause costly delays down the line.

If you're interested in our suggestions for software which correctly determines a load's compliance, contact us and we will be glad to share.