{"id":858096,"date":"2024-10-09T07:00:32","date_gmt":"2024-10-09T11:00:32","guid":{"rendered":"https:\/\/www.thecompliancecenter.com\/ca\/?p=858096"},"modified":"2025-09-08T01:15:21","modified_gmt":"2025-09-08T05:15:21","slug":"segregating-dangerous-goods-under-the-imdg-code","status":"publish","type":"post","link":"https:\/\/www.thecompliancecenter.com\/ca\/help-center\/articles\/segregating-dangerous-goods-under-the-imdg-code\/","title":{"rendered":"Segregating Dangerous Goods under the IMDG Code"},"content":{"rendered":"

This post was originally published in August 2021 and has been updated in October 2024 for accuracy.<\/i>\"\"<\/p>\n

One of the most common issues we get asked about at ICC The Compliance Center is segregation of dangerous goods. A shipper may have two different chemicals \u2013 can they ship them in the same packaging? Or even in the same freight container? The answer is important because having to separate parts of a shipment can increase the cost of transport by a lot.<\/span><\/p>\n

Unfortunately, the solution isn\u2019t always easy to find. Different <\/span>regulations<\/span><\/a> will have different requirements. For example, Canada\u2019s Transportation of Dangerous Goods Regulations<\/a><\/span> (TDG) doesn\u2019t have any specific guidelines other than a table in section 5.7<\/a><\/span> that only applies to class 1 Explosives. On the other hand, the Hazardous Materials Regulations<\/a><\/span> (HMR) in the U.S. system have a detailed table<\/a><\/span> indicating classes that have to be shipped on separate vehicles, those which may be shipped without restriction, and those which may be shipped on the same vehicle but must be separated to prevent commingling in case of an accident. But the most complex system for segregation is that for marine shipments under the International Maritime Dangerous Goods (IMDG) Code<\/a><\/span>. Not following these rules can result in your shipment being stopped at the port if you\u2019ve mistakenly combined two substances that the Code has classified as requiring segregation.<\/span><\/p>\n

Basics of IMDG Segregation<\/b><\/h2>\n

First, why is segregation so important for marine shipment. Well, if you\u2019ve ever seen a ship at sea in a storm<\/a><\/span>, you\u2019ll understand how chemicals could mix if they both leak at the wrong time. And marine carriers transport millions of tonnes<\/a><\/span>\u00a0of dangerous goods per year. So, it\u2019s important to keep chemicals from mixing during the trip.<\/span><\/p>\n

This has led the International Maritime Organization (IMO)<\/a><\/span>,<\/span><\/a> which created the IMDG Code<\/em><\/a><\/span>, to develop a system that relies on three steps of protection:<\/span><\/p>\n

    \n
  1. A generic segregation-by-class table found in section 7.2.4, <\/span>IMDG Code<\/span><\/i> Volume 1<\/span><\/li>\n
  2. Substance-specific guidelines based on codes found in the List of Dangerous Goods, <\/span>IMDG Code<\/span><\/i> Volume 2<\/span><\/li>\n
  3. Shipper and carrier knowledge of the substances involved<\/span><\/li>\n<\/ol>\n

    The most important thing to remember when planning a marine load is section 7.3.4.1, which states that:<\/span><\/p>\n

    \u201cDangerous goods which have to be segregated from each other according to the provisions in chapter 7.2. shall not be transported in the same cargo transport unit\u2026\u201d\u00a0<\/span><\/em><\/p>\n

    In other words, if you determine that there are any applicable segregation requirements, you can\u2019t put the two dangerous goods in the same cargo transport unit together, nor may you put them in the same package or overpack.<\/span><\/p>\n

    So, let\u2019s take a look at how this works.<\/span><\/p>\n

    Step 1 \u2013 Consult the Segregation Table<\/b><\/h2>\n

    The rules for segregation by class can be found in <\/span>IMDG Code<\/span><\/i> Part 7. There are a number of complexities for the crew of the vessel as to where on the ship dangerous goods of differing classes may be loaded \u2013 on deck, next to each other in compartments inside the hull, or in separate compartments. However, let\u2019s concentrate on what the shipper needs to know. Can the classes of dangerous goods go in the same Cargo Transport Unit (CTU) or will they have to be placed in separate CTUs so they can be stowed in different areas? (Note that of course if goods can\u2019t be placed in the same CTU, you obviously cannot package them together.)<\/span><\/p>\n

    The table for segregation by class can be found in section 7.2.4, as follows;<\/span><\/p>\n

    \"\"<\/p>\n

    To determine the segregation for two classes, you would read a row for one class (across) and for the other class read a column (down). Where they intersect, you will either find the letter \u201cX\u201d or a number. The numbers (1, 2, 3 or 4) will tell the people stowing the goods how far apart they must be separated, as follows:<\/span><\/p>\n

    \u201c1\u201d \u2013 \u201caway from\u201d (normally, CTUs at least 3 metres apart)<\/span><\/p>\n

    \u201c2\u201d \u2013 \u201cseparated from\u201d (normally, CTUs at least 6 metres apart)<\/span><\/p>\n

    \u201c3\u201d \u2013 \u201cseparated by a complete compartment or hold from\u201d<\/span><\/p>\n

    \u201c4\u201d \u2013 \u201cseparated longitudinally by an intervening complete compartment or hold from\u201d<\/span><\/p>\n

    Note that \u201c1\u201d indicates the smallest required separation, and \u201c4\u201d the greatest. But for the shipper this doesn\u2019t really matter \u2013 <\/span>any number indicates those classes cannot be put in the same CTU<\/span><\/i>.<\/span><\/p>\n

    (Technically, section 7.3.4.1 allows you to ship goods that must be stowed \u201caway from\u201d each other, indicated by a \u201c1\u201d on the table, in the same CTU if you can obtain a permit from the \u201ccompetent authority,\u201d such as Transport Canada or the U.S. Department of Transportation. However, applying for a permit or equivalency certificate can be a time-consuming procedure, and a shipper is not guaranteed success if they apply.)<\/span><\/p>\n

    Let\u2019s look at a couple of examples. First, let\u2019s see if you could ship a flammable gas such as UN1978, PROPANE, in class 2.1 in the same CTU as UN1203, GASOLINE, a flammable liquid.<\/span><\/p>\n

    We find the compatibility in this case by reading across for class 2.1 and down for class 3:<\/span><\/p>\n

    \"\"<\/p>\n

    Unfortunately for our planning, there is a number (\u201c2\u201d) where the row and column intersect. This means that we cannot put these two products into the same CTU for an IMDG shipment.<\/span><\/p>\n

    On the other hand, let\u2019s consider a shipment of a hand sanitizer based on UN1170, ETHANOL (class 3) with UN2555, NITROCELLULOSE WITH WATER (class 4.1). We\u2019ll look at class 3 as a row going across, and class 4.1 as a column going down:<\/span><\/p>\n

    \"\"<\/p>\n

    In this case, there\u2019s an \u201cX\u201d where the row and column intersect. This means that there is no automatic segregation between class 3 and class 4.1 materials.<\/span><\/p>\n

    But before we start loading our nitrocellulose and ethanol into the same freight container, we have another step to take. Next, we must check these specific substances to see if there is any other compatibility issue between them beyond the generic class compatibility.<\/span><\/p>\n

    Step 2 \u2013 Consult Segregation Requirements in the Dangerous Goods List<\/strong><\/h2>\n

    Just because two classes in general don\u2019t require segregation doesn\u2019t mean that two specific substances in those classes are in the clear. Our next step is to go to the Dangerous Goods List in Volume 2 of the <\/span>IMDG Code<\/span><\/i>, and check column 16b, headed \u201cSegregation.\u201d<\/span><\/p>\n

    In this column, we can find two sorts of codes \u2013 \u201cSG\u201d codes (Segregation) and \u201cSGG\u201d codes (Segregation Group). These will give more guidance regarding segregating specific substances and articles.<\/span><\/p>\n

    So, let\u2019s first look up UN1170, ETHANOL:<\/span><\/p>\n

    \"\"<\/p>\n

    Here, column 16b is blank. That means UN1170 doesn\u2019t have any specific extra segregation requirements.\u00a0<\/span><\/p>\n

    But it\u2019s a little different when we look up UN2555, NITROCELLULOSE WITH WATER:<\/span><\/p>\n

    \"\"<\/p>\n

    Here we have two codes in column 16b \u2013 SG7 and SG30. To find out what these codes mean, we must go to <\/span>IMDG Code<\/span><\/i> section 7.2.8, where they explain what these \u201csegregation codes\u201d represent.<\/span><\/p>\n

    \"\"<\/p>\n

    The first code, SG7, means that this product needs to be segregated \u201caway from\u201d class 3 materials. In other words, it\u2019s as if there were a \u201c1\u201d between these specific substances on the generic segregation by class table. These substances cannot be placed in the same CTU, even though the generic table indicates there is no specific segregation by class since the segregation code demands these two specific products be segregated.<\/span><\/p>\n

    The second code doesn\u2019t affect this specific shipment, but it brings up another complication. Along with the SG codes, there may be \u201cSGG\u201d codes. These are \u201cSegregation Group\u201d codes, which apply to certain <\/span>families<\/span><\/i> of chemicals, regardless of their class. These chemical families will have special additional segregation requirements. The table can be found in section 7.2.5.2 and covers 18 common chemical families that can cause dangerous reactions:<\/span><\/p>\n

    \"\"<\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

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     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

    According to our entry for UN2555, the chemical must be segregated from anything placed in the segregation group SGG7, \u201cheavy metals and their salts.\u201d This would include compounds of metals with heavy atomic weights<\/a><\/span>, such as mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), thallium (Tl), and lead (Pb).\u00a0<\/span><\/p>\n

    It\u2019s the shipper\u2019s responsibility to assign substances to SGG codes (segregation groups) as appropriate. This is described in <\/span>IMDG Code<\/span><\/i> section 3.1.4. A number of common chemicals are assigned to their corresponding groups in section 3.1.4.4, but if a chemical is not listed, the shipper must make their own decision. So, for example, if you had a generic shipping name \u201cTOXIC LIQUID, INORGANIC, N.O.S.\u201d that contained cyanide compounds, you would assign it to <\/span>SGG6, Cyanides<\/b>.\u00a0<\/span><\/p>\n

    If the shipping name isn\u2019t listed in section 3.1.4.4, but the shipper believes the substance belongs in one of these groups, they must indicate the group code on the shipping document to allow the vessel crew to stow the substance safely. For example, the entry here might read \u201cUN 3287, TOXIC LIQUID, INORGANIC, N.O.S. (potassium cyanide, sodium cyanide), 6.1, PG II, IMDG Code segregation group 6\u201d.<\/span><\/p>\n

    Step 3 \u2013 Shipper and Carrier Knowledge<\/b><\/strong><\/h2>\n

    Let\u2019s imagine we have two products \u2013 say UN1203, GASOLINE, class 3 and UN1944, MATCHES, SAFETY, class 4.1. According to the table in section 7.2.4, these two classes do not require automatic segregation \u2013 that is, there is an \u201cX\u201d where the two classes intersect on the table. And when we check column 16b, there are no SG or SGG codes at all for both products. Does that mean we\u2019re clear to load them together?<\/span><\/p>\n

    Well, not quite. If you or the vessel operator believe that, despite this, there is a risk to the safety of cargo or the vessel itself from shipping the two substances in the same CTU, they should be segregated based on your understanding of the hazards. The hazards to consider are listed in section 7.2.6.1, and include:<\/span><\/p>\n