Dangerous goods are incompatible to each other in case they react dangerously when they come in contact due to leakage or spillage, or any other accident or increase the intensity of fire or explode if they burn together.
Interpreting segregation provisions of IMDG Code may seem complicated and there are chances one may miss a step or two ending up offering containers packed with incompatible goods for loading on board vessel. A vessel carrying incompatible goods in same container becomes an unsafe vessel and may result in serious consequences such as explosion, fire or loss of lives.
How do we ensure that incompatible goods are not packed or stowed together?
For checking segregation between dangerous goods in packaged form there are;
1. Segregation Table
2. Segregation Rules in column 16b of IMDG Code
3. Segregation terms such as;
a) “Away from”;
b) “Separated from”;
c) “Separated by a complete compartment or hold from”;
d) “Separated longitudinally by an intervening complete compartment or hold from”.
e) Exemptions to segregation
f) Special Segregation provisions
Segregation Table – IMDG Code 37th Amendment
Basic steps to check segregation
- Refer general segregation provisions of Chapter 7.2 and If Limited Quantity or Excepted Quantity, 18.104.22.168 or 22.214.171.124 – apply same
- Check & apply Column 16b and DGD requirements, if any (section 126.96.36.199.11 of IMDG Code)
- Use Segregation Table
Worked Examples of Segregation
Let us check segregation between certain dangerous goods and reach the conclusion taking above three steps which may lead to further steps to achieve compliance to segregation requirements.
UN 1263 PAINT, Class 3 PG II
UN 1944 MATCHES, SAFETY, Class 4.1 PG III
- Column 16b of above both UN Numbers does not contain any segregation codes
- Intersecting column between classes 3 and 4.1 in segregation table shows “x”
Conclusion = Both may be packed in same container or stowed together
UN 1263 PAINT, Class 3 PG II
UN 1310 AMMONIUM PICRATE, WETTED, Class 4.1 PG I
- Column 16b of UN Number 1310 reads SG7 and SG30.
- 7.2.8 of IMDG Code states SG7 = as ‘Stow “away from” class 3’, SG30 = ‘Stow “away from” heavy metals and their salts’ respectively
Conclusion = UN 1310 cannot be packed with UN1263 in same container.
UN 1467 GUANIDINE NITRATE, Class 5.1 PG III
UN 1485 POTASSIUM CHLORATE, Class 5.1 PG II
- Column 16b of UN 1467 reads SG45 and UN 1485 reads SG38 & SG49
- Refer section 7.2.8 of IMDG code
- a) SG38 Stow “separated from” ammonium compounds.
- b) SG45 Stow “separated from” chlorates.
- c) SG 49 Stow “separated from” cyanides
- Refer section 188.8.131.52 of IMDG Code and go to section 184.108.40.206.
- In 220.127.116.11 UN 1485 is listed under segregation group 4 Chlorates
Conclusion = UN 1467 which must be separated from chlorates hence cannot be loaded with UN 1485 Potassium Chlorate.
UN 1385 SODIUM SULPHIDE, ANHYDROUS, Class 4.2 PG II
UN 1849 SODIUM SULPHIDE, HYDRATED. Class 8 PG II
- Column 16b of UN 1385 and UN 1849 reads SG35
- Refer section 7.2.8 of IMDG Code which states SG35 as Stow “separated from” acids.
- Refer section 18.104.22.168 of IMDG Code and go to section 22.214.171.124. Both UN 1385 and 1849 are not listed in Acid list
- Check segregation table, intersection between Class 4.2 and Class 8 reads “1” which means away from each other.
However general segregation provision in section 126.96.36.199.1 exempt the requirement of segregation table between dangerous goods of different classes which comprise the same substance but vary only in their water content hence both UN 1385 and UN 1849 may be loaded in same container.
Segregation on board Container ships
While loading containers on ships stowage planners ashore will plan the positions in such a way that segregation between containers are maintained this will be further checked by Mate.
For example, if there are two 20 ft boxes each containing goods as below
Box 1 UN 1263 Class 3
Box 2 UN 1485 Class 5.1
Intersecting column of Segregation table between Classes 3 and 5.1 reads “2” which means these goods must be separated from each other.
On containerships with closed cargo holds segregation between containers carrying classes 3 and 5.1 need to be in accordance with section 188.8.131.52 which is further illustrated in Maritime Safety Committee circular no. MSC.1/Circ.1440 as shown in below illustration
If you have a question on IMDG Code Segregation you may ask here