There are many dangerous goods permitted for transport in portable tanks and type of tank is indicated with T code in dangerous goods list in IMDG Code.

Tank types T1 to T22 are assigned to various dangerous goods of class 1, classes 3 – 9 solids and liquids. T23 is for certain self-reactive substances type F and certain organic peroxides of type F. T50 is for non-refrigerated liquefied gases and certain chemicals under pressure and T75 is for refrigerated liquefied gases.

Some shippers have their own tanks dedicated for their products and many shippers approach tank operators for shipping their goods.

Let us look at three aspects when shippers use operators’ tanks of T1-T21

1. Current process in the industry for selecting tanks for specific dangerous goods;
2. Why this process is prone to risks? ; and
3. How tank must be selected to minimize risks?

Point no.1 above does not apply to all shippers but what many in the industry do.

1. Current process for selecting tanks

Usually, shippers only provide the Safety Data Sheet (SDS) and the tank operator checks whether the cargo is permitted in operator’s tank type and compatibility with shell material in order to protect their equipment from damage and compliance to IMDG Code. 

Most shippers never ask for a specific type of tank or make the decision on compatibility or compliance to IMDG Code by themselves.

2. Why this process is prone to risks?

Goods prohibited in tanks:

Some substances are prohibited from transport in portable tanks. These substances are considered too dangerous for transport in bulk typically because of their instability or because they pose an unacceptably high level of risk when transported in bulk quantities under normal conditions of transport,

guiding principle of UNMR

When a substance is not permitted in tank there will be no T code assigned in dangerous goods list. Thus, there is a great risk when shipper without referring IMDG Code approach a tank operator and operator also miss to verify IMDG Code and release an empty tank for substance which is prohibited in tanks.

Wrong tank type: Portable tank instructions T1 to T22 specify the applicable minimum test pressure, the minimum shell thickness (in mm of reference steel), and the pressure relief and bottom-opening provisions and is assigned in dangerous goods list of IMDG Code.

How a wrong tank may be selected if shipper and tank operator does not verify IMDG Code?

Below goods in PG I, II & III are assigned with tanks T14, T11 and T7 respectively.

When a specific portable tank instruction is specified in the Dangerous Goods List, additional portable tanks which possess higher test pressures, greater shell thicknesses, more stringent bottom opening and pressure relief device arrangements may be used.

IMDG Code part 4

According to above table additional portable tanks permitted for UN 1986 PG I, II & II are as below :

T11 is majority of tanks in operators’ fleets, if shipper and tank operator both misses to verify IMDG Code and operator release a T11 tank for UN 1986 PG I, as in above example, things may go very wrong. Shipment may be arrested by port authority cargo will then require to be transferred to an authorized tank, also may result in incidents/accidents.

Except for a few large shippers (who have their own manufacturing facilities with their own technical departments) where there is set process of checking tanks that have reported to the plant, it is highly improbable that such an error would be pointed out after the tank reports at the site for filling. 

Many of the filling sites rely more on the experience of their filling team to point out any discrepancies as these teams have practical experience dealing with the same type of cargo and tanks. 

Some shippers who use third party tanks also appoint their own surveyors to inspect the tanks before, during and after the loading at the filling point to avoid any kind of issues. Mostly these surveyors check the cleanliness of the tank and not compliance to IMDG Code.

The prevailing practice by many shippers relinquishing their duties for selecting tanks and solely relying on tank operators is wrong and risky practice.

There is a gap with regard to mandatory training of IMDG Code, written SOP, checklists which can be implemented so that such errors are minimized as there are many stake holders in the process, such as shippers, forwarders, traders, tank operators, carriers. 

All the stake holders need to be on same page of understanding the Code, compliance process for tank selection to avoid mishaps during transportation which may result in loss of lives, damage to cargo and tanks.

3. How tank must be selected to minimize risks?

For each entry of UN No., IMDG Code Dangerous Goods List column 13 indicates with a T code whether the substance or material can be carried in tanks.

If there is no T code in column 13, substance or material shall not be carried in tank unless specifically approved by competent authority.

Column 14 of IMDG Code Dangerous Goods List contains tank provisions applicable to portable tanks.

1. Look up UN Number and PG entry in dangerous goods list of IMDG Code
2. Check special provision in column 6 and apply same, when applicable
3. Check Tank Code and Tank Provisions in column 13 and 14
4. Check section 4.2.5.2.5 and identify permitted tanks (Determination of the appropriate portable tank instructions)
5. Check section 4.2.5.2.6 and ensure compliance (Portable tank instructions)
6. Ensure compliance to tank provisions in section 4.2.5.3 (Portable tank special provisions)

Above is not an exhaustive list of steps, shippers must refer to IMDG Code and other national/regional regulations and adhere to applicable provisions of same. 

What are shippers’ responsibilities when using tanks for transporting dangerous goods?

Shipper has various responsibilities which includes

• Correct classification of dangerous goods
• Selection of appropriate tank
• Verify the validity of the test certificates provided by the tank operator prior to filling…..

Read full responsibilities here