IMDG Code requires every portable tank to be marked with minimum required information such as: 

Owner information
Manufacturing information
Approval information
Pressures
Temperatures
Materials
Capacity
Periodic inspections and tests

These marks must be stamped on a corrosion-resistant plate and the plate be fitted in a conspicuous place readily accessible for inspection.
If for any reason the plate cannot be permanently attached to the shell, then the shell must be marked with information required by the pressure-vessel code.

• Owner information
• Owner’s registration number;

• Manufacturing information
• Country of manufacture;
• Year of manufacture;
• Manufacturer’s name or mark;
• Manufacturer’s serial number;

• Approval information
• The United Nations packaging symbol:
• This symbol shall not be used for any purpose other than certifying that a packaging, a flexible bulk 
• container, a portable tank or a MEGC complies with the relevant requirements in chapters 6.1, 6.2, 6.3, 6.5, 6.6, 6.7 or 6.9 of IMDG Code;
• Approval country;
• Authorized body for the design approval;
• Design approval number;
• Letters “AA”, if the design was approved under alternative arrangements (see 6.7.1.2 of IMDG Code);
• Pressure-vessel code to which the shell is designed;

• Pressures
• MAWP (in bar gauge or kPa gauge); (The unit used must be indicated)
• Test pressure (in bar gauge or kPa gauge); (The unit used must be indicated)
• Initial pressure test date (month and year);
• Identification mark of the initial pressure test witness;
• External design pressure (see 6.7.2.2.10. of IMDG Code) (in bar gauge or kPa gauge); (The unit used must be indicated)
• MAWP for heating/cooling system (in bar gauge or kPa gauge) (The unit used must be indicated)  (when applicable);

• Temperatures
• Design temperature range (in °C); (The unit used must be indicated)

• Materials
• Shell material(s) and material standard reference(s);
• Equivalent thickness in reference steel (in mm); (The unit used must be indicated)  and Lining material (when applicable);

• Capacity
• tank water capacity at 20°C (in litres); (The unit used must be indicated)

• Periodic inspections and tests
• type of the most recent periodic test (2.5-year, 5-year or exceptional);
• date of the most recent periodic test (month and year);
• test pressure (in bar gauge or kPa gauge) (The unit used must be indicated) of the most recent periodic test (ifapplicable); 
• identification mark of the authorized body who performed or witnessed the most recent test.

The following information must be durably marked either on the portable tank itself or on a metal plate firmly secured to the portable tank:

• Name of the operator
• Name of non-refrigerated liquefied gas(es) permitted for transport
• Maximum permissible load mass for each non-refrigerated liquefied gas permitted in kg
• Maximum permissible gross mass (MPGM) in kg
• Unladen (tare) mass in kg
• Portable tank instruction in accordance with section 4.2.5.2.6 of IMDG Code.

Offshore Portable Tanks

A portable tank designed and approved for handling in open seas must be marked with the words “OFFSHORE PORTABLE TANK” on the identification plate.