What are the requirements for Inert Gas or IG Plant on Tanker Ships?

Written by Amit Sharma

New statutory requirements for fixed inert gas systems will enter into force on 1 January, 2016, as a result of changes to SOLAS, the Fire Safety Systems (FSS) Code and the International Bulk Chemical (IBC) Code.

  1. The fitting of a fixed inert gas system will be required for tankers of 8,000 tonnes deadweIGht (dwt) and over, constructed (keel laid) on or after 1 January, 2016. Previously, this applied only to tankers of 20,000 tonnes dwt and over.
  2. Tankers 8,000 dwt and over, carrying low-flashpoint cargoes, and constructed (keel laid) on or after 1 January, 2016, must be provided with a fixed inert gas system complying with Chapter 15 of the amended FSS Code (or an equivalent system – subject to acceptance by the flag administration)
  3. The existing clause in SOLAS Regulation II-2/4.5.5.2 for waiving the requirements for a fixed inert gas system still applies to all gas carriers, but for chemical tankers it now only applies to those constructed before 1 January, 2016. This means that chemical tankers constructed (keel laid) on or after 1 January, 2016, and carrying flammable cargoes such as those listed in the IBC Code chapters 17 and 18, will be required to have a fixed inert gas system, regardless of cargo tank size and tank washing machine capacities.
Operational requirements for chemical tankers 

New SOLAS regulation II-2/16.3.3 clarifies the operational requirements for inert gas systems, and the sequence of applying the inerting medium into the cargo tanks.

  1. Regulation II-2/16.3.3 allows chemical tankers the option to begin inerting their cargo tanks after the cargo tank has been loaded, but before commencing unloading, but only if nitrogen is used as the inerting medium. In this instance, the nitrogen inerting should continue until the cargo tank has been purged and freed of all flammable vapours prior to gas freeing.
  2. The changes to the IBC Code clarify the operational procedures for new and existing chemical tankers.
  3. Chemical tankers which carry products containing oxygen-dependent inhibitors.

The oxygen content of the Inert Gas  supplied to cargo tanks should be 5% or less. However, it is to be noted that too less content of oxygen in the IG would introduce other impurities into the cargo tanks.

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General arrangement of the inert gas system.

The general arrangement of the inert gas system is as follows:

About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.

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