New requirements for installing and operating inert gas systems

Effective from January 1st, 2016

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.

Main changes

• 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.
• 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).
• 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 nowonly 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.

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, butonly 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.

The changes to the IBC Code clarify the operational procedures for new and existing chemical tankers.

Chemical tankers which carry products containing oxygen-dependent inhibitors

Operators of chemical tankers that are required to be inerted and carry products containing oxygen-dependent inhibitors should note the following requirement, specified in Chapter 15.13.5 of the amended IBC Code:

“application of inert gas shall not take place before loading or during the voyage, but shall be applied before commencement of unloading”.

IMO circulars MSC.1/Circ.1501 and MSC-MEPC.5/Circ.10 should be read in conjunction with this requirement. These circulars state that when a product containing an oxygen-dependent inhibitor is carried on a ship for which inerting is required, the inert gas system shall be operated to maintain the oxygen level in the vapour space of the tank at or above the minimum level of oxygen required under paragraph 15.13 of the IBC Code and as specified in the cargo’s Certificate of Protection.

Relevant IMO resolutions

The changes to SOLAS, the FSS Code and the IBC Code are contained in the following IMO resolutions:

• Amendments to SOLAS regulations II-2/4.5.5 and 16.3.3: MSC.365(93)
• Amendments to Chapter 15 of the FSS Code: MSC.367(93)
• Amendments to the IBC Code: MSC.369(93)

Source:Lloyd’s Register