LR VI.2 Nitrogen Generator Systems on Chemical Tankers of 8,000 tonnes DWT and above
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Clasifications Register Rules and Regulations - Rules and Regulations for the Construction and Classification of Ships for the Carriage of Liquid Chemicals in Bulk, July 2022 - LR VI Cargo Tank Inerting Arrangements - LR VI.2 Nitrogen Generator Systems on Chemical Tankers of 8,000 tonnes DWT and above

LR VI.2 Nitrogen Generator Systems on Chemical Tankers of 8,000 tonnes DWT and above

LR VI.2.1 The following requirements apply where a nitrogen generator system is fitted on board tankers of 8,000 tonnes DWT and above. For the purpose, the inert gas is to be produced by separating air into its component gases by passing compressed air through a bundle of hollow fibres, semi-permeable membranes or adsorber materials.

LR VI.2.2 In addition to the applicable requirements of Chapter 15 - Inert Gas Systems of the FSS Code, as amended by Resolution MSC.367(93) – Amendments to the International Code for Fire Safety Systems (FSS Code) – (Adopted on 22 May 2014) , the nitrogen generator system is to comply with SOLAS Regulations II-2/4 5.3 Cargo tank venting, 5.6 Inerting, purging and gas-freeing and 6 Protection of cargo tank structure against pressure or vaccuum in tankers.

LR VI.2.3 A nitrogen generator consisting of a feed air treatment system and any number of membrane or adsorber modules in parallel is to be capable of delivering nitrogen to the cargo tanks at the rate required by paragraph 2.2.1.2.4 of Chapter 15 - Inert Gas Systems of the FSS Code, as amended by Resolution MSC.367(93) – Amendments to the International Code for Fire Safety Systems (FSS Code) – (Adopted on 22 May 2014) .

LR VI.2.4 The nitrogen generator is to be capable of delivering high purity nitrogen with an oxygen content in accordance with paragraph 2.2.1.2.5 of Chapter 15 - Inert Gas Systems of the FSS Code, as amended by Resolution MSC.367(93) – Amendments to the International Code for Fire Safety Systems (FSS Code) – (Adopted on 22 May 2014) . In addition to meeting the venting requirements of paragraph 2.2.2.4 of Chapter 15 - Inert Gas Systems of the FSS Code, as amended by Resolution MSC.367(93) – Amendments to the International Code for Fire Safety Systems (FSS Code) – (Adopted on 22 May 2014) , the system is to be fitted with automatic means to discharge “off-spec” gas to the atmosphere during start-up and abnormal operation.

LR VI.2.5 The system is to be provided with one or more compressors to generate enough positive pressure to be capable of delivering the total volume of gas required by 2.2.1.2 of Chapter 15 - Inert Gas Systems of the FSS Code, as amended by Resolution MSC.367(93) – Amendments to the International Code for Fire Safety Systems (FSS Code) – (Adopted on 22 May 2014) . Where two compressors are provided, the total required capacity of the system is preferably to be divided equally between the two compressors, and in no case is one compressor to have a capacity less than 1/3 of the total capacity required.

LR VI.2.6 Where the nitrogen system includes a nitrogen storage tank which has sufficient capacity to deliver the total volume of gas required by 2.2.1.2 of Chapter 15 - Inert Gas Systems of the FSS Code, as amended by Resolution MSC.367(93) – Amendments to the International Code for Fire Safety Systems (FSS Code) – (Adopted on 22 May 2014) , in the event of failure of a compressor a single compressor may be accepted provided that sufficient spares are carried on board to enable the failure to be rectified by the ship’s crew. The list of spare parts required is to be supplied by the manufacturer and supported by a reliability analysis of the specific system submitted to and verified by LR. The size of the nitrogen storage tank is to be specified.

LR VI.2.7 The feed air treatment system fitted to remove free water, particles and traces of oil from the compressed air, as required by 2.4.1.2 of Chapter 15 - Inert Gas Systems of the FSS Code, as amended by Resolution MSC.367(93) – Amendments to the International Code for Fire Safety Systems (FSS Code) – (Adopted on 22 May 2014) , is also to maintain the specification temperature.

LR VI.2.8 The oxygen-enriched air from the nitrogen generator and the nitrogen-product enriched gas from the protective devices of the nitrogen receiver are to be arranged to discharge to a safe location on the open deck. This safe location needs to address the two types of discharges separately.

For oxygen-enriched air from the nitrogen generator, safe locations on the open deck are:

  • outside of hazardous areas as defined by Pt 6, Ch 2, 13.5 Discharge lighting of the Rules for Ships;
  • not within 3 m of areas traversed by personnel;
  • not within 6 m of air intakes for machinery and all ventilation inlets.

For nitrogen-product enriched gas from the protective devices of the nitrogen receiver, safe locations on the open deck are:

  • not within 3 m of areas traversed by personnel;
  • not within 6 m of air intakes for machinery and all ventilation inlets/outlets.

LR VI.2.9 In order to permit maintenance, means of isolation are to be fitted between the generator and the receiver.

Parent topic: LR VI Cargo Tank Inerting Arrangements
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