1.2.1 The status of these Guidelines is advisory.
                           They are intended to cover the design and operation of:
                        
                        
                        
                        
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                                 .1 inert gas systems that are required on new
                                 tankers by regulation 60 of chapter II-2 of
                                 the 1978 SOLAS Protocol and in accordance with regulation 62;
                                 
                               
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                                 .2 inert gas systems that are required on existing
                                 tankers by regulation 60 of chapter II-2 of
                                 the 1978 SOLAS Protocol and in accordance with regulation 62.20;
                                 
                               
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                                 .3 inert gas systems which are fitted but not
                                 required to comply with the requirements of regulation 60 of chapter II-2 of the 1978 SOLAS Protocol.
                                 
                               
 
                     
                     
                     
                        
                        
                         
                           1.2.2 However, for existing inert gas systems
                           the Guidelines are directed primarily at operational procedures and
                           are not intended to be interpreted as requiring modifications to existing
                           equipment other than those which are required on ships to which regulation 62.20 applies.
                           
                        
                        
                        
                      
                     
                     
                     
                        
                        
                         
                           1.2.3 The content of these Guidelines is based
                           on current general practice used in the design and operation of inert
                           gas systems using flue gas from the uptake from the ship's main or
                           auxiliary boilers, and installed on crude oil tankers and combination
                           carriers. The Guidelines do not exclude other sources of inert gas,
                           such as systems incorporating independent inert gas generators, other
                           designs, materials or operational procedures. All such divergences
                           should be carefully assessed to ensure that they achieve the objectives
                           of these Guidelines.