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The American Bureau of Shipping (ABS), a provider of classification and technical services to the marine and offshore industries, has updated its 'Guide for Exhaust Emission Abatement' for 2018.

The 62-page document includes separate sections for exhaust gas cleaning (EGC) systems for the removal of sulphur oxide (SOx) emissions; selective catalytic reduction (SCR) systems; exhaust gas recirculation (EGR) systems; and exhaust emission monitoring systems.

ABS explains: "This Guide has been developed in order to provide guidance and requirements for the design and construction of exhaust emission abatement systems, focusing on SOx scrubbers, SCR systems, and EGR arrangements, and may be applied to all vessel types. An exhaust emission abatement system is considered to be fully approved upon verification of compliance with both the ABS requirements and the applicable IMO Regulations and Guidelines.

"This Guide covers only the Classification approval aspects, and statutory approval would be made by ABS as a separate parallel process in the capacity of a Recognized Organization for the vast majority of flag Administrations."

ABS notes that the objective of the Guide is "to provide criteria for the design, construction, installation, survey, and operation of machinery and equipment associated with exhaust emission abatement systems in order to minimize risks to the vessel, crew, and the environment. The intent is that these requirements supplement the statutory emissions performance testing, survey, and certification requirements of the aforementioned IMO Regulations and Guidelines".

ABS also explains that detailed requirements are provided in each of the sections of the document to achieve the aforementioned objective in accordance with the following key principles and requirements:

- Installation and operation of an exhaust emission abatement system is to be compatible with the fuel oil combustion unit and not to cause any adverse effects on the FOCU performance, such as excessive back pressures/temperatures, or is to incorporate additional features to mitigate such effects.

- Materials of construction and workmanship are to be in accordance with the requirements of the ABS Rules for Materials and Welding (Part 2) or to an alternate standard specifically approved in accordance with the design of the exhaust emission abatement system.

- Exhaust emission abatement systems are to be designed to enable continued operation of the FOCU at the times the EGC system is not in operation, either through operational selection, equipment failure, or system deterioration through partial blocking/clogging.

- Where applicable, exhaust emission abatement units and their associated equipment and systems are to be designed to minimize the risks associated with the storage, handling, consumption, and disposal of hazardous or non-hazardous chemicals or consumables essential for operation of the EGC system. Appropriate personnel protection arrangements and equipment are to be provided.

- As applicable, means are to be provided to suitably mitigate the risk to the FOCU or vessel from internal flooding associated with water scrubbing systems.

- Redundancy of equipment is to be provided for those rotating and reciprocating components that form part of the exhaust emission abatement unit supplementary systems, such as pumps, fans, blowers, etc., and due diligence is to be exercised and demonstrated in the assessment of critical components, equipment, and systems. Alternatively the carriage of spare parts onboard or alternative means of compliance or operation will be accepted to meet this objective.

- Means are to be provided to prevent the passage or leakage of exhaust gases to other equipment or spaces that may then pose a safety risk to that equipment or a health risk to the vessel’s crew or passengers.

- Exhaust emission abatement systems are to be arranged for easy inspection and maintenance and where applicable the ability to replace internal components is to be provided.

- Hot surfaces of exhaust emission abatement units or their associated equipment or systems likely to come into contact with the crew during operation are to be suitably guarded or insulated. Where the surface temperatures are likely to exceed 220C (428F), they are to be suitably insulated with non-combustible materials.

- Appropriate storage and operational arrangements and procedures are to be in place for any specialized or hazardous gases used in exhaust emission abatement units or monitoring systems.

- Automation, instrumentation, monitoring, and control systems are to be provided to facilitate automated operation and monitoring of exhaust emission abatement systems.

- Operation and maintenance manuals are to be provided for all exhaust emission abatement units and associated equipment and systems to facilitate handling, operation, maintenance, and repair.