Section 1 General requirements
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Offshore Units, July 2022 - Part 5 Main and Auxiliary Machinery - Chapter 26 Fresh Water Systems - Section 1 General requirements

Section 1 General requirements

Parent topic: Chapter 26 Fresh Water Systems

1.1 Definitions

1.1.1 For the purpose of this Chapter, the following definitions apply:
  1. Fresh water – Water that is not salty and is used on board offshore units. Fresh water may be supplied to the offshore unit or be produced on board by the desalination of sea water. The density of fresh water is to be taken as 1000 kg/m3.
  2. Potable water – Drinkable water that meets the water quality defined in a recognised National or International Standard which is to be specified by the Owner and agreed by LR and is designated for drinking, domestic services and food preparation, e.g. the World Health Organisation’s Guidelines for Drinking Water Quality or Seahealth Denmark - Drinking Water On Board Ships - A guidance about how to provide clean drinking water or Water Report 129 – Safe, Sufficient and Good Potable Water Offshore by the Norwegian Institute of Public Health. Potable water is obtained by the sterilisation of fresh water.

1.2 Goal

1.2.1 The goal of this Chapter is to provide requirements for the design, construction and inspection of sea water desalination plants and fresh water systems installed in offshore units in order to minimise the risks to the asset, environment and persons on board resulting from fresh water which does not meet its required quality, insufficient supply of fresh water, foreign matter in the fresh water system and inadequately designed sea water desalination plants and fresh water systems.

1.3 Application

1.3.1 This Chapter is applicable to sea water desalination plants and fresh water systems installed in offshore units. Examples of fresh water systems are, but are not limited to:
  1. Water systems for potable water.
  2. Cooling water systems.
  3. Chilled water systems for air conditioning.
  4. Window washing systems.
  5. Life safety systems including emergency eyewash, emergency facewash and emergency shower systems.

1.3.2 Compliance with this Chapter does not guarantee compliance with statutory requirements concerning fresh water of any National Authority/Coastal State Authority.

1.3.3 Offshore units with an installed fresh water system (including sea water desalination plant, if fitted) which complies with this Chapter and Pt 1, Ch 3, 2.8 Sea Water Desalination Plants and Fresh Water Systems will be eligible for the assignment of the class notation FWS (Fresh Water System). Where an installed fresh water system for potable water is compliant with this Chapter, a descriptive note Potable Water System may be entered on the Class Direct website. Where an installed sea water desalination plant is compliant with this Chapter, a descriptive note Sea Water Desalination Plant may be entered on the Class Direct website.

1.3.4 A risk assessment in accordance with a recognised National or International Standard, such as those detailed in IEC/ISO 31010 Risk Management - Risk Assessment techniques, is required to justify dispensations from this Chapter, see also Pt 5, Ch 15, 1.1 Application for the use of a risk assessment to identify safety critical systems.

1.3.5 The requirements of this Chapter supplement the requirements of ISO 15748-1 Ships and marine technology – Potable water supply on ships and marine structures. Part 1: Planning and design. In addition to the requirements in this Chapter, fresh water systems for potable water are to comply with ISO 15748-1.

1.3.6 Guidance on the design of potable water systems is given in Water Report 129 – Safe, Sufficient and Good Potable Water Offshore by the Norwegian Institute of Public Health and Guide to Ship Sanitation by the World Health Organisation.

1.4 Documentation required for design review

1.4.1 The following plans (in diagrammatic form, where applicable) and information for the fresh water system are to be submitted in addition to those required by Pt 5, Ch 13, 1.3 Plans and particulars of the Rules and Regulations for the Classification of Ships, July 2022:
  1. Piping arrangements.
  2. Major component parts, pipe sizes, system flow rates and pressures.
  3. Capacities of pumps and plants.
  4. Arrangements of alarms, control systems and safeguards.
  5. Arrangements of electrical systems including power supplies.
  6. Fresh water storage tanks.
  7. Segregation and access arrangements for compartments and associated control rooms/stations.
  8. Arrangements and structure of compartments used and intersected by the fresh water system.
  9. Arrangements for desalination, if fitted.
  10. Arrangements for the monitoring and quality control of fresh water production.
1.4.2 The following documents are to be submitted for approval.
  1. Fresh Water System Design Description

    This is a document that describes the design of the fresh water system. The Fresh Water System Design Description details the system’s capability and functionality under all normal and reasonably foreseeable abnormal operating and fault conditions. The System Design Description documents are to be agreed between the designer and the Owner. LR may accept alternative documents where these provide the information which would be included within the Fresh Water System Design Description. In such cases the relevant sections providing the information required to provide equivalence with the Fresh Water System Design Description are to be identified.

  2. Testing procedures

    These are procedures detailing a schedule of testing and trials to demonstrate that systems are capable of operating as described in Pt 5, Ch 26, 3 System arrangements and as required by Pt 5, Ch 26, 5 Testing.

  3. Coating Specification and Certificates

    Specifications of coatings in contact with fresh water, including certificates for the testing of toxicity and tainting of coatings in contact with fresh water by an independent laboratory

  4. Specifications of Materials

    Specifications of metallic and non-metallic materials in contact with fresh water.

1.4.3 Operating manuals for sea water desalination plant, if fitted, and fresh water systems are to be provided on board and submitted for information where requested by LR. The manuals are to include the following information:
  1. Particulars and a description of the systems for the sea water desalination and storage and distribution of fresh water. The particulars are to include system arrangement plans showing each mode of operation of each system.
  2. Operating arrangements for each mode of operation for the equipment and systems installed.
  3. Cleaning arrangements and any precautions required for the use, storage and disposal of any recommended chemicals used for cleaning systems and equipment.
  4. Coating and maintenance instructions for fresh water storage tanks.
  5. Cleaning instructions for filters, calorifiers and other equipment where bacteria may accumulate in fresh water systems.
  6. Maintenance instructions and fault finding procedures for the equipment and systems.
  7. Preservation procedure for short and long term periods laid up or out of service, as applicable. See also Pt 1, Ch 2, 3.5 Existing installations – Periodical Surveys 3.5.26.

1.4.4 Calculations for the personal daily allowance of potable water and the required storage capacities for potable and other fresh water are to be submitted for review, see Pt 5, Ch 26, 3.1 Water storage facilities 3.1.1.

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