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 6 Control and Electrical Engineering - Chapter 1 Control Engineering Systems - Section 1 General requirements

Section 1 General requirements

1.1 General

1.1.1 The requirements of this Chapter apply to all offshore units defined in Pt 1, Ch 2 Classification Regulations. Where applicable, the relevant requirements for control, alarm and safety systems as stated in Pt 6, Ch 1 Control Engineering Systemsof the Rules for Ships are to be complied with.

1.1.2 Control engineering systems are to:
  • provide control of required services and habitability requirements during defined operational conditions;
  • provide control of the engineering systems necessary to ensure availability of essential and emergency safety systems during all normal and reasonably foreseeable abnormal conditions;
  • provide control of the engineering systems necessary to ensure transitional power supplies remain available;
  • be suitably protected against damage to itself under fault conditions and to prevent injury to personnel; and
  • not fail in a way which may cause machinery and systems located in hazardous areas to create additional fire or explosion risk.

1.1.3 These requirements apply to manned offshore units. Special consideration will be given to unmanned offshore units which are controlled from the shore or from another offshore installation.

1.1.4 Where reference is made in this Chapter to the requirements of the Rules for Ships, references therein to ‘ship(s)’ are to be understood to apply to ‘unit(s)’.

1.2 Documentation required for design review

1.2.2 Where control, alarm and safety systems are intended for machinery or equipment as defined in Pt 6, Ch 1, 1.2 Documentation required for design review 1.2.3, the documentation stated in Pt 6, Ch 1, 1.2 Documentation required for design review 1.2.2 of the Rules for Ships is to be submitted.

1.2.3 Documentation for the control, alarm and safety systems of the following is to be submitted as applicable:
  1. Propulsion and positioning systems:
    • Controllable pitch propellers.
    • Dynamic positioning systems.
    • Positional mooring and single point mooring systems.
    • Propelling machinery including essential auxiliaries.
    • Steering gear.
    • Thruster-assisted positional mooring systems.
    • Thruster units.
  2. Utilities and services:
    • Air compressors.
    • Bilge and ballast systems.
    • Diving systems including compression chambers.
    • Electric generating plant.
    • Fixed water based local application fire-fighting systems.
    • Evaporating and distilling systems.
    • General service plant air and control and instrument air systems.
    • Heating Ventilation and Air Conditioning (HVAC) systems including arrangements provided in respect of Pt 6, Ch 1, 1.3 Control, alarm and safety equipment 1.3.3.
    • Incinerators.
    • Inert gas generators.
    • Main propelling machinery including essential auxiliaries.
    • Lifting appliances.
    • Mechanical refrigeration systems.
    • Fuel oil transfer and storage (purifiers and oil heaters).
    • Oily water separators.
    • Steam raising plant (boilers and their ancillary equipment).
    • Cargo and ballast pumps in hazardous areas.
    • Tempered water systems.
    • Waste heat boiler.
    • Windlasses.
    • Valve position indicating systems, see Pt 6, Ch 1, 2.7 Valve control systems.
    • Miscellaneous machinery or equipment (where control, alarm and safety systems are specified by other Sections of the Rules).
    • Cargo tank, storage tank, ballast tank and void space instrumentation where specified by other Sections of the Rules (e.g. water ingress detection, gas detection).
    • Thermal fluid heaters.
  3. Process plant equipment:
    • Coalescers, skimmers and dehydrators.
    • Export pumps and compressors.
    • Gas compressors.
    • Gas lift systems.
    • Glycol contactors and regenerators.
    • Heat exchangers.
    • HP and LP flare systems.
    • Process analysers.
    • Production and test separator vessels.
    • Production transfer and storage systems.
    • Sand detection systems.
    • Scrubbers.
    • Sphere launching and receiving systems.
    • Surge, flash and knock out drums.
    • Water, gas and chemical injection systems.
    • Well head, choke and header systems.
    • Wireline systems.
  4. Drilling plant equipment:
    • Blow out preventer stacks and diverter systems.
    • Cement and barytes storage and handling systems.
    • Choke and kill systems.
    • Drawworks and eddy current brakes.
    • Mud logging systems.
    • Mud and cement pumps.
    • Mud treatment systems.
    • Rotary table.
    • Wireline systems.
  5. Pipe-laying systems
  6. Riser systems.

1.2.4  System operational concept. A description of how the control, alarm and safety systems for the main and auxiliary machinery and systems essential for the propulsion and safety of the unit provide effective means for operation and control during all unit operational conditions.

1.2.5  Alarm systems. Details of the overall alarm system, linking the main control station, subsidiary control stations, workstation(s) for navigation and manoeuvring and where applicable, the bridge area, the accommodation and other areas where duty personnel may be present are to be submitted.

1.2.6  Programmable electronic systems. In addition to the documentation required by Pt 6, Ch 1, 1.2 Documentation required for design review 1.2.2 and Pt 6, Ch 1, 1.2 Documentation required for design review 1.2.6 of the Rules for Ships, details of self-monitoring techniques are to be submitted.

1.2.7  Wireless data communication. For wireless data communication equipment the documentation required by Pt 6, Ch 1, 1.2 Documentation required for design review 1.2.7 of the Rules for Ships is to be submitted.

1.2.8  Control stations. Documentation required to be submitted is given in Pt 6, Ch 1, 1.2 Documentation required for design review 1.2.8 of the Rules for Ships.

1.2.9  Approved system. Where it is intended to employ a standard system which has been previously approved, documentation is not required to be submitted, providing there have been no changes in the applicable Rule requirements. The building port, where applicable, the specific project and date of the previous approval are to be advised.

1.3 Control, alarm and safety equipment

1.3.1 The requirements for control, alarm and safety equipment are given in Pt 6, Ch 1, 1.4 Control, alarm and safety equipmentof the Rules for Ships, which are to be complied with. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.3.3 Where equipment requires a controlled environment, alternative arrangements, whether permanently installed or of a temporary nature, are to be provided to maintain the required environment in the event of a failure of the normal air conditioning system, see also Pt 5, Ch 14, 12.4 Miscellaneous machinery 12.4.1 in Pt 5, Ch 14, 12 Control, alarm and safety systems of machinery of the Rules for Ships. Details of these arrangements are to be submitted for consideration.

1.4 Alterations and additions

1.4.1 The requirements for alterations and additions are given in Pt 6, Ch 1, 1.5 Alterations and additionsof the Rules for Ships, which are to be complied with. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.4.2 For ESD systems, see Pt 7, Ch 1, 1 General requirements, software modifications are to be undertaken in accordance with IEC 61508-1:2010, Functional safety of electrical/electronic/ programmable electronic safety-related systems – Part 1: General requirements, Section 7.16, or alternative relevant International or National Standard.

1.5 Definitions

1.5.1 Definitions are given in Pt 6, Ch 1, 1.6 Definitionsof the Rules for Ships, which are to be complied with.


Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.