Section 5 Mechanical equipment
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Offshore Units, July 2022 - Part 3 Functional Unit Types and Special Features - Chapter 8 Process Plant Facility - Section 5 Mechanical equipment

Section 5 Mechanical equipment

Parent topic: Chapter 8 Process Plant Facility

5.1 General

5.1.1 The Rules in this Section are applicable to all types of mechanical equipment associated with the production and process plant, with the exception of pressure vessels which are dealt with in Pt 3, Ch 8, 4 Pressure vessels and bulk storage.

5.1.2 Mechanical equipment is to be designed in accordance with internationally recognised and agreed Codes and Standards and in accordance with the requirements of Pt 3, Ch 8, 1 General.

5.1.3 The list in Pt 12, Ch 1 Recognised Codes and Standards gives reference to some generally recognised Codes and Standards frequently specified for drilling and production equipment. These Codes and Standards may be used for certification, but the additional requirements given in these Rules apply and will take precedence over the Codes and Standards wherever conflict occurs.

5.1.4 Production and process plant equipment is to be suitable for the service intended and for the maximum loads, pressures, temperatures and environmental conditions to which the system may be subjected.

5.2 Plans and data submissions

5.2.1 Design documentation for mechanical equipment is to be submitted in accordance with the equipment categories and certification requirements defined in Pt 3, Ch 8, 1 General.

5.2.2 The submitted information should include the following, as applicable to the equipment categories:
  • Design specification, including data of working medium and pressures.
  • Minimum/maximum temperatures, corrosion allowance, environmental and external loads.
  • Plans, including sufficient detail and dimensions to evaluate the design.
  • Strength calculations as applicable.
  • Material specifications and welding details.

5.3 Equipment certification

5.3.1 Equipment categories and certification of production and process plant equipment are to be in accordance with the requirements of Pt 3, Ch 8, 1 General.

5.3.2 A general guide to specific equipment categories are given in Table 19.1.3 Production equipment with its categories in Pt 12, Ch 1 Recognised Codes and Standards.

5.3.3 Hoisting and pipe handling equipment are to comply with Pt 3, Ch 7, 6 Competence.

5.3.4 Associated equipment such as engines, electric motors, generators, turbines, etc., are to comply with the applicable Sections of the Rules.

5.4 Materials

5.4.1 Materials are to comply with Ch 1, 4 General requirements for manufacture and the Rules for Materials, except where modified by this Section.

5.4.2 The selected materials are to be suitable for the purpose intended and must have adequate properties of strength and ductility and materials to be welded shall be of weldable quality.

5.4.3 As a minimum, Charpy impact tests are required to be carried out at the minimum design temperature (MDT) and exhibit minimum impact energies of 34J for minimum specified yield strengths of up to 360 MPa and 40J for higher yield strengths. For equipment used in LNG applications, the impact test temperature and energy requirements are to be in accordance with Pt 4, Ch 2 Materials.

5.4.4 For selection of acceptable materials suitable for hydrogen sulphide contaminated products (sour service), reference is to be made to the ISO 15156/NACE Standard in Pt 12, Ch 1, 33.1 Recognised codes and standards for reliability centred maintenance.

5.4.5 Grey iron castings are not to be used for critical components.

5.4.6 Proposals to use spheroidal graphite iron castings for critical components operating below 0°C will be specially considered by LR in each case.

5.4.7 In general, bolts and nuts are to comply with the Standards listed in Pt 12 Recognised Codes and Standards for the Classification of Offshore Units.

5.4.8 Bolts and nuts for major structural and mechanical components are to have a tensile strength of not less than 600 N/mm2.

5.4.9 For general service the specified tensile strength of bolting material should not exceed 1000 N/mm2.

5.4.10 Where required, materials of high heat resistance are to be used and the ratings are to be verified.

5.5 Design and construction

5.5.1 The design strength of production and process plant equipment is to comply generally with Pt 5 Main and Auxiliary Machinery, as applicable, and with LR agreed Codes and Standards.

5.5.2 All equipment included in this Section is to be suitable for the design environmental conditions for the unit.

5.5.3 Combustion equipment and combustion engines are not normally to be located in a hazardous area, unless the air space is pressurised to make the area non-hazardous in accordance with the following criteria:
  • Pressurisation air is to be taken from a safe area.
  • An alarm is to be fitted to indicate loss of air pressure.
  • An air lock system with self-closing doors is to be fitted.
  • The exhaust outlet is to be located in a non-hazardous area, and be fitted with spark arresters, see Pt 3, Ch 8, 5.5 Design and construction 5.5.4.
  • The combustion air inlet is to be located in a non-hazardous area.
  • Automatic shut-down is to be arranged to prevent overspeeding in the event of accidental ingestion of flammable gases or vapours.

5.5.4 Efficient spark arresters, of LR approved type, are to be fitted to the exhaust from all combustion equipment, except from exhaust gas turbines. Water cooled spark arresting equipment is to be fitted with means to give a warning in the event of failing cooling water supply.

5.5.5 Exhaust gases are to be discharged so that they will not cause inconvenience to personnel or a dangerous situation during helicopter operations.

5.5.6 The equipment and systems are to be designed, installed, and protected so as to be safe with regard to the risk of fire, explosions, leakages and accidents.

5.5.7 For any equipment using magnetic bearings, a system overview of magnetic bearing systems fitted to the equipment is to be submitted to LR for information. Any equipment which uses active magnetic bearings is to be supplied with a back-up system, such that in the event of a power failure of the active magnetic system the equipment can be brought to a safe condition. Details of the back-up system are to be submitted to LR for approval. If the back-up system has a finite life then the manufacturer is to advise LR and the Owner what the life of the back-up system is. The Owner is to ensure that the life of the back-up system is monitored, so that the equipment is not operated beyond the life of the back-up system.

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