Section 3 Intermediate Surveys – Hull and machinery requirements
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Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Offshore Units, July 2022 - Part 1 Regulations - Chapter 3 Periodical Survey Regulations - Section 3 Intermediate Surveys – Hull and machinery requirements

Section 3 Intermediate Surveys – Hull and machinery requirements

Parent topic: Chapter 3 Periodical Survey Regulations

3.1 General

3.1.1 Intermediate Surveys are to be held concurrently with statutory annual or other relevant statutory surveys wherever practicable.

3.2 Intermediate Surveys

3.2.1 The requirements of Pt 1, Ch 3, 2 Annual Surveys – Hull and machinery requirements are to be complied with, so far as applicable.

3.2.2 A general examination of salt-water ballast spaces is to be carried out by the Surveyor as required by Pt 1, Ch 3, 3.2 Intermediate Surveys 3.2.3 and Pt 1, Ch 3, 3.2 Intermediate Surveys 3.2.4. If such examinations reveal no visible structural defects, the examination may be limited to a verification that the protective coating remains in GOOD or FAIR condition, as defined in Pt 1, Ch 3, 1.5 Definitions. When considered necessary by the Surveyor, thickness measurement of the structure is to be carried out.

3.2.3 For all units over five years of age and up to 10 years of age, representative salt-water ballast tanks and other spaces are to be examined as follows:
  • Column-stabilised units and tension-leg units

    Representative ballast tanks in pontoons, lower hulls, and free-flooding compartments as accessible, and at least two ballast tanks in columns and upper hull, if applicable.

  • Self-elevating units

    Representative ballast tanks and at least two representative pre-load tanks. Accessible free-flooding compartments in mat or footings.

  • Ship units and other surface type units

    One peak tank and at least two other representative ballast tanks between the peak bulkheads used primarily for water ballast.

  • Deep draught caissons

    Representative ballast tanks where accessible.

  • All unit types

    Particular attention is to be given to corrosion control systems in ballast tanks, free-flooding areas and other locations subjected to sea water from both sides where accessible.

For tanks other than independent double bottom tanks, where a protective coating is found in POOR condition, as defined in Pt 1, Ch 3, 1.5 Definitions, or other defects are found, where a soft or semi-hard coating has been applied or where a protective coating was not applied from the time of construction, the examination is to be extended to other ballast tanks of the same type. For independent double bottom tanks where substantial corrosion or other defects are found, the examination is to be extended to other ballast tanks of the same type.

3.2.4 For all unit types over 10 years of age, the following is required:
  1. All salt-water ballast tanks and free-flooding areas are to be examined.
  2. The anchors on units assigned the character (1) are to be partially lowered and raised using the windlass.

3.2.5 The Surveyor is to carry out an examination and thickness measurement of structure identified at the previous Special Survey as having substantial corrosion, see Section 5.

3.2.6 In addition to Pt 1, Ch 3, 1.5 Definitions 1.5.1 to Pt 1, Ch 3, 1.5 Definitions 1.5.7 on units with crude oil bulk storage tanks, the following are to be dealt with where applicable:
  1. An examination of oil storage, crude oil washing, bunker, ballast, steam and vent piping on weather decks, as well as vent masts and headers. If, upon examination, there is any doubt as to the condition of the piping, the piping may be required to be pressure tested, gauged, or both.
  2. A general examination within the areas deemed as dangerous, such as cargo pump-rooms and spaces adjacent to and zones above cargo tanks, for defective and non-certified safe type electrical equipment, improperly installed, defective and dead-end wiring. An electrical insulation resistance test of the circuits terminating in, or passing through, the dangerous areas is to be carried out. If the unit is not in a gas-free condition, the results of previously recorded test readings may be accepted.

3.2.7 For all units, the electrical generating sets are to be examined under working conditions to verify compliance with Pt 6, Ch 2, 2.2 Number and rating of generators and converting equipment.

3.2.8 The following are to be examined where accessible:
  • Turret and circumturret structure.
  • Turret bearings and seals.
  • Swivel stack bearings and seals.
  • Mooring arm pivots and bearings.
3.2.9 For units with crude oil bulk storage tanks, in addition to Pt 1, Ch 3, 3.2 Intermediate Surveys 3.2.6, the following is required for units over 10 years and less than 15 years of age:
  1. Overall survey of all salt-water ballast tanks, including any combined salt-water ballast/crude oil storage tanks.
  2. Overall survey of at least two representative crude oil storage tanks.
  3. Close-up Survey of salt-water ballast tanks to the same extent as the previous Special Survey and two combined cargo/ballast tanks. Where protective coatings are found to be in GOOD condition, as defined in Pt 1, Ch 3, 1.5 Definitions , the extent of Close-up Survey may be specially considered.
  4. The thickness measurement requirements of Pt 1, Ch 3, 3.2 Intermediate Surveys 3.2.7 are to be complied with. In areas where substantial corrosion, as defined in Pt 1, Ch 3, 1.5 Definitions, has been noted, additional measurements are to be carried out to the satisfaction of the Surveyor. The survey will not be considered complete until these additional thickness measurements have been carried out.
  5. Machinery and boiler spaces, including tank tops, bilges and cofferdams, sea suctions and overboard discharges, are to be generally examined.
3.2.10 For units with crude oil bulk storage tanks, in addition to Pt 1, Ch 3, 3.2 Intermediate Surveys 3.2.8 and Pt 1, Ch 3, 3.2 Intermediate Surveys 3.2.12, the following is required for units over 15 years of age:
  1. A survey to the same extent as the previous Special Survey (applicable only to ESP surveys, see Pt 1, Ch 3, 7.1 General 7.1.2 of the Rules for Ships).
  2. Pressure testing of cargo and ballast tanks is to be carried out if deemed necessary by the attending Surveyor.

3.2.11 When hull/structure surveys are to be carried out on the Continuous Survey basis, for all unit types over 10 years of age to comply with the intermediate survey, all salt-water ballast tanks and free-flooding areas are to be examined. The frequency of inspection all salt-water ballast tanks and free-flooding areas is to be reduced to two and half years from the customary five year period. One of the surveys in the five year cycle may be limited to an overall examination of the tank. See also Pt 1, Ch 3, 1.6 Planned survey programme.

3.2.12 For natural gas fuel installations see also Pt 1, Ch 3, 21.7 Intermediate Surveys.

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