1 General

  1.1.1 The Code shall apply to all self-propelled double-hull oil tankers of 500 gross tonnage and above.

  1.1.2 The Code shall apply to surveys of hull structure and piping systems in way of cargo tanks, pump-rooms, cofferdams, pipe tunnels, void spaces within the cargo area and all ballast tanks.

  1.1.3 The Code contains the minimum extent of examination, thickness measurements and tank testing. The survey shall be extended when substantial corrosion and/or structural defects are found and include additional close-up survey when necessary.

  1.1.4 The surveys shall be carried out during the surveys prescribed by regulation I/10 of the Convention, unless expressly provided otherwise in this Code.

  1.2.1 Double-hull oil tanker is a ship which is constructed primarily for the carriage of oil in bulk, which has the cargo tanks protected by a double-hull which extends for the entire length of the cargo area, consisting of double sides and double-bottom spaces for the carriage of water ballast or void spaces.

  1.2.2 Ballast tank is a tank which is used primarily for the carriage of salt water ballast.

  1.2.3 Combined cargo/ballast tank, if referred to within the Code, is a tank which is used for the carriage of cargo or ballast water as a routine part of the vessel's operation and will be treated as a Ballast Tank. Cargo tanks in which water ballast might be carried only in exceptional cases per MARPOL regulation I/18.3 are to be treated as cargo tanks.

  1.2.4 Overall survey is a survey intended to report on the overall condition of the hull structure and determine the extent of additional close-up surveys.

  1.2.5 Close-up survey is a survey where the details of structural components are within the close visual inspection range of the surveyor, i.e. normally within reach of hand.

  1.2.6 Transverse section is the cross section of the hull perpendicular to the ship's centreline and includes all longitudinal members such as plating, longitudinals and girders at the deck, sides, bottom, inner bottom and longitudinal bulkheads. For transversely framed oil tankers, a transverse section includes adjacent frames and their end connections in way of transverse sections.

  1.2.7 Representative tanks are those which are expected to reflect the condition of other tanks of similar type and service and with similar corrosion prevention systems. When selecting representative tanks, account shall be taken of the service and repair history on board and identifiable critical structural areas and/or suspect areas.

  1.2.8 Suspect areas are locations showing substantial corrosion and/or are considered by the surveyor to be prone to rapid wastage.

  1.2.9 Substantial corrosion is an extent of corrosion such that assessment of corrosion pattern indicates a wastage in excess of 75% of allowable margins, but within acceptable limits. For ships built under the IACS Common Structural Rules, substantial corrosion is an extent of corrosion such that the assessment of the corrosion pattern indicates a measured thickness between t_ren + 0.5mm and t_ren. Renewal thickness (t_ren) is the minimum allowable thickness, in mm, below which renewal of structural members is to be carried out.

  1.2.10 Corrosion prevention system is normally considered a full hard protective coating. Hard protective coating should usually be epoxy coating or equivalent. Other coating systems, which are neither soft nor semi-hard coatings, may be considered acceptable as alternatives provided that they are applied and maintained in compliance with the manufacturer's specification.

  1.2.11 Coating condition is defined as follows:

• GOOD	condition with only minor spot rusting;
  FAIR	condition with local breakdown of coating at edges of stiffeners and weld connections and/or light rusting over 20% or more of areas under consideration, but less than as defined for POOR condition; and
  POOR	condition with general breakdown of coating over 20% or more of areas or hard scale at 10% or more of areas under consideration.

  1.2.12 Critical structural areas are locations which have been identified from calculations to require monitoring or from the service history of the subject ship or from similar or sister ships, if applicable, to be sensitive to cracking, buckling or corrosion which would impair the structural integrity of the ship.

  1.2.13 Cargo area is that part of the ship which contains cargo tanks, slop tanks and cargo/ballast pump-rooms, cofferdams, ballast tanks and void spaces adjacent to cargo tanks and also deck areas throughout the entire length and breadth of the part of the ship over the above-mentioned spaces.

  1.2.14 Intermediate survey is a survey carried out either at the second or the third annual survey.

  1.2.15 Prompt and thorough repair is a permanent repair completed at the time of survey to the satisfaction of the surveyor, therein removing the need for the imposition of any associated condition of classification or recommendation.

  1.2.16 Special consideration or Specially considered (in connection with close-up surveys and thickness measurements) means sufficient close-up inspection and thickness measurements are taken to confirm the actual average condition of the structure under coating.

  1.2.17 Pitting corrosion is defined as scattered corrosion spots/areas with local material reductions which are greater than the general corrosion in the surrounding area. Pitting intensity is defined in figure 1.

  1.2.18 Edge corrosion is defined as local material loss at the free edges of plates, stiffeners, primary support members and around openings. An example of edge corrosion is shown in figure 2.

  1.2.19 Grooving corrosion is typically local material loss adjacent to weld joints along abutting stiffeners and at stiffener or plate butts or seams. An example of groove corrosion is shown in figure 3.

  1.2.20 Administration means the Administration or organization recognized by the Administration.

Figure 1: Pitting intensity diagrams

Figure 2: Edge corrosion

Figure 3: Grooving corrosion

  1.3.1 Any damage in association with wastage over the allowable limits (including buckling, grooving, detachment or fracture), or extensive areas of wastage over the allowable limits, which affects or, in the opinion of the Administration, will affect the ship's structural, watertight or weathertight integrity, shall be promptly and thoroughly (see 1.2.15) repaired. Areas to be considered include:

• .1 bottom structure and bottom plating;

• .2 side structure and side plating;

• .3 deck structure and deck plating;

• .4 watertight or oiltight bulkheads; and

• .5 hatch covers and hatch coamings, where fitted. (combination carriers)

For locations where adequate repair facilities are not available, the Administration may allow the ship to proceed directly to a repair facility. This may require discharging the cargo and/or temporary repairs for the intended voyage.

  1.3.2 Additionally, when a survey results in the identification of corrosion or structural defects, either of which, in the opinion of the Administration, will impair the ship's fitness for continued service, remedial measures shall be implemented before the ship continues in service.

 1.3.3 Where the damage found on the structure mentioned in paragraph 1.3.1 above is isolated and of a localized nature which does not affect the ship's structural integrity (as for example a minor hole in a cross-deck strip), consideration may be given by the surveyor to allow an appropriate temporary repair to restore watertight or weathertight integrity after evaluation of the surrounding structure and impose an associated condition or recommendation with a specific time limit in order to complete the permanent repair and retain the validity of the relevant statutory certification.

 1.4.1 On oil tankers 20,000 tonnes deadweight (dwt) and above starting with renewal survey No.3, at renewal and intermediate hull surveys, the survey of hull structure and piping systems to which this Code applies shall be carried out by at least two surveyors of an Administration.

1.4.2 This requires that at least two surveyors attend on board at the same time to perform the required survey. Though each attending surveyor is not required to perform all aspects of the required survey, they shall consult with each other and do joint overall and close-up surveys to the extent necessary to determine the condition of the vessel areas to which this Code applies. The extent of these surveys shall be sufficient for the surveyors to agree on actions required to complete the survey with respect to renewals, repairs, and other recommendations or conditions. Each surveyor shall co-sign the survey report or indicate their concurrence in an equivalent manner.

1.4.3 The following surveys may be witnessed by a single surveyor:

• .1 thickness measurements;

• .2 tank testing; and

• .3 repairs carried out in association with intermediate and renewal hull surveys, the extent of which have been agreed upon by the required two surveyors during the course of the surveys.

 In any kind of survey, i.e. renewal, intermediate, annual or other surveys having the scope of the foregoing ones, for structures in areas where close-up surveys are required, thickness measurements, when required by annex 2, shall be carried out simultaneously with close-up surveys.