Annex 11B – Recommended Procedures for Thickness Measurements of Double-Hull Oil Tankers Built Under the IACS Common Structural Rules^footnote

  1 These procedures should be used for recording thickness measurements of ships built under the IACS Common Structural Rules.

  2 Reporting forms TM1-DHT(CSR), TM2-DHT(CSR)(i), TM2-DHT(CSR)(ii), TM3-DHT(CSR), TM4-DHT(CSR), TM5-DHT(CSR) and TM6-DHT(CSR) (see appendix 2) should be used for recording thickness measurements. The as-built thickness and the voluntary thickness addition and renewal thickness (minimum allowable thickness) should be stated in the aforementioned forms.

  3 Appendix 3 contains guidance diagrams and notes clarifying the areas for thickness measurement and the respective reporting forms.

  4 The reporting forms should, where appropriate, be supplemented by data presented on structural sketches.

 TM1-DHT(CSR)

Report on thickness measurement of all deck plating, all bottom plating or side shell plating^footnote

 Notes to report TM1-DHT(CSR)

1 This report should be used for recording the thickness measurement of:

• .1 all strength deck plating within cargo length area;

• .2 all keel, bottom shell plating and bilge plating within the cargo length area;

• .3 side shell plating including selected wind and water strakes outside the cargo length area; and

• .4 all wind and water strakes within the cargo length area.

  2 The strake position should be clearly indicated as follows:

• .1 for strength deck indicate the number of the strake of plating inboard from the stringer plate;

• .2 for bottom plating indicate the number of the strake of plating outboard from the keel plate; and

• .3 for side shell plating give number of the strake of plating sheer strake and letter as shown on shell expansion.

  3 Measurements should be taken at the forward and aft areas of all plates cross ballast/cargo tank boundaries and where plates cross ballast/cargo tank boundaries, separate measurements for the area of plating in way of each type of tank should be recorded.

  4 The single measurements recorded should represent the average of multiple measurements.

  5 The remaining corrosion addition should be recorded with result of gauged thickness minus renewal thickness. If the result is negative, the structure in way should be renewed, and the mark "R" should be indicated in the right-hand column. If the result is between 0 and 0.5 mm (0 included), the structure in way should be additionally gauged, and the mark "S" should be indicated in the right-hand column.

 TM2-DHT(CSR)(i)

Report on thickness measurement of shell and deck plating (one, two or three transverse sections)

 Notes to report TM2-DHT(CSR)(i)

1 This report should be used for recording the thickness measurement of strength deck plating and sheer strake plating transverse sections (one, two or three sections within the cargo length area, comprising of the structural items (0), (1) and (2) as shown on the diagram of typical transverse section (appendix 3)).

  2 The topside area comprises deck plating, stringer plate and sheer strake (including rounded gunwales).

  3 The exact frame station of measurement should be stated.

  4 The single measurements recorded should represent the average of multiple measurements.

  5 The remaining corrosion addition should be recorded with result of gauged thickness minus renewal thickness. If the result is negative, the structure in way should be renewed, and the mark "R" should be indicated in the right-hand column. If the result is between 0 and 0.5 mm (0 included), the structure in way should be additionally gauged, and the mark "S" should be indicated in the right-hand column.

 TM2-DHT(CSR)(ii)

Report on thickness measurement of shell plating (one, two or three transverse sections)

 Notes to report TM2-DHT(CSR)(ii)

1 This report should be used for recording the thickness measurement of shell plating transverse sections (one, two or three sections within cargo length area comprising of the structural items (3), (4), (5) and (6) as shown on the diagram of typical transverse section (appendix 3)).

  2 The bottom area comprises keel, bottom and bilge plating.

  3 The exact frame station of measurement should be stated.

  4 The single measurements recorded should represent the average of multiple measurements.

  5 The remaining corrosion addition should be recorded with the result of the gauged thickness minus the renewal thickness. If the result is negative, the structure in way should be renewed, and the mark "R" should be indicated in the right-hand column. If the result is between 0 and 0.5 mm (0 included), the structure in way should be additionally gauged, and the mark "S" should be indicated in the right-hand column.

 TM3-DHT(CSR)

Report on thickness measurement of longitudinal members(one, two or three transverse sections)

 Notes to report TM3-DHT(CSR)

1 This report should be used for recording the thickness measurement of longitudinal members at transverse sections (one, two, or three sections within the cargo length area, comprising of the appropriate structural items (10) to (29) as shown on diagram of typical transverse section (appendix 3)).

  2 The exact frame station of measurement should be stated.

  3 The single measurements recorded should represent the average of multiple measurements.

  4 The remaining corrosion addition should be recorded with the result of the gauged thickness minus the renewal thickness. If the result is negative, the structure in way should be renewed, and the mark "R" should be indicated in the right-hand column. If the result is between 0 and 0.5 mm (0 included), the structure in way should be additionally gauged, and the mark "S" should be indicated in the right-hand column.

 TM4-DHT(CSR)

Report on thickness measurement of transverse structural members in the cargo oil and water ballast tanks within the cargo tank length

 Notes to report TM4-DHT(CSR)

1 This report should be used for recording the thickness measurement of transverse structural members, comprising of the appropriate structural items (30) to (36) as shown on diagram of typical transverse section (appendix 3).

  2 Guidance for areas of measurement is indicated on the diagrams shown in appendix 3.

  3 The single measurements recorded should represent the average of multiple measurements.

  4 The remaining corrosion addition should be recorded with the result of the gauged thickness minus the renewal thickness. If the result is negative, the structure in way should be renewed, and the mark "R" should be indicated in the right-hand column. If the result is between 0 and 0.5 mm (0 included), the structure in way should be additionally gauged, and the mark "S" should be indicated in the right-hand column.

 TM5-DHT(CSR)

Report on thickness of watertight/oiltight transverse bulkheads within the cargo and ballast tanks

 Notes to report TM5-DHT(CSR)

1 This report form should be used for recording the thickness measurement of watertight/oiltight transverse bulkheads.

  2 Guidance for areas of measurement is indicated on the diagrams shown in appendix 3.

  3 The single measurements recorded should represent the average of multiple measurements.

  4 The remaining corrosion addition should be recorded with the result of the gauged thickness minus the renewal thickness. If the result is negative, the structure in way should be renewed, and the mark "R" should be indicated in the right-hand column. If the result is between 0 and 0.5 mm (0 included), the structure in way should be additionally gauged, and the mark "S" should be indicated in the right-hand column.

 TM6-DHT(CSR)

Report on thickness measurement of miscellaneous structural members

 Notes to report TM6-DHT(CSR)

1 This report should be used for recording the thickness measurement of miscellaneous structural members.

  2 The single measurements recorded should represent the average of multiple measurements.

  3 The remaining corrosion addition should be recorded with the result of the gauged thickness minus the renewal thickness. If the result is negative, the structure in way should be renewed, and the mark "R" should be indicated in the right-hand column. If the result is between 0 and 0.5 mm (0 included), the structure in way should be additionally gauged, and the mark "S" should be indicated in the right-hand column.