Annex 11A – Recommended Procedures for Thickness Measurements of Double-Hull Oil Tankers Not Built Under the IACS Common Structural Rules^footnote

  1 These procedures should be used for recording thickness measurements as required by annexes 2 and 4.

  2 Reporting forms TM1-DHT, TM2-DHT(i), TM2-DHT(ii), TM3-DHT, TM4-DHT, TM5-DHT and TM6-DHT, set out in appendix 2, should be used for recording thickness measurements and the maximum allowable diminution should be stated. The maximum allowable diminution could be stated in an attached document.

  3 Appendix 3 contains guidance diagrams and notes relating to the reporting forms and the requirements for thickness measurement.

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

 TM1-DHT

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

 Notes to the report TM1-DHT:

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

• .1 All strength deck plating within the cargo area.

• .2 All keel, bottom shell plating and bilge plating within the cargo area.

• .3 Side shell plating including selected wind and water strakes outside cargo area.

• .4 All wind and water strakes within cargo 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.

• .3 For side shell plating give number of the strake of plating below sheerstrake and letter as shown on shell expansion.

  3 Measurements should be taken at the forward and aft areas of all plates 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 maximum allowable diminution could be stated in an attached document.

 TM2-DHT(i)

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

 Notes to the report TM2-DHT(i):

1 This report form should be used for recording the thickness measurements of strength deck plating and sheerstrake plating transverse sections:

• One, two or three sections within the cargo area comprising of the structural items (0), (1) and (2) as shown on the diagrams of typical transverse sections (appendix 3).

  2 The topside area comprises deck plating, stringer plate and sheerstrake (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 maximum allowable diminution could be stated in an attached document.

 TM2-DHT(ii)

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

 Notes to the report TM2-DHT(ii):

1 This report should be used for recording the thickness measurements of shell plating transverse sections:

• One, two or three sections within the cargo area comprising of the structural items (3), (4) and (5) and (6) as shown on the diagrams of typical transverse sections (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 maximum allowable diminution could be stated in an attached document.

 TM3-DHT

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

 Notes to the report TM3-DHT:

1 This report should be used for recording the thickness measurements of longitudinal members at transverse sections:

• One, two or three sections within the cargo area comprising of the appropriate structural items (10) to (29) as shown on the diagrams of typical transverse sections (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 maximum allowable diminution could be stated in an attached document.

 TM4-DHT

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

 Notes to the report TM4-DHT:

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

  2 Guidance for areas of measurement is indicated in appendix 3.

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

  4 The maximum allowable diminution could be stated in an attached document.

 Report on thickness measurement of watertight/oiltight transverse bulkheads (within the cargo tank or cargo hold spaces)

 Notes to the report TM5-DHT:

1 This report should be used for recording the thickness measurement of W.T./O.T. transverse bulkheads.

  2 Guidance for areas of measurement is indicated in appendix 3.

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

  4 The maximum allowable diminution could be stated in an attached document.

 TM6-DHT

Report on thickness measurement of miscellaneous structural members

 Notes to the report TM6-DHT:

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 maximum allowable diminution could be stated in an attached document.