Annex 10 - Recommended Procedures for Thickness Measurements of Double Hull Oil Tankers
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Resolutions - Assembly - IMO Resolution A.744(18) – Guidelines on the Enhanced Programme of Inspections During Surveys for Bulk Carriers and Oil Tankers – (Adopted on 4 November 1993) - Annex B - Guidelines on the Enhanced Programme of Inspection During Surveys for Oil Tankers - Part A - Guidelines on the Enhanced Programme of Inspections During Surveys of Double Hull Oil Tankers - Annex 10 - Recommended Procedures for Thickness Measurements of Double Hull Oil Tankers

Annex 10 - Recommended Procedures for Thickness Measurements of Double Hull Oil Tankers

Parent topic: Part A - Guidelines on the Enhanced Programme of Inspections During Surveys of Double Hull Oil Tankers

General

  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.

  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.

Appendix 1

Ship’s name: ...................................................................................................................
IMO number: ..................................................................................................................
Class/Administration identity number: ...............................................................................
Port of registry: ...............................................................................................................
Gross tonnage: ................................................................................................................
Deadweight: ....................................................................................................................
Date of build: ..................................................................................................................
Classification society: .......................................................................................................
   
Name of company performing thickness measurement: ....................................................
Thickness measurement company certified by: .................................................................
Certificate number: ..............................................................................................................
Certificate valid from: ................................. to ................................................................
Place of measurement: .......................................................................................................
First date of measurement: .................................................................................................
Last date of measurement: .................................................................................................
Renewal survey/intermediate surveyfootnote due: ..........................................................................
Details of measurement equipment: ...................................................................................
Qualification of operator: ......................................................................................................
   
Report number: .......................................... consisting of ......................... pages.
Name of operator: ...................................... Name of surveyor: .....................................
Signature of operator: ................................ Signature of surveyor: ................................
   
Company official stamp: ............................ Administration: ...........................................
  Official stamp: ............................................

Appendix 2

Report on Thickness Measurement of all Deck Plating, all Bottom Shell Plating or Side Shell Plating footnote

  Ships's name ............................. Class identity No. ........................................
  Report No. ..................................                  
STRAKE
POSITION 		 
PLATE
POSITION 		No.
or
letter 		Org
Thk.
mm 		Forward Reading Aft Reading %
11th for Gauged Diminution
P 		Diminution S Gauged Diminution
P 		Diminution S
10th P S mm % mm % P S mm % mm % P S
mm
9th                                
8th                                
7th                                
6th                                
5th                                
4th                                
3rd                                
2nd                                
1st                                
Amidships                                
1st aft                                
2nd                                
3rd                                
4th                                
5th                                
6th                                
7th                                
8th                                
9th                                
10th                                
11th                                
                                 
  Operators Signature ........................... Surveyors Signature ...........................
                                 
NOTES TO THE REPORT TM1-DHT:
1This 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 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 are to represent the average of multiple measurements.

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

Report on THICKNESS MEASUREMENT OF SHELL AND DECK PLATING (one, two or three transverse sections)
                                                       
  Ship's name ........................................... Class identity No. ................................... Report No. ..............................................
STRENGTH DECK AND SHEERSTRAKE PLATING
  FIRST TRANSVERSE SECTION AT FRAME NUMBER SECOND TRANSVERSE SECTION AT FRAME NUMBER THIRD TRANSVERSE SECTION AT FRAME NUMBER
STRAKE
POSITION 		No. or Letter Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S 		No. or Letter Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S 		No. or Letter Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S
mm mm P S mm % mm %   mm mm P S mm % mm %   mm mm P S mm % mm %
Stringer
Plate 		                                                     
1st strake
inboard 		                                                     
2nd                                                      
3rd                                                      
4th                                                      
5th                                                      
6th                                                      
7th                                                      
8th                                                      
9th                                                      
10th                                                      
11th                                                      
12th                                                      
13th                                                      
14th                                                      
Centre
strake 		                                                     
Sheer strake                                                      
TOPSIDE
TOTAL 		                                                     
                                                       
  Operators Signature .............................. Surveyors Signature ..............................                  
                                                       
NOTES TO THE REPORT TM2-DHT (i)
1This 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 illustrated in appendix 3 of annex 10.

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 are to represent the average of multiple measurements.

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

Report on THICKNESS MEASUREMENT OF SHELL AND DECK PLATING (one, two or three transverse sections)
                                                       
  Ship's name ........................................... Class identity No. ................................... Report No. ..............................................
SHELL PLATING
  FIRST TRANSVERSE SECTION AT FRAME NUMBER SECOND TRANSVERSE SECTION AT FRAME NUMBER THIRD TRANSVERSE SECTION AT FRAME NUMBER
STRAKE
POSITION 		No. or Letter Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S 		No. or Letter Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S 		No. or Letter Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S
mm mm P S mm % mm %   mm mm P S mm % mm %   mm mm P S mm % mm %
1st below sheer strake                                                      
2nd                                                      
3rd                                                      
4th                                                      
5th                                                      
6th                                                      
7th                                                      
8th                                                      
9th                                                      
10th                                                      
.......                                                      
17th                                                      
18th                                                      
19th                                                      
20th                                                      
Keel strake                                                      
Bottom total                                                      
                                                       
  Operators Signature .............................. Surveyors Signature ..............................                  
                                                       
NOTES TO THE REPORT TM2-DHT (ii)
1This report form 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 illustrated in appendix 3 of annex 10.

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 are to represent the average of multiple measurements.

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

Report on THICKNESS MEASUREMENT OF LONGITUDINAL MEMBERS (one, two or three transverse sections)
                                                       
  Ship's name ........................................... Class identity No. ................................... Report No. ..............................................
  FIRST TRANSVERSE SECTION AT FRAME NUMBER SECOND TRANSVERSE SECTION AT FRAME NUMBER THIRD TRANSVERSE SECTION AT FRAME NUMBER
Structural
member 		Item
No 		Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S 		Item
No 		Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S 		Item
No 		Org.
Thk. 		Max.
Alwb.
Dim. 		Gauged Diminution
P 		Diminution
S
mm mm P S mm % mm %   mm mm P S mm % mm %   mm mm P S mm % mm %
                                                       
                                                       
                                                       
                                                       
                                                       
                                                       
                                                       
                                                       
                                                       
                                                       
  Operators Signature .............................. Surveyors Signature ..............................                  
                                                       
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 illustrated in appendix 3 of annex 10.

2 The exact frame station of measurement should be stated.

3 The single measurements recorded are to represent the average of multiple measurements.

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

Report on THICKNESS MEASUREMENT OF TRANSVERSE STRUCTURAL MEMBERS
In the cargo oil and water ballast tanks within the cargo tank length
Ship's name ......................................... Class identity No. ...................... Report No. ............................................
TANK DESCRIPTION
LOCATION OF STRUCTURE
STRUCTURAL
MEMBER 		ITEM Original Thickness
mm 		Max.
Alwb.
Dim.
mm 		Gauged Diminution
P 		Diminution
S
P S mm % mm %
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
                   
Operators Signature ................................ Surveyors Signature ........................      
                   
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 illustrated in appendix 3 of annex 10.

2 Guidance for areas of measurement is indicated in appendix 3 of annex 10. The single measurements recorded are to represent the average of multiple measurements.

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

Report on THICKNESS OF W.T./O.T TRANSVERSE BULKHEADS
within the cargo tank or cargo hold spaces
Ship's name ......................................... Class identity No. ...................... Report No. ............................................
TANK/HOLD Description
LOCATION OF STRUCTURE FRAME No
STRUCTURAL COMPONENT
(Plating, Stiffener) 		Original Thickness
mm 		Max.
Alwb.
Dim.
mm 		Gauged Diminution
P 		Diminution
S
Port Starboard mm % mm %
                 
                 
                 
                 
                 
                 
                 
                 
Operators Signature ................................ Surveyors Signature ........................      
                 
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 of annex 10.

3 The single measurements recorded are to represent the average of multiple measurements.

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

Report on THICKNESS MEASUREMENT OF MISCELLANEOUS STRUCTURAL MEMBERS
Ship’s name ......................................... Class identity No. ............................. Report No. ............................
STRUCTURAL MEMBER SKETCH
LOCATION OF STRUCTURE  
Description Org. Thk. mm Max. Alwb. Dim. mm Gauged Diminution P Diminution S
P S mm % mm %
                 
                 
                 
                 
                 
                 
                 
                 
                   
Operators Signature ................................ Surveyors Signature ........................        
                   
NOTES TO THE REPORT TM6-DHT

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

2The single measurements recorded are to represent the average of multiple measurements.

3The maximum allowable diminution could be stated in an attached document.

Appendix 3 - Thickness measurement - Double hull oil tankers

Typical transverse section of a double hull oil tanker above 150,000 dwt with indication of longitudinal and transverse members

Figure A Thickness measurement - Double hull oil tankers

Typical transverse section of a double hull oil tanker up to 150,000 dwt with indication of longitudinal and transverse members

Figure B Thickness measurement - Double hull oil tankers

Transverse section outline. The diagram may be used for those ships typical sections are not applicable

Figure C Thickness measurement - Double hull oil tankers

Areas subject to close-up survey and thickness measurements - areas (1) to (5) as defined in annex 1 Thickness to be reported on TM3-DHT, TM4-DHT and TM5-DHT as appropriate

Figure D Thickness measurement - Double hull oil tankers

Thickness measurement - Double hull oil tankers

Areas subject to close-up survey and thickness measurements - areas (6) to (7) as defined in annex 1 - Thickness to be reported on TM3-DHT and TM4-DHT as appropriate

Figure E

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