Annex 4 - Requirements for Extent of Thickness Measurements at Areas of Substantial Corrosion.
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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 B - Guidelines on the Enhanced Programme of Inspections During Surveys of Oil Tankers other than Double Hull Oil Tankers - Annex 4 - Requirements for Extent of Thickness Measurements at Areas of Substantial Corrosion.

Annex 4 - Requirements for Extent of Thickness Measurements at Areas of Substantial Corrosion.

Table A Bottom Structure

  STRUCTURAL MEMBER EXTENT OF MEASUREMENT PATTERN OF MEASUREMENT
1. Bottom plating Minimum of 3 bays across tank, including aft bay. Measurements around and under all bell mouths. 5 point pattern for each panel between longitudinals and webs
2. Bottom longitudinals Minimum of 3 longitudinals in each bay where bottom plating measured. 3 measurements in line across flange and 3 measurements on vertical web
3. Bottom girders and brackets At fore and aft transverse bulkhead bracket toes and in centre of tanks. Vertical line of single measurements on web plating with one measurement between each panel stiffener, or a minimum of three measurements across face flat. 5 point pattern on girder/bulkhead brackets.
4. Bottom transverse 3 webs in bays where bottom plating measured, with measurements at both ends and middle 5 point pattern over 2 square metre area single measurements on face flat.
5. Panel stiffening Where fitted single measurements

Table B Deck Structure

  Structural Member Extent of Measurement Pattern of Measurement
1 Deck Plating Two band Cross tank Minimum of three measurements per plate per band
2 Deck Longitudinals Minimum of three longitudinals in each of two bays 3 Measurements in line vertically on webs, and 2 measurements on flange (if fitted).
3 Deck girders and brackets At fore and aft transverse bulkhead, bracket toes and in centre of tanks Vertical line of single measurements on web plating with one measurement between each panel stiffener, or a minimum of three measurements. Two measurements across face flat.
4 Deck Transverse webs Minimum of two webs with measurements at middle an d both ends of span 5 point pattern over about 2 square metre areas. Single measurements on face flat.
5 Panel Stiffening Where available Single Measurements.

Table C Shell and Longitudinal Bulkheads

  Structural Member Extent of Measurement Pattern of Measurement
1 Deckhead and bottom strakes, and strakes in way of stringer platforms Plating between each pair of longitudinals in a minimum of 3 bays Single measurement
2 All other strakes Plating between every third pair of longitudinals in a minimum of 3 bays Single measurement
3 Longitudinals deckhead and bottom strakes Each Longitudinal in same three bays 3 measurements across web and 1 measurement on flange
4 Longitudinals all others Every third longitudinal in same 3 bays 3 measurements across web and 1 measurement on flange
5 Longitudinals bracket Minimum of three at top, middle and bottom of tank in same 3 bays. 5 point pattern over area of bracket
6 Web frames and cross ties 3 webs with minimum of three locations on each web, including in way of cross tie connections 5 point pattern over about 2 square metre area, plus single measurements on web frame and cross tie face flats

Table D Transverse Bulkheads and Swash Bulkheads

Structural Member Extent of Measurement Pattern of Measurement
1. Deckhead and button strakes, in way of stringer platforms Plating between pair of stiffeners at three locations approx. 1/4, 1/2 and 3/4 width of tank 5 points pattern between stiffeners over 1 metre length
2. All other strakes Plating between pair of stiffeneners at mifddle location Single measurement
3. Strakes in corrugated bulkheads Plating for each change of scantling at centre of panel and at flange or fabricated connection 5 point pattern over about 1 square metre of plating
4. Stiffeners Minimum of three typical stiffeners 5 point pattern over span between bracket connections (2 measurements across web at each bracket connection, and one at centre of span). For flange, single measurements at each bracket toe and at centre of span.
5. Brackets Minimum of three at top, middle and bottom of tank. 5 point pattern over area of bracket
6. Deep webs girders Measurements of toe bracket and centre of span For web, 5 point pattern over about 1 square metre. 3 Measurements across face flat.
7. Stringer platforms All stringers with measurements at both ends and middle 5 point pattern over 1 square metre of area plus single measurements near bracket toes and on face flats.

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