Annex 4 – Requirements for Extent of Thickness Measurements at Areas of Substantial Corrosion of Oil Tankers Other Than Double-Hull Oil Tankers
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - International Codes - 2011 ESP Code – International Code on the Enhanced Programme of Inspections During Surveys of Bulk Carriers and Oil Tankers, 2011 – Resolution A.1049(27) - Annex B – Code on the Enhanced Programme of Inspections During Surveys of Oil Tankers - Part B – Code 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 of Oil Tankers Other Than Double-Hull Oil Tankers

Annex 4 – Requirements for Extent of Thickness Measurements at Areas of Substantial Corrosion of Oil Tankers Other Than Double-Hull Oil Tankers

Renewal survey within the cargo area length

Bottom structure

Structural
member 		Extent of measurement Pattern of measurement
Bottom plating Minimum of three bays across tank, including aft bay. Measurements around and under all bell mouths Five-point pattern for each panel between longitudinals and floors
Bottom longitudinals Minimum of three longitudinals in each bay where bottom plating measured Three measurements in line across flange and three measurements on vertical web
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. Two measurements across face flat. Five-point pattern on girder/bulkhead brackets
Bottom transverse webs Three webs in bays where bottom plating measured, with measurements at both ends and middle Five-point pattern over 2 m2 area
Panel stiffening Where fitted Single measurements

Deck structure

Structural
member 		Extent of measurement Pattern of measurement
Deck plating Two bands across tank Minimum of three measurements per plate per band
Deck longitudinals Minimum of three longitudinals in each of two bays Three measurements in line vertically on webs, and two measurements on flange (if fitted)
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. Five-point pattern on girder/bulkhead brackets
Deck transverse webs Minimum of two webs with measurements at middle and both ends of span Five-point pattern over 2 m2 area. Single measurements on face flat
Panel stiffening Where available Single measurements

Side shell and longitudinal bulkheads

Structural
member 		Extent of measurement Pattern of measurement
Deckhead and bottom strakes, and strakes in way of stringer platforms Plating between each pair of longitudinals in a minimum of three bays Single measurement
All other strakes Plating between every third pair of longitudinals in same three bays Single measurement
Longitudinals – deckhead and bottom strakes Each longitudinal in same three bays Three measurements across web and one measurement on flange
Longitudinals – all others Every third longitudinal in same three bays Three measurements across web and one measurement on flange
Longitudinals – bracket Minimum of three at top, middle and bottom of tank in same three bays Five-point pattern over area of bracket
Web frames and cross ties Three webs with minimum of three locations on each web, including in way of cross tie connections Five-point pattern over about 2 m2 area, plus single measurements on web frame and cross tie face flats

Transverse bulkheads and swash bulkheads

Structural
member 		Extent of measurement Pattern of measurement
Deckhead and bottom strakes, and strakes in way of stringer platforms Plating between pair of stiffeners at three locations – approximately quarter, half and three-quarters width of tank Five-point pattern between stiffeners over 1 m length
All other strakes Plating between pair of stiffeners at middle location Single measurement
Strakes in corrugated bulkheads Plating for each change of scantling at centre of panel and at flange or fabricated connection Five-point pattern over about 1 m2 of plating
Stiffeners Minimum of three typical stiffeners For web, five-point pattern over span between bracket connections (two 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
Brackets Minimum of three at top, middle and bottom of tank For web, five-point pattern over about 1 m2 area.

Three measurements across face flat

Stringer platforms All stringers with measurements at both ends and middle Five-point pattern over 1 m2 area plus single measurements near bracket toes and on face flats
Parent topic: Part B – Code on the Enhanced Programme of Inspections During Surveys of Oil Tankers other than Double-Hull Oil Tankers
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