Annex 4 – Requirements for Extent of Thickness Measurements at Areas of Substantial Corrosion of Double-Hull Oil Tankers within the Cargo Area Length
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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 A – Code on the Enhanced Programme of Inspections During Surveys of Double-Hull Oil Tankers - Annex 4 – Requirements for Extent of Thickness Measurements at Areas of Substantial Corrosion of Double-Hull Oil Tankers within the Cargo Area Length

Annex 4 – Requirements for Extent of Thickness Measurements at Areas of Substantial Corrosion of Double-Hull Oil Tankers within the Cargo Area Length

 
Bottom, inner bottom and hopper structure
Structural
member 		Extent of measurement Pattern of measurement
Bottom, inner bottom and hopper structure plating Minimum of three bays across double-bottom tank, including aft bay Measurements around and under all suction bell mouths Five-point pattern for each panel between longitudinals and floors
Bottom, inner bottom and hopper structure 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, including the watertight ones At fore and aft watertight floors and in centre of tanks Vertical line of single measurements on girder plating with one measurement between each panel stiffener, or a minimum of three measurements
Bottom floors, including the watertight ones Three floors in bays where bottom plating measured, with measurements at both ends and middle Five-point pattern over 2 m2 area
Hopper structure web frame ring Three floors in bays where bottom plating measured Five-point pattern over 1 m2 of plating. Single measurements on flange
Hopper structure transverse watertight bulkhead or swash bulkhead - lower ⅓ of bulkhead Five-point pattern over 1 m2 of plating
- upper ⅔ of bulkhead Five-point pattern over 2 m2 of plating
- stiffeners (minimum of three) For web, five-point pattern over span (two measurements across web at each end and one at centre of span). For flange, single measurements at each end and centre of span
Panel stiffening Where applicable Single measurements
Deck structure
Structural
member 		Extent of
measurement 		Pattern of measurement
Deck plating Two transverse bands across tank Minimum of three measurements per plate per band
Deck longitudinals Every third longitudinal in each of two bands with a minimum of one longitudinal Three measurements in line vertically on webs and two measurements on flange (if fitted)
Deck girders and brackets (usually in cargo tanks only) 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 flange. Five-point pattern on girder/bulkhead brackets
Deck transverse webs Minimum of two webs, with measurements at both ends and middle of span

Five-point pattern over 1 m2 area.

Single measurements on flange

Vertical web and transverse bulkhead in wing ballast tank (2 m from deck) Minimum of two webs, and both transverse bulkheads Five-point pattern over 1 m2 area
Panel stiffening Where applicable Single measurements
Structure in wing ballast tanks
Structural
member 		Extent of
measurement 		Pattern of measurement
Side shell and longitudinal bulkhead plating: Plating between each pair of longitudinals in a minimum of three bays (along the tank) Single measurement
- upper strake and strakes in way of horizontal girders

- all other strakes

 Plating between every third pair of longitudinals in same three bays Single measurement
Side shell and longitudinal bulkhead longitudinals on: Each longitudinal in same three bays Three measurements across web and one measurement on flange
- upper strake

- all other strakes

Every third longitudinal in same three bays Three measurements across web and one measurement on flange
Longitudinals brackets Minimum of three at top, middle and bottom of tank in same three bays Five-point pattern over area of bracket
Vertical web and transverse bulkheads (excluding deckhead area): Minimum of two webs and both transverse bulkheads Five-point pattern over approximately 2 m2 area
- strakes in way of horizontal girders

- other strakes

 Minimum of two webs and both transverse bulkheads Two measurements between each pair of vertical stiffeners
Horizontal girders Plating on each girder in a minimum of three bays Two measurements between each pair of longitudinal girder stiffeners
Panel stiffening Where applicable Single measurements
Longitudinal bulkheads in cargo tanks
Structural
member 		Extent of
measurement 		Pattern of measurement
Deckhead and bottom strakes, and strakes in way of the horizontal stringers of transverse bulkheads 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 on deckhead and bottom strakes Each longitudinal in same three bays Three measurements across web and one measurement on flange
All other longitudinals Every third longitudinal in same three bays Three measurements across web and one measurement on flange
Longitudinals brackets 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 approximately 2 m2 area of webs, plus single measurements on flanges of web frame and cross ties
Lower end brackets (opposite side of web frame) Minimum of three brackets Five-point pattern over approximately 2 m2 area of brackets, plus single measurements on bracket flanges
Transverse watertight and swash bulkheads in cargo tanks
Structural
member 		Extent of
measurement 		Pattern of measurement
Upper and lower stool, where fitted Transverse band within 25 mm of welded connection to inner bottom/deck plating

Transverse band within 25 mm of welded connection to shelf plate

Five-point pattern between stiffeners over 1 m length
Deckhead and bottom strakes, and strakes in way of horizontal stringers Plating between pair of stiffeners at three locations: approximately ¼, ½ and ¾ 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 of fabricated connection Five-point pattern over approximately 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 Five-point pattern over area of bracket
Horizontal stringers All stringers with measurements at both ends and middle Five-point pattern over 1 m2 area, plus single measurements near bracket toes and on flanges
Parent topic: Part A – Code on the Enhanced Programme of Inspections During Surveys of Double-Hull Oil Tankers
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