Section 8 Special Survey - Chemical Tankers - Hull requirements

8.1.1 The requirements of Pt 1, Ch 3, 2 Annual Surveys - Hull and machinery requirements, Pt 1, Ch 3, 4 Bottom Surveys – In Dry-Dock and In-Water - Hull and machinery requirements and Pt 1, Ch 3, 5 Special Survey - General - Hull requirements are to be complied with as applicable.

8.1.2 In order to maintain and/or assign the ESP notation, the following requirements apply to the surveys of the hull structure and piping systems in way of the cargo tanks, pump rooms, cofferdam, pipe tunnels, void spaces, double bottom tanks, etc. in way of the cargo tank area and all salt-water ballast tanks.

8.2.1 The Owner is to obtain, supply and maintain documentation on board as follows:

1. A survey file comprising reports of structural surveys, thickness measurement and executive hull summary in accordance with the 2011 ESP Code – International Code on the Enhanced Programme of Inspections During Surveys of Bulk Carriers and Oil Tankers, 2011 – Resolution A.1049(27).

2. Supporting documentation consisting of:

   1. Main structural plans of cargo tanks and ballast tanks.

   2. Previous repair history.

   3. Cargo and ballast history.

   4. Records of inspections by ship's personnel with reference to structural deterioration in general, leakages in bulkheads and piping and the condition of the corrosion prevention systems, if any.

   5. Extent of use of inert gas plant and tank cleaning procedures.

   6. Any other information that may help to identify critical structural areas and/or suspect areas requiring inspection.

   7. Survey Programme as required by Pt 1, Ch 3, 8.3 Planning for survey.

The complete documentation in Pt 1, Ch 3, 8.2 Documentation 8.2.1 is to be readily available for examination by the Surveyor and should be used as a basis for survey.

8.2.2 The documentation is to be kept on board for the lifetime of the ship.

8.3.1 A Survey Programme is to be submitted by the Owner and is to include the proposals for survey, including the means of providing access for Close-up Survey, thickness measurement, tank testing and should take account of the information detailed in Pt 1, Ch 3, 8.2 Documentation 8.2.1.

8.3.2 Prior to the development of the Survey Programme a Survey Planning Questionnaire is to be completed and submitted by the Owner, see Pt 1, Ch 3, 1.6 Preparation for survey and means of access 1.6.16.

8.4.1 All cargo tanks and salt-water ballast tanks including double bottom tanks, pump rooms, pipe tunnels, cofferdams and void spaces bounding cargo tanks, deck and outer hull are to be examined, and this examination is to be supplemented by Close-up Survey, thickness measurement and testing as applicable, to ensure that the structural integrity remains effective.

8.4.2 The examination is to be sufficient to ascertain substantial corrosion, significant deformation, fractures, damages or other structural deterioration and, if deemed necessary by the Surveyor, suitable non-destructive examination may be required.

8.4.3 Where substantial corrosion, as defined in Pt 1, Ch 3, 1.5 Definitions, is identified and is not rectified, this will be subject to re-examination at Annual and/or Intermediate Surveys. In the case of salt-water ballast tanks the examination will be required at Annual Survey and Intermediate Survey. In the case of cargo tanks the examination will be required at Intermediate Surveys.

8.4.4 All cargo piping on deck, and cargo and ballast piping, within those spaces indicated in Pt 1, Ch 3, 8.4 Overall Survey 8.4.1 are to be examined and tested under working conditions to ensure that tightness and condition remain satisfactory. Special attention is to be given to ballast piping in cargo tanks and any cargo piping in ballast tanks and void spaces.

8.4.5 The survey of stainless steel tanks may be carried out as an Overall Survey supplemented by Close-up Survey as deemed necessary by the Surveyor.

8.4.6 Where salt-water ballast tanks have been converted to void spaces the survey extent is to be based upon salt-water ballast tank requirements.

8.4.7 Where provided, in association with a corrosion control CC special features notation, as defined in the Register Book, the condition of the protective coating or corrosion prevention system of cargo tanks is to be examined.

8.4.8 The attachment to the structure and condition of anodes in tanks is to be examined.

8.4.9 Where fitted, the strums of the cargo suction pipes are to be removed or lifted to facilitate examination of the shell plating and bulkheads in the vicinity, unless other means for visual inspection of these parts are provided.

8.5.1 The minimum ballast tank testing requirements are given in Table 3.8.1 Tank testing requirements - Chemical tankers and, where required, the Surveyor may extend the tank testing if deemed necessary. Other arrangements for cargo tank testing will be considered on application. The remaining requirements for tank testing, as applicable, are given in Pt 1, Ch 3, 5.3 Examination and testing 5.3.6.

8.5.2 The minimum cargo tank testing requirements are given in Table 3.8.1 Tank testing requirements - Chemical tankers, boundaries of cargo tanks are to be tested to the highest point that liquid will rise to under service conditions. Other arrangements for cargo tank testing will be considered on application.
Cargo tank testing carried out by the ship’s crew under the direction of the Master may be accepted by the Surveyor provided the following conditions are complied with:

1. A tank testing procedure specifying fill heights, tanks being filled and bulkheads being tested has been submitted by the Owner and reviewed by LR prior to the testing being carried out.

2. There is no record of leakage, distortion or substantial corrosion that would affect the structural integrity of the tank.

3. The tank testing has been satisfactorily carried out within the special survey window not more than 3 months prior to the date of the survey on which the overall or close-up survey is completed.

4. The satisfactory results of the testing are recorded in the ship’s logbook.

5. The internal and external condition of the tanks and associated structure is found satisfactory by the Surveyor at the time of the overall and close-up survey.

8.6.1 The minimum requirements for Close-up Survey are given in Table 3.8.2 Minimum requirements for Close-up Survey - Single hull chemical tankers (Single hull chemical tankers) and Table 3.8.3 Minimum requirements for Close-up Survey - Double hull chemical tankers (Double hull chemical tankers).

8.6.2 The Surveyor may extend the Close-up Survey, if deemed necessary, taking into account the maintenance of the tanks under survey, the condition of the corrosion prevention system, and the following:

1. Structural arrangements or details which have suffered defects in similar spaces or on similar ships.

2. Spaces which have structures approved with reduced scantlings in association with an approved corrosion control system.

8.6.3 For areas in tanks where coatings are found to be in GOOD condition, as defined in Pt 1, Ch 3, 1.5 Definitions, the extent of Close-up Surveys may be specially considered.

8.7.1 The minimum requirements for thickness measurements are given in Table 3.8.4 Minimum requirements for thickness measurement - Single and double hull chemical tankers, see also Pt 1, Ch 3, 5.6 Thickness measurement.

8.7.2 In areas where substantial corrosion, as defined in Pt 1, Ch 3, 1.5 Definitions, has been noted, then additional measurements are to be carried out, as applicable, in accordance with Table 3.8.5 Thickness measurement - Single and double hull chemical tankers - Bottom, inner bottom and hopper structure with substantial corrosion, Table 3.8.6 Thickness measurement - Single and double hull chemical tankers - Deck structure with substantial corrosion, Table 3.8.7 Thickness measurement - Single and double hull chemical tankers - Side shell and longitudinal bulkheads with substantial corrosion and Table 3.8.8 Thickness measurement - Single and double hull chemical tankers - Transverse watertight bulkheads and swash bulkheads with substantial corrosion to determine the full extent of the corrosion pattern. The survey will not be considered complete until these additional thickness measurements have been carried out.

Table 3.8.5 Thickness measurement - Single and double hull chemical tankers - Bottom, inner bottom and hopper structure with substantial corrosion

Structural member		Extent of measurement		Pattern of measurement
(1)	Bottom, inner bottom and hopper plating.	Minimum of 3 bays across double bottom tank, including aft bay. Measurement around and under all suction strums		5 point pattern for each panel between longitudinals and floors.
(2)	Bottom, inner bottom and hopper 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, including watertight girders.	At the fore and aft watertight floors and in centre of tanks.		Vertical line of single measurements on girder plating with 1 measurement between each panel stiffener, or a minimum of 3 measurements. 2 measurements across face flat (if fitted).
(4)	Bottom floors, including watertight floors.	3 floors in bays where bottom plating measured, with measurements at both ends and middle.		5 point pattern over 2 m2 area.
(5)	Hopper web frame ring	3 floors in bays where bottom plating measured		5 point pattern over 1 m2 of plating. Single measurements on flange
(6)	Hopper transverse watertight bulkhead or swash bulkhead	(i)	Lower of bulkhead	(i)	5 point pattern over 1 m2 of plating
		(ii)	Upper of bulkhead	(ii)	5 point pattern over 2 m2 of plating
		(iii)	Stiffeners (minimum of 3)	(iii)	For web, 5 point pattern over span (2 measurements across web at each end and 1 at centre of span). For flange, single measurement at each end and centre of span
(7)	Panel stiffening	Where applicable		Single measurements

Table 3.8.8 Thickness measurement - Single and double hull chemical tankers - Transverse watertight bulkheads and swash bulkheads with substantial corrosion

Structural member		Extent of measurement		Pattern of measurement
(1)	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		5 point pattern between stiffeners over 1 m length
(2)	Top and bottom strakes, and strakes in way of horizontal stringers	Plating between pair of stiffeners at		5 point pattern between stiffeners over 1 m length
		3 locations; approximately , and width of tank
(3)	All other strakes	Plating between pair of stiffeners at middle location		Single measurement
(4)	Strakes in corrugated bulkheads	Plating for each change of scantling at centre of panel and at flange of fabricated connection		5 point pattern over approximately 1 m2 of plating
(5)	Stiffeners	Minimum of 3 typical stiffeners		For web, 5 point pattern over span between bracket connections (2 measurements across web at each bracket connection and 1 at centre of span). For flange, single measurement at bracket toe and at centre of span
(6)	Brackets	Minimum of 3 at top, middle and bottom of tank		5 point pattern over area of bracket
(7)	Horizontal stringers	All stringers with measurements at both ends and middle		5 point pattern over 1 m2 area, plus single measurements near bracket toes and on flanges
(8)	Deep webs and girders	Measurements at toe of bracket and centre of span		For webs, 5 point pattern over 1 m2 area. 3 measurements across face flat

8.8.1 Selected steel cargo pipes outside cargo tanks and ballast pipes passing through cargo tanks are to be:

1. Thickness measured at random or selected pipe lengths to be opened for internal inspection.

2. Pressure tested to the maximum working pressure.