Section 5 Hull Special Survey – Hull requirements

5.1.1 The Hull Special Survey is to be of sufficient extent to ensure that the hull is in a satisfactory condition and is fit for its intended purpose, subject to proper maintenance and operation and to periodical surveys being carried out as required by the Regulations.

5.1.2 The requirements of Ch 3, 2 Annual Surveys – Hull and machinery requirements for Annual Surveys, are to be complied with for all ships, as applicable.

5.2.1  The ship is to be prepared for overall survey. The preparation should be of sufficient extent to facilitate an examination to ascertain the extent of any excessive corrosion, deformation, fractures, damages and other structural deterioration.

5.2.2 The holds, tunnels, peak tanks, side and double bottom ballast tanks, engine and boiler spaces and other spaces are to be cleared and cleaned as necessary and prepared for examination. Platform plates in the engine and boiler spaces are to be lifted as may be necessary for the examination of the structure below. Where necessary, close and spar ceiling, lining and pipe casings are to be removed for examination of the structure.

5.2.3 The steelwork is to be exposed and cleaned, and rust removed as may be required for its proper examination by the Surveyor.

5.2.4 All tanks are to be cleaned as necessary to permit examination, where this is required.

5.2.5 The chain locker is to be cleaned internally and the anchors and chain cables (including stern anchor and chain cable where applicable, see Ch 3, 5.2 Preparation 5.2.6) cleaned and ranged or placed in an accessible position for inspection. If any length of chain cable is found to be reduced in mean diameter at its most worn part by 12 per cent or more from its nominal diameter, it is to be renewed. The windlass is to be examined.

5.2.6 For those ships with a special service notation which includes areas off the East Coast of Canada, the stern anchor and chain cables are to be examined as required by Ch 3, 5.2 Preparation 5.2.5.

5.2.7 Where on self-unloading bulk carriers, plastic sheathing is fitted to the hopper plating, selected areas of sheathing are to be removed for examination of the plating beneath as considered necessary by the Surveyor, see also Ch 3, 1.2 Surveys for damage or alterations 1.2.1.

5.2.8 Tanks (excluding peak tanks) used exclusively for fuel oil, domestic fresh water or lubricating oil, need not be examined internally provided that the Surveyor is satisfied with the condition, after both external examination and test. Where the boundary of the tank is common with the side shell structure, an internal examination may be required by the Surveyor.

5.3.1 All spaces within the hull and superstructure are to be examined.

5.3.2 All tanks are to be tested by a head sufficient to give the maximum pressure that can be experienced in service. Tanks may be tested afloat provided that their internal examination is also carried out afloat.

5.3.3 Where repairs are effected to the shell plating or bulkheads, any tanks in way are to be tested to the Surveyor’s satisfaction on completion of such repairs.

5.3.4 In cases where the inner surface of the bottom plating is covered with cement, asphalt, or other composition, the removal of this covering may be dispensed with, provided that it is inspected, tested by beating or chipping and found sound and adhering satisfactorily to the steel.

5.3.5 All decks, casings, superstructures and hatch covers are to be examined.

5.3.6 Mechanically operated hatch covers are to be tested to confirm satisfactory operation including stowage, the effectiveness of sealing arrangements and operational testing of power components, wires and chains.

5.3.7 The masts and standing rigging are to be examined.

5.3.8 The hand pumps, suctions and watertight doors are to be examined and tested as necessary.

5.3.9 The Surveyor is to be satisfied as to the efficient condition and operation of the helm indicator and protection of aft steering wheel and gear.

5.3.10 Ship side valves (i.e. sea connections, scuppers and sanitary discharges) are to be tested once reassembled.

5.4.1 The Surveyor may require to measure the thickness of the material in any portion of the structure where signs of wastage are evident or wastage is normally found. Any parts of the structure which are found defective or excessively reduced in scantlings are to be made good by materials of the approved scantlings and quality. The minimum requirements for thickness measurements are given in Table 3.5.1 Thickness Measurements - Lakers.

5.4.2 For those areas of plates and stiffeners where diminution levels are found to be approaching the allowable margins as defined in Table 3.5.2 Maximum permissible diminution levels of individual plates and stiffeners, further measurement may be required at Annual and Intermediate Surveys to confirm the continued satisfactory condition of the structure.

5.4.3 Thickness measurements are to be taken at the forward and aft areas of all plates. The measurements are to represent the average of the multiple measurements taken on each plate and/or stiffener. Where measured plates are required to be renewed, the thicknesses of adjacent plates in the same strake are to be measured.

5.4.4 Thickness measurements are normally to be taken by means of ultrasonic test equipment and are to be carried out by a firm approved in accordance with LR’s Approval for Thickness Measurement of Hull Structures.

5.4.5 The work of approved firms is subject to check testing by the Surveyor.

5.4.6 Thickness measurements may be carried out in association with the fourth Annual Survey.

5.4.7 The Surveyor may extend the scope of thickness measurement, if deemed necessary.

5.4.8 Where substantial corrosion is identified and not rectified, this will be subject to re-examination and gauging as necessary at Annual and Intermediate Surveys.

5.4.9 At each Special Survey, thickness measurements are to be taken in way of critical areas, as considered necessary by the Surveyor. Critical areas are to include locations throughout the ship that show substantial corrosion and/or are considered prone to rapid wastage.

5.5.1 A report is to be prepared by the approved firm carrying out the thickness measurement. The report is to give the location of measurement, the thickness measured as well as the corresponding original thickness. The report is to give the date when the measurement was carried out, the type of measuring equipment, names of personnel and their qualifications, and is to be signed by the Operator.

5.5.2 The thickness measurement report is to be verified and signed by the Surveyor.