Section 4 Special Survey – Hull requirements

4.1.1 The ship is to be placed in dry dock or on a slipway, cleaned and be at a sufficient height above the dock floor or the ground for examination of shell plating, sternframe, rudder(s), etc. If necessary, proper staging is to be erected for this examination. On side slipways it may be required to remove cradles for examination of the bottom plating. Each rudder is to be lifted for examination of pintles if considered necessary by the Surveyor.

4.1.2 The holds, peaks, deep and wing tanks, engine and boiler spaces, and other spaces, are to be cleared and cleaned as necessary, and the bilges and limbers all fore and aft are to be cleaned and prepared for examination as required by Pt 1, Ch 3, 4.2 Examination and testing. Platform plates in 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.

4.1.3 In ships having a single bottom, a sufficient amount of close ceiling is to be lifted on each side from the bottom and bilges to permit the structure below to be examined.

4.1.4 In ships having a double bottom, a sufficient amount of ceiling is to be removed from the bilges and inner bottom to enable the condition of the plating to be ascertained. If it is found that the plating is clean and in good condition, and free from rust, the removal of the remainder of ceiling may be dispensed with. The Surveyor may waive the removal of heavy reinforced compositions if there is no evidence of leakages, cracking or other faults in the composition.

4.1.5 The steelwork is to be exposed and cleaned as may be required for its proper examination by the Surveyor.

4.2.1 The requirements of an Intermediate Survey are to be complied with, see Pt 1, Ch 3, 3 Intermediate Survey – Hull requirements.

4.2.2 All items and spaces required to be cleared and cleaned for examination by Pt 1, Ch 3, 4.1 Preparation are to be examined. Careful examination is to be made of parts of the structure particularly liable to excessive corrosion, or to deterioration from causes such as chafing, lying on the ground, or handling of cargo.

4.2.3 The Surveyor may require to gauge, by ultrasonic thickness measurement or other approved means, 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 materially reduced in scantlings are to be made good by materials of approved scantlings and quality. Attention is to be given to the structure in way of discontinuities. Surfaces are to be re-coated as necessary.

4.2.4 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.

4.2.5 Double bottom tanks, peak tanks and all other tanks are to be tested by a head sufficient to give the normal maximum pressure that can be experienced in service. Tanks may be tested afloat provided that their internal examination is also carried out afloat. Tanks forming part of the main structure, except as stated below, are to be cleaned and examined internally, special attention being given to tanks under boiler spaces. Tanks (excluding peak tanks) used exclusively for fuel oil or fresh water in ships less than 15 years old need not be examined internally, provided that, after external examination and testing in accordance with the requirements set out above, the Surveyor finds the condition of these compartments satisfactory.

4.2.6 Spaces which are inaccessible for examination, e.g. low double bottom tanks, boxed in webframes, spaces under tanks not forming part of the ship’s structure are to be examined externally and gauged as necessary. In case of doubt, openings are to be made in the structure for examination of the interior so that the Surveyor can be satisfied as to the efficient condition of the structure.

4.2.7 All decks, casings and superstructures are to be examined. Attention is to be given to the corners of openings and other discontinuities in way of strength decks and top sides.

4.2.8 Wood decks or sheathing are to be examined. If decay or rot is found or the wood is excessively worn, the wood is to be renewed. Attention is to be given to the condition of the plating under wood decks, sheathing or other deck covering. If it is found that such coverings are broken, or are not adhering closely to the plating, sections are to be removed, as necessary, to ascertain the condition of the plating. See also Pt 1, Ch 3, 1.2 Surveys for damage or alterations 1.2.1.

4.2.9 The anchors are to be examined. If the chain cables are ranged they are to be examined. Chain cables of ships over 10 years old are to be ranged at each Special Survey. 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.

4.2.10 The Surveyor is to satisfy himself that there are suitable mooring ropes and a towline when these are a Rule requirement.

4.2.11 The steering gear, and its connections and control systems (main and alternative) are to be examined. The various parts of the auxiliary steering gear are to be assembled, examined and tested. The helm indicator is to be examined and tested.

4.2.12 The hand pumps, suctions, watertight doors, air and sounding pipes are to be examined.

4.2.13 The Surveyor is to satisfy himself as to the efficient condition of the following:

1. Means of escape from: machinery spaces, crew and passenger spaces, and spaces in which crew are normally employed.

2. Means of communication between: bridge and engineroom control station.

3. Fire protection, detection and extinction.

4.2.14 For surveys of machinery, electrical equipment, boilers, steam pipes, screwshafts and inert gas systems, see Pt 1, Ch 3, 10 Machinery surveys – General requirements.

4.2.15 The sea connections, scuppers and sanitary discharges, and their attachments to the hull and the gratings at the sea inlets are to be examined. Ship side valves (i.e. sea connections, scuppers and sanitary discharges) are to be tested once reassembled.

4.3.1 The general minimum requirements for thickness measurements for all ship types are given in Table 3.4.1 Thickness measurements - All ship types. The Surveyor may extend the thickness measurements as deemed necessary.

4.3.2 Thickness measurements may be carried out in the 12 months preceding the due date of the Special Survey or when the Special Survey is extended as well in the 12 months preceding the revised Special Survey due date.

4.3.3 In areas where substantial corrosion (defined as wastage of individual plates and stiffeners in excess of 75 per cent of allowable margins, but within acceptable limits) has been noted, additional measurements are to be carried out, as deemed necessary by the attending Surveyor.

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

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

4.3.6 Where a 10 per cent area reduction of deck plating and longitudinals is exceeded, a check of the buckling capacity of the upper deck is to be carried out for all tankers.