Section 5 Special Survey - Structural requirements

5.1.1 The survey is to be of sufficient extent to ensure that the linkspan and related piping, where appropriate, is in satisfactory condition, subject to proper maintenance and operation and to periodical surveys being carried out as required by the Regulations.

5.1.2 The requirements of Pt 1, Ch 3, 2 Annual Surveys - Structural and machinery are to be complied with as applicable for all linkspans.

5.1.3 A Docking or In-water Survey in accordance with the requirements of Pt 1, Ch 3, 3 Docking Surveys and In-water Surveys - Structural and machinery requirements is to be carried out as part of the Special Survey.

5.2.1 The linkspan is to be prepared for overall survey in accordance with the requirements of Table 3.5.1 Survey preparation, where appropriate. The preparation should be of sufficient extent to permit as clear a view as reasonably practicable of corrosion, fractures, or other damages apparent on visual examination.

5.3.1 All spaces within the linkspan are to be examined where appropriate.

5.3.2 In certain circumstances the internal examination of fresh water and hydraulic/oil tanks, where appropriate, may be waived. For the minimum extent of tank internal examination, see Table 3.5.2 Tank internal examination requirements.

5.3.3 For salt-water ballast and buoyancy tanks, where a protective coating is found in POOR condition as defined in Pt 1, Ch 3, 1.4 Definitions 1.4.8 and it is not renewed, where a soft coating has been applied or where no protective coating has been applied from the time of construction, maintenance of class will be subject to the space in question being internally examined and gauged as necessary at Annual Surveys.

5.3.4 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.

5.3.5 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 these repairs.

5.3.6 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.

5.3.7 All decks and/or ramps, bridges, walkways and associated fittings, casings and superstructures are to be examined.

5.3.8 Wood decks or sheathing, if fitted, are to be examined; if decay or rot is found or the wood is excessively worn the wood is to be renewed. When a wood deck, laid on stringers and ties, has worn by 20 per cent or more, it is to be renewed. Attention is to be given to the condition of the plating under wood decks, sheathing or other deck and/or ramp 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).

5.3.9 Where provided, the mooring and tethering systems are to be examined. 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.

5.3.10 Watertight doors, air and sounding pipes, as appropriate, are to be examined and operationally tested as applicable.

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. Attention is to be given to the structure in way of discontinuities.

5.4.2 The minimum requirements for thickness measurement are given in Table 3.5.3 Thickness measurement.

5.4.3 Thickness measurements are normally to be by means of ultrasonic test equipment and are to be carried out by a firm qualified as Grade 1 or Grade 2 according to Clasifications Register Approval for Thickness Measurement of Hull Structures.

5.4.4 The degree of supervision or check testing by the Surveyor is dependent upon the grade of approval extended to the firm carrying out the thickness measurements:

1. The work of firms having Grade 1 approval is subject to check testing by the Surveyor.

2. Thickness measurements by firms having Grade 2 approval is to be carried out with the Surveyor substantially in attendance.

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

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

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 and supervisor.

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