Annex 13 – Procedural Requirements for Thickness Measurements

 Thickness measurements required in the context of hull structural surveys, if not carried out by the Administration, shall be witnessed by a surveyor of the Administration. The attendance of the surveyor shall be recorded. This also applies to thickness measurements taken during voyages.

  2.1 Prior to commencement of the renewal or intermediate survey, a meeting shall be held between the attending surveyor(s), the master of the ship or an appropriately qualified representative appointed by the master or company, the owner's representative(s) in attendance and the thickness measurement firm's representative(s) so as to ensure the safe and efficient execution of the surveys and thickness measurements to be carried out on board.

  2.2 Communication with the thickness measurement operator(s) and owner's representative(s) shall be agreed during the meeting, with respect to the following:

• .1 reporting of thickness measurements on regular basis to the attending surveyor; and

• .2 prompt notification to the surveyor in case of findings such as:

  • .1 excessive and/or extensive corrosion or pitting/grooving of any significance;

  • .2 structural defects like buckling, fractures and deformed structures;

  • .3 detached and/or holed structure; and

  • .4 corrosion of welds.

  2.3 When thickness measurements are taken in association with intermediate or renewal surveys, a documented record indicating where and when the meeting took place and who attended (the name of the surveyor(s), the master of the ship or an appropriately qualified representative appointed by the master or company, the owner's representative(s) and the representative(s) of the thickness measurement firm(s)) shall be maintained.

  3.1 The surveyor shall decide the final extent and location of thickness measurements after overall survey of representative spaces on board.

  3.2 In case the owner prefers to commence the thickness measurements prior to the overall survey, then the surveyor shall advise that the planned extent and locations of thickness measurements are subject to confirmation during the overall survey. Based on findings, the surveyor may require additional thickness measurements to be taken.

  3.3 The surveyor shall direct the gauging operation by selecting locations such that readings taken represent, on average, the condition of the structure for that area.

  3.4 Thickness measurements taken mainly to evaluate the extent of corrosion, which may affect the hull girder strength, shall be carried out in a systematic manner such that all longitudinal structural members are gauged, as required.

  3.5 Where thickness measurements indicate substantial corrosion or wastage in excess of allowable diminution, the surveyor shall determine locations for additional thickness measurements in order to delineate areas of substantial corrosion and to identify structural members for repairs/renewals.

  3.6 Thickness measurements of structures in areas where close-up surveys are required shall be carried out simultaneously with the close-up survey.

  4.1 Upon completion of the thickness measurements, the surveyor shall confirm that no further gaugings are needed, or specify additional gaugings.

  4.2 If, where special consideration is allowed by this Code, the extent of thickness measurements is reduced, the surveyor’s special consideration shall be reported.

  4.3 In case thickness measurements are partly carried out, the extent of the remaining thickness measurements shall be reported for the use of the next surveyor.