Hull Survyes of Oil Tankers

Procedures for class related services, see 2.1.4 of this Chapter. Provision for surveys, see 2.1.5 of this Chapter.

Preparation for enhanced survey for ESP ships, see 2.1.6 of this Chapter.

2.11.1 Annual Surveys

In addition to the requiements of the Annual Survey in 2.5, those items herein are to be carried out.

The survey is to consist of an examination for the purpose of ensuring, as far as practicable, that the hull and piping are maintained in a satisfactory condition and should take into account the service history, condition and extent of the corrosion prevention system of ballast tanks and areas identified in the survey report file.

(a) Examination of the Hull

(i) Examination of the hull plating and its closing appliances as far as can be seen.

(ii) Examination of watertight penetrations as far as practicable

(b) Examination of weather decks

(i) Examination of cargo tank openings including gaskets, covers, coamings and flame screens.

(ii) Examination of cargo tanks pressure/vacuum valves and flame screens.

(iii) Examination of flame screens on vents to all bunker tanks.

(iv) Examination of cargo, crude oil washing, bunker and vent piping systems, including vent masts and headers.

(c) Examination of Cargo pump rooms and pipe tunnels if fitted.

(i) Examination of all pumproom bulkheads for signs of oil leakage or fractures and, in particular, the sealing arrangements of all penetrations of pumproom bulkheads.

(ii) Examination of the condition of all piping systems.

(d) Examination of Ballast Tanks

Examination of Ballast Tanks where required as a consequence of the results of the Special Survey (see 2.11.3(c)) and Intermediate Survey (see 2.11.2(b)(i) and 2.11.2(b)(ii) ) is to be carried out. When considered necessary by the Surveyor, or when extensive corrosion exists, thickness measurements are to be carried out and if the results of these thickness measurements indicate that Substantial Corrosion is found, the extent of thickness measurements is to be increased in accordance with Table I 2-4B. These extended thickness measurements are to be carried out before the survey is credited as completed. Suspect Areas identified at previous surveys are to be examined. Areas of substantial corrosion identified at previous surveys are to have thickness measurements taken.

2.11.2 Intermediate Survey

Those items which are additional to the requirements of the Annual Surveys in 2.11.1 and the applicable requirements of the Intermediate Survey in 2.6 may be surveyed either at or between the 2nd and 3rd Annual Survey;

Concurrent crediting to both Intermediate Survey (IS) and Special Survey (SS) for surveys and thickness measurements of spaces are not acceptable.

(a) General

(i) The survey extent is dependent on the age of the vessel as specified in 2.11.2(b) to 2.11.2(d).

(ii) For weather decks, an examination as far as applicable of cargo, crude o il washing, bunker, ballast, steam and vent piping systems as well as vent masts and headers is to be carried out. If upon examination there is any doubt as to the condition of the piping, the piping may be required to be pressure tested, thickness measured or both.

(b) Oil Tankers 5 – 10 Years of Age, the following is to apply:

(i) All Ballast Tanks are to be examined. When considered necessary by the Surveyor, thickness measurement and testing are to be carried out to ensure that the structural integrity remains effective.

(ii) A Ballast Tank is to be examined at subsequent annual intervals where:

(1) a hard protective coating has not been applied from the time of construction, or (2) a soft or semi-hard coating has been applied, or

(3) substantial corrosion is found within the tank, or

(4) the hard protective coating is found to be in less than GOOD condition and the hard protective coating is not repaired to the satisfaction of the Surveyor.

(iii) In addition to the requirements above, suspect areas identified at previous surveys are to be examined.

(c) Oil Tankers 10 - 15 years of Age, the following is to apply:

(i) The requirements of the Intermediate Survey are to be to the same extent as the previous Special Survey as required in 2.11.3 and 2.1.6(a). However, pressure testing of cargo and ballast tanks and the requirements for longitudinal strength evaluation of Hull Girder as required in 2.1.6(f) are not required unless deemed necessary by the attending Surveyor.

(ii) In application of 2.11.2(c)(i) above, the Intermediate Survey may be commenced at the second Annual Survey and be progressed during the succeeding year with a view to completion at the third Annual Survey in lieu of the application of 1.6.4(c)(ii) of the Part.

(iii) In application of 2.11.2(c)(i) above, an In-water survey may be considered in lieu of the requirements of 2.11.3(b).

(d) Oil Tankers over 15 years of Age, the following is to apply:

(i) The requirements of the Intermediate Survey are to be to the same extent as the pr evious Special Survey as required in 2.11.3 and 2.1.6(a). However, pressure testing of cargo and ballast tanks and the requirements for longitudinal strength evaluation of Hull Girder as required in 2.1.6(f) are not required unless deemed necessary by the attending Surveyor.

(ii) In application of 2.11.2(d)(i) above, the Intermediate Survey may be commenced at the second Annual Survey and be progressed during the succeeding year with a view to completion at the third Annual Survey in lieu of the application of 1.6.4(c)(ii) of the Part.

(iii) In application of 2.11.2(d)(i) above, a survey in dry dock is to be part of the Intermediate Survey. The overall and close-up surveys and thickness measurements, as applicable, of the lower portions of the cargo tanks and water ballast tanks⁽¹⁾ are to be carried out in accordance with the applicable requirements for Intermediate Surveys, if not already performed.

Note:

(1) Lower portions of the cargo and ballast tanks are considered to be the parts below light ballast water line.

2.11.3 Special Survey

Concurrent crediting to both Intermediate Survey (IS) and Special Survey (SS) for surveys and thickness measurements of spaces are not acceptable.

(a) General

(i) The Special Survey is to include, in addition to the requirements of the Annual Survey in 2.11.1 and the applicable requirements of the Special Survey in 2.7, examination, tests and checks of sufficient extent to ensure that the hull and related piping, as required in 2.11.3(a)(iii), is in a satisfactory condition and is fit for its intended purpose for the new period of class of 5 years to be assigned, subject to proper maintenance and operation and to periodical surveys being carried out at the due dates.

(ii) All cargo tanks, Ballast Tanks, including double bottom tanks, pumprooms, pipe tunnels, cofferdams and void spaces bounding cargo tanks, decks and outer hull are to be examined, and this examination is to be supplemented by thickness measurement and testing required in 2.11.3(e) and 2.11.3(f), to ensure that the structural integrity remains effective. The aim of the examination is to discover Substantial Corrosion, significant deformation, fractures, damages or other structural deterioration, that may be present.

(iii) Cargo piping on deck, including Crude Oil Washing (COW) piping, Cargo and Ballast piping within the above tanks and spaces are to be examined and operationally tested to working pressure to attending Surveyor’s satisfaction to ensure that tightness and condition remain satisfactory. Special attention is to be given to any ballast piping in cargo tanks and cargo piping in ballast tanks and void spaces, and Surveyors are to be advised on all occasions when this piping, including valves and fittings are open during repair periods and can be examined internally.

(b) Bottom Survey in dry dock

(i) A Bottom Survey in dry dock is to be a part of the Special Survey. The overall and close -up surveys and thickness measurements, as applicable, of the lower portions of the cargo tanks and ballast tanks⁽¹⁾ are to be carried out in accordance with the applicable requirements for Special Surveys, if not already performed.

Note:

(1) Lower portions of the cargo and ballast tanks are considered to be the parts below light ballast water line.

(c) Tank Protection

(i) Where provided, the condition of the corrosion prevention system of cargo tanks is to be examined.

A Ballast Tank is to be examined at subsequent annual intervals where:

(1) a hard protective coating has not been applied from the time of construction, or (2) a soft or semi-hard coating has been applied, or

(3) substantial corrosion is found within the tank, or

(4) the hard protective coating is found to be in less than GOOD condition and the hard protective coating is not repaired to the satisfaction of the Surveyor. Thickness measurements are to be carried out as deemed necessary by the Surveyor.

(d) Extent of overall and close-up survey

(i) An overall survey of all tanks and spaces is to be carried out at each Special Survey.

(ii) The minimum requirements for close-up surveys at Special Survey are given in Table I 2-5A.

(iii) The Surveyor may extend the close-up survey as deemed necessary taking into account the maintenance of the tanks under survey, the condition of the corrosion prevention system and also in the following cases:

(1) In particular, tanks having structural arrangements or details which have suffered defects in similar tanks or on similar ships according to available information.

(2) In tanks which have structures approved with reduced scantlings due to an approved corrosion control system.

(iv) For areas in tanks where hard protective coatings are found to be in a GOOD condition as defined in 2.1.2(l), the extent of close-up surveys according to Table I 2-5A may be specially considered.

(e) Extent of Thickness Measurement

(i) The minimum requirements for thickness measurements at Special Survey are given in Table I 2 -3B (ii) Provisions for extended measurements for areas with Substantial Corrosion are given in Table I 2

-4B, and as may be additionally specified in the Survey Programme as required by 2.1.6(a). These extended thickness measurements are to be carried out before the survey is credited as completed.

Suspect Areas identified at previous surveys are to be examined. Areas of substantial corrosion identified at previous surveys are to have thickness measurements taken.

(iii) The Surveyor may further extend the thickness measurements as deemed necessary.

(iv) For areas in tanks where hard protective coating are found to be in a GOOD condition as defined in 2.1.2(l), the extent of thickness measurements according to Table I 2-3B may be specially considered.

(v) Transverse sections are to be chosen where the largest reductions are suspected to occur or are revealed from deck plating measurements.

(vi) In cases where 2 or 3 sections are to be measured, at least one is to include a Ballast Tank within 0.5L amidships.

In case of oil tankers of 130 m in length and upwards (as defined in the International Convention on Load Lines in force) and more than 10 years of age, for the evaluation of the ship’s longitudinal strength as required in 2.1.6(f), the sampling method of thickness measurements is given in IACS UR Z10.1-Annex III Appendix 3.

(f) Extent of Tank Testing

(i) The minimum requirements for ballast tank testing at Special Survey are given in 2.11.3(f)(iii) and Table I 2-2.

The minimum requirements for cargo tank testing at Special Survey are given in 2.11.3(f)(iv) and Table I 2-2.

Cargo tank testing carried out by the vessel’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 the Society 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 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 is recorded in the vessel’s logbook;

(5) the internal and external condition of the tanks and associated structure are found satisfactory by the Surveyor at the time of the overall and close up survey.

(ii) The Surveyor may extend the tank testing as deemed necessary.

(iii) Boundaries of ballast tanks are to be tested with a head of liquid to the top of air pipes.

(iv) Boundaries of cargo tanks are to be tested to the highest point that liquid will rise under service conditions.