CORROSION PROTECTION OF CARGO OIL TANK OF CRUDE OIL TANKERS

CORROSION PROTECTION OF CARGO OIL TANK OF CRUDE OIL TANKERS

Following a number of accidents on board tankers that resulted in structural failure, the Maritime Safety Committee (MSC) of the International Maritime Organization (IMO) has adopted at MSC 87 corrosion protection measures of cargo oil tanks. As a consequence to this other resolutions and guidelines have been adopted as outlined in this Circular.

Through resolution MSC.291(87) a new regulation 3-11 has been adopted in SOLAS II-1/ Part A-1. The regulation includes mandatory coating standards which are to be adopted at the same time, for the corrosion protection of cargo oil tank of new crude oil tankers of 5000 dwt and above engaged on international voyages. For the definition of a “crude oil tanker” the regulations makes reference to items 1.11.1 and 1.11.4 of the Supplement to the International Oil Pollution Prevention Certificate (Form B). The requirements do not apply to combination carriers and chemical tankers.

As per paragraph 4 of the regulation, the Administration may exempt a crude oil tanker form the requirements and allow the use of novel prototype alternatives to the coating system provided they are subject to suitable controls, regular assessment and acknowledgment of the need for immediate remedial action if the system fails or is shown to be failing. Additionally, an exemption may be granted by the Administration if the crude oil tanker is build to be engaged solely in the carriage of cargoes and cargo handling operations not causing corrosion.

The entry into force follows the same manner with SOLAS regulation II-1/3-2 were it depends on the date that the building contract is placed, the keel lay date or delivery date. The new regulation is applicable to new crude oil tankers that the date of building contract or the keel lay date is on January 1, 2013. Alternatively, this regulation is applicable to new crude oil tankers that the delivery date is on or after January 1, 2016.

As a consequence to the above new regulation, IMO has adopted performance standard for protective coatings for cargo oil tanks of crude oil tankers through resolution MSC.288(87). The performance standard include requirements for area of application, design of the coating system, primary and secondary surface preparation, inspection and verification requirements, test procedures etc.

MSC 87 has also adopted performance standard for alternative means of corrosion protection for cargo oil tanks of crude oil tankers through MSC.289(87). As of the date of the development of the Standard, the only well known alternative means of protective coating is the corrosion resistance steel.

If this is to be used as alternative means, it shall comply with the Performance Standard for corrosion resistant steel as set out in the annex of the resolution. In case alternative methods are developed, these are to be implemented in additional annexes of the resolution.

Also, through MSC.1/Circ.1381 modifications to footnotes in the coating performance standards

adopted by resolution MSC.215(82) and MSC.288(87) have been adopted. In MSC.288(87) the footnote has been updated to include new performance standards for cargo oil tanks of crude oil tankers were as MSC.215(87) footnote has been modified to include new performance standards for protective coating in ballast water tanks.

These amendments are applicable to all ship types of 500 gt or more that SOLAS regulations II-1/3-2 and/or 3-11 apply.

Lastly, guidelines on the procedures for in-service maintenance and repair of coating systems for cargo oil tanks of crude oil tankers have been adopted through MSC.1/Circ.1399. These guidelines have been adopted following amendments to SOLAS II-1/3-11. Guidelines include repair and maintenance for coating in cargo tanks of all crude oil tankers as well as procedures and recommendations of the coating technical file (CTF)




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