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Overview of the convention on the Control of Harmful Anti-fouling Systems (AFS) on ships

The various types of ship coatings
Overview of 2001 AFS Convention

Overview of 2001 AFS Convention

Shipping’s battle with the forces of nature is one that has been fought from the days of wooden ships. The biggest problem then with biofouling was destruction of the wooden hull by wood-boring organisms. Weed and barnacle growth was considered less of a problem but one which had to be treated because – just as with steel ships – it slows the vessel and adds weight that could be better employed carrying cargo. This is where Anti-fouling Systems on ships come in.

Over time, preventing biofouling has involved the use of many different materials and chemicals from sheets of copper to poisonous compounds. Some of these were very successful but their undesirable side effects attracted the attention of science and the environmental movement, which wanted to see them controlled and prohibited from use.

Unlike so much IMO regulation which details what ships must do or carry, the International Convention on the Control of Harmful Anti-fouling Systems (AFS) on Ships, which was adopted in October 2001 but only came into force on 17 September 2008, is totally geared to preventing the use of certain products. The convention covers all vessels including FSUs and FPSOs.

Ban on Tributyltin and organotins

Initially the product at which the convention was aimed was tributyltin (TBT), a substance developed through the 1960s and first used in the 1970s and which the IMO itself concedes is probably the most effective biocide so far devised for the maritime industry.

TBT belongs to a wider family of chemical compounds called organotins. Other compounds within the organotin family are still permitted in coatings as a catalyst for the curing process if organotin content does not exceed the allowable limit of 250mg/kg of paint. Some concerns have been raised that the quantities in some products are increasing and could be having a similar effect to TBT on mollusc reproductive systems. This is an ongoing issue that is being monitored at the IMO.

Before the AFS Convention came into force, all of the leading coatings manufacturers had already ceased production of TBT products and were developing replacement products. Not all of the new coatings used on the hulls are affected by the convention because the technologies that have been developed sometimes are designed not to kill but merely to make attachment to the hull more difficult.

There are now three different methods used in products for coating for the underwater parts of a ship: antifoulings, which contain a biocide to kill organisms that adhere to the hull; foul-release coatings, which are designed to prevent organisms attaching by a variety of methods; and hardcoats, which present a smooth surface that can be cleaned using equipment that would remove or damage the other two types of coating. The technologies employed in each case may vary from product to product and some manufacturers describe some products as having more than one means of operation.

Enforcement of AFS Convention

As with most IMO treaties, there is provision for countries to opt out of it but should they do so their vessels will not be welcome in most parts of the world. Any party to the treaty is obliged to apply it to vessels flying its flag or which it would otherwise have some control over, and to prevent any vessel of whatever flag entering its ports. Since most of the world’s major economies are parties to the treaty, only a very few domestic vessels and some trading between adjacent countries that are not signatories can afford to ignore the treaty.

Testing for banned products by Port State Control inspectors is allowed under the convention but there is very little evidence to suggest that this is done on any great scale. Ships above 400gt are obliged to undergo an initial survey before they are put into service or before their International Anti-fouling System Certificates required under Regulation 2 or 3 of the convention are issued for the first time. Ships are also obliged to undergo surveys when their anti-fouling systems are changed or replaced, and the details of their survey recorded on the certificate.

The certificate records the type of antifouling used, its manufacturer, where it was applied and by whom and even extends to the colour of the coating. Generally, as long as the certificate appears to be in order, PSC inspectors are unlikely to order tests on the coatings although this can never be discounted. The convention includes a clause that states that a ship shall be entitled to compensation if it is unduly detained or delayed while undergoing inspection for possible violations of the convention. 

The Blacklist

The International Convention on the Control of Harmful Anti-fouling Systems on Ships does not approve any products but is purely a prohibiting convention with a blacklist of banned substances. Today, TBT organotin is still the only substance on the banned list, which is contained as Annex I to the convention. However, there are expectations that other products may be added over time.

For any product to be added to the IMO’s blacklist, an amendment is required under article 16 of the convention which will first be subject to a lengthy investigation process described in Articles 6 and 7. As the shipping industry in general and coatings manufacturers in particular are likely to be aware of any move to add a substance to the banned list well in advance of any action actually being taken, the length of time needed for the process is not likely to cause headaches for operators Even so, the convention does allow any vessel affected by an amendment to Annex I a period of grace of up to 60 months or until the coatings were due for renewal, whichever is the earlier.

Copper-based coatings

Copper-based products, which now feature in many biocidal anti-fouling products, are often mentioned as being likely candidates for future banning. However, in August 2016 the prospect of an imminent ban on copper receded when it was announced that, after thorough scientific evaluation of the use of dicopper oxide, copper thiocyanate and coated copper flake as antifouling substances within the EU Biocidal Products Regulation 528/2012, the European Chemicals Agency’s Biocidal Product Committee determined that these copper compounds should be approved for use as active substances in commercial and yacht (pleasure craft) antifouling products. The committee also allowed its application by both professional and nonprofessional users.

These three compounds are the only copper compounds to have received approval to date but importantly they are the forms of copper most commonly used in current antifouling paints, either as a sole biocide or in conjunction with a co-biocide. As always with EU regulations, things are not straightforward, and the regulations required that manufacturers submitted applications for approval of all their copper-based antifouling products by 1 January 2018 after which acceptance was not guaranteed. Products containing zinc pyrithione have a later deadline. Paints must be approved by each country in which they will be marketed.

Biofouling Regulations

Biofouling Regulations

It is somewhat ironic that the ban on TBT was brought in because a build-up of the biocides from anti-foulings was causing casualties among some species and yet new regulation looks certain to encourage more of the same in a bid to stop the spread of invasive species.

The realisation that species can be transferred around the world other than in ballast water seems to have finally dawned on regulators and in July 2011 the IMO issued EPC.207(62) entitled 2011 Guidelines for the control and management of ship’s biofouling to minimize the transfer of invasive aquatic species.

The document came with a request for IMO member states to take action to implement the guidelines as fully as possible. So far there has been no international movement to make the guidelines binding but, just as with the matter of ballast water treatment, some local attempts are being made to enact legislation. Not surprisingly, California has been a leader in this regard as there are no Federal US regulations on the issue – although the USCG regulations on ballast water treatment do make mention of biofouling management.

Australia and New Zealand also have local regulations and some ships have already fallen foul of these rules. In at least two cases, ships were either prevented from entering New Zealand waters or were required to move after having arrived and their biofouling management found to be deficient. The ships were not allowed to return until their hulls were declared sufficiently free of fouling. No financial penalties were imposed by the authorities, but the operational costs associated with use of divers, cleaning of the hull and delays were substantial.

Biofouling Management Plans

The IMO guidelines have been picked up by several classification societies and some coatings manufacturers. Consequently, there are now a number of model biofouling management plan (BMP) templates available free of charge along with ready advice.

A typical BMP will record details of hull coatings and provide practical guidance on measures to minimise the risk of transferring invasive species from ships’ biofouling. That guidance would cover maintenance of anti-fouling systems and operational strategies such as matching coatings to environmental conditions likely to be encountered.

A good BMP would ensure that factors such as slow steaming or long periods of inactivity are taken into account, paying particular attention to areas such as propellers, rudders, thrusters, anchors and chains, sea chests and chain lockers where conditions can permit organisms to survive for quite long periods.

Unless a vessel’s flag state or a port state declares otherwise, the guidelines are voluntary but are something that a prudent ship operator should consider implementing. As well as providing practical experience for the time when global regulation eventually arrives, successfully managing biofouling also has a beneficial effect on ship efficiency and thus reduces fuel bills.

The GloFouling Partnerships project

One reason advanced for the present lack of commitment to making the guidelines mandatory is that the delays and machinations around ratification of the ballast water convention has been a factor.

That may be changing. In summer 2017 the GloFouling Partnerships project – a collaboration between the Global Environment Facility (GEF), the United Nations Development Programme (UNDP) and the IMO – was established.

This development mirrors events around ballast water where the 2004 convention and the framework for approving systems were driven by the GloBallast partnership. The new body will address the transfer of aquatic species through biofouling and will focus on the implementation of the IMO guidelines.

The GEF, UNDP and IMO collaboration has already proved to be highly successful through its three-tier implementation model (termed ‘Glo-X’) for driving legal, policy and  institutional reforms, delivering capacity- building activities and encouraging technology transfer through public-private partnerships at the global, regional and national levels. The GloBallast project completed its work in 2017 when the Ballast Convention came into effect and the ongoing GloMEEP project is aimed at supporting the implementation of energy efficiency measures for shipping.

In November 2018, 12 countries were selected to spearhead the work of the GloFouling project: Brazil, Ecuador, Fiji, Indonesia, Jordan, Madagascar, Mauritius, Mexico, Peru, the Philippines, Sri Lanka and Tonga. The GEF provided a $6.9M grant to deliver a range of governance reforms at national levels, through numerous capacity-building activities, training workshops and opportunities for technology adoption to help address the issue of invasive species.

Strong participation from private sector stakeholders is also expected. While the IMO will focus on shipping, UNESCO’s Intergovernmental Oceanographic Commission (IOC) will join the three main partners to lead the approach to other marine sectors with a view to developing best practices that may address the transfer of invasive aquatic species through improved biofouling management.

IOC-UNESCO is working with the GloFouling project to increase awareness of this environmental challenge among key stakeholders. The World Ocean Council (WOC) has been selected to engage and channel the participation of private sector companies for the development of best industry practices in non-shipping sectors such as aquaculture and oil and gas extraction.

In October 2019, an IMO-GloFouling R&D Forum was held in Melbourne aimed at bringing together regulatory bodies, stakeholders and representatives from shipping and other maritime industries, academia, leading scientific experts and technology development leaders in the field of biofouling management for a comprehensive overview of research and development and technology commercialisation. This first edition of the IMO-GloFouling R&D Forum was described as an opportunity to discuss the main aspects of biofouling management in shipping just

Performance standard for protective coatings (PSPC)

Performance standard for protective coatings (PSPC)

PSPC Overview

While protection against corrosion in dry cargo holds and some cargo tanks is voluntary, protecting against corrosion and the coatings used in the ballast tanks of most vessels and crude oil tanks are now regulated under IMO performance standards for protective coatings (PSPC). The first of these, affecting only ballast tanks and double-side skin spaces of bulk carriers, was adopted in 2006 and came into effect in 2008 as Resolution MSC.215(82).

It has applied to newbuild contracts from that date. Thus most vessels in service are covered by the new standards but existing ships built before 2008 and those contracted before then but commenced later are not covered by the regulation.

In practice, shipbuilders are responsible for implementing the PSPC requirements during new construction. Before construction begins, the yard, class society and coatings sub-contractors agree surface preparation, coating process and inspection procedures. The details are entered into the ship’s Technical Coating File along with full details and MSDs of the products used.

This PSPC applies only to dedicated seawater ballast tanks in all types of ships above 500gt and double side skin spaces in bulk carriers above 150m loa that are constructed of steel.

It does not apply to cargo holds in bulk carriers that are sometimes used for ballast purposes. It is based on a detailed specification and requirements that intend to provide a target useful coating life of 15 years, which is considered to be the time period from initial application over which the coating system is intended to remain in ‘good’ condition.

‘Good’ is not a vague term but is defined as: “A condition with spot rusting on less than 3% of the area under consideration without visible failure of the coating. Rusting at edges or welds should be on less than 20% of edges or weld lines in the area under consideration”. The actual useful life will vary, depending on numerous variables including actual conditions encountered in service.

While there is a requirement for the owner to maintain the coatings to the standards during the life of the ship, the most onerous part of the regulation is directed at coating manufacturers, coatings contractors and inspectors. The PSPC is formulated around two-coat epoxy coatings but permits alternatives such as Nippon Paints’ NOA 60HS Self-Indicating one-coat epoxy coating system.

Two coats were stipulated for the simple reason that the second and lighter colour coat allows easy identification of areas where coverage has been missed. The one coat epoxy system has a very different colour depending upon the coating thickness making it relatively easy to see both under and overcoated areas.

Coatings Technical File

On delivery of the ship, the owner should also be given a Coatings Technical File (CTF) detailing the coatings used, shipyard work records, type-approval certificates, results of inspections during construction and guidance on repair and maintenance.

Once the ship is in service, the owner will be responsible for recording all repairs and recoating activities together with appropriate documents. The flag state should not issue a SOLAS Safety Construction Certificate until the CTF is completed and its own inspection recorded.

The PSPC requirements say that products used for ballast tank coatings must be type-approved but they go far beyond that simple statement with information on how the type-approval process should be carried out. A great deal of the PSPC is about preparation of the tank surfaces and structures. This is understandable given that even the best coatings will fail if surfaces have not been properly prepared. Inspection standards are also covered in the standard.

Effect of ballast treatment on coatings

Effect of ballast treatment on coatings

One aspect that was not covered in the PSPC, and which some consider a serious omission, is the potential for some ballast water treatments systems – particularly those that make use of active substances – to be incompatible with the particular coatings used on individual ships. There is a degree of dispute between coatings manufacturers and treatment system suppliers as to which of them should test for compatibility.

Some treatment system makers have begun tests with different coatings and can give assurance but with so many systems and coatings on the market there are many permutations and owners should initiate discussions on compatibility at an early stage if later problems are to be avoided.

Most of the many paint products marketed as suitable for ballast tank coatings are epoxy systems with high abrasion resistance. The ability of the coating to be able to withstand abrasion is essential given that, even after filtering, most ballast water will contain fine grit and sand. With the constant moving of the vessel when at sea, the presence of this grit can easily strip less-robust coatings in a very short period allowing corrosion to set in quite quickly.

Crude oil tank coatings and PSPC

Four years after the PSPC for ballast tanks was adopted by the IMO, a similar regulation was adopted to cover the cargo tanks of crude oil tankers. It would appear that the move was necessary due to the move from single-hull to double-hull crude oil tankers. The phenomenon of accelerated corrosion in cargo oil tanks had begun to be investigated in the mid to late 1990s when double-hull tankers became common.

A 1997 report by the Oil Companies International Marine Forum (OCIMF) suggested that, in addition to the more conventional corrosion mechanisms, a possible contributory cause of accelerated corrosion has been microbial attack from bacteria in the cargo oil.

It would appear that, as crude oil is often loaded at temperatures higher than ambient air and sea temperatures, during the loaded passage the temperature of the cargo tank structure is being maintained at higher levels than normal due to the insulating effect of the double hull spaces.

SOLAS Regulation II-1/3-11, which entered into force on 1 January 2012, on corrosion protection of cargo oil tanks of crude oil tankers, requires cargo oil tanks to be protected against corrosion and makes IMO Resolution MSC.288(87) Performance Standard for Protective Coatings for Cargo Oil Tanks of Crude Oil Tankers mandatory.

These regulations are generally referred to as PSPC COT. As with the PSPC for ballast tanks, the regulation is directed more to the shipyard and coating supplier than to the vessel owner although the obligation to maintain and repair does pass to the owner on delivery.

Since SOLAS did not actually contain a definition of a crude oil tanker, it was necessary to address this omission as well.

The new regulation came into force in January 2012 and applies to crude oil tankers of 5,000dwt and above for which the building contract is placed on or after 1 January 2013 or, in the absence of a building contract, the keels of which are laid or which are at a similar stage of construction on or after 1 July 2013, or the delivery of which is on or after 1 January 2016.

It was already common practice to apply protective coatings in the upper and lower areas of cargo oil tanks but the IMO PSPC COT regulations set out more exact specifications. The following areas are the minimum areas that shall be protected according to the IMO text:

  • Deckhead with complete internal structure, including brackets connecting to longitudinal and transverse bulkheads. In tanks with ring frame girder construction the underdeck transverse framing to be coated down to level of the first tripping bracket below the upper faceplate.
  • Longitudinal and transverse bulkheads to be coated to the uppermost means of access level. The uppermost means of access and its supporting brackets to be fully coated.
  • On cargo tank bulkheads without an uppermost means of access the coating to extend to 10% of the tanks height at centreline but need not extend more than 3m down from the deck.
  • Flat inner bottom and all structure to height of 0.3m above inner bottom to be coated.

Coatings must be type-approved according to strict guidelines aimed at simulating exposure to a generic crude oil.

The development of a testing protocol for new products was entrusted by the IMO to the International Paint and Printing Ink Council. To undertake this work, the council established a working group that was composed of representatives from class societies, shipowner groups, shipyards, testing laboratories and coating companies.

The PSPC COT approval process for the actual coating on a vessel follows closely the procedures used in the PSPC for ballast tanks including the requirements for surface preparation, for a CTF and a target useful life of 15 years in ‘good’ condition for the coating.

Most of the leading coatings manufacturers have developed type-approved coatings to meet the standard so compliance should not present any problems for owners.

Corrosion resistant steel as an alternative to coatings

For owners looking for an alternative option to coatings for newbuildings, Japanese class society ClassNK has developed what it claims as the world’s first set of guidelines for the application of corrosion-resistant steels to the cargo oil tanks of oil tankers. They were accepted as an alternative to coatings as part of Resolution MSC.289(87).

As a result, crude oil tankers over 5,000dwt contracted for construction after 1 January 2013 are able to use corrosion-resistant steel for the inner surfaces of cargo oil tanks. As the use of corrosion-resistant steel eliminates the need for the expensive facilities, preparation and finishing work associated with coating application, while reducing the need for maintenance and coating reapplication, the demand for such steels is expected to grow in the future.

The Guidelines on Corrosion Resistant Steel for COT document was released in January 2012.  Clearly construction of any ship using this material could not have begun until then and given the two to three year lead time for new buildings, ships constructed of it would only have been delivered from 2014/15 onwards. It is too early to estimate how the cost of corrosion-resistant steel will compare with conventional material through the lifetime of a ship. ClassNK is confident that any additional cost will be more than offset by avoiding the additional time, labour and resources needed to apply coatings.

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