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‘Corrosion Management: An Iceberg for Indian Shipping Industry’
- M Valliappan, Corrosion Management Consultant, We CAN Control Corrosion in India Network
According to Assocham analysis, 466 vessels of Indian fleet have crossed operational life of more than 20 years. These aged vessels need refurbishment, which involves whopping investments. Corrosion in ships is taking a toll on the industry. This article emphasises that efforts on minimising the life cycle cost through implementing corrosion control methods and appropriate integrity assurance programs is the need of the hour for Indian maritime sector.

India envisages growth potential in shipping industry. The capacity expansion would be undertaken across cargo ships segment such as bulk carriers, tankers, etc. New building of ships is to be used for offshore oil & gas exploration, towage and coastal security. On the other hand, there is a greater shipping demand to deal with refurbishment of aged carriers. Industry analysis showed that over 41 per cent of Indian ships having crossed 20 years of operations leading to opportunities worth Rs 20,000 crore in the shipbuilding and ship-repair industry sector. Ships older than 20 years require frequent and extensive repair and maintenance. This augurs well for the Rs 7,300-crore worth shipbuilding industry, according to an analysis of Indian Shipping Fleet: Size, Capacity and Age Composition conducted by The Associated Chambers of Commerce and Industry of India (Assocham). It is said that India has a total of 1,122 ships in its fleet and 41 per cent of these, or 466 vessels, fall in the age group of 20 years and more. Considering that the average life of a shipping vessel is about 26 years, most of the existing vessels need to be replaced. An average cost of constructing a large vessel is about USD 100 million. Therefore, the size of this opportunity would be USD 3.3 billion.

This whopping figure of refurbishment cost triggers the industrial community to explore the causes for failures. Although these opportunities are often linked with investment in this sector, this is not a good news for the life cycle analysis and material conservation. How do these failures happen? Corrosion of ship construction materials, the serious concern, often neglected by the industry is paving the way for greater impact in the life cycle cost. Marine fouling is another alarming area that fuels the parameters responsible for corrosion damage. These failures pose greater challenges to the ship owners not only in the materials part, but also leading to high demand for energy consumption and sizeable investment on environmental management.

Shipbuilding is a basic metal industry and depends heavily on the use and forming of steel, at least with respect to the construction of larger ships, while smaller ships and boats can be constructed of aluminum, wood or composite materials such as fiberglass. Base materials include iron-containing steel (i.e. carbon steel) and non-iron-containing metals. Various grades of mild and high strength steel are used for the structural framework of most ships, while aluminum and other non-iron-containing materials are used for some superstructures and other areas with specific requirements for corrosion resistance.

Ships are built for a specified design life. A design life is specified so that all calculations with regard to the ship’s construction are focused on the exposure of the structure to the risks involved. The new IACS Common Structure Rules are said to conform to the 25 year design life set by the IMO Goal Based Standards, however, they set much lower corrosion allowances than the ones set by the present 20 year lifetime rules. The ship’s actual service life may be longer or shorter depending on the actual operating conditions and maintenance of the ship throughout its life cycle. Experience has shown that the present corrosion allowances of even the more conservative classification society are marginally adequate for a 20-year design life vessel. For certain parts of the ship they are clearly inadequate. Ship hulls need protection against corrosion and the attachment of marine organisms such as algae and barnacles, known as biofouling that negatively affects the hydrodynamics of the hull, increasing drag and thus the necessary propulsive power. As well as increasing fuel costs up to 40 per cent this also necessitates regular visits to shipyards for hull cleaning.

There are various forms of corrosion encountered in shipping industry. Many different types of destructive attack can occur to structures, ships and other equipment used in sea water service. The effects of corrosion on naval operation have become more prominent as the acquisition of new equipment has slowed and more reliance is placed on the service of aging equipment. Recent studies in the US indicate corrosion is having an enormous impact on military costs, representing one of the largest through life cost components of military systems. These costs include the direct costs such as the manpower and material that are used to repair the damage resulting from corrosion and the indirect costs that were they to be quantified, would significantly increase the total reported costs, such as the vessel or systems degraded availability. Corrosion also poses numerous safety risks and is currently a source of major concern to platform managers. Generic corrosion susceptible areas: Outer hull; Ballast tanks; Fuel tanks; Fresh, grey, black water tanks; Bilges; Pipe work and cooling systems; Holds and storage tanks; Boilers and engines; Rudders; Propellers; Bearings; Flanges; Valves; Pumps; Void spaces; Sea chests; Stabilizers.

Ship owners and operators recognise intuitively that combating corrosion impacts significantly upon vessels’ reliability, availability, through life costs and budget availability for replacement projects. It is highlighted that corrosion should be viewed as an acquisition risk and as such should be managed like any other risk by inviting procurers to consider at an early stage a number of corrosion prevention or reducing measures to mitigate the effects of corrosion and attendant through life costs.

In order to maintain shipping capacity to serve seaborne trade, new ships have to be built to replace those scrapped. The cost of building, manning, operating, maintaining and repairing a ship throughout its life is borne by society at large through market mechanisms. A life cycle analysis indicated that ships built with sufficient corrosion allowances, truly adequate for the ship’s design life, have a lower life cycle cost per annum despite the fact that such ships would carry a slightly smaller quantity of cargo.

It is argued in the related cost analysis that steel renewals required because of the degradation of structural steel, despite the commercially acceptable effective maintenance carried out at scheduled repair periods, cannot be considered maintenance. Designing ships that need to have main structural elements or extensive scantlings replaced during their design life, misrepresents the concept of “Design Life”.

In some instances, it is not possible to prevent corrosion either by design or material selection and so management of the corrosion rate and its process must be considered. Depending upon the structure to be protected and its operating environment, there is a wide range of anticorrosion strategies that may be used. It is important to ensure that the selected option is feasible and is available at the construction location. Corrosion prevention and control methods can include adding additional layers of protection such as paint or galvanising, the use of cathodic protection as sacrificial anodes or as an Impressed Current Cathodic Protection (ICCP) system. The effectiveness of each method will depend upon the local conditions and on the method itself.

There is a greater challenge associated with implementing corrosion control methods, especially protective coatings. Construction, maintenance, and repair activities involve the generation and daily handling of a large number of toxic materials, fumes and fluids. It is essential that specifications, procedures and the various different steps in the coating application process (including, but not limited to, surface preparation) are strictly applied by the shipbuilder in order to prevent premature decay and/or deterioration of the coating system.

Indian Scenario
The Indian shipping industry in the current scenario has not been so proactive in embracing the use of environment friendly technologies. The industry has accepted and implemented all the technologies and practices, which have become mandatory to be used in the ships. There is large scope for voluntary use of some of the technologies that are friendly to environment and also help in bringing down the operating and maintenance cost of ship. However, the ship owners, in general, are not ready to try the newer technologies unless they find visible and tangible benefits of using them. The primary reason for this is the cyclicity of the shipping industry. Shipping companies first tend to expand to newer fleet and sometimes diversify on the gains they make from high charter rates. Rest of the time they try to make their ends meet. This does not leave much room for them to try newer technologies. Most of the companies are conservative in their approach.

We see opportunities for establishment of academic and research institutions to effectively deal with developments in nautical science and engineering through various government schemes. But the effective dissemination of life cycle analysis of shipping industry, especially corrosion management, is questionable.

It is argued in shipping industry that the implementation of a full-fledged life-cycle approach would not be an easy task. The process goes well beyond environmental management systems, which to some extent have been implemented by the industry, and demands greater information sharing and collaboration between input manufacturers, construction yards, shipping companies, ship owners and dismantling and recycling yards.

Although efforts on minimising life cycle threats are taken through various initiatives, the present status of collaboration between these sources raises questions on the effective utilisation of produced results. There are various stages of shipping industry project that call for involvement of corrosion management as depicted in the figure.

Corrosion Management appears to be an iceberg for shipping industry in India. If the efforts on minimising the life cycle cost through implementing corrosion control methods and appropriate integrity assurance programs are attempted at very slow nautical pace, we will end up in loosing the significant material resources and heavily impacting our marine environment.