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MARINE METALS
Although titanium applications in the offshore industry represent a small percentage of global consumption, the metal's prospects look secure. While recent sub-sea developments are expected to promote titanium's marine uses, there will be no dramatic growth offshore, writes Jennie Wilkinson.
Titanium, a metal traditionally linked with aircraft, is also used at sea in offshore applications. The aerospace industry dominates global demand for the metal, accounting for more than 50% of its overall consumption, while smaller applications (representing a few percent of global demand each), make up the rest. These include the chemical processing industry, medical and sports equipment and other industrial and miscellaneous applications.
Approximately 56,000 tonnes of the metal was consumed in 2000 (see MBM February), with a further 29,000 tonnes used in ferro-titanium production for steelmaking and in other alloying.
The offshore industry currently represents an estimated 5% of worldwide titanium demand, mainly for applications in the oil and gas sector. A major reason for low demand from this sector is because of titanium's relatively high cost - the Metal Bulletin free market price for sponge grades is US$5-7/kg.
While titanium has been used in this market for around twenty years, the main developments for titanium applications in offshore exploration in the oil and gas sector have only occurred in the past decade - perhaps another reason for its slow growth, in addition to the fact that demand from the oil and gas industry tends to be cyclical and projectspecific.
Titanium is immune to certain types of marine fouling, making it a suitable choice of material either on the "topside" of platforms or underwater. It is used predominantly in seawater pipework systems installed for ballast, cooling and fire protection duties, as well as for drill pipes, tapered stress joints, risers, flowlines and valves.
The metal's oxide film provides a barrier against corrosion in either flowing or static seawater at temperatures up to 130 deg C. Titanium is also immune to crevice corrosion in temperatures up to at least 80 deg C in seawater - conditions in which some stainless steels are limited to 10 deg C - and is also corrosion-resistant to hydrocarbons and other crude oil constituents. This corrosion resistance gives the metal a long sub-sea life...