A. Introduction

The high strength, low weight and outstanding corrosion resistance of titanium and its alloys have led to a wide and diversified range of successful applications in aerospace, chemical and petrochemical plant, power generation, oil and gas extraction, automotive, medical, sports and other industries. All product forms available in other industrial metals are available in titanium, among these one of the more important is commercially pure titanium thin wall welded tube, and several hundred million metres of such tube are today in service worldwide in an extensive range of chemical and petrochemical plant heat exchangers and desalination and power plant condensers Titanium resists corrosion in a wide range of aggressive media, and is immune to all of the processes of corrosion which occur in condenser operation, and which continue to cause damage or threaten operational efficiency for units tubed with less corrosion resistant metals and alloys Heaton et al. (1979). These processes are each considered in detail, in the following sections, and the mechanism for the resistance or immunity of titanium is explained. A family of titanium alloys permits design cither in thin wall welded tube, or heavier wall seamless tube or pipe to optimise the engineering properties of titanium for heat exchangers and associated equipment. Retubing of existing units may require modifications to the design to compensate for the lower modulus and density of titanium as well as its possible influence as a cathode in a mixed metal system. A checklist of essential requirements is given. Experience gathered from hundreds of heat exchangers and condensers operating in widely varying conditions has progressively exposed practices that are prejudicial to the normal long life expectation of titanium tubes.

These are identified, and guidelines are given for their reduction or elimination. Heat exchanger performance is always a significant factor in the overall operational efficiency of plant. The widespread use of low cost titanium tube which is highly resistant or immune to corrosion has not only reduced the cost of plant ownership, but set new standards in plant reliability, safety and environmental protection CodeWeld Titanium Tubing (1996).

B. Product availability

Historically the aerospace industry has been overall the largest consumer of titanium. That situation no longer applies, there now being substantial use in many non-aerospace applications including heat exchangers for newer markets in the marine and offshore oil and gas industries. Capacity in the titanium industry is adequate to supply all these new applications and new markets. Titanium available from major producers in Russia has increased the power of the industry to deliver competitively, on time, in a range of products equal to that in any other metal. Total productive capacity for titanium worldwide still exceeds the long term forecasts of demand. In these circumstances long term competitive pricing and relative price stability for heat exchanger applications may be expected.