Titanium and titanium alloys have very good stability in organic compounds except for five organic acids (formic acid, acetic acid, oxalic acid, trichloroacetic acid, and trifluoroacetic acid) at higher temperatures. Therefore, titanium is an excellent structural material in petroleum refining and petrochemical industry and can be used for making various reactors, pressure vessels, heat exchangers, separator piping, distillation tower top condenser lining, and the like.
In oil and gas drilling, the United Kingdom uses titanium drilling equipment in 5% H2S and 25% NaCl with a depth of 600m and 262°C. The former Soviet Union used titanium pumps, titanium valves, and titanium flushing brine equipment. In China, the natural gas wellhead is used to solve the corrosion of high-temperature H2S, CO2 and water vapor of 600-700 atm. The valve plate, valve seat and valve stem of Ti-6Al-4V are used, which has a good long-term effect.
Offshore oil and gas exploration is subject to seawater corrosion and stress corrosion for a long time. Ti-6Al-4V is widely used as a petroleum platform pillar, rope support, high-pressure pump, riser and coupling for seawater circulation pressurization system. Because Ti-6A1-4V is not only resistant to seawater corrosion but also has high toughness, high yield strength, and high fatigue limit. Recently, titanium prestressed oil pipe joints have been selected abroad. This joint is quick and easy to assemble, light in weight and maintains elastic sealing. Titanium is the best-preferred material. China’s offshore oil industry is entering a stage of large-scale development.