Titanium Grade 1-4 is pure Titanium, the other grades are alloys. Pure Titanium is used due to it's high corrosion resistance, the alloys because of the extremely high strength to weight ratio.
Grade 1 - Pure Titanium, relatively low strength and high ducility. Plate heat exchangers
Grade 2 - The pure titanium most used. The best combination of strength, ducility and weldability. Piping systems.
Grade 3 - High strength Titanium, used for Matrix-plates in shell and tube heat exchangers.
Grade 5 - The most manufactured titanium alloy. Exceedingly high strength. High heat resistance. Aerospace, subsea.
Grade 7 - Superior corrosion resistance in reducing and oxiding enviroments. Chemical Industry.
Grade 9 - Very high strength and corrosion resistance. Hydraulic piping, subsea.
Grade 11 - Applications as for gr 7. Suitable for deep drawing.
Grade 12 - Better heat resistance than pure Titanium. Applications as for grade 7 and 11. Shell and tube heat exchangers.
Visit the Ti-TEK (UK) Ltd website for more information on Grades of Titanium