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The cost of components and equipment properly designed in titanium is never as high as the price by weight of the metal suggests.
Many designs are based on use of metal by surface area rather then by weight. The strength, lower density and good corrosion resistance of taitanium are all factors which keeps its cost down.
Case Study – Elf Petroleum Norge Offshore Pipework
Elf Petroleum Norge has been an active contributor to cost optimisation and usage of the effect from the cold forming techniques. A pilot project has been set up in Frigg field.
The Scenario
A carbon steel pipe system for seawater was exchanged because of corrosion. Pipe diameter was 6inches (150mm), estiomated pressure 19 bar and total pipe length was 200 metres or 660 feet.
Carbon steel and titanium were evaluated and compared.
Carbon Steel Cost Considerations
The cost for the carbon steel alternative contained purchase pre-fabrication, installation and transport costs. All costs were calculated according to general practice with welded fittings, sand blasting, painting etc.
Titanium Cost Considerations
The costs for titanium were based upon an effective usage of some of the special properties of the material such as ductility, corrosion resistance, low modulus, strength and density.
Fabrication Advantages
Cold bending techniques resulted in a reduction of more than 80% of the welding work. Purchase of bends, fittings and welded flanges were avoided. The purchase could be reduced to straight pipes and loose stainless steel (316) flanges. Pipe ends were flanged with portable pressing out tools. Welding was avoided during the erection period.
Corrosion Advantages
Surface treatment like sand blasting and painting was unnecessary because of the good corrosion resistance.
Weight and Density Advantages
The good strength to density ratio resulted in low weight of the simple “pipe spool”. A 6 inch tube with a length as much as 6 metres would be carried by one person without any help by lifting or transport equipment.
Maintenance and lifetime costs are not included in the coat comparison.
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