The cost of equipment properly
designed in titanium is never as high as the price by weight of the metal
suggests. Most designs are based on use of metal by surface area rather
than by weight, and the strength, lower density and corrosion resistance
of titanium are all factors which keep costs down.
Index on econimcal topics:
First Cost
Running cost
Maintenance and downtime
Availability of titanium
Production and range of semi-finished products
Guidelines to design cost control
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First cost
A cost comparison carried out for two heat exchangers and a pressure vessel
shows how titanium
provides the least expensive initial cost, compared to a range of corrosion
resistant materials, even
before life-cycle benefits are considered.
| Material |
Cost comparison |
| Vessels |
Heat Exchangers |
| Ti Grade 2 |
1.0 |
1.0 |
| Ti Grade 7 |
1.3 |
1.3 |
| Ti Grade 12 |
1.05 |
1.1 |
| Incoloy 825* |
1.1 |
1.1 |
| Zr Grade 702 |
1.3 |
1.4 |
| Hastelloy B-2^ |
1.6 |
1.6 |
| Hastelloy C-276^ |
1.5 |
1.6 |
*Registered name of INCO.
^Registered name of Haynes.
Although pipe and tube are normally quoted and sold by metre, substantial
tonnages may be sold by weight. Hence there may be a tendency to exclude
titanium as apparently uneconomical. A more studied approach would almost
certainly show not only that titanium has lower first cost, but also substantial
life cost savings and downstream technical benefits. Weight for weight,
a titanium pipe of the same diameter and schedule will be almost twice
as long as pipe made from any one its more dense competitors. Reduction
of the schedule can cut pipe by weight by over 70%, with a substantial
reduction in the total purchase price.
Running costs
Titanium offers a many opportunities for reducing operating costs:
- Conservation of energy In aircraft reciprocating
engines and other mobile equipment, weight saving translates
into better fuel economy.
- Improved heat transfer The efficient, sustained
heat transfer provided by titanium not only improves energy
conservation, but also helps to reduce process cycle times.
- Resistance to aggressive raw materials The use
of titanium in petrochemical plant, for example, allows less
expensive crude oil to be processed even though it contains
higher levels of hydrogen sulphide.
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In many applications,
titanium has replaced heavier, less serviceable or less cost-effective
materials. Titanium-based systems offer reliability. Many have substantially
exceeded performance and service life expectations.
Maintenance and downtime
Maintenance and downtime costs may be a very significant element in plants
designed for a long service life. Titanium inherently saves cost through
reliable performance. Welded titanium tube supplied for power plant surface
condenser use has, for some time, been sold with a 40 year performance
guarantee. More recently a similar guarantee has been extended to grade
2 and grade 3 tubeplates for the same application. Many of the earlier
installations of welded tube have now
outlived their original guarantee periods several times over.
Availability of titanium
Titanium is the fourth most abundant metal in the earths crust. Capacity
for production substantially exceeds long term forecasts of demand. Product
prices are low and stable. Titanium and rutile ore are both sourced in
friendly countries with stable regimes, unlike nickel or chromium, and
so the price of titanium has never been subject to crisis or political
factors. The ready availability of titanium in a wide and ever increasing
range of products forms has assured its growth as a basic
general engineering material. Today a network of mills, stockists, machinists
and fabricators ensure that the demands of design quality and speed of
delivery can be met. The extraction of titanium is a multi-stage process,
the first metallic product being 'sponge'. This product has no value as
an engineering material, and needs to be consolidated and melted to produce
ingots from which semi-finished products may be manufactured.
Production and range of semi-finished products
Titanium ingots are the proper starting point of metal manufacture and
are handled as the other industrial metals and alloys by forging or rolling
to produce intermediate billet or slab. Billet provides the material for
manufacture of forgings, bar, wire, and extruded or rolled/drawn seamless
tube and pipe. Slab provides the starting material for the production
of plate,strip, sheet and foil welded tube produced from strip. Castings
are produced either from remelted ingot or billet, or from
electrodes made up from revert material. Cast weldments enable large components
exceeding the limits of individual casting weight, typically 750kg(1650lb),
to be supplied. A combination of forging, machining and fabrication provides
the route to all requirements for engineering products.
Guidelines to design cost control
Do:
- Check available standard products and specifications to obtain
best availability and lowest costs.
- Use design strategies based on using minimum material thickness.
- Exploit corrosion resistant characteristics to the full.
- Consider the use of liners and claddings in preference to
solid design where heavy sections are unavoidable.
- Use welded fabrication where practical in preference to forging
and machining.
- Consult suppliers and fabricators at the earliest stage of
design
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Do
not:
- Simply substitute titanium into existing designs.
- Budget for titanium project costs by weight, especially not
by the weight of steel or copper alloys.
- Specify little used alloys or forms.
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Titanium 