The following guidelines will assist you in choosing the most economical
 grade of stainless steel for a particular application.  Basically, the
 stainless steel must have properties (strength, corrosion resistance, etc.)
 suitable for the application, be capable of fabrication into the  desired
 part, and be readily available in the product form desired.

The listing that follows ranks the stainless steels by decreasing cost,
 (Type 330 the most expensive) and by decreasing corrosion resistance
 (Type 409 being the least corrosion resistant).

     Alloy     Relative Cost
     -----     -------------
     330            2.5       These are relative guidelines only.  Cost is
     310            2.3        dependent on product form, quantity and other
     309            2.0        factors.
     316            1.3
     304L           1.1
     304 *          1.0
     301            0.9
     201            0.8
     430            0.7
     409            0.6

* Type 304 is often a good choice for the best combination of properties and
   cost.

- Can Type 301 be used instead of Type 304 ? - Compare.
- Can an alloy in the 400 series be used instead of the 300 series?
- Use 304 rather than 304L, unless weld corrosion resistance is critical.

Consider the overall, installed, cost for the use of stainless steel.  Often
 it is justified when total service life is evaluated versus a lower initial
 cost for non-stainless steel.

The engineer's objective is to select and use the least expensive material
 which will meet the requirements of the service conditions, and perform in an
 acceptable manner over the desired service life of the equipment.  When
 fabrication and installation costs are taken into account, in addition to the
 cost of the raw materials, the engineer often finds that the most durable
 material is only slightly more expensive than the least durable.  When the
 owner also considers life cycle, or downstream maintenance costs, he often
 finds he can not afford the lower cost material.  In comparing costs, it is
 desirable to consider costs under the following general headings.
   1. Cost of raw materials
   2. Manufactured cost - Materials plus labor to manufacture.  Includes
       items such as pumps, valves, filters, pipe, fittings, pressure vessels,
       heat exchangers, etc.
   3. Installed cost - Manufactured cost plus labor to install.  The cost of
       installing piping greatly alters the comparative costs of the pipe and
       fittings.
   4. Life cycle, or maintenance and repair costs - The costs of periodic
       maintenance and renewal can make the lower cost material the most
       expensive to use in the long run.

Manufactured or OEM costs are obtained from the manufacturers.  Installed
 costs can often be found in the open literature under costs.  Chemical
 Engineering magazine has published a number of excellent articles on
 equipment and installed costs.  Life cycle and downstream costs are tracked
 by individual companies and by the larger engineering firms but are seldom
 published.

For further information consult NiDI Publication 10 002  "Evaluating the
 Installed Cost of Corrosion Resistant Piping".