Selection of the proper type of steel to resist corrosion is

the main prerequisite in obtaining satisfactory service. Choice

of a grade that will resist the expected environment, with a

factor of safety for normal operational variations, has been

generally carried out in one or two steps where service data

are not available. The first has been to check handbooks and

trade literature to determine which materials might be suit-

able. Since this information is usually based on chemically

pure reagents, it has often been necessary to carry out spool

or other plant tests. The latter procedure is, of course, feas-

ible only if the process is already in operation.

The purpose of this guide is to aid the materials or cor-

rosion engineer in selecting the proper type of material for

corrosion resistance by making available the vast amount of

data accumulated over many years by The International

Nickel Company, Inc. Since they cover the corrosion resist-

ance under commercial conditions in commercial mediums

as well as in chemically pure reagents, it is possible in many

cases to arrive at the best grade without additional tests.

Nevertheless, since these data are the results of actual tests,

other factors such as presence of contaminants, resistance

of welded joints, galvanic attack, nonuniformity of solutions

and differences in operating conditions also have to be taken

into consideration. For instance, a heated surface will usually

corrode faster than t~e same material exposed at the tem-

perature of the solution. Some applications also involve ero-

sion or abrasion, the effects of which cannot be predicted from

simple corrosion tests.