Page 190 - Plant design and economics for chemical engineers

164 PLANT DESIGN AND ECONOMICS FOR CHEMICAL ENGINEERS
index value at present time
Present cost = original cost
index value at time original cost was obtained

Cost indexes can be used to give a general estimate, but no index can take
into account all factors, such as special technological advancements or local
conditions. The common indexes permit fairly accurate estimates if the time
period involved is less than 10 years.
Many different types of cost indexes are published regularly. Some of
these can be used for estimating equipment costs; others apply specifically to
labor, construction, materials, or other specialized fields. The most common of
these indexes are the Marshall and Swif all-industry and process-industry equip-
ment indexes, the Engineering News-Record construction index, the Nelson-Farrar
refnev construction index, and the Chemical Engineering plant cost index. Table 3
presents a list of values for various types of indexes over the past 15 years.

Marshall and Swift Equipment Cost Indexes-f

The Marshall and Swift (formerly known as Marshall and Stevens) equipment
indexes are normally divided into two categories. The all-industry equipment
index is simply the arithmetic average of individual indexes for 47 different types
of industrial, commercial, and housing equipment. The process-industry equip-
ment index is a weighted average of eight of these, with the weighting based on
the total product value of the various pr ess industries. The percentages used
for the weighting in a typical year are as fo ows: cement 2; chemicals, 48; clay
?3eum, 22; and rubber, 8.
products, 2; glass, 3; paint, 5; paper, 10; petr
The Marshall and Swift indexes are based on an index value of 100 for the
year 1926. These indexes take into consideration the cost of machinery and
major equipment plus costs for installation, fixtures, tools, office furniture, and
other minor equipment. All costs reported in this text are based on a Marshall
and Swift all-industry index of 904 as reported for January 1, 1990 unless
indicated otherwise.

Engineering News-Record Construction
Cost Index*
Relative construction costs at various dates can be estimated by the use of the
Engineering News-Record construction index. This index shows the variation in

tValues for the Marshall and Swift equipment cost indexes are published each month in Chemical
Engineering. For a complete description of these indexes, see R. W. Stevens, Chetn. Eng., 54(11):124
(Nov., 1947). See also Chem. Eng., 85(11):189 (May 8, 1978) and 92(9):75 (April 29, 1985).
SThe Engineering News-Record construction cost index appears weekly in the Engineering News-
Record. For a complete description of this index and the revised basis, see Eng. News-Record,
143(9):398 (1949); 178(11):87 (1967). History is in March issue each year; for example, see Eng.
News-Record, 220(11):54 (March 1.5, 1988).