Steels_ Metallurgy and Applications, Third Edition

Stainless steels 377

Table 4.22

~pe Maximum pit density (l~m)

Unsheltered Sheltered

Washed Unwashed Washed Unwashed

304 55

315 37

316 25

317 22

After Stone et al. 43

85 88 102

39 50 72

24 46 70

18 25 24

Figure 4.44 North Sea oil rig with accommodation module clad in ~pe 316 stainless
steel (Courtesy of British Steel Stainless)

architecture in place of traditional painted mild steel. An example is shown in
Figure 4.44. In the North Sea, the environment is particularly aggressive and the
high corrosion resistance of Type 316 is attractive. However, fire resistance is a
very important requirement which rules out the use of organic materials and also
raises questions as to the integrity of low melting point metals such as aluminium.
In the event of fire, stainless steel is also preferable to painted mild steel because
of its higher strength at elevated temperature and the elimination of the smoke
or toxic hazards associated with burning paint.
Because no corrosion allowance is required, stainless steel module walls can be
up to 50% thinner than similar components in mild steel, resulting in significant