Page 394 - Corrosion Engineering Principles and Practice

362 C h a p t e r 9 A t m o s p h e r i c C o r r o s i o n 363

Sulfur Dioxide Chloride
Sulfur Dioxide Deposition Rate Chloride Deposition Rate
2
Category (mg/m day) Category (mg/m day)
2
P ≤10 S ≤3
0 0
P 11–35 S 4–60
1 1
P 36–80 S 61–300
2 2
P 81–200 S 301–1500
3 3
TABLE 9.2 ISO 9223 Classification of Sulfur Dioxide and Chloride Pollution
Levels
Time of
Wetness Wetness Time of Wetness Examples of
Category (percent) (hours per year) Environments
T <0.1 <10 Indoor with
1
climatic control
T 0.1–3 10–250 Indoor without
2
climatic control
T 3–30 250–2500 Outdoor in dry,
3
cold climates
T 30–60 2500–5500 Outdoor in other
4
climates
T >60 >5500 Damp climates
5
TABLE 9.3 ISO 9223 Classification of Time of Wetness

TOW Cl - SO Steel Cu & Zn Al
2
T S or S P 1 1 1
1 0 1 1
P 1 1 1
2
P 1–2 1 1
3
S P 1 1 2
2 1
P 1 1 2
2
P 1–2 1–2 2–3
3
S P 1–2 1 2
3 1
P 1–2 1–2 2–3
2
P 2 2 3
3
T S or S P 1 1 1
2 0 1 1
P 1–2 1–2 1–2
2
P 2 2 3–4
3
TABLE 9.4 ISO 9223 Corrosivity Categories of Atmosphere