21
Table 20. Dimensioning corrosion of unconcreted micropiles in 100 years in different conditions.*
Conditions
Corrosion in 100 years [mm]
Homogeneous natural soil conditions above and below ground water level
1.2
Compacted mineral soil fills above and below ground water level
1.5
Non-compacted mineral soil fills above and below ground water level
2.0
* Jouko Törnqvist: Corrosion steel pipe piles. Dimensioning based on empirical material VTT Technical Research Centre of Finland (2005).
• Espoo (2005)
Table 21. Recommended values for thickness reduction of bearing piles and sheet piling installed in fresh or sea water
due to corrosion [mm].
Design life required in designs
5 years
25 years
50 years
75 years
100 years
Normal fresh water (river, navigable channel, ...)
in a high stress (water line)
0.15
0.55
0.90
1.15
1.40
Badly polluted fresh water (sewage, industrial waste water...)
in a high stress area (water line)
0.30
1.30
2.30
3.30
4.30
Sea water in temperate climate in high stress area
(shallow water and splash zones)
0.55
1.90
3.75
5.60
7.50
Sea water in temperate climate in areas permanently under water
and tidal zones.
0.25
0.90
1.75
2.60
3.50
Note:
1) Corrosion rate is usually highest in a splash or tidal zone at low tide level. In most cases, however, the highest flexural stresses occur
in areas permanently under water.
2) Values for 5 and 25 years are based on measurements, while others have been extrapolated.
Table 19. Average surface corrosion [mm] of unprotected steel piles in soil above and below ground water level.
Target service life
5 years
25 years
50 years
75 years
100 years
Normal conditions
Undisturbed natural soils (sand, silt, clay, …)
Non-compacted, non-aggressive mineral soil fills
(clay, sand, silt, …)
0.00
0.18
0.30
0.70
0.60
1.20
0.90
1.70
1.20
2.20
Exceptional or aggressive conditions
Contaminated natural soils and soils in industrial areas
Aggressive natural soils (swamp, marsh, peat, …)
Non-compacted aggressive fills (ash, slag, …)
0.15
0.20
0.50
0.75
1.00
2.00
1.50
1.75
3.25
2.25
2.50
4.50
3.00
3.25
5.75
Note: Corrosion rates are lower in compacted than in non-compacted fills. In the case of compacted fills, the values for
non-compacted fills can be divided by two.
The values are indicative. Local conditions must be taken into account.
The values for a service life of 5 and 25 years are based on measurements, other values have been extrapolated.
Corrosion in air in one hundred years: 1 mm in normal climate and 2 mm near the sea.