SEDL / STP / STP741-EB / STP28253S

Corrosion and Corrosivity of Steel in Norwegian Marine Sediments

Fischer, KP
Senior research engineer, The Ship Research Institute of Norway, Sandefjord,

Bue, B
Research scientist, Norsk Hydro, Sandvika,

Pages: 9    Published: Jan 1981

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Abstract

Various guidelines are to be found in the literature for evaluation of soil corrosivity based on parameters like resistivity, pH, water content, redox-potential, content of salt, and bacterial activity. Corrosion studies of steel piles and pipes in Norwegian marine clayey sediments show that these parameters are not always applicable. Studies of piles in undisturbed marine clays below the groundwater table indicate a limited correlation between the resistivity and the corrosion rate. The highest corrosion rates found amount to 30 μm/year indicating that pile corrosion is not a severe problem under the aforementioned conditions. The environmental conditions for pipes are generally much more complex than for piles, as the backfill is disturbed and often includes material other than the original sediment. Studies of pipes in a heterogeneous environment indicate differential aeration to be the most common corrosion cause.

Corrosivity evaluations are also performed with electrochemical probes.