Corrosion depth

At the specimen surface, soft corroded layer was formed during immersion and the layer could be easily removed by wiping lightly with acetone-soaked paper and in some conditions this layer was dissolved spontaneously. The thickness of this layer was defined as corrosion depth x, and measured at various test conditions. As shown in Figure 5, corrosion depth increases linearly with time, and... 

Figure 5. Variation of corrosion depth of MTHPA-EP with immersion time in various conditions.

In MTHPA-EP and iso-UP resins, the strength of the resin below the corroded layer of specimen was same as that of before immersion. Assuming that the corroded layer has no strength, the prediction of strength after immersion was made by estimating the corrosion depth in the following way. 

Corrosion creeping from the scribe to the interface of the E-coat and the substrate surface for the surfaces with poor adhesion. The corrosion depth is similar to that of away from the scribe... 

Figure 7 Corrosion depth of a group of lance and spearheads excavated in 1994. (a) Plan view, where solid lines indicate modem excavations and dashed lines show excavations during the 19th century, (b) Vertical profile (seen from SE) where dashed line indicates interface between peat and gyttja. Solid line at each point represent a projection of the lance or spear head to the vertical view plane, so long steep lines indicate artefacts deposited in a steep angle. Numbers to the left are metres above sea level...

Table 8.6 Corrosion of steel, copper, lead and zinc in soils. Maximum corrosion depth (mm) after given periods of exposure. (Adapted from Uhlig [8.10].) The width and length of the samples are from a few inches to one foot.

Design with sufficient corrosion allowance. Pipes, tanks, containers and other equipment are often made with a wall thickness twice the corrosion depth expected during the desired lifetime. However, this must of course depend on load and maximum permissible stresses too. 

If it is decided after phase 1 to go ead with a recovery program, targets for recovery will have to be determined. For that purpose targets will have to be classified according to their physical condition, i.e. state of corrosion, depth of burial, physical size, type of shell etc. The technologies for a recovery will have to be adapted to suit targets within their respective classes. A prime concern, however, will be the recovery of fundamentally intact munitions, i.e. not free lumps of agent. 

They require rigorous, sometimes sensitive calibration between corrosion current and corrosion depth. 

Figure 3 Connection between corrosion mass ioss in the spiash zone and iocaiiy varying corrosion depth in the immersion zone after 3.5 years, materiais see Tabie 18 [15,16]...

Steel Test duration Test conditions Pitting corrosion depth. 

The corrosion depths determined after the test period under washers are listed in Table 42. 

Table 42 Crevice corrosion depths after 1 year in 1.4404,1.4539 and 1.4547 [176]...

Material Cathodic Test duration. Maximum corrosion depth. Corroded surface. 

In stagnant seawater, after 3 years of exposure, the maximum pitting corrosion depths in Table 64 were measured, clearly demonstrating the positive influence of the Cr and Mo content in these alloys. 

Table 64 Maximum pitting corrosion depths after 3 years in stagnating natural seawater of Ni-based alloys [204]...

Some of the samples were cathodically protected by contact with iron or zinc anodes. The corrosion potential was measured at intervals throughout the entire exposure duration and the depth of the crevice corrosion sites was determined. Table 67 shows the corrosion depth results in stagnating seawater and Table 68 shows the results in flowing seawater. 

Table 67 Corrosion depths in samples in stagnant seawater [205]...

Name Abbreviated designation DIN-Mat. Corrosion depth ajler 1.6 a, mm... 

FIG. 7.20. Corrosion depth of the BOR 60 fuel rod cladding (Crl6NH5Mo2) for various fuel types. 

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