Corrosion defects

The specific test was made into a specialized bunker of one partner of the CIAPES program. All the vessel was covered by AE sensors to locate witli accuracy AE sources. The corrosion defect was situated on the bottom of the vessel. The service pressure of the vessel was 8 bars, so the vessel was first submitted to a proof test at 12 bars. During this test, the pressure was increased with load holds in order to verify the assessment criteria. After the first hold at 4 bars, a cluster was located at the position of the defect. The number of events located in this cluster increased during all the test (figure 1). 

The Zond VD - 96 is intended for the detection of cracks, precipitates, inclusions etc. and corrosive defects with the preliminary estimation of their depth in various objects of magnetic and non - magnetic steels, non-ferrous and refractory metals and welds including coatings. 

High sensitivity for both small surface cracks and bigger inner fractures and corrosive defects under the layer of a non - magnetic metal to 7 mm, also through the skins. 

Corrosive defects detection under the airframe skin and protective coatings. 

Corrosive defects detection in the body load - carrying structures, engine parts, camshafts etc. 

Figures 21a and 21b are SEM micrographs of metal line corrosion defects from the top view and from the cross-sectional view. The cause was...

Fig. 21. SEM micrographs for metal line corrosion defects post-CMP cleaning from (a) a top view and (b) a cross-sectional view.

Figure 22.5 shows the current map above the surface of the sol-gel film loaded with NIR-sensitive containers recorded after 24 h of immersion before and after irradiation with an IR-laser. The corrosion disappears immediately after irradiation of the local defect area. Thus, the healing of the corrosion defect is induced by remote IR opening of the inhibitor-loaded containers near the defects. Moreover, these films are characterized by high anticorrosion ability during aging. 

What if vessel ruptures due to internal corrosion, defective materials, or poor... 

FIGURE 4.33 (a) The corrosion defects observed after annealing for 8 h at 180°C. (b) The corrosion defects observed after annealing for 128 h at 180°C. 

In-line inspections (ILI) are useful in obtaining a profile of defects in a pipeline. High-resolution UT and MFL ILI tools can be used to determine the geometry and orientation of corrosion defects. 

Some field data on corrosion defects such as (i) perforation (ii) surface rust (iii) blistering, and (iv) other defects are given in Table 4.37. 

With a given size of a crack-like surface flaw (a) and a known geometrical function Y, the values of Kic and Kiscc can be used to calculate the permissible stress by Equation (7.11), for applications in air and the actual corrosive environment, respectively. For corrosive conditions one must take into account the deepest local corrosion defect that may develop during the plarmed lifetime. 

Analysis of electrochemical current noise Detection of pitting corrosion defects, signatures of specific corrosion types (pitting or crevice vs general) W(Mxl et al. (2002), Sulyma and Roy (2010h), Monticelli et al. (1998)... 

Different from PR/FM and scratches, one unique characteristic of HM, DE, and corrosion-related defects is their time dependence the longer the wafer remains in the ambient, the more corrosion defects there will be. Such queue time effects on defects begin immediately after barrier metal is deposited and will not stop until the cap layer is deposited on the post-CMP Cu surface. HM defects are found to increase with increasing queue time between anneal and CMP as well as between CMP and cap [22]. The hndings reveal the time dependence nature of corrosive attack that can lead to HM defects. 

Corrosion defects developed are similar to those observed on weathering (blisters, pits, cracks, flaking). 

After four years of operation, a decrease of the potential by over 100 mV was noted on the whole surface of the pipeline. The protection current density did not exceed 7 mA m . Gravimetric and resistometric tests have shown an over 95% effectiveness of CP. No corrosion defects were stated on LIDA anodes. The installation is still... 

Once corrosion defects have been found, the remaining strength of the pipe should be estimated using a standard calculation routine... 

Metal loss tools are used to detect defects that have resulted in wall thinning in a pipeline. They can discriminate to some extent between manufacturing defects, corrosion defects and mechanical damage. There are two main typ>es of tools ... 

Under static conditions at T = 600°C there is only a slight tendancy of HN80MT to intergranular cracking and corrosion defects are observed along grain boundaries at a... 

A sound corrosion failure model should thus be based on core principles with extensions into real-world applications through adaptive revision mechanisms. A universal representation describing the interactions among defects, faults, and failures of a system is shown in Fig. 4.15. The arrows in this figure imply that quantifiable relations, characteristic of a specific system, exist between a defect, a fault, and a failure. The nature of various corrosion defects is introduced in Chap. 5, Corrosion Failures, in the section on forms of corrosion. Also in Chap. 5, the factors causing these defects have been related to the fun-... 

Figure 4.20 An object-oriented representation of the probability of detection of a corrosion defect.

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