Erosion-Corrosion and cavitation

In this chapter, we have not discussed materials corrosion under mechanical stresses, such as environmental cracking, stress corrosion cracking, erosion-corrosion, and cavitation-corrosion. [Pg.585]

Movement of the electrolyte over a metal surface can cause erosion corrosion, impingement, or cavitation. The corrosiveness of the environment will accelerate the degree of corrosion. Standardized methods for evaluating erosion corrosion and cavitation involve immersion testing in the laboratory or operating system. Analysis is typically performed by visual examination and weight loss data. The following standards are commonly used to evaluate susceptibility to erosion corrosion and cavitation ... [Pg.179]

ASTM G 40, Terminology Relating to Wear and Erosion— This contains terms and their definitions relating erosion corrosion and cavitation of materials. [Pg.179]

Indirect attack can also occur because of turbulence associated with flow over and around a deposit. Increased turbulence may initiate attack (see Chap. 11, Erosion-Corrosion and Chap. 12, Cavitation Damage ). [Pg.69]

Erosion-corrosion, including cavitation erosion and fretting corrosion Intergranular corrosion, including sensitization and exfoliation Dealloying... [Pg.15]

It is often localized at areas where water changes direction. Cavitation (damage due to the formation and coUapse of bubbles in high velocity turbines, propellers, etc) is a form of erosion corrosion. Its appearance is similar to closely spaced pits, although the surface is usually rough. [Pg.268]

Erosion and cavitation both can degrade materials simply by mechanical means or by combining the effects of mechanical deterioration and corrosion to produce a synergistic result. However, the mechanisms by which erosion and cavitation operate, and the resulting damage, are quite distinct. [Pg.271]

Plate anodes were used for corrosion protection in order to avoid damage due to erosion and cavitation. These consisted of enamelled steel bodies in which a metal oxide-coated titanium anode 1 dm in surface area was fitted. The enamel... [Pg.470]

Noise generation and erosion/corrosion considerations limit the maximum water velocity in pipework systems. Noise is caused by the free air present in the water, sudden pressure drops (which, in turn, cause cavitation or the flashing of water into steam), turbulence or a combination of these. [Pg.408]

Erosion-corrosion in the widest sense of the term will include impingement attack, cavitation damage and fretting corrosion, but since the latter two are dealt with in separate sections (see Sections 8.7 and 8.8) they will not be considered here. [Pg.190]

This type of damage is dealt with comprehensively in Section 8.8. It can be particularly severe in seawater giving rise to cavitation corrosion or cavitation erosion mechanisms, and hence can be a considerable problem in marine and offshore engineering. Components that may suffer in this way include the suction faces of propellers, the suction areas of pump impellers and casings, diffusers, shaft brackets, rudders and diesel-engine cylinder liners. There is also evidence that cavitation conditions can develop in seawater, drilling mud and produced oil/gas waterlines with turbulent high rates of flow. [Pg.81]

In considering these tests it should be remembered that the phenomenon of cavitation-erosion is often accompained by corrosion effects and that a synergistic effect may operate between the mechanically and chemically induced forms of attack. In fact the term cavitation-erosion-corrosion may often be more applicable in describing the requirements of a test procedure. The subject has recently been discussed by Wood etal. °. [Pg.1054]

Formation of vapor bubbles in rapidly flowing or turbulent water causing risk of pumping failure and erosion and/or corrosion. Due to an increase in velocity at the pump head resulting in a localized pressure reduction and the subsequent collapse of the vapor into voids or cavities. Where FW temperatures are high (over perhaps 195-205 °F) the pump velocity can reduce FW vapor pressure below that corresponding to the temperature of the liquid and cavitation can occur accompanied by some noise. Warning of severe pump cavitation is often indicated by a heavy noise. [Pg.722]

The erosion effects of cavitation on solid surfaces have been extensively investigated both in terms of surface erosion [68] and corrosion [69]. The consequences of these effects on metal reactivity are important since passivating coatings are frequently present on a metal surface (e. g. oxides, carbonates and hydroxides) and can be removed by the impacts caused by collapsing cavitation bubbles. An illustration can be found with the activation of nickel powder and the determination of the change in its surface composition under the influence of cavitation by Auger spectroscopy (Fig. 3.6) [70]. [Pg.93]

Cooling system pipework and components can suffer corrosion and damage (such as cavitation, erosion, and stress corrosion) under a variety of operating conditions and from many causative agents. The various forms that corrosion and damage may take are discussed more fully later in the text however, an instant, if simplistic, corrosion vulnerability summary affecting some common metals and alloys is given in Table 4.2. [Pg.93]

When a system consists of a flowing component which impinges on a part or some parts of the structure we encounter erosion-corrosion, or abrasive wear and cavitation. The design must be such that localized constrictions are avoided or sharp directional... [Pg.73]

There are several ways to harden alloys. A certain procedure to increase the resistance to the erosion corrosion is the hardening by solid solution. One adds an element to another to produce a solid solution that is resistant to the corrosion by hardening the metal. The thermal treatment is also a method to harden a metal or alloy, but it changes the microstructure and can induce a greater susceptibility to corrosion. Hardening by cold work is also an important procedure and it is the reason for using stainless steel to resist cavitation erosion. This material, initially hard, attains an even harder surface by cold work and becomes more resistant to attack and erosion. [Pg.402]

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