Investigating in-service failures of water pipes from a multiaxial notch fatigue point of view: A conceptual study

Many mechanisms and processes can cause deterioration and ultimately failure of water distribution pipes during in-service operation, amongst these is damage caused by metal fatigue. This paper summarises an attempt at formalising a novel methodology suitable for estimating the number of years taken for a through thickness fatigue crack to form in this complex scenario. The devised method is based on the so-called modified Wo¨hler curve method and can be applied to estimate fatigue damage of water pipes independently from the degree of multiaxiality and non-proportionality of the load history. The computational approach of the proposed fatigue life estimation technique makes full use of an incremental procedure: fatigue damage is evaluated year by year by assuming that all variable involved in the process can change over time. The detrimental effect of corrosion pits is directly accounted for by treating them as conventional notches whose size increases with time. Finally, by taking as reference information the number of years for a blowout hole to form, the proposed approach is used to show how the lifetime of grey cast iron pipes can be remarkably shortened by fatigue

Corrosion behaviour of micro-plasma arc welded stainless steels in H3PO4 under flowing conditions at different temperatures

[EN] This paper studies the general corrosion behaviour of the micro-plasma arc welded AISI 316L stainless steel in phosphoric acid at different temperatures (25-60°C) and at a Reynolds number of 1456. Galvanic corrosion has been studied using zero-resistance ammeter (ZRA) measurements and polarization curves (by the mixed potential theory). Results show that the microstructure of the stainless steel is modified due to the micro-plasma arc welding procedure. Coupled current density values obtained from polarization curves increase with temperature. ZRA tests present the highest iG values at 60°C; however, the values are very close to zero for all the temperatures studied. This is in agreement with the low value of the compatibility limit and of the parameter which evaluates the importance of the galvanic phenomenon. Both techniques present the most positive potentials at the highest temperature. This study reveals that micro-plasma arc welded AISI 316L stainless steels are appropriated working in the studied H3PO4 media from a corrosion point of view for all the temperatures analysedThe authors would like to express their gratitude to the Spanish MAEC (PCI Mediterráneo C/8196/07, C/018046/08, D/023608/09) and to Asuncion Jaime for her translation assistance.Sánchez Tovar, R.; Montañés Sanjuan, MT.; García Antón, J.; Guenbour, A.; Ben Bachir, A. (2011). Corrosion behaviour of micro-plasma arc welded stainless steels in H3PO4 under flowing conditions at different temperatures. Corrosion Science. 53(4):1237-1246. https://doi.org/10.1016/j.corsci.2010.12.017S1237124653

Wear and corrosion interactions on titanium in oral environment : literature review

The oral cavity is a complex environment where corrosive substances from dietary, human saliva, and oral biofilms may accumulate in retentive areas of dental implant systems and prostheses promoting corrosion at their surfaces. Additionally, during mastication, micromovements may occur between prosthetic joints causing a relative motion between contacting surfaces, leading to wear. Both processes (wear and corrosion) result in a bio-tribocorrosion system once that occurs in contact with biological tissues and fluids. This review paper is focused on the aspects related to the corrosion and wear behavior of titanium-based structures in the oral environment. Furthermore, the clinical relevance of the oral environment is focused on the harmful effect that acidic substances and biofilms, formed in human saliva, may have on titanium surfaces. In fact, a progressive degradation of titanium by wear and corrosion (tribocorrosion) mechanisms can take place affecting the performance of titanium-based implant and prostheses. Also, the formation of wear debris and metallic ions due to the tribocorrosion phenomena can become toxic for human tissues. This review gathers knowledge from areas like materials sciences, microbiology, and dentistry contributing to a better understanding of bio-tribocorrosion processes in the oral environment.(undefined

Corrosion Inhibitors

Publisher Summary This chapter discusses various corrosion inhibitors and neutralizers and their application in petroleum industry. Corrosion and scale deposition are the two most costly problems in oil industries. Corrosion inhibitors have been divided into many groups, such as: cathodic and anodic inhibitors, inorganic and organic corrosion inhibitors, or filming and nonfilming inhibitors. From the chemists's point of view, corrosion inhibitors can be classified into the following broad groupings: amides and imidazolines, salts of nitrogenous molecules with carboxylic acids, nitrogen quaternaries, polyoxylated amines, amides, imidazolines, and nitrogen heterocyclics. Low molecular weight corrosion inhibitors often change the surface tension of water. These groups act as surfactants, since they form a protective layer on the metal surfaces. Polymeric corrosion inhibitors act in the same way as ordinary low molecular weight inhibitors. Polymeric film-forming corrosion inhibitors differ from polymer coatings as they exhibit a specific interaction with the surface before the dry film is formed. Corrosion problems may occur in numerous systems within the petroleum industry. Many anticorrosion compositions involve environmentally dangerous products, such as chromates, fatty amines of high molecular weights, imidazolines, etc. The use of some of the alternatives, for instance, polyphosphate or polyphosphonate, is limited because they precipitate in the presence of the salts of alkaline earth metals, or because of their high costs

Corrosion, jil.II, 2nd.ed/ Shreir

viii, hal tak beraturan.: bibl.: ill.; 22 cm

Corrosion, jil.I, 2nd.ed./ Shreir

xxvi, hal tak beraturan.: bibl.: ill.; 22 cm