Abstract

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.

Abstract

Seawater, which covers nearly 70% of the earth's surface, is a living medium that is generally considered to be the most corrosive of the natural environments. Engineering materials find utility in a wide range of seawater applications, for example, piling on wharfs, offshore platforms and subsea pipelines, ships and submarines, seawater-cooled power and chemical plants, desalination plants, undersea telecommunications hardware and habitats, aquariums, and so forth. The effects of environmental variables on seawater corrosivity are discussed, including composition, pH, temperature, velocity, calcareous deposits, microorganisms, and biofouling. The corrosion behavior of important materials in seawater is described. Corrosion mechanisms and corrosion-control methods are outlined.

Abstract

"jats:p"The research material used in the study was the martensitic creep-resistant steel P92 used for the manufacture of pipes being part of power generation units subject to heavy load. The research problem focused on two issues. The first one was to analyze how the plastic deformation cumulated in the material in low-cycle fatigue conditions affects the characteristics of the material in creep conditions in a temperature of 600ºC. The other one was concerned with analysis of a reverse situation, i.e. how the initial plastic deformation of the material in creep conditions changes the mechanical characteristics of the steel under low-cycle fatigue conditions in a temperature of 600ºC. Document type: Article