Corrosion Terminology - B's

Corrosion Terminology - B's

back fill—material placed in a hole to fill the space around the anodes, vent pipe, and buried components of a cathodic protection system.

Barcol hardness—a hardness value obtained by measuring the resistance of rubbers, plastics, or coatings to indentation by a steel impress or under spring load in accordance with Test Method D2583.

barrier coating(1) a coating that has a high resistance to permeation of liquids and/or gases. (2)a coating that is applied over a previously coated surface to prevent damage to the underlying coating during subsequent handling.

beach marks—the characteristic markings on the fracture surfaces produced by fatigue crack propagation. [also known as arrest marks,clam shell marks, and conchoidal marks]

beta curve—a plot of dynamic (fluctuating) interference current or related proportional voltage (ordinate) versus the corresponding structure-to-electrolyte potentials at a selected location on the affected structure (abscissa).

binder—the nonvolatile portion of the vehicle of a formulated coating material.

bituminous coating—an asphalt or coal-tar compound used to provide a protective coating for a surface.

blast angle(1) the angle of the blast nozzle with reference to the surface during abrasive blast cleaning. (2) the angle of the abrasive particles propelled from a centrifugal blasting wheel with reference to the surface being abrasive blast cleaned.

blister—a dome-shaped projection on the surface of a coating resulting from the local loss of adhesion and lifting of the film from an underlying coat or from the base substrate.

blooming—see blushing.

blow down(1) the injection of air or water under high pressure through a tube to the anode area for the purpose of purging the annular space and possibly correcting high resistance caused by gas blockage.[cathodic protection use] (2) the process of discharging a significant portion of the aqueous solution in order to remove accumulated salts, deposits, and other impurities. [boiler or cooling water tower use]

blushing—whitening and loss of gloss of a coating, usually organic, caused by moisture. [also known as blooming]

bracelet anode—a galvanic anode with geometry suitable for direct attachment around the circumference of a pipeline. This may be a half-shell bracelet consisting of two semicircular sections or a segmented bracelet consisting of a large number of individual sections.

braze(1) a bond produced as the result of heating an assembly to the brazing temperature greater than 450 °C [840 °F] and less than the solidus temperature of the base metal using a brazing filler metal distributed and retained between the closely fitted faying surfaces of the joint by capillary action. (2)the act of creating a braze.

breakdown potential—the least noble potential at which pitting or crevice corrosion, or both, will initiate and propagate in a specific environment.

Brinell hardness—hardness value, measured in accordance with ISO 6506-1 or Test Method E10, using a 1 to 10 mm diameter tungsten carbide ball and a force of approximately 9.807 to 29.420 N (1 to 3000 kgf).

brittle fracture—fracture that occurs with little or no plastic deformation of the material. [contrast with ductile fracture]

brush-offblast cleaned surface—an abrasive blast cleaned steel surface that is free of all visible contaminants and foreign matter but may have some tightly adherent mill scale, rust, or coating. [See NACE No. 4/SSPC-SP 7 for detailed specification.]

burnish—process of smoothing surfaces using frictional contact between the material and some other hard pieces of hard material (e.g., hardened steel balls).