دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

a type of corrosion found when dissimilar metals are joined. One part becomes the cathode and the other the anode where accelerated corrosion may be seen.

different metals that may form an anode-cathode pair in corrosion cell conditions.

corrosion between two dissimilar metals - couplings, centralizers, pumps, packers, profiles – usually severe metal loss on one metal near contact point. May see galvanic loss on a single metal with current.

n: the production of current flow when two dissimilar metals are placed in an electrolyte.

n: electrolytic cell created by the difference in electrical potential between two dissimilar metals.

n: a type of corrosion that occurs when a small electric current flows from one piece of metal equipment to another. It is particularly prevalent when two dissimilar metals are present in an environment in which electricity can flow (as two dissimilar joints of tubing in an oil or gas well).

n: a unit that produces electricity from the chemical reaction of conductors of dissimilar metals through an electrolyte. In a primary cell, the chemical energy has its origin within the cell, and the chemical reaction is not reversible. Also called a voltaic cell. See dry cell, wet cell.

n: a device consisting of two dissimilar metals bonded together, with electrical connections to each. When the device is exposed to heat, an electrical current is generated, the magnitude of which varies with the temperature. It is used to measure temperatures higher than those that can be measured by an ordinary thermometer, such as those in engine exhaust.

n: an instrument that measures temperature. Thermometers provide a way to estimate temperature from its effect on a substance with known characteristics (such as a gas that expands when heated). Various types of thermometers measure temperature by measuring the change in pressure of a gas kept at a constant volume, the change in electrical resistance of metals, or the galvanic effect of dissimilar metals in contact. The most common thermometer is the mercury-filled glass tube, which indicates temperature by the expansion of the liquid mercury.