REDUCERS - Solvents or thinners added to a coating, varnish, resin, latex or emulsion for the purpose of lowering its viscosity and/or nonvolatile content.
REDUCTION - Gain of electrons by a constituent of a chemical reaction.
REFERENCE ELECTRODE - An electrode whose open-circuit potential is constant under similar conditions of measurement, which is used for measuring the relative potentials of other electrodes.
REFERENCE HALF-CELL - See Reference Electrode.
REFLECTANCE - The ability of a coating film to reflect or return the light that falls upon its surface.
REINFORCEMENT - Glass cloth, chopped fibers, or mat used to provide additional tensile and flexural strength and other properties to a coating or lining.
RELATIVE HUMIDITY - The ratio of the actual pressure of existing water vapor to the maximum possible (saturation) pressure of water vapor in the atmosphere at the same temperature, expressed as a percentage.
RELEASE AGENTS - Materials used to prevent bonding of concrete to a surface.
REMOTE EARTH - A location on the earth far enough from the affected structure that the soil potential gradients associated with currents entering the earth from the affected structure are insignificant.
REPLICA TAPE - A specially constructed tape (e.g., Testex PRESS-0-FILM) used to measure surface profile. The tape is pressed against the surface to produce an impression of the surface profile; then, the impression in the tape is measured with a micrometer. The use of replica tape is described in ASTM D 4417 and NACE RP0287.
RESIN - A general term used to designate any polymer, natural or synthetic, used as binder for coating materials.
RESISTIVITY - (1) The resistance per unit length of a substance with uniform cross section. (2) A measure of the ability of an electrolyte (e.g., soil) to resist the flow of electric charge (e.g., cathodic protection current). Resistivity data are used to design a groundbed for a cathodic protection system.
RESPIRATOR - (1) A device that supplies oxygen or a mixture of oxygen and carbon dioxide for breathing, used especially in artificial respiration. (2) A screenlike device worn over the mouth or nose or both to protect the respiratory tract. Synonym - inhalator. There are quite a variety of respirators, ranging from disposable dust masks to self-contained breathing apparatus. All have specific uses and limitations.
REST POTENTIAL - See Corrosion Potential.
REVERSIBLE POTENTIAL - See Equilibrium Potential.
RIMMED STEEL - An incompletely deoxidized steel. Also called Rimming Steel.
RISER - (1) That section of pipeline extending from the ocean floor up to an offshore platform. (2) The vertical tube in a steam generator convection bank that circulates water and steam upward.
RUDDER - A device used to steer the vessel
RUN - See Sag.
RUST - Corrosion product consisting of various iron oxides and hydrated iron oxides. (This term properly applies only to iron and ferrous alloys.)
RUST BLOOM - The first sign of rust on newly cleaned steel, indicated by slight surface discoloration.
RUST GRADE - In visual standards, the initial condition of unpainted steel before surface preparation. SSPC-Vis 1, a visual standard for the surface preparation of steel, outlines the following four rust grades: (1) RUST GRADE A- the steel surface is completely covered with adherent mill scale; little or no rust is visible. (2) RUST GRADE B- The steel surface is covered with both mill scale and rust. (3) RUST GRADE C- The steel surface is completely covered with rust; little or no pitting is visible. (4) RUST GRADE D- the steel surface is completely covered with rust; pitting is visible.