lamellar corrosion—see exfoliation corrosion.
Langelier Saturation Index—a number calculated from total dissolved solids, calcium concentration, total alkalinity, pH, and solution temperature that shows the tendency of a water solution to precipitate or dissolve calcium carbonate,wherein an index less than –0.3 indicates that the water tends to be corrosive,while an index greater than +0.3 indicates scale forming potential. [also called Langelier Index or Saturation Index]
latex paint—a paint containing a stable aqueous dispersion of synthetic resin, produced by emulsion polymerization, as the principal constituent of the binder. (Modifying resins may also be present.)
leveling—(1) the process whereby a wet-applied coating flows out after application to minimize any surface irregularities produced by the process of application. (2)smoothing of a surface by electro-chemical means to reduce surface roughness. (3) flattening of sheet or plate.
lifting—softening and raising or wrinkling of a previous coat by the application of a subsequent coat.
limiting current density—see diffusion-limited current density.
line current—the direct current flowing in a pipeline.
lining—a coating or layer of sheet material adhered to or in intimate contact with the interior surface of a container used to protect the container against corrosion by its contents and/or to protect the contents of the container from contamination by the container material.
liquid metal cracking—environmental cracking caused by contact with a liquid metal.
local corrosion cell—an electro-chemical cell created on a metal surface because of a difference in potential between adjacent areas on that surface.
localized corrosion—corrosion at discrete sites (e.g., pitting or crevice corrosion).
long-line current—current flowing through the earth between an anodic and a cathodic area that returns along an underground metallic structure. (Usually used only where the areas are separated by considerable distance and where the current flow results from concentration-cell action.)
low-alloy steel—alloy steel with a total alloying element content of less than approximately 5 mass percent.
low-carbonsteel—steelhaving less than 0.30 mass percent carbon and no intentional alloying additions.
low-pressure water cleaning—water cleaning performed at pressures less than 34 MPa(5,000 psig). [also called power washing or pressure washing]
Luggin capillary—see Luggin-Haber probe.
Luggin-Haber probe—advice used in measuring the potential of an electrode with a significant current density imposed on its surface. (The probe minimizes the IR drop that would otherwise be included in the measurement and without significantly disturbing the current distribution on that electrode.) [also called Luggin capillary or Luggin probe]
Luggin probe—see Luggin-Haber probe.