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Corrosion Monitoring & Inspection Glossary - L

  • Lack of Fusion (LOF): In a weld, any area or zone that lacks complete melting and coalescence (fusion) of a portion of the weld. This may occur between weld passes or between weld and base materials.

  • Lack of Penetration (LOP): In the welding process, failure to achieve fusion of the base metal to the desired or planned depth.

  • Lamination: A type of imperfection or discontinuity with separation or weakness, usually aligned parallel to the worked surface of a metal.

  • Launcher: A pipeline facility used to insert a pig into a pressurized pipeline, may be referred to as pig trap.

  • Leak: A small opening, crack, or hole in a pipeline causing some product loss, not necessarily immediately impairing the operation of the pipeline.

  • Linear polarization resistance (LPR): Corrosion monitoring technique using two or three electrodes to provide an indication of the change in resistance to polarization.

  • Liquefied Natural Gas (LNG): Natural gas liquefied by refrigeration or pressure in order to facilitate storage or transport.

  • Liquefied Petroleum Gas (LPG): Petroleum gases (butane, propane, etc.) liquefied by refrigeration or pressure to facilitate storage or transport.

  • Loading Rate: Rate at which pressure increases in a pipeline.

  • Longitudinal Channeling: Narrow, deep (channel-like), axially oriented corrosion, often along a longitudinal seam weld.

  • Low Vapor-Pressure (LVP) Liquid: Hydrocarbons or hydrocarbon mixtures in the liquid or quasi-liquid state with a vapor pressure of 107 kPa absolute or less at 38C.

Corrosion Inspection and Monitoring