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
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.
Narrow, deep (channel-like), axially oriented corrosion, often along a longitudinal
Low Vapor-Pressure (LVP) Liquid:
hydrocarbon mixtures in the liquid or quasi-liquid state with a vapor pressure
of 107 kPa absolute or less at 38°C.