A thin elongated piece of metal rolled into the surface of the pipe, often metallurgically attached at one end. Sometimes reported as lapA piece of metal that has been rolled or otherwise worked against the surface of the metal but is not fixed, usually with a trapped residue of oxide or scale be… or laminationA planar discontinuity, usually oriented parallel or near parallel to the pipe surface, is the result of inconsistencies in the material used in the pipe manufa….