English: A close-up view of the surface of a pipeline showing indications of w:stress corrosion cracking (two clusters of small black lines), as revealed by w:magnetic particle inspection (MPI). The surface was prepared with white contrast paint, and magnetic particles in a liquid suspension were sprayed onto the surface while it was magnetized. Cracks which would normally have been invisible are detectable due to the magnetic particles clustering at the crack openings. The scale at the bottom of the picture is in millimetres. Markings on the pipe were made by a technician for position reference.