Microbiologically-influenced corrosion damage in a water coolant header for remote process equipment

Stainless steel water piping, used to supply coolant for remote chemical separations equipment, developed several leaks during low-flow conditions resulting from an extended interruption of operations. All the leaks occurred at welds in the bottom zone of the pipe, which was blanketed with silt deposits from the unfiltered well water used for cooling. Ultrasonic, radiographic, and metallographic examinations of the leak sites revealed worm-hole pitting adjacent to the welds. Seepage at the penetrations was strongly acidic and resulted in corrosion on the external pipe surfaces beneath brown crusty deposits which had developed. Analyses of the water and deposits suggested a strong propensity toward microbiologically-influenced corrosion (MIC) and fouling