Cathodic

Cathodic is the complete working system of a buried-asset corrosion protection unit - the team that keeps a utility's underground steel pipelines from rusting through. It surveys the soil the pipe is buried in, designs and installs the impressed-current and sacrificial-anode systems that hold the steel at a protective potential, reads the test posts along every route at their due interval, runs the close-interval and coating-defect surveys that find the bare steel, investigates alternating-current and direct-current interference from railways and neighbouring pipelines, monitors the rectifiers that drive the whole system, tracks anode-bed consumption and remaining life, excavates and repairs what it finds, and proves its protection compliance to the regulator.

Fourteen real modules, each a browsable page with real seeded engineering data. PIPELINE ROUTE AND SEGMENTS carries the chainage, the wall thickness, the steel grade, the coating system applied at laying and the depth of cover. SOIL AND ENVIRONMENT SURVEY holds the resistivity in ohm-centimetres by the four-pin Wenner method, the pH, the chloride and sulphate concentrations, the redox potential and the resulting corrosivity classification. PROTECTION SYSTEM DESIGN states the current demand calculated from the bare-steel area and the coating breakdown factor assumed, against the current actually delivered. TEST POSTS AND READINGS is the routine measurement - the ON potential and the instant-OFF potential to a copper sulphate reference electrode, the IR drop, and the polarised potential against the minus-eight-hundred-and-fifty-millivolt criterion.

CLOSE INTERVAL AND COATING DEFECT SURVEYS, INTERFERENCE STUDIES against the thirty-amp-per-square-metre criterion, RECTIFIER MONITORING, ANODE BEDS AND CONSUMPTION with the mass consumed against the mass installed, EXCAVATION AND REPAIR with the metal loss measured against wall thickness, COATING CONDITION including the shielding risk where a disbonded tape wrap screens the current from the steel, REGULATORY COMPLIANCE and the POWER CONSUMPTION LEDGER complete the unit's view. A FIELD TECHNICIAN PORTAL gives a technician their round, and an INTEGRITY DASHBOARD closes the loop.

The signature drawing is the pipeline potential profile and stratigraphic section: chainage ruled along the horizontal axis and pipe-to-soil potential in millivolts up the vertical, the ON and instant-OFF potentials drawn as two stroked lines each named at its own terminal point, the minus-eight-hundred-and-fifty-millivolt criterion ruled as a datum across the whole plate, every stretch where the instant-OFF line falls short filled with a coarse halftone field and called out by its chainage range, each test post and rectifier marked at its real chainage, and the soil corrosivity drawn beneath as a ruled band of hatched and stippled beds keyed to a printed legend. Designed in a two-colour risograph field-survey zine crossed with a 1950s geological survey memoir plate: a soft newsprint ground, survey teal-black ink with visible two-ink misregistration on the display lettering, risograph teal hairlines and halftone fields, and a single fluorescent orange reserved strictly for a post failing the criterion, a soil point classified severe or worse, a defect graded for immediate excavation, a rectifier off supply, an anode bed with under three years of life or a non-conformance past its due date.