AMPP CP1 Tester key terms

Clothing and equipment worn to reduce exposure to workplace hazards, such as safety glasses, gloves, hard hats, flame-resistant clothing, and insulated footwear. On cathodic protection jobs it also includes voltage-rated gloves and tools when working near energized rectifiers or AC lines.

A formal procedure for de-energizing equipment, isolating every energy source, and applying personal locks and tags so a circuit or rectifier cannot be re-energized while a worker is servicing it.

A pre-job review in which the crew lists each step of the task, identifies the hazards present at each step, and records the controls that will be used before work begins.

An enclosed or partly enclosed area with limited entry or exit that is not built for continuous occupancy and may hold a hazardous atmosphere, engulfment risk, or other serious danger, such as a vault or pit.

Voltage differences that can drive current through a person's feet (step) or between hand and feet (touch) near an energized grounded object. A key shock hazard during rectifier faults and AC interference events.

A stable electrochemical half-cell that supplies a fixed reference voltage so potentials on a buried or submerged structure can be measured and compared against protection criteria. Common types include copper-copper sulfate and silver-silver chloride.

A portable reference half-cell made of copper in saturated copper sulfate solution, widely used for pipe-to-soil and structure-to-electrolyte potential measurements on buried metallic structures.

A voltmeter with very high input resistance, typically ten megohms or more, that draws almost no current from the measuring circuit so the potential reading is not reduced by meter loading.

A low-resistance precision resistor placed in a circuit so the small voltage drop across it can be converted into a current value, commonly used to measure rectifier output or bond current.

The documented comparison of an instrument's reading against a known reference standard of higher accuracy, used to confirm the instrument reads within tolerance and to establish any correction to apply.

A corrosion-control method that makes a metal structure the cathode of an electrochemical cell by supplying it with direct current, taken either from a rectifier and groundbed or from sacrificial anodes.

A cathodic protection system that uses an external DC power source, usually a rectifier, to drive current from an anode groundbed into the electrolyte and onto the protected structure.

A relatively active metal such as magnesium, zinc, or aluminum connected to a structure so it corrodes preferentially and releases current that protects the structure. It needs no external power supply.

An electrical device that converts AC power into the regulated direct current required by an impressed current cathodic protection system. Its output voltage and current are adjustable and are recorded during testing.

One or more anodes installed in soil or water together with their backfill and connecting cables, forming the electrode from which protective current is discharged into the electrolyte.

A metallic conductor that intentionally connects two structures, or a structure and a grounding system, to control current flow, equalize potentials, or drain stray current away from the structure.

The deliberate separation of a structure from other metallic paths using insulating flanges, joints, or fittings, so cathodic protection current is not lost through unintended connections.

Current that follows an unintended path through the earth or other conductors, often from foreign DC sources such as transit systems or other rectifiers, and can cause corrosion where it leaves a structure.

A marked location that gives access to test leads connected to a buried structure, casing, or anode, allowing potentials and currents to be measured without excavating.

A survey in which structure-to-electrolyte potentials are measured at closely spaced intervals along a pipeline, usually with a moving reference electrode and a data logger, to locate gaps in protection.

A switching device that cycles rectifier or anode current on and off at set intervals so instant-off potentials can be measured. Synchronized units let several test locations be read at the same moment.

A programmable electronic device that records voltages or currents at set time intervals, often synchronized with GPS, so survey readings can later be matched to distances or clock times.

The voltage difference measured between a buried or submerged structure and a reference electrode touching the electrolyte. It is the basic reading used to judge whether cathodic protection is adequate.

The structure-to-electrolyte potential read immediately after protective current is interrupted, before the structure can depolarize. It approximates the polarized potential with IR drop removed.

The portion of a measured potential caused by current flowing through the resistance of soil, coating, and circuit rather than by the structure's polarized condition. It must be removed to judge protection.

The shift of a structure's potential in the cathodic direction caused by buildup of cathodic charge at the metal surface. It is the part of the potential change that actually reflects corrosion protection.

A protection criterion stating that a structure is adequately protected when its potential has shifted at least 100 millivolts in the cathodic direction from its native potential, measured as formation or decay.

A widely used criterion requiring the structure-to-electrolyte potential, with IR drop removed and referenced to a copper-copper sulfate electrode, to be minus 850 millivolts or more negative.

The structure-to-electrolyte potential measured after the structure has been disconnected from all cathodic protection current long enough to depolarize and return to its natural, unprotected state.

A measure of how strongly soil resists the flow of electric current, reported in ohm-centimeters. Low resistivity means more corrosive conditions and affects groundbed design; it is commonly determined by the Wenner four-pin method.

A meter that measures current by sensing the magnetic field around a conductor, allowing bond, anode, or casing current readings to be taken without breaking or opening the circuit.

The written or electronic record kept during fieldwork noting dates, locations, weather, equipment used, readings taken, and unusual conditions, so results can be reconstructed and defended later.

Readings recorded before any adjustment is made (as-found) and again after adjustment (as-left), used to document equipment condition and confirm that changes to a system were deliberate.

The documented result of an instrument calibration, including the standard used and its traceability, the date, the technician, readings before and after adjustment, and the acceptance tolerance.

Comparison of readings from the same location over months or years to reveal slow changes in protection level, current demand, or coating condition that a single survey would not show.

The written summary of a survey or test that presents scope, methods, equipment, results, and conclusions, and states whether the system meets the applicable protection criteria.