AMPP CP2 Technician flashcards
AMPP CP2 Technician · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Ohm's law
- Ohm's law states that voltage equals current multiplied by resistance, V = I × R; it is used to calculate CP circuit current, voltage drops, and groundbed resistance effects.
- Kirchhoff's current law
- Kirchhoff's current law states that the total current entering a circuit node equals the total current leaving it, which supports analysis of parallel CP current paths and bonds.
- Series circuit resistance
- In a series circuit, resistances add directly: R_total equals the sum of individual resistances. Series elements carry the same current and divide voltage across each resistance.
- Parallel circuit resistance
- In a parallel circuit, the reciprocal of total resistance equals the sum of the reciprocals of individual resistances. Parallel paths share current inversely according to their resistance.
- 850 mV CSE criterion
- The 850 mV criterion requires a structure-to-electrolyte potential at least −850 mV versus copper/copper sulfate with cathodic protection applied, with IR drop considered.
- 100 mV polarization criterion
- The 100 mV criterion accepts cathodic protection when the structure is polarized at least 100 mV from its native potential to its polarized potential, measured after IR drop is removed.
- Instant-off potential
- Instant-off potential is measured immediately after all CP current is interrupted. It removes most IR drop and approximates the true polarized potential of the structure.
- Overprotection
- Overprotection is excessive negative polarization, often below about −1.2 V versus copper/copper sulfate. It can cause coating disbondment, hydrogen evolution, and hydrogen embrittlement.
- Close interval survey
- A close interval survey measures pipe-to-soil potentials at closely spaced intervals along a pipeline, commonly every 1 to 2.5 meters, to identify coating and CP problems.
- Wenner four-pin method
- The Wenner method measures soil resistivity using four equally spaced pins. Resistivity equals 2πaR, where a is pin spacing and R is measured resistance.
- DCVG survey
- Direct current voltage gradient surveying locates coating defects by detecting voltage gradients in the soil caused by CP current discharging at holidays.
- Current interrupter
- A current interrupter periodically switches CP current on and off so technicians can measure instant-off potentials and separate IR drop from true polarization.
- Magnesium anode
- Magnesium galvanic anodes have an open-circuit potential near −1.75 V versus copper/copper sulfate and are used in moderate- to high-resistivity soils for steel structures.
- Zinc anode
- Zinc galvanic anodes have an open-circuit potential near −1.10 V versus copper/copper sulfate and are used in low-resistivity soils and seawater.
- Galvanic anode backfill
- Galvanic anode backfill, typically gypsum and bentonite, lowers anode-to-soil resistance and promotes uniform anode consumption by maintaining a conductive environment.
- Anode consumption rate
- Anode consumption rate is the mass of anode material consumed per ampere-year. Typical values are about 8.8 lb/A·yr for magnesium and 25 lb/A·yr for zinc.
- Rectifier
- A rectifier converts alternating current to direct current for impressed current cathodic protection. It uses a transformer and rectifier stack and allows output adjustment.
- Coke breeze
- Coke breeze is a conductive carbonaceous backfill around impressed-current anodes. It lowers groundbed resistance and helps distribute current uniformly around the anode.
- MMO anode
- Mixed metal oxide anodes are impressed-current anodes with a catalytic oxide coating on a titanium substrate. They are durable and commonly installed in coke breeze.
- Groundbed resistance
- Groundbed resistance is the resistance between the anode groundbed and the surrounding electrolyte. It largely determines rectifier voltage needed for a required CP current.
- Stray current
- Stray current is current flowing through unintended paths. Corrosion occurs where the current discharges from a metallic structure into the surrounding electrolyte.
- Drainage bond
- A drainage bond is a controlled electrical connection that diverts stray current from a structure to the current source or return path, reducing discharge and corrosion.
- Current pickup
- Current pickup is an area where stray current enters a structure, causing a negative potential shift. Corrosion risk is low at pickup and high at discharge areas.
- Telluric current
- Telluric currents are naturally occurring currents induced in the earth by geomagnetic activity. They cause fluctuating structure potentials and can interfere with CP surveys.
- Cathodic disbondment
- Cathodic disbondment is the loss of coating adhesion around a defect caused by cathodic reactions. It is worsened by excessive negative potentials and poor coating quality.
- Coating holiday
- A coating holiday is a breach or defect in a protective coating that exposes steel to electrolyte. CP current concentrates at holidays to protect the exposed metal.
- Coating shielding
- Coating shielding occurs when a disbonded coating blocks CP current from reaching the steel, allowing corrosion to continue beneath an apparently intact coating.
- Fusion-bonded epoxy
- Fusion-bonded epoxy is a thermoset pipeline coating applied as a powder and cured to form a tough dielectric barrier. It is commonly used with cathodic protection.
- Lockout tagout
- Lockout/tagout isolates hazardous energy before maintenance. For rectifiers, it requires switching off, locking the disconnect, and verifying absence of voltage.
- Hydrogen evolution
- Hydrogen evolution is the cathodic generation of hydrogen gas during cathodic protection. In confined spaces it creates a flammability hazard and requires ventilation and gas monitoring.
- Rectifier troubleshooting
- Rectifier troubleshooting checks AC supply, fuses, tap settings, DC output, polarity, groundbed resistance, and cable continuity to locate loss of protection current.
- Confined space entry
- Confined space entry requires atmospheric testing, ventilation, an attendant, and rescue provisions. CP work in vaults or tanks can expose workers to hydrogen and oxygen deficiency.