Extended Operational and Trade Vocabulary

Marine Cathodic Protection and Anodes glossary

The cathodic-protection vocabulary: active sacrificial and impressed-current anodes, active-passive metals (stainless steel, titanium) in seawater, the Ag/AgCl reference electrode for potential measurement, and the polarization and current-demand terms. Grounds each term in the corrosion-control method or the measurement standard it belongs to.

271 defined terms.

Showing 250 on this page (page 1 of 2).

A

Active Anode: A sacrificial or impressed-current anode that is presently delivering protective current to the structure rather than sitting idle or disconnected.
Active-Passive Metal: An alloy such as stainless steel or titanium that can exist in either a corroding active state or a film-protected passive state in seawater.
Aegir Marine: A Netherlands-based supplier of cathodic protection hardware, sterntube seals, and propulsion services to merchant and offshore vessels.
Ag/AgCl Reference Electrode: A silver/silver-chloride electrode in seawater that serves as the standard reference for marine cathodic protection potential measurements.
Al-Zn-In Alloy: The standard sacrificial-anode alloy chemistry defined in DNV-RP-B401 for seawater service.
Alloying Element: A minor metal added to anode base metal, such as indium in aluminum anodes, to prevent passivation and ensure consistent dissolution.
Aluminum Anode: A sacrificial anode of Al-Zn-In alloy with density 2.77 g/cc, theoretical capacity 2,977 Ah/kg, and closed-circuit potential of about -1.10 V vs Ag/AgCl, widely used for ship hulls and offshore…
Aluminum Bronze: A copper-aluminum alloy used for propellers and seawater valves, sitting near -0.30 V vs Ag/AgCl in the galvanic series.
Aluminum Ion Generator: The aluminum-anode side of a marine growth prevention system that releases Al ions to inhibit corrosion of downstream copper-nickel piping.
Ammeter Shunt: A calibrated low-resistance device installed in series with anode cables to measure current output of an ICCP zone.
Amphoteric Behavior: The tendency of aluminum and zinc to dissolve in both acidic and alkaline electrolytes, relevant to anode performance in mud zones.
Anode: Metallic component sacrificed or driven electrochemically to protect a steel structure from corrosion.
Anode Bank: A grouping of multiple anodes wired in parallel to a common ICCP rectifier output.
Anode Bracket: The steel support welded to a hull or jacket that mechanically retains a bracelet or stand-off anode.
Anode Cable: The insulated conductor that connects an ICCP anode to the positive terminal of the transformer-rectifier.
Anode Capacity: The total charge in ampere-hours that a unit mass of anode material can deliver before being consumed.
Anode Consumption Rate: The mass of anode lost per ampere-year of current output, used to size anode mass against design life.
Anode Core: The steel insert cast inside a sacrificial anode that provides structural attachment and electrical continuity.
Anode Current Output: The instantaneous current in amperes flowing from a single anode or anode bank into the seawater.
Anode Depletion: The progressive loss of anode mass over service life that ultimately limits cathodic protection availability.
Anode Design Life: The intended service period, often 5 years for ship hulls or 25 to 30 years for offshore jackets, on which anode mass is calculated.
Anode Distribution: The placement pattern of anodes across a structure to achieve uniform potential coverage.
Anode Driving Voltage: The potential difference between the anode closed-circuit potential and the protected steel potential that drives the protective current.
Anode Insert: The steel reinforcement, usually pipe or strap, cast into a sacrificial anode for handling and attachment.
Anode Lead Wire: A short flexible cable joining an ICCP anode pigtail to the main feeder cable.
Anode Mass: The net weight of active anode material excluding the steel core, used as the basis of design-life calculations.
Anode Pigtail: The factory-installed cable stub on an ICCP anode that exits through the hull penetration to the cable box.
Anode Polarization Period: The interval of about two to four weeks after immersion during which steel and anodes settle to steady-state potentials.
Anode Resistance: The combined Faradaic and electrolyte resistance that limits the current output of a sacrificial anode.
Anode Shield: Dielectric coating applied around a hull-mounted impressed-current or sacrificial anode to prevent cathodic disbondment of adjacent paint.
Anode Stand-Off: The radial distance between a sacrificial anode surface and the structure, set to improve current spread and reduce resistance.
Anode Stud: The threaded fastener welded to the hull onto which a bolt-on anode is secured.
Anode Tail: The pigtail conductor protruding from an ICCP anode body.
Anode Utilization Factor: A dimensionless factor near 0.9 for slab anodes and 0.85 for bracelets that derates anode mass to account for the unusable fragment at end of life.
Anode Well: A recessed pocket in the hull plating that houses an ICCP anode and its dielectric shield assembly.
Anodic dissolution: Mechanism by which copper-based antifouling biocides are released into seawater.
Anti-Fouling Paint: A coating applied below the waterline whose biocidal action complements but does not replace cathodic protection.
ASTM G42: Standard test method for cathodic disbonding of pipeline coatings subjected to elevated temperatures.
ASTM G8: Standard test methods for cathodic disbonding of pipeline coatings.
Atom Anodes: A commercial supplier of sacrificial anodes for marine and offshore applications.
Automatic Potential Control: An ICCP control mode in which the rectifier adjusts output current to hold the structure potential at a fixed reference value.

B

Backfill: Granular or rock material placed in a trench above a buried subsea cable to restore the seabed profile.
Ballast Tank Anode: A sacrificial anode, usually aluminum, fitted inside seawater ballast tanks to control internal corrosion.
Bare Steel Current Density: The current of about 50 to 150 mA/m^2 required to polarize uncoated steel in seawater to the protection criterion.
Bimetallic Couple: An electrical contact between two dissimilar metals in an electrolyte that drives galvanic corrosion of the more active member.
Bolt-On Anode: A sacrificial anode mechanically attached to the structure with bolts or studs rather than welded.
Bonding Cable: A conductor that electrically connects isolated metallic items to the cathodic protection network so they share the same potential.
Bow Thruster Anode: A sacrificial anode mounted inside the bow thruster tunnel to protect tunnel plating and thruster components.
Bracelet Anode: A clamp-style sacrificial anode in two half-shells installed around pipelines, risers, or shaft sleeves.
Brackish water: Water with salinity between fresh water and seawater, roughly 0.5 to 30 PSU.
Brass: A copper-zinc alloy whose galvanic potential of about -0.30 V vs Ag/AgCl requires consideration when coupled to steel hulls.
Buried Steel: Steel in soil or mud whose cathodic protection follows ISO 15589 and NACE SP0169 criteria.

C

Cable Box: A junction enclosure on the hull interior where ICCP anode and reference electrode cables terminate before running to the control panel.
Calcareous Deposit: A calcium carbonate and magnesium hydroxide film that forms on cathodically polarized steel in seawater and reduces protective current demand.
Calomel Electrode: A mercury/mercurous-chloride reference electrode used chiefly in laboratory CP measurements as the SCE.
Carbon steel: Primary material for monopile, transition piece, and jacket fabrication in offshore wind structures.
Cargo Tank CP: Cathodic protection applied inside chemical tanker cargo tanks of stainless steel and prohibited inside crude oil cargo tanks because of spark risk.
Cast Anode: A sacrificial anode produced by pouring molten zinc, aluminum, or magnesium alloy into a mold containing the steel insert.
Cast Iron: A ferrous alloy with potential near -0.60 V vs Ag/AgCl, found in older sea valves and pump bodies.
Cathelco: A UK-based ICCP and marine growth prevention system supplier founded in 1949 in Chesterfield, now part of the Evac Group.
Cathode: The electrode of an electrochemical cell at which reduction occurs and which receives protective current from the electrolyte.
Cathodic disbondment: Loss of adhesion between coating and steel under cathodic polarization, a key qualification test for tank coatings.
Cathodic Polarization: The shift of a metal potential in the negative direction caused by the flow of protective cathodic current.
Cathodic Protection: Sacrificial or impressed current system protecting subsea steel from corrosion.
Cathodic Protection Criterion: The acceptance threshold for protection, typically a steel potential more negative than -800 mV vs Ag/AgCl in seawater.
Cathodic protection survey: Inspection of sacrificial anodes and impressed current systems.
CathodicGuard: An ICCP equipment brand offering hull and ballast tank protection packages.
Cathwell: A Norwegian manufacturer of sacrificial anodes and ICCP systems for marine and offshore use.
Closed-Circuit Potential: The operating potential of an anode when delivering current to a cathode through the electrolyte.
CMI: Comite Maritime International, NGO contributor to maritime-law unification.
Coated Steel Current Density: The reduced current demand of 5 to 15 mA/m^2 used for designing CP on well-coated immersed surfaces with limited holidays.
Coke Breeze: A carbonaceous backfill used around onshore ICCP anodes to provide a low-resistance interface with soil.
Concentration Cell: A corrosion cell driven by differences in ion or oxygen concentration along a metal surface rather than dissimilar metals.
Conductivity: Electrical conductivity of seawater, used in the CTD to derive salinity.
Continuity Bond: A welded or bolted electrical connection that ensures a section of structure is included in the CP circuit.
Continuous Monitoring: Ongoing observation of shipboard and shore systems to detect security events.
Cooling Water Line CP: Cathodic protection and MGPS treatment applied to copper-nickel seawater cooling piping.
Copper Ion Generator: The copper-anode side of a marine growth prevention system that releases Cu ions to inhibit barnacle and mussel settlement.
Copper-Nickel 70/30: A more corrosion-resistant seawater alloy with potential near -0.28 V vs Ag/AgCl used in heat exchanger tubing.
Copper-Nickel 90/10: A seawater piping alloy with potential near -0.30 V vs Ag/AgCl, commonly protected by an MGPS rather than direct CP.
Corrintec: A US supplier of cathodic protection products and corrosion-monitoring services.
Corrosion Cell: The electrochemical system comprising anode, cathode, electrolyte, and metallic path that drives metal loss.
Corrosion Coupon: A weighed metal specimen exposed to the service environment and re-weighed after retrieval to determine mass-loss corrosion rate.
Corrosion Monitoring: Periodic or continuous assessment of plate thickness loss using ultrasonic gauging or gravimetric coupons.
Coupon Mass Loss: The gravimetric corrosion-rate measurement obtained from exposed corrosion coupons.
Crevice Corrosion: Localized attack within shielded geometries on passive alloys such as stainless steels, mitigated in part by cathodic polarization.
Critical Pitting Potential: The potential above which pitting initiates on a passive alloy in a given electrolyte.
CSE: Continuous service equipment, machinery in continuous use on UMS ships.
Cumming Aluminum Anodes: A commercial brand of aluminum sacrificial anodes for marine service.
Current Demand: The total protective current in amperes required by a structure, equal to current density times exposed area.
Current Density: The protective current per unit area of immersed structure, expressed in mA/m^2.
Current Drain: An unwanted current pickup by foreign structures that increases the load on an ICCP system.
Current Output: The amperage delivered by a rectifier or anode bank to the protected structure.

D

Daily CP Log: A record of anode current, hull potential, and rectifier output captured each day to evidence continuous CP performance.
DC Power Source: The rectifier or transformer-rectifier that supplies direct current to the anodes of an ICCP system.
De Nora: A supplier of mixed-metal-oxide anodes and electrochemical equipment for cathodic protection.
Depolarization: The decay of cathodic polarization once protective current is interrupted, used in instant-off measurements.
Design Life: The intended service duration on which CP system mass and component sizing are based.
Dielectric Coating: The high-resistance epoxy and glass laminate forming the anode shield around ICCP anodes.
Dielectric Shield: An anode-shield assembly extending 1.5 to 2 m around an ICCP anode to control current distribution and prevent paint blistering.
Differential Aeration Cell: A corrosion cell driven by variations in dissolved-oxygen concentration along a metal surface.
Disc Anode: An ICCP anode of circular flat geometry mounted flush with the hull or in a recessed well.
DNV-RP-B401: The DNV recommended practice for cathodic protection design of offshore structures, including approved anode alloy chemistries.
Drag Anode: A trailing anode towed behind a vessel, used in some specialty surveys and rarely in modern hull CP.
Drop Cell: A handheld reference electrode lowered into the water on a cable to take spot potential readings of a hull or structure.
Drop-Cell Survey: A potential survey performed using a drop cell traversed around the structure.
Dry-dock interval: 5-year class survey cycle.

E

Electrical Continuity: Test ensuring grounding integrity of saturation electrical systems.
Electrical Isolation: The deliberate insulation of one structure from another to prevent current drain or stray-current corrosion.
Electrochemical Cell: A system of anode, cathode, electrolyte, and metallic path in which redox reactions drive ionic current.
Electrochemical Equivalent: The mass of metal dissolved per unit charge passed, derived from Faraday's law.
Electrolyte: The ionically conductive medium, such as seawater or soil, that completes the corrosion or CP circuit.
EN 12473: The European standard giving general principles of cathodic protection in seawater.
EN 12495: The European standard for cathodic protection of fixed steel offshore structures.
EN 13173: The European standard for cathodic protection of steel offshore floating structures.
EN 16222: The European standard for cathodic protection of ship hulls.
End-of-Life Potential: The hull potential predicted when anodes have reached their utilization-factor limit.
Epoxy Anode Shield: The epoxy-based dielectric coating component of an ICCP anode shield assembly.
ER Probe: An electrical resistance corrosion probe whose resistance increases as the sensing element loses metal.
EVAC Group: Finnish manufacturer of marine sanitary systems also supplying port reception modules for greywater and blackwater.

F

Faradaic Resistance: The polarization-related contribution to anode resistance arising from electrochemical reactions at the anode surface.
Faraday's Law: The relationship between charge passed and mass of metal dissolved, fundamental to anode capacity calculations.
Feeder Cable: The main conductor running from the ICCP rectifier to the anode junction box.
Field Gradient Survey: A subsea CP survey method that infers current pickup by measuring potential gradients in the electrolyte.
Fixed Reference Electrode: A permanently installed Ag/AgCl or Zn electrode wired to the CP control panel for continuous monitoring.
Flush Mount Anode: A sacrificial or ICCP anode recessed into the hull plating so that its outer surface is flush with the surrounding plate.
Free Corrosion Potential: The natural rest potential of a metal in an electrolyte in the absence of applied current.
Fresh Water Anode: A magnesium anode of high driving voltage selected for low-conductivity fresh water service.
FUMACO Aluminum Anodes: A commercial brand of aluminum sacrificial anodes for marine service.

G

Galvanic anode: Zinc/aluminum anode per ASTM B418/F1182.
Galvanic Cell: A corrosion cell formed by two dissimilar metals in electrical contact within an electrolyte.
Galvanic Corrosion: Accelerated corrosion of a less noble metal in electrical contact with a more noble metal in an electrolyte.
Galvanic Couple: Two dissimilar metals connected electrically in an electrolyte that establish an anode and cathode of differing potential.
Galvanic series: Ranking of metals by electrochemical potential in seawater, used to design CP systems.
Galvotec Alloys: A US-based manufacturer of zinc and aluminum sacrificial anodes.
Glass flake epoxy: Highly chemical- and water-resistant epoxy containing glass flake pigment, common in ballast tanks and offshore submerged zones.
Glass Mat Reinforcement: The glass-fiber mat embedded in epoxy that forms the structural layer of an anode shield.
Graphite Anode: An onshore ICCP anode material with potential near +0.30 V vs Ag/AgCl, largely superseded by mixed-metal-oxide anodes at sea.
Gravimetric Method: The mass-loss approach to corrosion-rate measurement based on weighing exposed coupons.
Grounding Cell: A buried sacrificial anode assembly used as a low-resistance earth for AC grounding while also providing CP current.

H

Half-Cell: A common term for a reference electrode used in CP potential measurements.
Hamworthy MGPS: A marine growth prevention system brand integrated within marine engineering packages.
Hastelloy: A nickel alloy family with potential near +0.05 V vs Ag/AgCl that is typically the cathode in mixed marine couples.
High Potential Anode: An anode chemistry, typically magnesium, with a more negative closed-circuit potential than standard zinc or aluminum.
Holiday: Coating discontinuity such as a missed area, pinhole, or thin spot.
Hull Anode: A sacrificial anode welded or bolted directly to the ship hull below the waterline.
Hull coating: Composite coating system applied to underwater hull, including anticorrosive primer, tie coat, and antifouling topcoat.
Hull Potential: The steel-to-electrolyte potential measured along the hull and compared against the CP criterion.
Hydrogen embrittlement: Material degradation in pipes and tanks exposed to hydrogen.
Hydrogen Evolution: The cathodic reduction of water to hydrogen gas that can occur at potentials more negative than about -1100 mV.

I

ICCP: Impressed Current Cathodic Protection, a hull protection system using rectified DC and inert anodes to polarize the hull.
ICCP Anode Well: The hull pocket housing an ICCP anode together with its pigtail penetration and dielectric shield.
ICCP Control Panel: The cabinet containing rectifier, reference-electrode input, control logic, and alarm displays for an ICCP system.
ICCP Rectifier: The transformer-rectifier unit that converts shipboard AC to controlled DC for ICCP service.
Impressed Current: Protective current supplied by an external DC source rather than by galvanic action of a sacrificial anode.
Inconel: A nickel-chromium alloy family with potential near +0.10 V vs Ag/AgCl that behaves as a cathode in typical marine couples.
Indium Activator: The trace indium addition that prevents passivation of Al-Zn-In sacrificial anodes in seawater.
Inert Anode: An ICCP anode such as MMO or platinized titanium that delivers current with negligible consumption.
Inlet Box CP: Cathodic protection arrangement inside sea inlet chests, often combining sacrificial anodes with an MGPS.
Insert Bar: The steel bar cast inside a sacrificial anode for mechanical support and electrical connection.
Instant-Off Potential: The hull or structure potential measured immediately after CP current is interrupted, used to remove IR drop from the reading.
Insulating Flange: A pipe flange fitted with dielectric gaskets and sleeves to electrically isolate piping sections for CP purposes.
Internal CP: Cathodic protection applied to the wetted internal surfaces of ballast tanks, sea chests, and similar enclosed spaces.
Ion Generator: A controlled electrochemical source of metal ions, such as the copper and aluminum electrodes of an MGPS.
IR Drop: The voltage drop in the electrolyte and circuit that appears in on-potential readings and is removed by instant-off measurements.
ISO 13174: The international standard for cathodic protection of harbor installations.
ISO 15589-1: The international standard for cathodic protection of pipeline transportation systems on land.
ISO 15589-2: The international standard for cathodic protection of pipeline transportation systems offshore.

J

Junction box: Enclosure terminating cables on instruments and motors, with IP rating per zone classification.

L

Lead-Silver Anode: An older impressed-current anode material of Pb-Ag alloy used in marine ICCP installations before mixed-metal oxides became standard.
Linear Polarization Resistance: A corrosion-monitoring technique that infers instantaneous corrosion rate from the small-signal polarization slope at the corrosion potential.
Local Action Cell: A microscopic corrosion cell within a single metal surface caused by compositional or microstructural inhomogeneity.
Long-Line Current: Stray or telluric current that flows along extended pipelines or hulls and influences CP requirements.
Low-Voltage Anode: A sacrificial anode chemistry, such as zinc or aluminum, characterized by modest driving voltage relative to magnesium.
LPR Probe: A linear polarization resistance probe installed in a process stream to give a continuous corrosion-rate signal.

M

Magnesium Anode: A sacrificial anode of Mg-Al-Zn alloy with density 1.74 g/cc, theoretical capacity 2,205 Ah/kg, and potential of about -1.55 V vs Ag/AgCl, used in fresh water and soil and prohibited in crude oil…
Marine growth: Biofouling on subsea structures considered in hydrodynamic load assessment and operational inspection.
Mass-Loss Coupon: A weighed metal specimen retrieved after defined exposure to quantify corrosion rate gravimetrically.
MGPS: Marine Growth Prevention System, a copper-aluminum electrochemical package fitted in sea chests and cooling lines to suppress fouling and corrosion.
MIL-A-18001K: The US military specification for zinc sacrificial anodes used in seawater.
MIL-A-24779: The US military specification covering aluminum sacrificial anodes for shipboard service.
Mixed Metal Oxide Anode: An MMO-coated titanium anode used as the standard inert anode for modern marine ICCP systems.
MME Group: A Netherlands-based supplier of sacrificial anodes and corrosion-monitoring equipment.
MMO Anode: The common abbreviation for a mixed-metal-oxide titanium anode used in ICCP systems.
Monel 400: A copper-nickel alloy with potential near -0.10 V vs Ag/AgCl, used in seawater valves and shafting.
Monitoring Reference Electrode: A permanently installed Ag/AgCl or Zn electrode whose signal is wired to the CP control panel for continuous structure-potential measurement.
Mud Zone Anode: An aluminum or zinc anode designed for service in the seabed mud line where electrolyte resistivity and oxygen access differ from open seawater.
Multi-Anode Array: A configuration of several anodes arranged to deliver distributed protective current over a large structure.

N

NACE RP0387: The NACE practice for sacrificial anode casting quality.
NACE RP0492: The NACE recommended practice for marine cathodic protection maintenance.
NACE SP0169: The NACE standard practice giving cathodic protection criteria for buried or submerged metallic piping, including the -800 mV vs Ag/AgCl seawater criterion adopted for marine steel.
NACE SP0176: The NACE standard for corrosion control of submerged areas of permanently installed steel offshore structures.
NACE SP0204: The NACE standard practice on marine cathodic protection design considerations.
NACE SP0387: The NACE standard on metallurgical and inspection requirements for cast sacrificial anodes.
NACE SP0408: The NACE standard for cathodic protection of reinforcing steel in buried or submerged concrete structures.
Native Potential: The free-corrosion potential of a structure prior to application of any cathodic protection current.
Naval Brass: A leaded copper-zinc-tin alloy with potential near -0.30 V vs Ag/AgCl, used in propeller shafting and valve trim.
Nickel 200: Commercially pure nickel with potential near -0.25 V vs Ag/AgCl, occasionally found in seawater service.
Northern Foundry: A North American supplier of zinc and aluminum sacrificial anodes for marine service.

O

Off-Potential: A potential reading taken with all CP current interrupted; see instant-off.
Offshore CP: Cathodic protection applied to fixed and floating offshore structures, typically using aluminum sacrificial anodes designed for 25 to 30 year life at 80 to 120 mA/m^2.
On-Potential: A potential reading taken with CP current flowing, which includes IR drop in the electrolyte.
Open-Circuit Potential: The rest potential of an anode or structure when no current is flowing in the external circuit.
Output Current: The amperage delivered by an ICCP rectifier to the anode circuit.
Output Voltage: The DC voltage produced by an ICCP rectifier across the anode-to-structure circuit.
Over-Protection: A condition of more negative potential than about -1100 mV vs Ag/AgCl that can cause hydrogen evolution and cathodic disbondment of coatings.

P

Pacific Anodes: A regional supplier of sacrificial anodes for marine service.
Passive Film: The thin protective oxide on alloys such as stainless steel or titanium that lowers their corrosion rate and shifts their potential noble.
Performance Metals: A US-based manufacturer of marine sacrificial anodes.
Permanent Reference Electrode: A reference electrode installed for the design life of the structure and wired to the CP monitoring system.
Pitting Corrosion: Localized pit type corrosion; mapped and gauged during ESP.
Platinized Titanium Anode: A titanium anode coated with a thin platinum layer used as an inert anode in some marine ICCP installations.
Plus Marine: A commercial supplier of cathodic protection products for marine service.
Polarization: Orientation of the electric field of a radio wave, used for frequency reuse on satellites.
Polarization Curve: The plot of potential against logarithm of current density used to characterize electrochemical kinetics.
Polarization Decay: The slow return of a polarized structure toward its native potential after CP interruption, used to evaluate the 100 mV decay criterion.
Potential Profile: The variation of structure-to-electrolyte potential along the length or depth of a protected asset.
Potential Survey: A campaign of potential measurements using a reference electrode to map CP performance.
Power Supply Unit: The transformer-rectifier and control electronics that energize an ICCP zone.
Pressure-Compensated Reference Electrode: A reference electrode designed to operate accurately under the hydrostatic pressure of deep-water service.
Propeller Anode: A sacrificial anode mounted on or near the propeller assembly, including rope-guard anodes that share its protection.
Pt/Ti Anode: A platinized-titanium ICCP anode, often supplied in pencil or disc form.

R

Reactivation: The breakdown of an aluminum anode oxide film, restored by indium or other activator additions to maintain steady dissolution.
Rectifier: The shipboard or shore-based device that converts AC supply into the controlled DC output of an ICCP system.
Reference Cell: Another term for a reference electrode used in CP measurements.
Reference electrode: Electrode of known potential, such as silver-silver chloride, used to monitor cathodic protection.
Reference Electrode Array: A set of permanent reference electrodes distributed across a hull or structure for continuous CP monitoring.
Remote Earth: A point in the electrolyte sufficiently distant from the structure that potential gradients have decayed to background.
Resistivity: The intrinsic electrolyte property, opposite of conductivity, that influences anode-to-cathode circuit resistance.
Rope Guard Anode: A sacrificial anode mounted on the rope guard ahead of the propeller to protect the stern bossing and shaft area.
ROV CP Survey: An offshore cathodic protection survey performed with reference electrodes and probes mounted on a remotely operated vehicle.
Rudder Anode: A sacrificial anode mounted on the rudder blade or stock to protect the rudder structure.

S

Sacrificial anode: Zinc/aluminum anode for hull and tank protection.
SCE: The saturated calomel electrode used as a laboratory reference electrode for CP and corrosion measurements.
Sea Chest Anode: A sacrificial anode mounted inside a sea inlet chest to protect the chest plating and adjoining piping.
Sea Strainer CP: Cathodic protection of sea strainer bodies and internals, typically by replaceable sacrificial anodes.
Sea Water Inlet CP: The combination of sacrificial anodes and MGPS that protects sea inlet chests and downstream cooling piping.
Sherwin-Williams Cathodic Protection: A commercial supplier of cathodic protection materials and coatings within the broader Sherwin-Williams portfolio.
Shipboard Reference Electrode: A hull-mounted Ag/AgCl or Zn electrode wired to the ICCP control panel.
Slab Anode: A flat rectangular sacrificial anode bolted or welded onto the hull, the most common geometry for ship CP.
SMP Sacrificial Marine Anodes: A commercial supplier of sacrificial anodes for the marine sector.
Spark Hazard: The ignition risk that prohibits the use of magnesium anodes inside flammable atmospheres, such as crude oil cargo tanks under SOLAS II-2.
Stainless Steel 304 Active: Active-state stainless 304 with potential near -0.40 V vs Ag/AgCl in seawater.
Stainless Steel 316 Passive: Passive-state stainless 316 with potential near +0.05 V vs Ag/AgCl in seawater.
Stand-Off Anode: A sacrificial anode mounted on brackets that hold the anode away from the hull or jacket surface.
Standard Potential: The thermodynamic potential of an electrode reaction at unit activity, the basis from which seawater galvanic-series values are derived.
Stern Anode: A sacrificial anode mounted at the stern to protect the after hull, sterntube, and adjacent fittings.
Stray Current: An unintended current in soil, water, or structure that can cause accelerated corrosion at points of discharge.
Stray Current Corrosion: Localized metal loss caused by stray current leaving a structure into the electrolyte.
Stuffing Box CP: Cathodic protection of stuffing-box and sea-box assemblies, generally by small replaceable sacrificial anodes.