AMPP ICS key terms

Metal loss driven by dissolved carbon dioxide forming carbonic acid in produced water. It often produces smooth, mesa-shaped, or pitted attack and depends strongly on partial pressure, pH, temperature, and flow.

Corrosion caused by dissolved hydrogen sulfide in produced fluids. It can form iron sulfide films that sometimes slow attack, and it introduces sulfide stress cracking and hydrogen-induced cracking hazards in susceptible steels.

Deterioration accelerated by the metabolic activity of microorganisms such as sulfate-reducing bacteria, often appearing as localized pitting, black deposits, and sulfide odors under stagnant or low-flow conditions.

Anaerobic microorganisms that reduce sulfate to sulfide, producing corrosive sulfide species and promoting pitting and under-deposit attack in oxygen-free, often stagnant, water environments.

Microorganisms attached to surfaces within a biofilm. They are the population most directly responsible for microbially influenced corrosion, and they are sampled by scraping or swabbing surfaces rather than from bulk fluid.

Free-floating microorganisms suspended in the bulk fluid. Their counts indicate the general microbial load of the water but do not reliably represent the attached population causing corrosion on pipe walls.

A structured community of microorganisms and their excretory products adhering to a surface. It creates localized chemistry differences and shelters cells from biocides, making it a common site for under-deposit pitting.

Accelerated metal loss where flowing fluid or entrained solids continually remove protective films or corrosion products. Attack concentrates at changes in direction, welds, and areas of high local velocity or turbulence.

The pattern in which multiphase fluids travel through a pipe, such as stratified, slug, annular, or dispersed flow. The regime controls where water wets the wall and where shear stresses promote or remove protective films.

The condition in which an aqueous phase contacts and continuously wets the internal pipe surface. Corrosion requires water wetting, so understanding when and where it occurs is central to predicting internal attack.

The fraction of carbon dioxide in a gas multiplied by total system pressure, expressed in pressure units. It is a common screening parameter for estimating the corrosivity of wet hydrocarbon service.

Localized attack that occurs beneath accumulated solids, scale, or corrosion products. The deposit shields the surface and creates a differential environment that concentrates attack into deep pits.

A form of localized CO2 corrosion in which flat-topped, table-like plateaus of metal remain while surrounding areas are thinned. It is associated with partially protective iron carbonate films breaking down locally.

A corrosion product film that can form on steel in CO2-containing water and, when dense and continuous, slows further metal loss. It becomes less protective at high flow, low pH, or when it is disrupted.

Localized corrosion that penetrates deeply over a small area while the surrounding surface remains largely intact. It is difficult to detect by general wall-loss averages and is a frequent cause of unexpected leaks.

Accelerated attack that occurs when two dissimilar metals are electrically connected in an electrolyte, causing the more active metal to corrode faster. It is a concern at transitions between different pipe materials or weld overlays.

Brittle cracking of high-strength steels under the combined action of tensile stress and aqueous hydrogen sulfide. It is a safety-critical failure mode addressed by material hardness limits and qualification standards.

Stepwise internal cracking caused by hydrogen atoms diffusing into steel and recombining at inclusions or laminations. It is associated with wet sour service and evaluated by standardized laboratory testing.

The standard specifying materials and environmental limits for service in oil and gas production containing hydrogen sulfide. It defines acceptable steels, hardness limits, and qualification requirements for sour service.

A metallic material such as a stainless steel, duplex, or nickel-based alloy selected for its ability to resist a specific corrosive environment. Selection depends on chloride level, temperature, pH, and partial pressures of acid gases.

A calculated index based mainly on chromium, molybdenum, and nitrogen content used to rank the pitting resistance of stainless and similar alloys. It helps compare candidate alloys against expected chloride and temperature conditions.

Cracking of susceptible alloys, particularly austenitic stainless steels, under the combined action of tensile stress, chlorides, and elevated temperature. It is a risk when choosing alloy piping for hot chloride-bearing service.

Metal loss caused by dissolved oxygen in water, producing rapid and often localized attack. Oxygen ingress is a major concern in water injection, hydrotest, and stagnant systems and is controlled by deaeration and oxygen scavengers.

A chemical added continuously or in batches that adsorbs onto metal surfaces to slow corrosion. Effectiveness depends on correct dosage, good mixing, adequate contact time, and reaching all wetted surfaces.

The measured concentration of active corrosion inhibitor remaining in the produced water, used as an indicator that target dosage is being maintained. It does not by itself prove that the film is protecting the pipe.

Chemical dosing intended to kill or suppress microorganisms in a system, often applied in batch and alternating between products to limit resistance. It is combined with cleaning to remove biofilms that shield sessile bacteria.

A chemical such as a sulfite or bisulfite compound dosed to remove dissolved oxygen from water. It supports mechanical deaeration and protects injection and closed-loop systems from oxygen-driven corrosion.

A planned schedule of pipeline pig runs to remove liquids, solids, and deposits or to distribute inhibitor films. Regular pigging reduces under-deposit attack and stagnant water accumulation.

Intermittent injection of a concentrated chemical or liquid slug to coat pipe walls or displace fluids in low-flow lines. It is used where continuous injection is impractical or where film persistence is required.

A small specimen of known material and weight installed in a pipeline or vessel and later retrieved to measure metal loss and inspect attack morphology. Coupons provide direct evidence of corrosion rate at their location.

An instrument that infers metal loss from the increase in electrical resistance of a thin exposed element as it corrodes. It gives near-continuous trend data but is less sensitive to localized pitting than other methods.

An electrochemical technique that estimates instantaneous corrosion rate from the current response to a small applied potential change. It works well in conductive aqueous systems and responds quickly to changes in treatment or conditions.

The speed at which metal is lost, commonly expressed in millimeters per year or mils per year. It is compared against a target or allowance to decide whether mitigation or inspection changes are needed.

The electrical potential of a metal surface relative to a reference electrode in an electrolyte. It indicates corrosion tendency and is used in cathodic protection and electrochemical monitoring.

A stable half-cell, such as silver/silver chloride or copper/copper sulfate, used as a benchmark when measuring pipe-to-electrolyte potentials. Its type must be stated because readings differ between references.

A technique that applies an external current or sacrificial anode to shift a metal's potential to a less corrosive range. It is used for tanks, buried lines, and internal surfaces of water-handling equipment.

A pipeline survey using instrumented tools, such as magnetic flux leakage or ultrasonic wall-thickness tools, to detect and size metal loss. Results feed remaining-life calculations and integrity repair decisions.

A structured process that predicts where internal corrosion is most likely, then uses excavation and nondestructive examination at those locations to verify pipeline integrity where in-line inspection is not feasible.

The current pipe wall thickness after metal loss has occurred, determined by inspection or calculated from measured rates. It is compared with a required minimum to judge fitness for continued service.

An engineering evaluation of whether a component with known flaws or wall loss can safely continue operating under its intended conditions. It may set operating limits, reinspection intervals, or repair requirements.

A structured investigation to determine the underlying physical, chemical, and operational reasons a failure occurred, rather than only the immediate mechanism. Findings drive corrective actions that prevent recurrence.

The technical examination of a failed component using visual, metallurgical, and chemical methods to identify the corrosion mechanism and contributing conditions. It supplies evidence that supports root cause conclusions.

A measurable value, such as corrosion rate, inhibitor availability, or inspection completion, used to judge whether an integrity program is achieving its objectives. Indicators should be reviewed periodically and acted upon.

A scheduled, documented evaluation by responsible management of program performance, risks, and improvement actions. It confirms that corrosion control remains effective as conditions, personnel, and regulations change.

A formal process for evaluating and approving changes to equipment, chemicals, operating conditions, or procedures before implementation. It ensures that corrosion risks and control measures are reassessed when something changes.

A documented framework describing threats, assessment methods, mitigation activities, and review cycles for maintaining the mechanical integrity of equipment. It ties monitoring data and inspection results to decisions and records.

A toxic, flammable gas that can deaden the sense of smell at higher concentrations and cause rapid incapacitation. Field work requires gas detection, respiratory protection, and rescue planning before entry or hot work.

Entering an enclosed or poorly ventilated area such as a tank or vessel, which requires atmospheric testing, permits, ventilation, attendants, and rescue provisions. Internal corrosion work frequently involves such entries.

A procedure that isolates and secures energy sources before maintenance or inspection work begins. It prevents unexpected startup or release of stored energy while personnel are working on equipment.

An independent control system designed to bring a process to a safe state when predefined conditions are exceeded. It is applied where corrosion-driven loss of containment could create major safety consequences.

The defined period and format for keeping monitoring, inspection, treatment, and compliance records so they remain retrievable and defensible. Retention periods are set by regulation, contract, and company policy.

A structured review that checks whether corrosion control activities, documentation, and reporting meet applicable legal and regulatory requirements. Findings are tracked to closure with assigned responsibility and dates.