Contents
- How to use this guide
- Where it fits
- The 4 KPIs that matter
- How inhibitors work (in plain terms)
- Quick selection map (what drives choice)
- Dosing & injection: what to control
- Verification methods (what “good” looks like)
- Compatibility & side effects (emulsions, foaming, deposits)
- Troubleshooting signals
- Specification & acceptance checks
- Handling & storage
- RFQ notes (what to include)
How to use this guide
This is a decision aid for B2B oil & gas teams. Use it to align procurement, EHS, and operations on: selection criteria (what the inhibitor must handle), acceptance checks (what you can verify on receipt), and monitoring signals (how you confirm performance in the field).
Safety-first note: Corrosion inhibitors can interact with other production chemicals and process conditions.
Always follow site EHS rules and supplier SDS. Avoid giving “dose-by-guess” instructions—verify delivery, mixing, and monitoring trends.
Where it fits
- Process goal: reduce corrosion rate (and pitting risk) while maintaining operability (separation, fluids handling, HSE).
- Operating window: temperature, pressure, water cut, CO2/H2S, flow regime, shear, solids.
- Interfaces: carbon steel and alloys, elastomers, coatings/liners, injection hardware.
- Constraints: discharge limits, VOC/flash point limits, chemical registration/site rules, compatibility with existing chemical program.
The 4 KPIs that matter
Surface coverage
Does a protective film actually form on the metal at your conditions?
Film persistence
Does the film stay in place under shear, slugging, and changes in water cut?
Measurable corrosion control
Do coupons/probes and iron trends confirm improvement (not just one data point)?
No unacceptable side effects
No emulsion upsets, foaming, deposits, or downstream interference.
How inhibitors work (in plain terms)
Most production corrosion inhibitors are film-forming: they adsorb onto metal surfaces and create a barrier that slows corrosion reactions. The practical challenge is not “having inhibitor in the line”—it’s achieving surface coverage at the places where corrosion is active (often where water contacts steel).
Key idea: Corrosion risk and inhibitor performance are strongly driven by where the water phase is,
how it moves (flow regime), and how aggressively conditions strip films (shear/slugging/solids).
Quick selection map (what drives choice)
| Driver | Why it matters | What to clarify in selection |
|---|---|---|
| CO2 (sweet) vs H2S (sour) | Different corrosion mechanisms and risk profiles (uniform vs pitting/SSC concerns) | Gas composition, partial pressures (if available), and metallurgy constraints |
| Water cut & water chemistry | Corrosion typically occurs in the water phase at the steel interface | Water cut range, salinity/chlorides, pH/alkalinity, solids, scaling tendency |
| Temperature | Affects reaction rates, inhibitor adsorption, and solvent behavior | Normal and peak temperature (including warm-up/startup) |
| Flow regime & shear | High shear/slugging can strip films; low flow can create under-deposit risk | Flow range, slugging frequency, critical locations (elbows, low points, deadlegs) |
| Compatibility with chemical program | Some inhibitors can destabilize separation or interfere with other actives | Existing demulsifier/scale inhibitor/biocide program and known constraints |
| Downstream constraints | Flash point/VOC, discharge, and process equipment sensitivity can limit options | Solvent limits, discharge limits, and any “no-go” ingredients per site policy |
Dosing & injection: what to control
This section is intentionally “control-focused” rather than giving numeric dosing advice. Inhibitor performance is mostly won or lost on delivery and verification.
| Control point | What goes wrong | Practical checks |
|---|---|---|
| Injection location | Inhibitor doesn’t reach the corrosion-active area or mixes poorly | Confirm injection point rationale; ensure it’s upstream of turbulence/mixing and relevant water-wet zones |
| Pump calibration & stroke verification | “Setpoint” doesn’t equal delivered rate | Calibrate pumps, verify actual drawdown vs expected, track tank change-outs vs rate |
| Quill/nozzle integrity | Plugging, backflow, or injection into the wrong phase | Inspect/maintain quills, strainers, check valves; confirm no leaks or plugging |
| Batch vs continuous logic | Film never establishes or collapses during upsets | Agree on “film establishment” approach and how upsets are handled; document in SOP |
| Product conditioning (temperature/viscosity) | Cold product won’t pump or mixes poorly | Confirm pour point/viscosity; storage temperature; heat tracing policy if required |
Verification methods (what “good” looks like)
Verification is strongest when you trend multiple indicators together instead of relying on a single number. Use at least one direct corrosion measurement and one supporting process/chemistry indicator.
| Method | What it tells you | Common pitfalls |
|---|---|---|
| Corrosion coupons | Average corrosion rate over exposure period; can show pitting/attack patterns | Placement not representative; retrieval intervals too short/long; handling/cleaning variability |
| ER probes | Trend of metal loss over time (good for operational trending) | Noise during upsets; location sensitivity; interpreting short-term spikes without context |
| LPR probes | Electrochemical corrosion rate (fast feedback in suitable environments) | Not applicable in all multiphase/low-conductivity conditions; fouling effects |
| Iron trends (produced water / filters) | Supporting indicator for corrosion or solids/under-deposit issues | Iron can come from scale/solids release; sampling inconsistency |
| Inspection / pigging debris | Under-deposit corrosion risk; solids type changes | Debris composition not always corrosion; needs lab characterization to be actionable |
Good practice: When changing inhibitor or injection strategy, define a short “verification plan”: where coupons/probes are placed, what trends will be reviewed (and how often), and which side-effect metrics matter (separation, foaming, deposits).
Compatibility & side effects
| Side effect / conflict | What it looks like | What to check first |
|---|---|---|
| Emulsion stability problems | Slower separation, higher BS&W, interface rag layers | Compatibility with demulsifier; injection points; treat rates trending; lab bottle tests (site protocol) |
| Foaming | Separator upsets, carryover, level control instability | Solvent/surfactant profile; interaction with other chemicals; operating changes |
| Deposits / sludge | Filter plugging, injector fouling, solids increase | Incompatibility with scale inhibitor or water chemistry; cold storage precipitation; mixing order |
| Elastomer issues | Swelling/softening/leaks over time | Elastomer list (NBR/EPDM/FKM, etc.), solvent type, temperature, exposure time |
Troubleshooting signals
If performance drops, these are common early indicators and what to check first:
| Signal | Likely causes | First checks |
|---|---|---|
| Corrosion coupon fails | Delivery issue, film stripping (shear/slugging), changing CO2/H2S/water cut, under-deposit conditions | Verify pump calibration & drawdown, check injection hardware, review operating upsets, confirm coupon placement and handling |
| Emulsion stability problems | Chemical incompatibility, injection point interaction, over-treatment | Review chemical program and timing, confirm injection locations, run controlled compatibility check per site protocol |
| Souring indicators rising | Microbial activity changes (MIC risk), biocide strategy gaps, system conditions changed | Review biocide program/monitoring, sampling plan, and whether corrosion is MIC-driven in certain zones |
| Injector/quill plugging | Solids, precipitation in cold conditions, incompatible mixes | Filter/strainer inspection, product pour point/viscosity, storage temperature, mixing segregation |
If you share your current operating window (temperature, water cut, CO2/H2S), metallurgy, injection setup, and the last 3–6 data points (coupons/probes + iron + separation metrics), we can usually narrow down the cause quickly.
Specification & acceptance checks
When comparing products, ask for the data you can verify on receipt:
| Category | What to request | Why it matters |
|---|---|---|
| Identity | Product name/grade, manufacturer, batch/lot traceability | Repeatable field results and defensible change control |
| Quality (COA) | Appearance, density, viscosity, active content (as specified), water content (if applicable) | Ensures pumpability and consistent film-forming performance |
| Solvent & handling profile | Solvent type/class, flash point (where relevant), pour point, storage temperature limits | Safety, logistics, and winter operability |
| Compatibility expectations | Notes on demulsifier/scale inhibitor/biocide compatibility; mixing/injection guidance | Prevents separation upsets and precipitation/plugging events |
| Safety | Up-to-date SDS, PPE, incompatibilities, spill response basics | Safe storage/transfer and avoidance of hazardous interactions |
| Logistics | Packaging (drum/IBC/bulk), closures, labeling, lead time, Incoterms, shelf life | Procurement-ready supply planning and traceability |
Handling & storage
- Store sealed in original packaging, away from incompatible materials and ignition sources (as per SDS).
- Use secondary containment and clear labeling at storage and dosing points.
- For transfers: verify hose/elastomer compatibility; use spill-control basics and bonding/grounding where required.
- Keep injection systems clean (filters/strainers) and document maintenance; many “chemistry problems” are delivery problems.
RFQ notes (what to include)
- Asset & location: upstream line, flowline, separator, produced water system, or other (where the corrosion is observed).
- Operating window: temperature range, pressure, flow range, slugging frequency.
- Fluids: water cut range, CO2/H2S presence, produced water chemistry (chlorides/salinity, pH if available), solids/sand.
- Materials: carbon steel vs CRA, coatings/liners, and elastomers in contact.
- Current program: demulsifier, scale inhibitor, biocide, and any known compatibility constraints.
- Monitoring: coupon/probe locations and recent trends, iron trends, inspection/pigging findings.
- Procurement needs: packaging preference, monthly volume, delivery country, documentation (COA/SDS), and site compliance requirements.
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Educational content only. Always follow site EHS rules and the supplier SDS for safe use.