API 571 Corrosion and Materials Training

Key takeaways

• Explain how prolonged high-temperature exposure changes microstructure without necessarily causing corrosion.
• Distinguish embrittlement (loss of toughness) from softening (loss of strength) from creep (time-dependent deformation to rupture).
• Correctly match each mechanism to its temperature window and alloy family.

Damage mechanisms covered

• 885°F (475°C) Embrittlement
• Sigma Phase Embrittlement
• Temper Embrittlement
• Graphitization
• Spheroidization / Softening
• Strain Aging
• Creep and Stress Rupture
• Short-Term Overheating – Stress Rupture, incl. Steam Blanketing

Key takeaways

• Distinguish single-event brittle fracture from cyclic fatigue mechanisms.
• Explain the role of stress concentration, cyclic loading and thermal transients.
• Correctly match a fatigue signature (beach marks, chevron marks, sponge-like pitting, directional grooving) to its root cause.

Damage mechanisms covered

• Brittle Fracture
• Mechanical Fatigue, incl. Vibration-Induced Fatigue
• Thermal Fatigue
• Thermal Shock
• Corrosion Fatigue
• Dissimilar Metal Weld Cracking
• Stress Relaxation / Reheat Cracking
• Cavitation
• Erosion / Erosion-Corrosion

Key takeaways

• Explain the shared ‘hot gas attacks a hot metal surface’ logic linking oxidation, sulfidation and the carburization family, differentiated only by process gas chemistry.
• Master HTHA in depth, given its exam weight and major-incident history.
• Correctly separate HTHA (internal fissuring, elevated temperature + H₂ partial pressure) from ordinary hydrogen embrittlement (ambient temperature, atomic hydrogen).

Damage mechanisms covered

• Oxidation
• Sulfidation
• Carburization
• Decarburization
• Nitriding
• Metal Dusting
• Fuel Ash Corrosion
• Refractory Degradation
• Gaseous Oxygen-Enhanced Ignition and Combustion
• High-Temperature H₂/H₂S Corrosion
• High-Temperature Hydrogen Attack — HTHA
• Titanium Hydriding

Key takeaways

• Master the wet H₂S damage family (SSC / HIC / SOHIC / Blistering) – the single most heavily examined topic area in API 571.
• Identify which combination of stress, hardness, and hydrogen charging produces each specific sub-form.
• Correctly separate HF acid damage mechanisms from wet H₂S mechanisms despite both being hydrogen-related.

Damage mechanisms covered

• Wet H₂S Damage — Blistering / HIC / SOHIC / SSC
• Hydrogen Embrittlement
• Hydrogen Stress Cracking in HF
• Hydrofluoric Acid Corrosion
• HF Stress Corrosion Cracking of Nickel Alloys
• Liquid Metal Embrittlement
• Amine Corrosion
• Amine Stress Corrosion Cracking
• Ammonia Stress Corrosion Cracking

Key takeaways

• Apply a single decision framework — susceptible material + specific aggressive species + tensile stress — across the SCC family.
• Correctly separate chloride SCC, caustic SCC, carbonate SCC, PASCC, and ethanol SCC, the most commonly confused group on the exam.

Damage mechanisms covered

• Chloride Stress Corrosion Cracking
• Caustic Corrosion
• Caustic Stress Corrosion Cracking
• Carbonate Stress Corrosion Cracking
• Polythionic Acid Stress Corrosion Cracking — PASCC
• Ethanol Stress Corrosion Cracking
• Ammonium Chloride / Amine Hydrochloride Corrosion
• Ammonium Bisulfide Corrosion — Alkaline Sour Water

Key takeaways

• Apply a single thinning/general-corrosion mental model (environment chemistry + wetness + deposit/crevice condition) across the largest mechanism group in API 571.
• Connect each mechanism directly to a practical UT thickness-monitoring strategy.

Damage mechanisms covered

• Atmospheric Corrosion
• Corrosion Under Insulation — CUI
• Cooling Water Corrosion
• Boiler Water & Steam Condensate Corrosion
• Soil Corrosion
• Brine Corrosion
• CO₂ Corrosion
• Concentration Cell Corrosion
• Galvanic Corrosion
• Microbiologically Influenced Corrosion — MIC
• Oxygenated Process Water Corrosion
• Flue Gas Dew Point Corrosion
• Sour Water Corrosion, Acidic
• Aqueous Organic Acid Corrosion
• Dealloying
• Graphitic Corrosion of Cast Irons

Key takeaways

• Complete coverage of the process-specific acid corrosion mechanisms (HCl, H₂SO₄, phosphoric, phenol, naphthenic acid).
• Run a live, full coverage check of all 67 mechanisms with the class to confirm nothing has been missed before moving into integration and review modules.

Damage mechanisms covered

• Hydrochloric Acid Corrosion
• Sulfuric Acid Corrosion
• Phosphoric Acid Corrosion
• Phenol / Carbolic Acid Corrosion
• Naphthenic Acid Corrosion

Key takeaways

• Reverse the direction of learning: instead of starting from a mechanism and asking where it occurs, start from a process unit’s PFD and derive every credible mechanism at each location.
• Build the exact skill tested by scenario-based exam questions and used in real turnaround scope development.

Key takeaways

• Under timed, no-notes conditions, correctly resolve the mechanism pairs and families most commonly confused on the exam.
• Work 4–5 full case studies cold, from symptom to root cause.

Mechanism pairs drilled

• Creep (long-term) vs. Short-Term Overheating (rapid)
• HTHA vs. Hydrogen Embrittlement
• SSC vs. HIC vs. SOHIC vs. Blistering
• Chloride SCC vs. PASCC
• Caustic / Carbonate / Amine SCC
• Sulfidation vs. High-Temp H₂/H₂S Corrosion
• Sulfidation resistance (Cr-driven) vs. Naphthenic Acid resistance (Mo-driven)
• Cavitation vs. Erosion/Erosion-Corrosion
• Dealloying/Graphitic Corrosion vs. normal thinning
• Brittle Fracture vs. Fatigue
• CUI vs. MIC vs. Concentration Cell Corrosion

Key takeaways

• Consolidate all 9 major mechanism families through rapid-fire revision.
• Complete full-length mock examinations under timed conditions.
• Practice scenario-based and mechanism-identification questions.
• Review incorrect answers and strengthen weak areas.
• Review high-yield concepts, curves, standards and key damage mechanisms.
• Complete a final API 571 exam revision before the certification exam.