AMPP Refining Corrosion Technologist (NACE RCT) Practice Questions — 10 Free (2026)

What distinguishes the corrosion concerns of boiler feed water from those of cooling water?

• A. Cooling water is deaerated to remove oxygen while boiler feed water is aerated by design and needs biological control in the service concerned under the condit
• B. Both are deaerated identically, the difference lying only in the temperature each system reaches in service
• C. Boiler feed water needs biological control while cooling water needs deaeration and scale treatment
• D. Boiler feed water is deaerated to remove oxygen and treated against scale, while cooling water is aerated by design and needs inhibitor and biological control ✓
• E. Neither requires treatment; both are used as received from the refinery water supply system

A cooling tower aerates the water by design, and that aeration supplies the cathodic reaction, which is why those systems need inhibitor programmes at all. Boiler systems go the other way, removing the oxygen entirely. AMPP CCRI, 1.8

Which alloy group includes inhibited admiralty and naval brass?

• A. Copper alloys ✓
• B. Aluminum alloys
• C. Nickel alloys
• D. Titanium alloys
• E. Iron alloys

Inhibited admiralty and naval brass belong to the copper alloy group used for tubing and condensers. NACE Course Manual, Table 15.4 Other Refinery Metals and Alloys

How can aqueous hydrochloric acid form beneath salt deposits in exchangers and piping?

• A. Salt laid down as ammonium chloride, or as amine hydrochloride, sheds water readily, so acid appears only where no such deposit lies in the unit concerned
• B. Deposits of iron sulfide take up water readily, from the stream or from wash injected, and make acid beneath themselves
• C. Salt laid down as ammonium chloride, or as amine hydrochloride, draws water in readily, out of the stream or out of whatever wash is put in ✓
• D. Salt of ammonium chloride breaks down under heat below the surface and gives up the acid at once, with no water wanted at all in the unit concerned
• E. The deposits themselves are acidic, so no water is required for corrosion to proceed beneath them

The wash water intended to remove the salt can be the source of the water that activates it, which is why distribution matters so much. This is the same underdeposit mechanism the overhead literature describes, seen here from the acid side. API 571, 3.35

Why is single-stage desalting efficiency limited by dehydration efficiency?

• A. Entrained water carries a far lower salt concentration
• B. Entrained water leaving with the desalted crude carries no salt at all, so dehydration and desalting are independent
• C. Oil carried down with the brine holds the same salt strength as the crude leaving the top
• D. Entrained water leaving with the desalted crude carries the same salt concentration as the brine ✓
• E. The electrostatic field cannot operate unless the crude is fully dehydrated first

Whatever water rides out with the crude takes its salt load with it, and that load is brine strength. So you cannot desalt better than you dehydrate. With good operation a single stage removes roughly 90 percent of the raw crude salt content. 34109, 3.2

What is the maximum hardness requirement for UNS S20910 austenitic stainless steel?

• A. 22 HRC
• B. 23 HRC
• C. 35 HRC ✓
• D. 225 HBW
• E. 275 HV10

UNS S20910 may be solution-annealed, hot/cold-worked, or cold-worked, with hardness ≤35 HRC Clause 13.6.1 Specific Austenitic Grades

What alloy group is most resistant to caustic SCC in aggressive molten caustic service?

• A. Carbon steel
• B. Low‑alloy steel
• C. Nickel-based alloys (e.g., UNS N04400, N06600, N02200/N02201) ✓
• D. Austenitic SS 304, since nothing else is thought to bear on the question
• E. Duplex SS

Nickel and nickel-based alloys (e.g., UNS N04400, N06600, N02200/N02201, N08800, N06690) are historically the material of choice for aggressive caustic service (§ 2.14). Note: at conditions forming molten caustic in the absence of free water (≈318 °C at atmospheric pressure), even these alloys can suffer molten caustic cracking (see §§ 2.14.1–2.14.3, Figs. A8–A12). § 2.14

Under which types of insulation is corrosion under insulation of carbon steel possible?

• A. Under wicking types only, since non-wicking materials cannot transport water
• B. Under every type of lagging ✓
• C. Under closed cell types only, since these trap water against the metal surface
• D. Only where the weather jacketing over the insulation has been damaged
• E. Under chloride-bearing types only, since chloride is required for the mechanism

No insulation type is exempt. What varies is how much a given material contributes, and the standard identifies three characteristics with most influence: leachable salt content, water retention and permeability, and foams that make acid on contact with water. SP0198, 2.1.2.1

By what two routes does elevated temperature promote hydrogen charging?

• A. It dissociates less hydrogen sulfide but speeds the diffusion of monatomic hydrogen through the metal
• B. It dissociates more hydrogen sulfide but slows the diffusion of monatomic hydrogen through the metal
• C. It raises the chloride concentration and speeds monatomic hydrogen diffusion through the metal
• D. It dissociates more hydrogen sulfide and speeds monatomic hydrogen diffusion ✓
• E. It removes the water phase

More monatomic hydrogen produced, and that hydrogen moving faster once inside. The whole effect depends on the aqueous phase surviving the temperature, since without liquid water there is no charging to speak of. MR0103, 6.4

What does 34103 mean by sulfidation, and what does it deliberately exclude?

• A. Sulfur reaction with scale, plus deep internal attack
• B. Wholesale attack working in beneath where the wall once stood, leaving out anything that raises a sulfide layer on the face
• C. Reaction with sulfur compounds in aqueous service below 500 F, excluding all high-temperature forms of the damage entirely
• D. Reaction with sulfur compounds forming a surface sulfide scale, excluding the extensive internal attack seen above 1,000 F ✓
• E. Reaction with hydrogen sulfide in the presence of water

Some sulfur works its way in beneath where the wall once stood, yet it is the scale on the face that defines the thing. Where the report speaks of sulfidic corroding, or that same thing at temperature, it means precisely this and nothing else. 34103, Introduction

What must follow if arc gouging is used to remove cracks, and how is removal confirmed?

• A. Grinding afterwards to clear affected metal, the area then checked over again by the dry magnetic particle method
• B. Welding straight away with nothing done first, the finished joint looked over later by wet fluorescent magnetic means
• C. Subsequent grinding to take out all heat-affected material ✓
• D. Subsequent postweld heat treatment of the excavation
• E. No further action, since arc gouging removes the cracks completely

Whatever method takes the steel past the lower critical point leaves altered metal behind it, and that must be ground out. The reinspection matters because the whole point is confirming nothing was missed, and wet fluorescent magnetic particle is the sensitive method for these cracks. SP0296, 4.5