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Corrosion and Materials Professional Questions and Answers

Question 1

Phosphoric acid corrosion in polymerization units is usually found under what circumstances?

Options:

A.

Turbulent flows

B.

Low velocity areas

C.

Two-phase flow

D.

When the acid dries out

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Question 2

Temper embrittlement is a metallurgical change that is:

Options:

A.

Not readily apparent but can be confirmed through tension testing

B.

Readily apparent and can be confirmed through impact testing

C.

Readily apparent and can be confirmed through metallography

D.

Not readily apparent but can be confirmed through impact testing

Question 3

Naphthenic acid corrosion (NAC) is most severe in what phase of flow?

Options:

A.

Two phase

B.

Hydrocarbon phase

C.

Water phase

D.

Vapor phase

Question 4

The likelihood of brittle fracture is best lessened by:

Options:

A.

Using thicker construction materials to lower the resulting stress

B.

Using carbon or low-alloy steels

C.

Frequent inspection of the piping or equipment involved

D.

Postweld heat treatment (PWHT)

Question 5

Which of the following is the main concern for the potential of brittle fracture in typical process service?

Options:

A.

Start-up and shutdown of equipment

B.

Overpressure during abnormal operation

C.

Abnormal, transient stresses on typical process piping

D.

Cyclic or intermittent services

Question 6

Which of the following is the most significant result of spheroidization in steels?

Options:

A.

Increased potential for stress corrosion cracking

B.

Increased hardness

C.

Loss of ductility

D.

Loss of strength

Question 7

What damage mechanism can occur in wet H₂S environments and is sometimes confused with wet H₂S damage?

Options:

A.

Ammonia cracking

B.

HCl cracking

C.

Amine cracking

D.

Polythionic cracking

Question 8

The potential for galvanic corrosion will increase when:

Options:

A.

insulating dissimilar metals with different electro-chemical potentials.

B.

using a relatively large volume of anodic material.

C.

applying a coating to both metals.

D.

different metals are in contact with presence of electrolyte.

Question 9

Damage from oxidation is usually determined by:

Options:

A.

Metallographic examination

B.

Ultrasonic thickness measurements

C.

Hardness testing

D.

Hammer testing

Question 10

The form of corrosion most often caused by sulfidation is typically described as:

Options:

A.

General or uniform corrosion

B.

High-temperature corrosion

C.

Localized erosion-corrosion

D.

Sulfide cracking corrosion

Question 11

(Repeated) The best method for finding damage from sigma phase embrittlement is:

Options:

A.

Hardness testing

B.

Ductility testing

C.

Magnetic particle testing

D.

Metallographic testing

Question 12

Carbonate stress corrosion cracking and alkaline stress corrosion cracking are:

Options:

A.

Not preventable by post-fabrication stress relieving of weldments.

B.

Closely related corrosion mechanisms.

C.

Mechanisms that affect carbon steels and austenitic stainless steels.

D.

Different only in the level of alkalinity needed to initiate attack.

Question 13

Which of the following statements is most accurate with regard to thermal fatigue?

Options:

A.

Thermal fatigue cracks generally initiate on the interior of a component due to high thermal stress

B.

Because of their ductility, carbon steels have lower resistance to thermal fatigue

C.

Visual examination is an ineffective method of monitoring thermal fatigue

D.

Controlled rates of heating and cooling during startup and shutdown can lower stresses

Question 14

Which of the following is considered resistant to cracking in hydrofluoric acid service?

Options:

A.

ASTM A-193 B5

B.

ASTM A-193 B7

C.

ASTM A-193 B7M

D.

ASTM A-325

Question 15

The primary cause of ammonium chloride corrosion is the formation of salts:

Options:

A.

That may precipitate from high-temperature streams as they are cooled

B.

During water washing operations in streams containing traces of chlorides

C.

That may deposit when water evaporates to dry-out conditions as streams are heated

D.

When steam is injected into streams containing traces of chlorides

Question 16

Which of the following damage mechanisms is related to steel hardness?

Options:

A.

Stress-oriented hydrogen-induced cracking

B.

Sulfide stress corrosion cracking

C.

Hydrogen-induced cracking

D.

Hydrogen blistering

Question 17

Which type of corrosion is most likely to occur in hydroprocess reactor effluent streams in units producing alkaline sour water?

Options:

A.

Amine

B.

Ammonium bisulfide

C.

Caustic

D.

Ammonium chloride

Question 18

Which of the following is the lowest threshold temperature at which creep damage is a concern in carbon steel with tensile strength > 60ksi (414 MPa)?

Options:

A.

600°F (316°C)

B.

700°F (371°C)

C.

800°F (427°C)

D.

900°F (482°C)

Question 19

Microbiologically induced corrosion is largely independent of the:

Options:

A.

Water content of the process

B.

Presence of hydrogen sulfide

C.

pH of the fluid

D.

Velocity of the flow stream

Question 20

Which of the following is a critical factor for chloride stress corrosion cracking?

Options:

A.

Presence of nickel content less than 8%

B.

Presence of oxygen

C.

Presence of nickel content higher than 35%

D.

Use in an alkaline pH region

Question 21

Aggressive ammonium chloride corrosion often occurs:

Options:

A.

When the salts precipitate from high-temperature streams as they cool.

B.

In the absence of a free water phase.

C.

When excess water washing dissolves too much ammonium chloride.

D.

When dry salts are exposed to a small amount of free water.

Question 22

Both sulfide stress corrosion cracking and stress-oriented hydrogen-induced cracking are most often found in:

Options:

A.

Areas where there is significant hydrogen blistering.

B.

Steel weldments.

C.

Hardened steels.

D.

Areas with temperatures above 300°F (149°C).

Question 23

In a naphthenic acid corrosive (NAC) environment, what is the effect of sulfur?

Options:

A.

No effect

B.

Sulfide cracking

C.

Inhibition

D.

Corrosion accelerator

Question 24

In a wet H2S-type environment, what fluid material will significantly increase the probability of blistering?

Options:

A.

Polythionic acid

B.

Cyanides

C.

Carbonates

D.

Amines

Question 25

Which of the following is related to all wet H₂S damage mechanisms?

Options:

A.

pH of <7 with dissolved H₂S present

B.

Localized zones of weld HAZ hardness above 200 HB

C.

Water vapor in the hydrocarbon phase

D.

Absorption and permeation of hydrogen

Question 26

Metal dusting usually occurs in the operating temperature range of:

Options:

A.

600°F–1200°F (315°C–650°C)

B.

900°F–1500°F (480°C–815°C)

C.

1200°F–1800°F (650°C–980°C)

D.

1500°F–2100°F (815°C–1150°C)

Question 27

Which of the following statements about high-temperature hydrogen attack is most accurate?

Options:

A.

Acoustic emission testing is not a proven method for the detection of high-temperature hydrogen attack damage.

B.

High-temperature hydrogen attack will most often be associated with the formation of surface blisters.

C.

High-temperature hydrogen attack damage is most often limited to welds and heat-affected zones.

D.

300 series stainless steels are also susceptible to high-temperature hydrogen attack at conditions normally seen in refinery units.

Question 28

Spheroidization is a change in the microstructure of steels that can occur after exposure to a minimum temperature of:

Options:

A.

650°F (345°C)

B.

700°F (370°C)

C.

850°F (455°C)

D.

1000°F (540°C)

Question 29

Which of the following can increase the corrosion rate of carbon steel via hydrofluoric (HF) acid corrosion?

Options:

A.

High nitrogen content in process

B.

Oxygen contamination

C.

HF acid concentration above 98%

D.

Weld hardness above 200 BHN

Question 30

The presence of which additional substance(s) will accelerate the corrosion of steel in the presence of sulfur compounds at high temperature?

Options:

A.

Hydrogen

B.

Oxygen

C.

Chlorides

D.

Sulfates

Question 31

What is the most effective way to mitigate aqueous organic acid corrosion in overhead streams?

Options:

A.

Increase the overhead temperature

B.

Water washing

C.

Injection of neutralizer

D.

Injection of filming amine

Question 32

An inspector has discovered significant cracking in a T-joint where hot and cold hydrogen-containing streams are mixing in a hydroprocess unit. What damage mechanism should the inspector suspect is the cause?

Options:

A.

Mixing point corrosion

B.

Injection point corrosion

C.

Thermal fatigue

D.

Hydrogen embrittlement

Question 33

Why are high-cycle fatigue cracks difficult to detect with nondestructive examination (NDE)?

Options:

A.

They are usually in 90° corners where inspection is difficult.

B.

Cracks are so tight they are often missed.

C.

Time required for crack growth is not predictable.

D.

They normally start on the I.D. surface.

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Total 110 questions