API API-571 Exam Tutorial FAQ (Part-1)

The API 571 Advanced Corrosion & Materials Professional Certification Preparation Program is designed to enhance the knowledge of corrosion processes among specialized inspectors, corrosion engineers, chemical engineers and other professionals across the entire petrochemical industry.

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Question No: 1

A 5Cr-1Mo piping system in the hydrogen unit shows significant internal wall loss after 2 years in service due to CO corrosion. Which material would be best suited to use to install a new pipe system?

A. Titanium

B. 9Cr-1Mo

C. A-106 Gr B

D. 316 SS

Answer: D


Question No: 2

MIC is often found in _________, bottom water of storage tanks, piping with stagnant or low flow and piping in contact with some soils.

A. Vessels

B. Heat exchangers

C. Drums

D. All of the above

Answer: B


Question No: 3

Where is PASCC normally located?

A. Adjacent to welds

B. On impellers

C. At stress risers

D. At flanges

Answer: A

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Question No: 4

Fatigue will not occur in carbon steel if stresses are below the:

A. Transition limit.

B. Endurance limit.

C. Hardening limit.

D. Speed limit.Answer: B


Question No: 5

300 Series SS can be used for sour water service at temperatures below ____________, where Chloride SCC is not likely.

A. 120º F

B. 140º F

C. 150º F

D. 175º F

Answer: B


Question No: 6

Blistering, HIC, SOHIC and SSC damage can occur wherever there is a ____________ environment.

A. Wet H²S

B. Hydrogen

C. Sulfur

D. Aqueous

Answer: A

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Question No: 7

Geometry, stress level, _________ and material properties are the predominate factors in determining the fatigue resistance of a component.

A. Temperature

B. Pressure

C. Velocity

D. Number of cycles

Answer: D


Question No: 8

With sour water corrosion, at a given pressure, the HS concentration in the sour water _________ as temperatures ________.

A. Increases, increases

B. Decreases, decreases

C. Increases, decreases

D. Decreases, increases

Answer: D


Question No: 9

Thermal fatigue cracks usually initiate on the _________ of the component. They are generally wide and filled with oxides due to the elevated temperatures.

A. Surface

B. ID

C. Welds

D. None of the above

Answer: A

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QuestionNo:10

Which of the following is not a major factor associated with boiler water condensate corrosion?

A. Operating pressure

B. Oxygen content

C. Carbon dioxide content

D. Process ph

E. Temperature

Answer: A


Question No : 11

Surface initiated cracks caused by environmental cracking of 300 Series SS and some nickel based alloys under the combined action of tensile stress, temperature and an aqueous chloride environmental is called ________. The presence of dissolved oxygen ___________ the propensity for cracking.

A. Cl SCC, Increases

B. Stress cracking, Increases

C. Cl SCC, Decreases

D. Stress cracking, Decreases

Answer: A


Question No : 12

_______ is the primary alloying agent that affects resistance to oxidation.

A. Chromium

B. Molybdenum

C. Silicon

D. Aluminum

Answer: A

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Question No : 13

Vessels constructed after December 1987 are subject to the requirements of ________ of ASME Section VIII, Division 1.

A. UW-26

B. UG-31

C. UB-54

D. UCS-66

Answer: D


Question No : 14

Which of these materials are susceptible to brittle fracture?

A. Carbon steels

B. Low alloy steels

C. 400 Series SS

D. All of the above

Answer: D


Question No : 15

Which of the following are susceptible to thermal fatigue?

A. SA-516-70

B. SA-182 Gr B

C. SA-53 Gr B

D. All of the above

Answer: D

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Question No : 16

Hardness is primarily an issue with SSC. Typical low strength carbon steels should be controlled to produce weld hardness less than ________.

A. 225 BHN

B. 237 BHN

C. 200 BHN

D. 240 BHN

Answer: C


Question No : 17

Titanium Hydriding damage occurs primarily in sour water strippers and amine units in the overhead condensers, heat exchanger tubes and other titanium equipment operating above _________.

A. 300º F

B. 270º F

C. 210º F

D. 165º F

Answer: D


Question No : 18

In HF service, carbon steel forms a protective _________ scale in dry concentrated acid. Loss of the protective scale through high velocities or turbulence will result in greatly accelerated corrosion rates.

A. Chloride

B. Fluoride

C. Iron sulfide

D. Iron oxide

Answer: B

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Question No : 19

________ of a component is the most important factor in determining the resistance of a component to mechanical fatigue.

A. Design

B. Temperature

C. Stress

D. Pressure

Answer: A


Question No : 20

_________ acid is most often used as a catalyst in polymerization units.

A. Polythionic

B. Naphthenic

C. Phosphoric

D. Sulfuric

Answer: C


Question No : 21

Type 304L SS is satisfactory for phosphoric acid concentration of 100% up to about _________. Type 321 is required from there to 225 F.

A. 140º F

B. 150º F

C. 100º F

D. 120º F

Answer: D

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Question No : 22

300 Series SS, 5Cr, 9Cr and 12Cr alloys are not susceptible to ________ at conditions normally seen in refineries.

A. Cl SCC

B. SOHIC

C. HTHA

D. HTLA

Answer: C


Question No : 23

Naphthenic acid corrosion is a form of high temperature corrosion that occurs primarily in crude and vacuum units and downstream units that process certain fractions that contain naphthenic acid. Which of the following materials is susceptible to naphthenic acid corrosion?

A. Carbon steel

B. 300 Series SS

C. 400 Series SS

D. All of the above

Answer: D


Question No : 24

______ is similar to HIC but is a potentially more damaging form of cracking which appears as arrays of cracks stacked on top of each other. The result is a through thickness crack that is perpendicular to the surface and is driven by high levels of stress.

A. MIC

B. SOHIC

C. Sulfuric SCC

D. None of the above

Answer: B

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Question No : 25

Caustic embrittlement is a form of stress corrosion cracking characterized by surface- initiated cracks that occur in piping and equipment exposed to caustic, primarily adjacent to non-PWHT welds. Which of the following materials is the most resistant to embrittlement?

A. Carbon steel

B. Nickel based alloys

C. Low alloy steels

D. 400 Series SS

Answer: B


Question No : 26

In piping and equipment, creep cracking can occur where high metal temperatures and _________ occur together. Creep cracking, once initiated, can progress rapidly.

A. Pressures

B. Stress risers

C. Velocities

D. None of the above

Answer: B


Question No : 27

Which of the following does not increases the likelihood of atmospheric corrosion?

A. Bird poop

B. Increasing annual rainfalls

C. Locations where moisture is trapped

D. Increasing operating pressures

E. Increasing amounts of airborne contaminates

Answer: D

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Question No : 28

SCC generally occurs below about _______.

A. 150º F

B. 180º F

C. 210º F

D. 240º F

Answer: B


QuestionNo:29

Amine stress corrosion cracking is a term applied to the cracking of steels under the combined actions of ________ and __________ in aqueous alkanolamine systems used to remove/absorb HS and/or CO and their mixtures from various gas and liquid hydrocarbon streams.

A. Temperature, pressure

B. Pressure, stress

C. Temperature, corrosion

D. Tensile stress, corrosion

Answer: D


Question No : 30

Corrosion due to acidic sour water containing HS at a pH between 4.5 and 7.0 is called sour water corrosion. Carbon dioxide (CO) may also be present. Which of the following materials is susceptible to sour water corrosion?

A. Carbon steel

B. 300 Series SS

C. 400 Series SS

D. Both B and C

Answer: A

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Question No : 31

Dissimilar metal welds with a 300 Series stainless steel weld metal on a ferritic steel may also result in narrow region of _________ at the toe of the weld, near the fusion line on the ferritic side.

A. Ductility

B. Hardness

C. Cracking

D. None of the above

Answer: B


Question No : 32

Units where graphitization may be suspected are the FCCU and the _____ unit.

A. Hydrotreater

B. Coker

C. Alky

D. None of the above

Answer: B


Question No : 33

________ is a form of carbon that may promote carburization, particularly during decoke cycles where temperatures exceed the normal operating temperatures.

A. Carbonic acid

B. Coke

C. Crude oil

D. None of the above

Answer: B

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Question No : 34

Primarily hot-wall piping and equipment in the following units can be affected by graphitization. FCC, catalytic reformer and ______.

A. Hydrotreater

B. Hydrocracker

C. Coker

D. Alky

Answer: C


Question No : 35

Stainless steels with sigma can normally withstand normal operating stresses but upon cooling to temperatures below _______ may show a complete lack of fracture toughness as measured by a Charpy impact test.

A. 800º F

B. 600º F

C. 500º F

D. 400º F

Answer: C


Question No : 36

With decarburization, the decarburized layer will be free of carbide phases. Carbon steel will be ______.

A. Annealed

B. Quenched

C. Pure iron

D. None of the above

Answer: C

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Question No : 37

Permanent deformation occurring at relatively low stress levels as a result of localized overheating is called ________.

A. Stress cracking

B. Brittle fracture

C. Temper embrittlement

D. Stress rupture

Answer: D


Question No : 38

Thermal fatigue cracks propagate ________ to the stress and are usually dagger shaped, transgranular and oxide-filled.

A. Axial

B. Diagonal

C. Transverse

D. Angular

Answer: C


Question No : 39

Components that have been carburized may have a change in the level of ________.

A. Carbon

B. Chromium

C. Ferromagnetism

D. Stress

Answer: C

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Question No : 40

Oxygen and iron in the wash water injected into reactor effluent can lead to __________ corrosion and fouling.

A. Increased

B. Decreased

C. Substantial

D. Minimal

Answer: A


Question No : 41

Convert these temperatures – 156º C and 450º F

A. 304º F, 151º C

B. 284º F, 218º C

C. 312º F, 232º C

D. 296º F, 246º C

Answer: C


Question No : 42

The creep threshold temperature for 1 ¼, 2 ¼, 5 and 9 Cr is ________.

A. 600º F

B. 700º F

C. 800º F

D. 1000º F

Answer: C

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Question No : 43

Hydrogen blisters may form at many different depths from the surface of the steel, in the middle of the plate or near a weld. In some cases, neighboring or adjacent blisters that are at slightly different depths (planes) may develop cracks that link them together. Interconnecting cracks between the blisters often have a __________ appearance.

A. Crescent

B. Eyebrow

C. Step like

D. Jagged

Answer: C


Question No : 44

Decarburization results in a __________, which can be confirmed by hardness testing.

A. Hardness

B. Softness

C. Brittleness

D. Oxidizing

Answer: B


Question No : 45

__________ is a form of damage found mostly in older vintage carbon steels and C-0.5 Mo low alloy steels under the combined effects of deformation and aging at an intermediate temperature.

A. Spheroidization

B. Thermal fatigue

C. Strain aging

D. None of the above

Answer: C

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Question No : 46

What structure is 410 stainless steel?

A. Martensitic

B. Austenitic

C. Duplex

D. Ferritic

Answer: A


Question No : 47

Atmospheric corrosion:

A. Can cause either uniform or localized wall loss.

B. Always causes localized wall loss.

C. Always causes uniform wall loss.

D. Is best detected using profile RT.

Answer: A


Question No : 48

300 Series SS is susceptible to LME when it comes in contact with molten ________.

A. Cadmium

B. Mercury

C. Zinc

D. Lead

Answer: C


Question No : 49

Caustic stress corrosion cracking typically propagates _______ to the weld in adjacent base metal but can occur in the weld deposit or heat affected zone.

A. Transverse

B. Perpendicular

C. Parallel

D. Across

Answer: C

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Question No : 50

Naphthenic acid corrosion is most severe in _________ flow; in areas of high velocity or turbulence and in distillation towers where hot vapors condense to form liquid phase droplets.

A. Single phase

B. Two phase

C. Three phase

D. Negative phase

Answer: B


Question No : 51

Steam blanketing is when the heat flow balance is disturbed; individual bubbles join to form a steam blanket, a condition known as Departure from Nucleate Boiling (DNB). Once a steam blanket forms, tube rupture can occur rapidly, as a result of _________.

A. Thermal fatigue

B. Short term overheating

C. Brittle fracture

D. Stress

Answer: B


Question No : 52

Phosphoric acid corrosion is usually found in ________ areas.

A. High velocity

B. Low velocity

C. High temperature

D. Low temperature

Answer: B

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QuestionNo:53

Corrosion in boiler feedwater and condensate return systems is usually the result of dissolved gases, oxygen and ________.

A. Carbon monoxide

B. Carbon dioxide

C. Material properties

D. H²S

Answer: B


Question No : 54

Preventative measures to minimize the potential for brittle fracture in existing equipment are limited to controlling _______ and ________, minimizing pressure at ambient temperatures during start-up and shutdown and periodic inspections at high stress locations.

A. Temperature, stress

B. Stress, pressure

C. Velocity, stress

D. Temperature, Pressure

Answer: D


Question No : 55

Which of the following materials is susceptible to carburization?

A. Low alloy steels

B. 300 Series SS

C. 400 Series SS

D. All of the above

Answer: D

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Question No : 56

Improved resistance to erosion is usually achieved through increasing substrate ________ using harder alloys, hard facing or face-hardening treatment.

A. Composition

B. Stress

C. Hardness

D. None of the above

Answer: C


Question No : 57

Sulfide stress cracking (SSC) is defined as cracking of metal under the combined action of tensile stress and corrosion in the presence of _________ and _________.

A. Sulfur, Oxide

B. Hydrogen, water

C. H²S, Oxygen

D. Water, H²S

Answer: D


Question No : 58

In order to minimize and prevent amine SCC, PWHT all carbon steel welds in accordance with API RP _____.

A. 751

B. 912

C. 510

D. 945

Answer: D


Question No : 59

Sulfidation usually creates:

A. Uniform corrosion.

B. Isolated pitting.

C. Intergranular cracking.

D. Transgranular cracking.

E. Hard and brittle zones.

F. Inspection nightmares.

Answer: A

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Question No : 60

All ________ based materials and low alloy materials, 300 Series SS and 400 Series SS are susceptible to Sulfidation.

A. Carbon

B. Steel

C. Chromium

D. Iron

Answer: D


Question No : 61

Creep and stress rupture is more likely in a _________ grained material than a _______ grained material.

A. Course, Fine

B. Fine, Course

C. Austenetic, Martensitic

D. None of the above

Answer: A


Question No : 62

_________ is most likely found in hard weld and heat-affected zones and in high strength components.

A. HIC

B. SSC

C. SOHIC

D. Blistering

Answer: B

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Question No : 63

A form of corrosion that can occur at the junction of dissimilar metals when they are joined together in a suitable electrolyte is __________.

A. Galvanic corrosion

B. Anodic corrosion

C. Cathodic corrosion

D. All of the above

Answer: A


Question No : 64

General or localized corrosion of carbon steels and other metals caused by dissolved salts, gases, organic compounds or microbiological activities is called ________.

A. Flue Gas Corrosion

B. Atmospheric Corrosion

C. Cooling Water Corrosion

D. None of the Above

E. All of the Above

Answer: C


Question No : 65

Hydriding of titanium is a metallurgical phenomenon in which hydrogen diffuses into the titanium and reacts to form an embrittling phase. This can result in a complete loss of _________ with no noticeable sign of corrosion or loss of thickness.

A. Strength

B. Ductility

C. Carbides

D. Hardness

Answer: B

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Question No : 66

What method is most used to assure boiler feed water corrosion is not occurring?

A. Spot UT readings at turbulent areas

B. Profile RT at turbulent areas

C. Profile RT at stagnant areas

D. Laboratory analysis of boiler feedwater

Answer: D


Question No : 67

In most cases, brittle fracture occurs only at temperatures below the Charpy impact transition temperature. Steel cleanliness and ________ have a significant influence on toughness and resistance to brittle fracture.

A. Alloy composition

B. Tensile strength

C. Grain size

D. Pressure

Answer: C


Question No : 68

Soil to Air interface areas are usually more susceptible to corrosion than the rest of the structure because of ___________ and __________ availability.

A. Moisture

B. Bacteria

C. Oxygen

D. B and C

E. A and C

Answer: E

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Question No : 69

__________ is a form of cracking that results when certain molten metals come in contact with specific alloys. Cracking can be very sudden and brittle in nature.

A. SCC

B. LME

C. AET

D. SOHIC

Answer: B


Question No : 70

Cracking of a metal due to stress relaxation during PWHT or in service at elevated temperatures is called ______. It is most often found in heavy wall sections.

A. Thermal cracking

B. Reheat cracking

C. Step-like cracking

D. None of the above

Answer: B


Question No : 71

Which of the following materials is affected by high temperature corrosion?

A. Carbon steel

B. 300 Series SS

C. 400 Series SS

D. All of the above

Answer: D

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QuestionNo:72

Nitriding layers are magnetic. Therefore, _________ should be checked for magnetism as an initial screening for nitriding.

A. 300 Series SS

B. 400 Series SS

C. Duplex SS

D. Low alloy steel

Answer: A


Question No : 73

Which of the following materials are susceptible to nitriding?

A. Carbon steel

B. 300 Series SS

C. 400 Series SS

D. All of the above

Answer: D


Question No : 74

Sigma phase in welds can be minimized by controlling ferrite in the range of _________ for Type 347 SS.

A. 3%-5%

B. 5%-7%

C. 7%-9%

D. 5%-9%

Answer: D

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Question No : 75

If wet electrodes or high moisture content flux is used, ________ can be charged into the steel resulting in delayed cracking.

A. Atomic hydrogen

B. Hydrogen

C. Oxygen

D. H²O

Answer: B


Question No : 76

To prevent carburization, select alloys with a strong surface oxide or sulfide film former such as ________.

A. Silicon

B. Molybdenum

C. Aluminum

D. Both A and C

Answer: D


QuestionNo:77

Which of these materials is not susceptible to amine cracking?

A. Carbon steel

B. 300 Series SS

C. 400 Series SS

D. Both B and C

Answer: D

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Question No : 78

Which of the following materials are affected by mechanical fatigue cracking?

A. Only carbon steel

B. Only carbon steel and chromes

C. Only carbon steel, and high nickel alloys

D. All materials

Answer: B


Question No : 79

Which API RP recommends programs to monitor small-bore piping, flange faces, blistering and HIC/SOHIC in HF alky units?

A. 574

B. 751

C. 571

D. 980

Answer: B


Question No : 80

Which of the following is not a critical factor that contributes to a brittle fracture?

A. The material’s fracture toughness

B. Maximum operating temperature

C. Stress concentration at a flaw

D. Magnitude of the residual stresses

Answer: B

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Question No : 81

Conditions favoring carburization include a high gas phase carbon activity and _______ oxygen potential.

A. Low

B. High

C. Negative

D. Positive

Answer: A


Question No : 82

Low creep ductility is __________ severe in high tensile strength materials and welds.

A. More

B. Less

C. Usually

D. Not

Answer: A


Question No : 83

Alloy 400 is susceptible to LME when it comes in contact with molten ________.

A. Cadmium

B. Mercury

C. Zinc

D. Lead

Answer: B

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Question No : 84

Sulfidation is primarily caused by:

A. Impacting particles.

B. Sulfur compounds decomposing at higher temperatures.

C. Sulfur compounds being created in the FCCU (Cat Cracking Unit).

D. Elemental sulfur collecting in stagnate areas, e.g. dead legs.

E. Operators failing to adequately control the ph of sulfur streams.

Answer: B


Question No : 85

__________ is a change in the microstructure of certain carbon steels and 0.5 Mo steels after long term operation in the 800 F to 1100 F range.

A. Graphitization

B. Softening

C. Temper Embrittlement

D. Creep

Answer: A


Question No : 86

Which material below is not susceptible to caustic corrosion?

A. Carbon steel

B. 400 Series SS

C. 300 Series SS

D. Low alloy steel

Answer: B

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Question No : 87

Which of the following materials is least affected by brittle fracture?

A. Carbon steel

B. Chromes

C. 300 series stainless steel

D. 400 series stainless steel

E. All stainless steels

Answer: C


Question No : 88

A form of corrosion caused by living organisms such as bacteria, algae or fungi is _______

A. HIC

B. SOHIC

C. MIC

D. None of the above

Answer: C

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Question No : 89

In HF service, carbon steel forms a protective fluoride scale in dry concentrated acid. Loss of the protective scale through high _________ or turbulence will result in greatly accelerated corrosion rates.

A. Temperature

B. Pressure

C. Velocities

D. None of the above

Answer: C


Question No : 90

With thermal fatigue, time to failure is a function of the magnitude of the stress and the number of cycles and decreases with _________ stress and ________ cycles.

A. Increasing, Decreasing

B. Increasing, Increasing

C. Decreasing, Decreasing

D. Decreasing, Increasing

Answer: B


Question No : 91

Which of the following materials is least affected by atmospheric corrosion?

A. Carbon steel

B. Chromes

C. Stainless steels

D. Copper alloyed with aluminum

Answer: C

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QuestionNo:92

Corrosion protection in the boiler is accomplished by laying down and continuously maintaining a layer of _____.

A. Manganese

B. Magnetite

C. Carbon monoxide

D. Carbonate

Answer: B


Question No : 93

300 Series SS, 400 Series SS and duplex SS are subject to pitting and localized corrosion under insulation. In addition, __________ are also subject to SCC if chlorides are present, while _________ are less susceptible.

A. Duplex SS, Low alloys

B. 300 Series SS, Duplex SS

C. Duplex SS, 300 Series Ss

D. None of the above

Answer: B

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Question No : 94

In general, the resistance of carbon steel and other alloys to High temperature corrosion is determined by the ________ content of the material.

A. Molybdenum

B. Chromium

C. Carbon

D. All of the above

Answer: B


Question No : 95

300 series stainless steel heater tubes in an oil-burning furnace in the hydrocracker began to leak and the furnace was brought down. What was the probable cause of the cracking?

A. Chloride stress corrosion

B. Polythionic acid stress corrosion

C. Amine stress corrosion

D. Stress oriented hydrogen induced cracking

Answer: B


Question No : 96

The major factors affecting high temperature sulfidation are the temperature, the presence of hydrogen, the concentration of HS and the __________.

A. Alloy content

B. Velocity

C. Pressure

D. Water content

Answer: A

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Question No : 97

What treatment is used to prevent boiler feed water corrosion?

A. Oxide scavengers are added to process

B. Oxygen scavengers are added to process

C. Sulfide scavengers are added to process

D. Sulfur scavengers are added to process

Answer: B


Question No : 98

Nickel based alloys usually contain ________ nickel.

A. 30%

B. 20%

C. 10%

D. 12%

Answer: A


Question No : 99

NAC may be found in hot hydrocarbon streams downstream of the crude and vacuum units, __________ any hydrogen mix point.

A. Upstream of

B. Downstream of

C. Adjacent to

D. Around

Answer: A

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Question No : 100

Cracks associated with brittle fracture will typically be _________.

A. Jagged

B. Branching

C. Straight

D. Perpendicular

Answer: C


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Author: Muhamad Aarif

A notorious book addict by night and an oil and gas executive by day. As Mark Twain said, "The man who doesn't read good books has no advantage over the man who can't read them." So, read, read, and read some more.

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