571 - P1 (50Q)

Question 1

Sudden rapid fracture under stress (residual or applied) where the material exhibits little
or no evidence of ductility or plastic deformation is called

Answer 1

brittle fracture

Question 2

Material affected by brittle fracture includes ____, _____ and ________.

Answer 2

carbon steel, low alloy steel and 400 series stainless steel.

Question 3

The three factors leading to brittle fracture are

Answer 3

fracture toughness, flaw size and residual stress.

Question 4

In most cases, brittle fracture occurs only at temperatures below the ________, the point at which the toughness of the material
drops off sharply

Answer 4

Charpy impact transition

temperature (or ductile-to-brittle transition temperature)

Question 5

Most processes run at elevated temperature so the main concern is for brittle fracture during __________. Thick wall equipment on any unit should be considered

Answer 5

startup, shutdown, or hydrotest/tightness testing

Question 6

Brittle fracture cracks are typically be ________, and largely devoid of any associated plastic deformation
(no shear lip or localized necking around the crack)

Answer 6

straight, non-branching

Question 7

Microscopically, the brittle fracture crack surface will be composed largely of ____________ and very little microvoid coalescence.

Answer 7

cleveage, with limited intergranular cracking

Question 8

For new equipment, brittle fracture is best prevented by using materials specifically designed for _________ operation including upset and autorefrigeration events.

Answer 8

low temperature

Question 9

Performing a ________ on the vessel if it was not originally done during manufacturing may reduce likelihood of brittle fracture.

Answer 9

post weld heat treatment (PWHT)

Question 10

A _______ followed by a lower temperature hydrotest to extend the Minimum Safe Operating Temperature (MSOT) envelope may be performed to reduce likelihood of brittle fracture.

Answer 10

“warm” pre-stress

Question 11

Pressure vessel designed using ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, prior to
the ___________ Addenda may be affected by brittle fracture. The requirements of _______ (impact
exemption curves) was later introduced to avoid crack due to brittle fracture.

Answer 11

December 1987, UCS 66

Question 12

________ is a mechanical form of degradation that occurs when a component is exposed to
cyclical stresses for an extended period, often resulting in sudden, unexpected failure.

Answer 12

Fatigue cracking

Question 13

All engineering alloys are subject to fatigue cracking although the ________ and _________
necessary to cause failure vary by material

Answer 13

stress levels, number of cycles

Question 14

Fatigue cracks usually initiate on the surface at notches or ________ under cyclic loading

Answer 14

stress raisers

Question 15

Materials like austenitic stainless steels and

aluminum that do not have an endurance limit will have a fatigue limit defined by _________.

Answer 15

the number of cycles at a given stress amplitude

Question 16

For alloys with endurance limits, _____ this limit, fatigue cracking will not occur, regardless of the number of cycles

Answer 16

below

Question 17

The signature mark of a fatigue failure is a ________ type fingerprint that has concentric rings called
________ emanating from the crack initiation site

Answer 17

“clam shell”, “beach marks”

Question 18

The best defense against fatigue cracking is ________.

Answer 18

good design

Question 19

Surface preparation and ________ application are critical for long-term protection against atmospheric corrosion.

Answer 19

proper coating

Question 20

Atmospheric corrosion rates increase with temperature up to about _________.

Answer 20

250oF (121oC)

Question 21

Piping that rests on ________ is very prone to atmospheric corrosion due to _______ between the pipe and the support.

Answer 21

pipe supports, water entrapment

Question 22

Corrosion under insulation becomes more severe at metal temperatures between the boiling point and _______, where water is less likely to vaporize and insulation stays wet longer

Answer 22

250oF (121oC)

Question 23

_______ techniques for identifying wet insulation.

Answer 23

Neutron backscatter

Question 24

CUI mitigation is best achieved by using appropriate __________ and maintaining the insulation /sealing /vapor barriers to prevent moisture ingress.

Answer 24

paints / coatings

Question 25

Because there are several types of MIC, organisms can survive and grow under severe conditions including lack of oxygen, light or dark, high salinity, pH range of _____, and temperatures from ______.

Answer 25

0 to 12, 0oF to 235oF (–17 oC to 113oC)

Question 26

MIC is most often found in heat exchangers, bottom water of storage tanks, piping with ________, and piping in contact with some soils.

Answer 26

stagnant or low flow

Question 27

Damage is often characterized by ________ within pits in carbon steel or subsurface cavities in
stainless steel.

Answer 27

cup-shaped pits

Question 28

To avoid MIC, systems that contain water (cooling water, storage tanks, etc.) should be treated with biocides such as ________ or proprietary compounds.

Answer 28

chlorine, bromine, ozone, ultraviolet light

Question 29

Material affected by soil corrosion are ______.

Answer 29

Carbon steel, cast iron and ductile iron

Question 30

The most common method used for monitoring underground structures is measuring the structure to
soil ____________ near the structure.

Answer 30

potential using dedicated reference electrodes

Question 31

Material affected by caustic corrosion are primarily

Answer 31

carbon steel, low alloy steels and 300 Series SS.

Question 32

Exposure to high solution strength caustic can result in general corrosion of carbon steel above ____ and very high corrosion rates above _____.

Answer 32

175oF (79oC), 200oF (93oC).

Question 33

_______ gauging is useful to detect and monitor general corrosion due to caustic.

Answer 33

UT thickness

Question 34

Material affected by ClSCC are

Answer 34

300 SS and Duplex SS

Question 35

The greatest susceptibility to ClSCC is at a nickel

content of _____, highly resistance at ____ and immune above ____.

Answer 35

8% to 12% , 35%, 45%

Question 36

Characteristic stress corrosion cracks have ______ and may be visually detectable by a _______ appearance of the surface

Answer 36

many branches, craze cracked

Question 37

RT is ______ to detect cracks except in advanced stages where a significant network of cracks has developed.

Answer 37

not sufficiently sensitive

Question 38

Caustic embrittlement is a form of stress corrosion cracking characterized by that ____________
occur in piping and equipment exposed to caustic, primarily adjacent to ______.

Answer 38

surface-initiated cracks, non-PWHT’d welds.

Question 39

If a concentrating mechanism is present, caustic

concentrations of _______ are sufficient to cause cracking.

Answer 39

50 to 100 ppm

Question 40

Caustic stress corrosion cracking typically propagates ______ to the weld in adjacent base metal but can
also occur in the weld deposit or heat-affected zones.

Answer 40

parallel

Question 41

Cracking can be effectively prevented by means of a ________. A heat treatment at _______ is considered an effective stress relieving heat treatment for carbon
steel.

Answer 41

PWHT, 1150°F (621°C)

Question 42

___ is not effective for finding tight, scale-filled cracks and should not be used for detection.

Answer 42

PT

Question 43

Corrosion of steel due to acidic sour water containing H2S at a pH between ________. Carbon dioxide
(CO2) may also be present.

Answer 43

4.5 and 7.0

Question 44

Sour water corrosion primarily affects _______

Answer 44

carbon steel

Question 45

___________________ are all critical factors affecting sour water corrosion.

Answer 45

H2S content, pH, temperature, velocity and oxygen concentration

Question 46

Sulfuric acid corrodes severely carbon steel ________ .

Answer 46

heat affected zones

Question 47

Carbon steel corrosion rates increase significantly if the flow velocity exceeds about __________ or at acid concentrations below ____.

Answer 47

2 to 3 fps (0.6 to 0.9 m/s), 65%

Question 48

Alloys such as __________ resist dilute acid corrosion and form a protective iron sulfate film on the surface.

Answer 48

Alloy 20, Alloy 904L and Alloy C-276

Question 49

Corrosion of steel by dilute acid is usually in the form of __________ and becomes more severe with increasing temperature and velocity.

Answer 49

overall metal loss or pitting

Question 50

_________ – a family of stainless steels that contain a mixed austenitic-ferritic structure
including Alloy 2205, 2304, and 2507

Answer 50

Duplex stainless steel