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API571 > Module 7(High Temp 400F ) > Flashcards

Module 7(High Temp 400F ) Flashcards

1
Q

Sulfidation (Sulfide Corrosion)

Occurs at what temperature? Greater / Begins?

A

500F / 450F

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2
Q

Sulfidation (Sulfide Corrosion)

Name of the curve?

A

Modified Mconomy

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3
Q

Sulfidation (Sulfide Corrosion)

What Presence increase CR?

A

hydrogen

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4
Q

Sulfidation (Sulfide Corrosion)

Affected Material? In increasing resistance?

A

CS –> low alloys –> 400SS –> 300SS

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5
Q 
Sulfidation (Sulfide Corrosion) 
critical factors (4)?
A
  1. chemical composition
  2. temperature
  3. concentration of Reactive sulfer
  4. CR content
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6
Q

Sulfidation (Sulfide Corrosion)

sulfidation is caused by _____ and other reactive ____ species formed by _____________

A
  1. h2s
  2. sulfur
  3. thermal decomposition
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7
Q

Sulfidation (Sulfide Corrosion)

What is key to predict CR?

A

reactive sulfer

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8
Q

Sulfidation (Sulfide Corrosion)

Damage or appearance? - looks generally? But also occur?

A
  1. general thinning

2. localized corrosive at high velocity

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9
Q

Sulfidation (Sulfide Corrosion)

Difference in degree of thinning is large between low

A

Si <0.1% S vs >0.1 Si

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10
Q

Sulfidation (Sulfide Corrosion)

Prevention? (3)

A
  1. upgrade to higher Cr
  2. Aluminum diffusion treatment of CS and low steel reduce sulfidation rates
  3. T >1193F sufidation rate of higher Ni can be reduce by selected an alloy with lower Ni content
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11
Q

High temp H2/H2S Corrosion

Occurs at what temperature?

A

> 450F

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12
Q

High temp H2/H2S Corrosion

Occurs due to the presence of (2)

A
  1. hydrogen

2. h2s

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13
Q

High temp H2/H2S Corrosion

What curve name?

A

Couper Gorman (w/ hydrogen)

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14
Q

High temp H2/H2S Corrosion

Affected Material? In increasing resistance?

A

CS –> low alloys –> 400SS –> 300SS

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15
Q

High temp H2/H2S Corrosion

Critical factors? (4)

A
  1. temp
  2. presence of H2
  3. concentration
  4. partial pressure of H2
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16
Q

High temp H2/H2S Corrosion

increasing ___ content increase CR , min ____%?

A

CR / 7-9%

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17
Q

High temp H2/H2S Corrosion

affected equipment

A
  1. downstream of hydrogen injection

2. hydrotreaters/hydrocrackers - higher partial pressure of h2s (heavy oil)

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18
Q

High temp H2/H2S Corrosion

appearance? (2)

A
  1. uniform loss in thickness

2. shiny gray scale that may be mistaken for unaffected material.

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19
Q

High temp H2/H2S Corrosion

scale increase ______ what?

A
  1. 5x the volume
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20
Q

High temp H2/H2S Corrosion

prevention?

A
  1. use high Cr material

2. aluminum diffusion treat is used reduce CR

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21
Q

High temp H2/H2S Corrosion

related damage mech?

A
  1. high temp sulfidation
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22
Q

Sulfidation (Sulfide Corrosion)

related m? (2)

A
  1. Sulfidation is also known as sulfidic corrosion.

2. high temp h2/h2s corrosion

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23
Q

Carburization

description

A
  1. carbon absorbed by the metal
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24
Q

Carburization

affected materials?

A

CS/low alloys/ 300/400SS Nickle

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25
Q

Carburization

adding ____ make it more rsistant?

A

Cr

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26
Q

Carburization

critical factor

A
  1. carbon content (high)
  2. susceptible material
  3. temp (>1000F)
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27
Q

Carburization

result in loss of ____Temp creep ductility and ______ and reduce ____

A
  1. high
  2. weldability
  3. reduce CR
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28
Q

Carburization

increase in _____ and loss ___-

A
  1. hardness

2. ductility

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29
Q

Carburization

can be confirmed by?

A

metallography

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30
Q

Carburization

appearance? and ____ feet

A

crumble / crow feet

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31
Q

Carburization

prevention? (2)

A
  1. reduce carbon activity

2. add low level reactive sulfer compound

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32
Q

Carburization

add what to ____ and how much _____ minimize carburization?

A
  1. LOW LEVEL REACTIVE Sulfer

2. <10 PPM

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33
Q

Carburization

type of NDE? ineffective? (1) and effective (2) and advance stages? (2)

A
  1. VT
  2. metallography / destructive sampling
  3. RT/UT
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34
Q

DeCarburization

description

A

removal of carbon at elevated temp

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35
Q

DeCarburization

affected material?

A

CS and low alloy steels

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36
Q 
DeCarburization
add \_\_\_ (2) for resistance
A
  1. CR

2. Mo

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37
Q 
DeCarburization
critical factor (3)
A
  1. time
  2. temperate
  3. lack of carbor activity
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38
Q

DeCarburization

affected equipment?

A

1.in hot hydrogen service in hydroprocesisng and CRU

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39
Q

DeCarburization

prevention (2)

A
  1. add CR / Mo

2. controlling the gas phase and alloy selection

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40
Q

DeCarburization

type of NDE? ineffective? (1) and effective (2) and advance stages? (2)

A
  1. VT
  2. metallography / destructive sampling
  3. RT/UT
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41
Q

Metal Dusting

description

A

aggressive form of carburization

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42
Q

Metal Dusting

process stream needs to contain (2)

A

o2 / carbor

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43
Q

Metal Dusting

affected material

A

no metal is immune

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44
Q

Metal Dusting

temp range ?

A

900-1500F

worst at 1500F

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45
Q 
Metal Dusting
affected equipmeny (3)
A
  1. gas turbines
  2. furnace
  3. reactors
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46
Q

Metal Dusting

appearance?

A
  1. uniform,
  2. small pits
  3. crumbly appears
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47
Q

Metal Dusting

corrosion product is a ______ carbon dust

A

voluminous

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48
Q

Metal Dusting
_(chemical)_____in the carburization atm form a protective atmosphere to prevent carbon from being absorbed onto the surface

A

Sulfer

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49
Q

Metal Dusting

related mechanism

A

carburization

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50
Q 
oxidation 
critical factor (2)
A
  1. temp

2. alloy composition

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51
Q

oxidation

increase ____component to procedure a more protective oxide

A

Cr

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52
Q

oxidation
temp for CS / 300SS
and increase with?

A

1000F for CS
1500F for Ss

with Temps

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53
Q

oxidation

appearance

A

general thinning

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54
Q

oxidation

prevention (1) , what is effective (2)

A
  1. upgrade material

2. Si and Al are effective

55
Q

oxidation

inspection/monitoring? (online-1)/(offline-1)

A
  1. monitor temp skin

2. Ut/RT when down

56
Q

Fuel Ash Corrosion **(NL)

containments (4)

A
  1. sulfur
  2. sodium
  3. potassium
  4. vanadium
57
Q

Fuel Ash Corrosion **(NL)

description

A

contaminants for deposit and melt on surface

58
Q

Fuel Ash Corrosion **(NL)

affect material

A

a. all materials

59
Q

Fuel Ash Corrosion **(NL)

resistant material

60
Q

Fuel Ash Corrosion **(NL)

critical factors? (3)

A
  1. containment
  2. metal temp
  3. alloy composition
61
Q 
Fuel Ash Corrosion **(NL)
affected equipment (1)
A
  1. tube hangers and supports
62
Q

Fuel Ash Corrosion **(NL)

can only occur when _______temp is high enough to _____ the deposits

A
  1. metal

2. melt

63
Q

Fuel Ash Corrosion **(NL)

appearances ? before after removal of scale

A
  1. hard glassy tenacious scale

2. alligator hide

64
Q

Fuel Ash Corrosion **(NL)

prevention? (3)

A
  1. blending or changing fuel
  2. proper burner design/management
  3. remove low o2 , or inject special additives
65
Q

Fuel Ash Corrosion **(NL)

Which NDE is effective?

66
Q

Nitriding **(NL)

Description

A
  1. N2 diffuses into the steel
67
Q

Nitriding **(NL)

affect material?

A

CS / low alloys

68
Q

Nitriding **(NL)

resistant material? usually use to prevent nitriding

69
Q

Nitriding **(NL)

temp range?

70
Q

Nitriding**(NL)

critical factor? (4)

A
  1. temp
  2. time
  3. partial pressure of N2
  4. alloy composition
71
Q

Nitriding**(NL)

is fairly uncommon at?

72
Q

Nitriding**(NL)

appearance ? Confined to the _______

A

dark gray appearance

SURFACE

73
Q

Nitriding**(NL)

low alloy steel up to ____ % chrome is accompanied by an increase in_____ and result in cracks

A

12%/volume

74
Q

Nitriding**(NL)

inspection method for hardness #?

75
Q

Nitriding**(NL)

layers are magnetic or non magnetic?

76
Q

Nitriding**(NL)

inspection method? generally (1) , advance stages (4)

A
  1. Metallurgy

2. PT/MT/Angle beam (SWUT/PAUT)

77
Q

Graphitization**(NL)

description - iron crystals decompose into free ____and ________

A

iron crystals decompose into free iron(ferrite) and carbon (graphite)

78
Q 
Graphitization**(NL)
affected material (20
A

CS

C-1/2 Mo

79
Q

Graphitization**(NL)

temp range

80
Q

Graphitization**(NL)

adding _____ at ___% will eliminate graphitization

A

chrome

0.7%

81
Q

Graphitization**(NL)

has been found in low-alloy C-Mo steeps up to ____% –_

82
Q

Graphitization**(NL)

2 types of Graphitization?

A
  1. random

2. concentrated

83
Q

Graphitization**(NL)

2 type of concentrated Graphitization + 1 description

A
  1. weld HAZ Graphitization - eye brow

2. Non-weld Graphitization - most damaging

84
Q

Graphitization**(NL)

_____—grades (carbon free) are less susceptible than coarse Pearlitic grades

85
Q

Graphitization**(NL)

prevention?

A

add more Cr

86
Q

Graphitization**(NL)

inspection/monitoring? good / not good

A
  1. metallography

2. FMR - b/c damage can occur at mid wall

87
Q

Graphitization**(NL)

related mechanism

A

Spheroidization and graphitization are competing mechanism , Spheroidzation tends to occur at 1025F

88
Q

Spheroidization**(NL)

description

A

carbides combine to form spheroidal particles

89
Q

Spheroidization**(NL)

affected material

A

CS and low alloy

90
Q

Spheroidization**(NL)

temp can occur at?

91
Q

Spheroidization**(NL)

what type grains is better?

A

course / (annealed)

92
Q

Spheroidization**(NL)

appearance?

A

not visible

93
Q

Spheroidization**(NL)

inspection method?

94
Q 
Temper Embrittlement (VL)
affected material?
A

2.25Cr-1Mo

95
Q 
Temper Embrittlement (VL)
description? \_\_\_\_shift of the low temp ductile/brittle transition temp
96
Q 
Temper Embrittlement (VL)
long exposure to \_\_\_\_\_F?
97
Q 
Temper Embrittlement (VL)
loss of \_\_\_\_\_
98
Q 
Temper Embrittlement (VL) 
critical factor (3)
A
  1. temp
  2. alloy composition
  3. time
99
Q 
Temper Embrittlement (VL)
appearance?
A

Not readily apparent / rarely occurs (also sigma/885 same)

100
Q 
Temper Embrittlement (VL)
more susceptibility due to presence of alloying elements (2) and trap elements (4)
A
  1. magnesium / silicon

2. phosphorus, tin , antimony, arsenic

101
Q 
Temper Embrittlement (VL)
develop more quick at \_\_\_\_ than in \_\_\_\_ but damage is more sever after \_\_\_Term exposure at 850F
A

900F / 800-850F / LONG

102
Q 
Temper Embrittlement (VL)
loss of toughness is not evident at \_\_\_\_\_temp , but may susceptible to brittle fracture during \_\_\_\_
A

operating / SD % SU

103
Q 
Temper Embrittlement (VL)
MPT (min pressure temp - limiting \_\_\_\_ %
104
Q 
Temper Embrittlement (VL)
MPT for old metals?
105
Q 
Temper Embrittlement (VL)
MPT for new metals
106
Q 
Temper Embrittlement (VL)
J factor / X factor
A 
J = base
X = weld
107
Q 
Temper Embrittlement (VL)
can be reversed if \_\_\_\_\_F at \_\_\_hours per \_\_\_"
A

1150F / 2hr per 1 “

108
Q 
Temper Embrittlement (VL)
inspection method?
A
  1. inspection not normally used
  2. test block and IMPACT test
    ensure proper pressurization/temp sequence
109
Q 
Temper Embrittlement (VL)
related mech?
A

brittle facture

110
Q

Graphitization**(NL)

At elevated temperatures, the carbide phases in these steels are unstable and may decompose into _____

A

graphite nodules.

111
Q

Softening

Spheroidization may cause a loss in strength and/or ______

A

creep resistance.

112
Q

Spheroidization can occur in a _hours at 1300oF (552oC), but may take ____ at 850oF (454oC).

A

few / several years

113
Q

Spheroidization affects hot wall piping and equipment in the FCC, catalytic reforming and coker unit

114
Q 
Temper Embrittlement (VL)
The \_\_\_\_and \_\_\_\_alloy steels are not significantly affected by temper embrittlement.
A

C-0.5Mo / 1.25Cr-0.5Mo

115
Q 
Temper Embrittlement (VL)
This form of damage will significantly reduce the structural integrity of a component containing a \_\_\_\_\_\_\_\_
A

crack-like flaw.

116
Q 
Temper Embrittlement (VL)
It should be noted that there have been \_\_\_\_ industry failures related directly to temper embrittlement
117
Q

How can temper embrittlement be confirmed?

A

impact test

118
Q

Oxidation
It is most often present as oxygen in the surrounding air (approximately _____%) used for combustion in fired heaters and boilers

119
Q

Oxidation
It is most often present as oxygen in the surrounding air (approximately _____%) used for combustion in fired heaters and boilers

120
Q

Oxidation

Most alloys, including carbon steels and low alloy steels, suffer general ___due to oxidation.

121
Q

Oxidation

Loss in thickness due to oxidation is usually measured using external________measurements.

A

ultrasonic thickness

122
Q

Sulfidation

Copper base alloys form sulfide at _____temperatures than carbon steel.

123
Q

Sulfidation
a) Process conditions should be monitored for increasing temperatures and/or changing sulfur levels. b) Temperatures can be monitored through the use of ______ and/or _________

A

tubeskin thermocouples / infrared thermography

124
Q

Carburization

needs low

125
Q

Carburization

Significant carburization occurs during ________

A

decoking cycles.

126
Q

Carburization

In the advanced stages of carburization where cracking has initiated, _______ and some magnetic techniques may be used.

127
Q

____ inhibits carburization

128
Q

DeCarburization

Steels operating in high temperature hydrogen environments should be selected in accordance with API RP _____

129
Q

DeCarburization

Pits usually form on the surface and may contain ___or ___-dust.

A

soot / graphite

130
Q

DeCarburization

In high nickel alloys, it is thought that metal dusting occurs without the ____of metal carbides

131
Q

Fuel Ash Corrosion
Corrosion typically occurs with ___or ___ that is contaminated with a combination of sulfur, sodium, potassium and/or vanadium

A

fuel oil or coal

132
Q

Fuel Ash Corrosion

Corrosion rates under reducing conditions may be __to __times faster than under oxidizing conditions.

133
Q

Fuel Ash Corrosion

Best NDE

134
Q

Nitriding

Stainless steels tend to form thin, brittle layers that may __and __ from thermal cycling or applied stress

A

crack and spall

API571 (13 decks)

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