Module 7(High Temp 400F ) Flashcards by Wynne liu

Sulfidation (Sulfide Corrosion)

Occurs at what temperature? Greater / Begins?

500F / 450F

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Sulfidation (Sulfide Corrosion)

Name of the curve?

Modified Mconomy

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Sulfidation (Sulfide Corrosion)

What Presence increase CR?

hydrogen

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Sulfidation (Sulfide Corrosion)

Affected Material? In increasing resistance?

CS –> low alloys –> 400SS –> 300SS

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Sulfidation (Sulfide Corrosion) 
critical factors (4)?

chemical composition
temperature
concentration of Reactive sulfer
CR content

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Sulfidation (Sulfide Corrosion)

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

h2s
sulfur
thermal decomposition

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Sulfidation (Sulfide Corrosion)

What is key to predict CR?

reactive sulfer

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Sulfidation (Sulfide Corrosion)

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

general thinning

2. localized corrosive at high velocity

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Sulfidation (Sulfide Corrosion)

Difference in degree of thinning is large between low

Si <0.1% S vs >0.1 Si

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Sulfidation (Sulfide Corrosion)

Prevention? (3)

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

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High temp H2/H2S Corrosion

Occurs at what temperature?

> 450F

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High temp H2/H2S Corrosion

Occurs due to the presence of (2)

hydrogen

2. h2s

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High temp H2/H2S Corrosion

What curve name?

Couper Gorman (w/ hydrogen)

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High temp H2/H2S Corrosion

Affected Material? In increasing resistance?

CS –> low alloys –> 400SS –> 300SS

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High temp H2/H2S Corrosion

Critical factors? (4)

temp
presence of H2
concentration
partial pressure of H2

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High temp H2/H2S Corrosion

increasing ___ content increase CR , min ____%?

CR / 7-9%

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High temp H2/H2S Corrosion

affected equipment

downstream of hydrogen injection

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

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High temp H2/H2S Corrosion

appearance? (2)

uniform loss in thickness

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

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High temp H2/H2S Corrosion

scale increase ______ what?

5x the volume

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High temp H2/H2S Corrosion

prevention?

use high Cr material

2. aluminum diffusion treat is used reduce CR

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High temp H2/H2S Corrosion

related damage mech?

high temp sulfidation

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Sulfidation (Sulfide Corrosion)

related m? (2)

Sulfidation is also known as sulfidic corrosion.

2. high temp h2/h2s corrosion

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Carburization

description

carbon absorbed by the metal

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Carburization

affected materials?

CS/low alloys/ 300/400SS Nickle

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Carburization | adding ____ make it more rsistant?

Carburization | critical factor

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

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

1. high 2. weldability 3. reduce CR

Carburization | increase in _____ and loss ___-

1. hardness | 2. ductility

Carburization | can be confirmed by?

metallography

Carburization | appearance? and ____ feet

crumble / crow feet

Carburization | prevention? (2)

1. reduce carbon activity | 2. add low level reactive sulfer compound

Carburization | add what to ____ and how much _____ minimize carburization?

1. LOW LEVEL REACTIVE Sulfer | 2. <10 PPM

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

1. VT 2. metallography / destructive sampling 3. RT/UT

DeCarburization | description

removal of carbon at elevated temp

DeCarburization | affected material?

CS and low alloy steels

``` DeCarburization add ___ (2) for resistance ```

1. CR | 2. Mo

``` DeCarburization critical factor (3) ```

1. time 2. temperate 3. lack of carbor activity

DeCarburization | affected equipment?

1.in hot hydrogen service in hydroprocesisng and CRU

DeCarburization | prevention (2)

1. add CR / Mo | 2. controlling the gas phase and alloy selection

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

1. VT 2. metallography / destructive sampling 3. RT/UT

Metal Dusting | description

aggressive form of carburization

Metal Dusting | process stream needs to contain (2)

o2 / carbor

Metal Dusting | affected material

no metal is immune

Metal Dusting | temp range ?

900-1500F | worst at 1500F

``` Metal Dusting affected equipmeny (3) ```

1. gas turbines 2. furnace 3. reactors

Metal Dusting | appearance?

1. uniform, 2. small pits 3. crumbly appears

Metal Dusting | corrosion product is a ______ carbon dust

voluminous

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

Sulfer

Metal Dusting | related mechanism

carburization

``` oxidation critical factor (2) ```

1. temp | 2. alloy composition

oxidation | increase ____component to procedure a more protective oxide

oxidation temp for CS / 300SS and increase with?

1000F for CS 1500F for Ss with Temps

oxidation | appearance

general thinning

oxidation | prevention (1) , what is effective (2)

1. upgrade material | 2. Si and Al are effective

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

1. monitor temp skin | 2. Ut/RT when down

Fuel Ash Corrosion **(NL) | containments (4)

1. sulfur 2. sodium 3. potassium 4. vanadium

Fuel Ash Corrosion **(NL) | description

contaminants for deposit and melt on surface

Fuel Ash Corrosion **(NL) | affect material

a. all materials

Fuel Ash Corrosion **(NL) | resistant material

50cr-50ni

Fuel Ash Corrosion **(NL) | critical factors? (3)

1. containment 2. metal temp 3. alloy composition

``` Fuel Ash Corrosion **(NL) affected equipment (1) ```

1. tube hangers and supports

Fuel Ash Corrosion **(NL) | can only occur when _______temp is high enough to _____ the deposits

1. metal | 2. melt

Fuel Ash Corrosion **(NL) | appearances ? before after removal of scale

1. hard glassy tenacious scale | 2. alligator hide

Fuel Ash Corrosion **(NL) | prevention? (3)

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

Fuel Ash Corrosion **(NL) | Which NDE is effective?

1. VT

Nitriding **(NL) | Description

1. N2 diffuses into the steel

Nitriding **(NL) | affect material?

CS / low alloys

Nitriding **(NL) | resistant material? usually use to prevent nitriding

30-80% Ni

Nitriding **(NL) | temp range?

600F-900F

Nitriding**(NL) | critical factor? (4)

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

Nitriding**(NL) | is fairly uncommon at?

refining

Nitriding**(NL) | appearance ? Confined to the _______

dark gray appearance SURFACE

Nitriding**(NL) | low alloy steel up to ____ % chrome is accompanied by an increase in_____ and result in cracks

12%/volume

Nitriding**(NL) | inspection method for hardness #?

400-500HB

Nitriding**(NL) | layers are magnetic or non magnetic?

magnetic

Nitriding**(NL) | inspection method? generally (1) , advance stages (4)

1. Metallurgy | 2. PT/MT/Angle beam (SWUT/PAUT)

Graphitization**(NL) | description - iron crystals decompose into free ____and ________

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

``` Graphitization**(NL) affected material (20 ```

CS | C-1/2 Mo

Graphitization**(NL) | temp range

800-1000F

Graphitization**(NL) | adding _____ at ___% will eliminate graphitization

chrome | 0.7%

Graphitization**(NL) | has been found in low-alloy C-Mo steeps up to ____% --_

1% Mo

Graphitization**(NL) | 2 types of Graphitization?

1. random | 2. concentrated

Graphitization**(NL) | 2 type of concentrated Graphitization + 1 description

1. weld HAZ Graphitization - eye brow | 2. Non-weld Graphitization - most damaging

Graphitization**(NL) | _____---grades (carbon free) are less susceptible than coarse Pearlitic grades

Bainitic

Graphitization**(NL) | prevention?

add more Cr

Graphitization**(NL) | inspection/monitoring? good / not good

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

Graphitization**(NL) | related mechanism

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

Spheroidization**(NL) | description

carbides combine to form spheroidal particles

Spheroidization**(NL) | affected material

CS and low alloy

Spheroidization**(NL) | temp can occur at?

1300F

Spheroidization**(NL) | what type grains is better?

course / (annealed)

Spheroidization**(NL) | appearance?

not visible

Spheroidization**(NL) | inspection method?

FMR

``` Temper Embrittlement (VL) affected material? ```

2.25Cr-1Mo

``` Temper Embrittlement (VL) description? ____shift of the low temp ductile/brittle transition temp ```

upward

``` Temper Embrittlement (VL) long exposure to _____F? ```

650-1070F

``` Temper Embrittlement (VL) loss of _____ ```

toughness

``` Temper Embrittlement (VL) critical factor (3) ```

1. temp 2. alloy composition 3. time

``` Temper Embrittlement (VL) appearance? ```

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

``` Temper Embrittlement (VL) more susceptibility due to presence of alloying elements (2) and trap elements (4) ```

1. magnesium / silicon | 2. phosphorus, tin , antimony, arsenic

``` Temper Embrittlement (VL) develop more quick at ____ than in ____ but damage is more sever after ___Term exposure at 850F ```

900F / 800-850F / LONG

``` Temper Embrittlement (VL) loss of toughness is not evident at _____temp , but may susceptible to brittle fracture during ____ ```

operating / SD % SU

``` Temper Embrittlement (VL) MPT (min pressure temp - limiting ____ % ```

25%

``` Temper Embrittlement (VL) MPT for old metals? ```

350F

``` Temper Embrittlement (VL) MPT for new metals ```

125F

``` Temper Embrittlement (VL) J factor / X factor ```

``` J = base X = weld ```

``` Temper Embrittlement (VL) can be reversed if _____F at ___hours per ___" ```

1150F / 2hr per 1 "

``` Temper Embrittlement (VL) inspection method? ```

1. inspection not normally used 2. test block and IMPACT test ensure proper pressurization/temp sequence

``` Temper Embrittlement (VL) related mech? ```

brittle facture

Graphitization**(NL) | At elevated temperatures, the carbide phases in these steels are unstable and may decompose into _____

graphite nodules.

Softening | Spheroidization may cause a loss in strength and/or ______

creep resistance.

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

few / several years

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

``` Temper Embrittlement (VL) The ____and ____alloy steels are not significantly affected by temper embrittlement. ```

C-0.5Mo / 1.25Cr-0.5Mo

``` Temper Embrittlement (VL) This form of damage will significantly reduce the structural integrity of a component containing a ________ ```

crack-like flaw.

``` Temper Embrittlement (VL) It should be noted that there have been ____ industry failures related directly to temper embrittlement ```

very few

How can temper embrittlement be confirmed?

impact test

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

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

thinning

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

ultrasonic thickness

Sulfidation | Copper base alloys form sulfide at _____temperatures than carbon steel.

lower

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 _________

tubeskin thermocouples / infrared thermography

Carburization | needs low

Carburization | Significant carburization occurs during ________

decoking cycles.

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

RT, UT

____ inhibits carburization

Sulfur

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

941.

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

soot / graphite

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

formation

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

fuel oil or coal

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

2 to 5

Fuel Ash Corrosion | Best NDE

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

crack and spall

Module 7(High Temp 400F ) Flashcards

(134 cards)