API RP 571 - Damage Mechanisms Spreadsheet urut
Damage Mechanisms
No
High Temperature Corrosion [>400°F 1 (204°C)]34
Sulfidation
Wet H2S Damage (Blistering/HIC/SOHIC/SSC)
REFINING Environment-Assisted2Cracking 62
Mechanical and Metallurgical Failure3 Mechanisms 8
Creep and Stress Rupture
NDUSTRY Uniform or Localized Loss 4in Thickness 52Phenomena
REFINING Environment-Assisted5Cracking 60
High Temp H2/H2S Corrosion
Polythionic Acid Stress Corrosion Cracking (PASCC)
NDUSTRY Uniform or Localized Loss 6in Thickness 54Phenomena Naphthenic Acid Corrosion (NAC)
NDUSTRY Uniform or Localized Loss 7in Thickness 49Phenomena
Ammonium Bisulfide Corrosion (Alkaline Sour Water)
NDUSTRY Uniform or Localized Loss 8in Thickness 50Phenomena
Ammonium Chloride Corrosion
NDUSTRY Uniform or Localized Loss 9in Thickness 51Phenomena Hydrochloric Acid (HCI) Corrosion
REFINING Other Mech.10
65
High Temperature Corrosion [>400°F 11 (204°C)]33
Mechanical and Metallurgical Failure 12Mechanisms 9
NDUSTRY Uniform or Localized Loss13 in Thickness 57Phenomena
High Temperature Hydrogen Attack (HTHA)
Oxidation
Thermal Fatigue
Sour Water Corrosion (Acidic)
Mechanical and Metallurgical Failure 14Mechanisms 18
Refractory Degradation
Mechanical and Metallurgical Failure 15Mechanisms 1
Graphitization
Mechanical and Metallurgical Failure 16Mechanisms 3
High Temperature Corrosion [>400°F 17 (204°C)]36
Temper Embrittlement
Decarburization
Environment – Assisted Cracking 18
42
Caustic Stress Corrosion Cracking (Caustic Embrittlement)
Uniform or Localized Loss of Thickness 19
30
Caustic Corrosion
Mechanical and Metallurgical Failure 20Mechanisms 14
Erosion/Erosion - Corrosion
REFINING Environment-Assisted21Cracking 64
Carbonate Stress Corrosion Cracking
REFINING Environment-Assisted22Cracking 61
Amine Stress Corrosion Cracking
Environment – Assisted Cracking 23
40
High Temperature Corrosion [>400°F 24 (204°C)]35
Chloride Stress Corrosion Cracking (CI-SCC)
Carburization
Environment – Assisted Cracking 25
45
Hydrogen Embrittlement (HE)
Mechanical and Metallurgical Failure 26Mechanisms 11
Steam Blanketing
Mechanical and Metallurgical Failure 27Mechanisms 13
Thermal Shock
Mechanical and Metallurgical Failure 28Mechanisms 15
Cavitation
Uniform or Localized Loss of Thickness 29
Graphitic Corrosion
32
Mechanical and Metallurgical Failure 30Mechanisms 10
Short Term Overheating -Stress Rupture
Mechanical and Metallurgical Failure 31Mechanisms 7
Brittle Fracture
Mechanical and Metallurgical Failure 32Mechanisms 6
Sigma Phase Embrittlement
Mechanical and Metallurgical Failure 33Mechanisms 5
885°F Embrittlement
Mechanical and Metallurgical Failure 34Mechanisms 2
Softening (Spheroidization)
Mechanical and Metallurgical Failure 35Mechanisms 19
Reheat Cracking
NDUSTRY Uniform or Localized Loss36 in Thickness 58Phenomena
Sulfuric Acid Corrosion
NDUSTRY Uniform or Localized Loss37 in Thickness 53Phenomena
Hydrofluoric (HF) Acid Corrosion
Uniform or Localized Loss of Thickness 38
27
Mechanical and Metallurgical Failure 39Mechanisms 12
REFINING Environment-Assisted40Cracking 63
Flue-Gas Dew-Point Corrosion
Dissimilar Metal Weld (DMW) Cracking
Hydrogen Stress Cracking -HF
Uniform or Localized Loss of Thickness 41
31
Dealloying
Uniform or Localized Loss of Thickness 42
26
CO2 Corrosion
Environment – Assisted Cracking 43
41
Corrosion Fatigue
High Temperature Corrosion [>400°F 44 (204°C)]38
Fuel Ash Corrosion
NDUSTRY Uniform or Localized Loss45 in Thickness 48Phenomena
Amine Corrosion
Uniform or Localized Loss of Thickness 46
23
Corrosion Under Insulation (CUI)
Uniform or Localized Loss of Thickness 47
22
Atmospheric Corrosion
Environment – Assisted Cracking 48
43
Ammonia Stress Corrosion Cracking
Uniform or Localized Loss of Thickness 49
24
Cooling Water Corrosion
Uniform or Localized Loss of Thickness 50
25
Boiler Water Condensate Corrosion
Uniform or Localized Loss of Thickness 51
28
Microbiologically Induced Corrosion (MIC)
Environment – Assisted Cracking 52
44
Liquid Metal Embrittlement (LME)
Uniform or Localized Loss of Thickness 53
21
Galvanic Corrosion
Mechanical and Metallurgical Failure 54Mechanisms 16
High Temperature Corrosion [>400°F 55 (204°C)]39
Mechanical Fatigue
Nitriding
Mechanical and Metallurgical Failure 56Mechanisms 17
Vibration-Induced Fatigue
REFINING Other Mech.57
66
Titanium Hydriding
Uniform or Localized Loss of Thickness 58
29
Soil Corrosion
High Temperature Corrosion [>400°F 59 (204°C)]37
Metal Dusting
Mechanical and Metallurgical Failure 60Mechanisms 4
Strain Aging
Environment – Assisted Cracking 61
Sulfate Stress Corrosion Cracking
47
NDUSTRY Uniform or Localized Loss62 in Thickness 56Phenomena
Phosphoric Acid Corrosion
NDUSTRY Uniform or Localized Loss63 in Thickness 55Phenomena Environment – Assisted Cracking 64
Phenol (Carbolic Acid) Corrosion
46
Ethanol Stress Corrosion Cracking (SCC)
Mechanical and Metallurgical Failure 65Mechanisms 20
Gaseous Oxygen-Enhanced Ignition and Combustion
NDUSTRY Uniform or Localized Loss66 in Thickness 59Phenomena
Aqueous Organic Acid Corrosion
Description of Damage
Temperature Range
> 500°F
Blistering, HIC, and SOHIC ambient to 300°F or higher; SSC < 180°F
SEE Table 4-2 For Threshold Temp: C.S. --> 700°F C-1/2 Mo --> 750°F 1.25Cr thru 9Cr ->800°F 304H -> 900°F 347H --> 1000°F > 500°F
Sensitization occurs 750°F -1500°F
425°F - 750°F; Has been reported°From 350°F - 800°F
< 150°F
< 300°F; May corrode well above water dewpoint of 300°F
Increases with increasing temp up to point where water vaporizes
Exposure to hydrogen at elevated temperatures
Oxidation of CS significant > 1000°F; 300 Series SS susceptible to scaling > 1500°F. SEE Table 4-6 For CR at elev. Temps
Temp swings exceeding 200°F
N/A
N/A
It is a change in the microstructure of certain carbon steels and 0.5 Mo steels after 800°F - 1100°F; Graphitization before long term operation in the 800 to 1100°F Spheroidization < 1025°F range may cause a loss in strength, ductility and/or creep resistance.
reduction in toughness. This change causes an upward shift in the ductile-to-brittle transition temperature, (by Charpy impact testing)
650°F - 1100°F; Quicker at 900°F but more severe in longterm exposure at 850°F
Elevated temperatures
Increasing temps increase likelihood and severity
High solution strength caustic general corrosion of CS above 175°F and very high CRates above 200°F.
N/A
Generally no temperature ranges; However, > 200°F if CO2 > 2% in gas scrubbing units
N/A
> 140°F
>1100°F
Ambient - 300°F; Decreases with increasing temp; Not likely to occur above 160°F to 180°F
Short-term, high-temp°Failures.
Significant Temperature Differentials
More likely at temps approaching the boiling point of the liquid
< 200°F in the presence of moisture or an aqueous phase
Local overheating above design temperature
Temperatures below ductile-to-brittle transition temp
1000°F-1750°F
is a loss in toughness due to a metallurgical change that occurs in alloys containing a°Ferrite phase, as a result of exposure in the temperatur range 600 to 1100.
600°F- 1000°F
May cause a loss in strength and/or creep resistance.
850°F - 1400°F; Spheroidization before Graphitization > 1025°F May Cause a loss in strength and or creep resistance. During PWHT or at elevated temps.
N/A
Increase with increasing temp; High CRates observed > 150°F
Sulfuric acid dewpoint < 280°F; Hydrochloric acid dewpoint < 130°F; pH <6
> 510°F
Aqueous HF environments
N/A
Increasing corrosion with increasing temp up to dewpoint < 300°F
N/A
Metal temps above the melting point of liquid species: Oil ash - melting points below 1000°F possible; Waterwall corrosion - melting points 700°F; Coal ash - melting points 1030°F to 1130°F
Increases with increasing temps; Above 220°F can result in acid gas°Flashing and severe localized corrosion
More severe 212°F - 250°F For CS Corrosion rates increase with temp up to about 250°F
Any temperature
Process side > 140°F; Brackish and salt water outlet > 115°F
N/A
0°F to 235°F; pH range 0-12 (Any)
N/A
N/A
N/A
> 600°F; Severe > 900°F
N/A
> 165°F
Corrosion rates increase with increasing metal temperature
900°F - 1500°F
found in most older vintage steels and 0-0.5 Mo low alloy steels under the combined effects of deformation and aging at an intermediate temperature. This results in an increase in hardness and strength with a reduction in ductility and toughness
Intermediate Temperature
N/A
Minimal below 250°F; Rapid CRates above 450°F
The spontaneous ignition or combustion of metallic and nonmetallic components can result in fires and explosions in certain oxygen-enriched gaseous environments if not properly designed, operated and maintained.
Affected Materials
Prevention
Inspection
CS, low alloys, 300 SS and 400 SS; Ni base alloys to varying degrees depending on Cr content; Copper base alloys at lower temps than CS
Upgrade to higher Cr; Al diffusion treatment of low alloys may reduce but not completely protect
Monitor process conditions and temperatures; UT For thickness loss; Proactive and retroactive PMI
CS and low alloys
All metals and alloys
Order of increasing resistance: CS, low alloys, 400 SS, and 300 SS
Sensitized austenitic SS; 300 SS, Alloy 600/600H, and Alloy 800/800H
Coatings or alloy cladding; Water wash to dilute HCN or inject ammonium polysulfide's Monitor free water phase; Crack to convert to thiocyanates; HIC- detection best with WFMT, EC, RT or resistant steels; PWHT can ACFM; SWUT For crack sizing; AET prevent SSC and help with SOHIC; Inhibitors
Minimize temperatures; Higher PWHT may help; Minimize hot spots in heaters
Combination of techniques; Tubes bulging, sagging, diametric growth
Use alloys with high chromium UT, VT and RT For thickness; Verify content; 300 SS are highly operating temps; Check process H2S resistant at service temps levels periodically Material selection; Flush with alkaline or soda ash to neutralize or purge with nitrogen or nitrogen/ammonia; Keep firebox above dewpoint; Heat treatment at 1650°F
2% - 2.5% molybdenum shows CS, low alloys, 300 SS, 400 SS, and improved resistance; Change or Ni base alloys blend crudes; Inhibitors
Flapper disc sanding to remove deposits and PT
RT or UT Thickness; Monitor TAN, sulfur, Fe, and Ni contents
Symmetrical/balanced flow in and out of air cooled Frequent UT and RT profile thickness; CS; 300 SS, duplex SS, Al alloys and exchangers; Maintain velocities IRIS and ECT tubes; Monitor water Ni base alloys more resistant 10 to 20 fps For CS, resistant injection materials > 20 fps; Water wash injection and low oxygen
All commonly used materials; Pitting resistant alloys more RT or UT Thickness; Monitor feed Order of increasing resistance: CS, have improved resistance; Limit streams; Corrosion coupons may be low alloys, 300 SS, Alloys 400, chlorides; Water wash;°Filming helpful if salts deposit on the duplex SS, 800, and 825, Alloys 625 inhibitors element and C276 and titanium.
All common materials of construction
Upgrade CS to Ni base can help; Remove chlorides (neutralize, water wash, absorb, etc.); Minimize carryover of water and salts
AUT or RT For thickness; Corrosion coupons; Check pH
Alloys with Cr (> 5 Cr) and Mo UT using combination of velocity Order of increasing resistance: CS, or tungsten and vanadium; Use ratio and backscatter (AUBT); In-situ C 0.5Mo, Mn-0.5Mo, 1Cr, 1.25Cr, a 25°F to 50 °F safety factor; metallography; VT For blistering; 2.25Cr-1 Mo, 2.25Cr-1Mo-V, 3Cr, 300 SS overlay and/or roll bond WFMT and RT in advanced stages 5Cr clad material with cracking CS and low alloys; All 300 SS, 400 SS and Ni base alloys oxidize to varying degrees
Upgrade alloy; Addition of Cr primary element For oxidation resistance
Monitor process conditions and temperatures; UT For thickness loss
All materials of construction
Design and operation; Liner to prevent cold liquid from contacting hot surface
VT, MT/PT, SWUT For cracking
Primarily CS; SS, Cu alloys, and Ni base alloys usually resistant
Material selection; 300 SS < 140”F; Cu and Ni resistant, but Cu vulnerable in ammonia
RT or UT Thickness; Monitor pH of ovhd accumulators; Corrosion coupons
Refractory materials
Selection; Design; Installation
VT during shutdown; IR online
Some grades of CS and 0.5Mo steels
Addition of 0.7% Cr
Full thickness sample metallography
Primarily 2.25Cr; Older 2.25Cr manuf. prior to 1972 particularly susceptible
CS and low alloys
CS, low alloys and 300 SS; Ni base alloys more resistant.
Pressurization sequence - MPT of 350°F For older steels and 150°F newer; Heat treat to 1150°F and cool rapidly For temporary reverse; Limit J and X Factors.
Control chemistry of gas phase; Field metallography; Hardness tests Cr and Mo Form more stable For softening carbides PWHT at 1150°F For CS; Alloy upgrade to Ni based alloys; Design/operation of injection system; Water wash equipment prior to steamout
Design; Adequate water Primarily CS, low alloys and 300 SS flooding; Burner management; Dilution of caustic Design; Erosion - harder alloys; Corrosion - corrosion resistant All metals, alloys and refractories alloys; Impingement plates; Tube ferrules PWHT at 1150°F; Material selection; Coatings or alloy CS and low alloys cladding; Water wash nonPWHT prior to steamout or heat treatment; Inhibitors PWHT all CS welds; Material selection (clad or solid); Water CS and low alloys wash non-PWHT CS prior to welding, heat treatment or steam out
300 SS; Ni 8% -12% most susceptible; Ni > 35% highly resistant, Ni > 45% nearly immune
Impact test sample blocks from original heat
Material selection; Low chloride water For hydrotest; Coatings under insulation; Avoid designs with stagnant areas where chlorides can concentrate
CS and low alloys, 300 SS and 400 Alloy selection (Si & Al SS, cast SS, Ni base alloys with oxidizers); Lower temperatures significant Fe content and HK/HP and higher oxygen/sulfur alloys partial pressures.
WFMT, EC, RT, ACFM For crack detection; PT not effective (tight, scale filled cracks); SWUT For crack depth UT Scans, RT, Injection points, Boroscope steam generating equipment VT, UT, RT; Corrosion coupons; IR scans For refractory Monitoring of pH and CO3-2 concentration; WFMT or ACFM For crack detection; SWUT For crack depth: AET Crack detection best with WFMT or ACFM; PT usually not effective; SWUT crack depths; AET
VT in some oases, PT (surface prep may be necessary), ECT, UT
Hardness/Field metallography if process side accessible; RT, UT, MT For cracking in advanced stages
Use lower strength steels; PWHT; Low hydrogen, dry electrodes, and preheat For CS, low alloys, 400 SS, Precipitation welding; Bake out at 400°F or Hardenable SS, some high strength higher; Controlled Ni base alloys. pressurization sequence; Protective lining, SS cladding, or weld overlay
MT or PT For surface cracks; UT may be helpful; RT not sensitive enough
CS and low alloys
Tube rupture quickly Follows DNB; Burner management; BFW treatment
Visual For bulging on tubes and burners
All metals and alloys
Minimize flow interruptions, severe restraint, rain/fire water deluge; Review injection points; Thermal sleeves
Highly localized; MT/PT to confirm cracking only
Most common materials of construction
Mechanical, design, or operational change; Sufficient NPSH; Streamline flow; Remove air; Decrease velocities; Fluid additives
Accoustic monitoring; Pumps may sound like pebbles being thrashed around; VT, UT, RT For loss of thickness
Primarily gray cast iron, but also nodular and malleable cast irons which tend to crumble when attacked
Difficult to predict; Internal coatings/cement linings For internal graphitic corrosion; external coatings or CP in corrosive soils
Loss of "metallic ring"; Reduction in hardness
All Fired heater tube materials and common materials of construction
Minimize temperature excursions; Burner management
Visual; IR monitoring; Tubeskin thermocouples
CS and low alloys esp. prior to 1987; 400 SS also susceptible
Material selection; Minimize pressure at ambient None to minimize; Susceptible temperatures; PWHT; "Warm" vessels inspect For pre-existing flaws pre-stress hydrotest
Ferritic, martensitic, austenitic, and duplex SS
SS with sigma may have lack of toughness below 500°F; Minimize weld metal ferrite content; Solution anneal at 1950°F and water quench to reverse
Testing of samples; Cracking during t/a or when below 500°F
Use low ferrite or non-ferritic Impact/bend test samples; Cracking Alloys containing a°Ferrite phase; alloys; Heat treat to 1100°F and during t/a or when below 200°F; 400 SS and Duplex SS cool rapidly Increase in hardness
CS and low alloys low alloys, 300 SS, and Ni base alloys; High Strength Low Alloys (HSLA) Order of increasing resistance: CS, 316L, Alloy 20, high Si cast iron, high Ni cast iron, Alloy B-2 and Alloy C276
Minimize exposure to elevated temps
Field metallography or removal of samples
Joint configurations in heavy walls; Minimize stress risers
UT and MT/PT For surface cracks; UT For embedded cracks
Materials selection; Proper operation; Caustic wash to neutralize
UT or RT of turbulent zones and hottest areas; Corrosion coupons
Monitor CS operating > 150”F Low alloys, 300 SS and 400 SS are For thickness; Minimize water, generally not suitable; CS, Cu-Ni oxygen, sulfur and other alloys, Alloy 400, an other Ni base contaminants in feed; Alloy 400 alloys have been used in some (solid or clad) used to eliminate applications blistering/HIC/SOHIC. PWHT to minimize possibility of SCC.
RT or UT Thickness; Monitor small bore piping, flange face corrosion, blistering/HIC/SOHIC
Maintain temps > 280°F; Avoid 300 SS if chlorides present; CS, low alloys and 300 SS UT For wall loss; VT and PT For SCC Soda Ash wash to neutralize the acids Ni based fillers; 300 SS rods Widely differing thermal expansion used in low temp location only; Visual and MT/PT For OD cracks; UT coefficients; Most common CS to Pup piece with intermediate For ID cracks Austenitio SS coefficient
CS and low alloys
PWHT; Weld hardness < 200 HB and no localized zones > 237 HB; CS with Carbon Equivalent < 0.43; B7M Bolts; Coatinas or allov cladding
WFMT For cracks; Hardness testing
Difficult to predict; Addition of VT (may change color but may Primarily copper alloys as well as alloying elements may help; CP require scale removal), Alloy 400 and cast iron or coatings may help Metallography, Loss of "metallic ring"
CS and low alloys
Cr > 12% (SS); Corrosion inhibitors; Increase pH > 6; Operation problems; 400 SS and Duplex SS resistant; Water analysis
VT, UT, RT
All metals and alloys
Reduce corrosion (inhibitors, material selection, coatings, BFW chemical control, etc.); PWHT; Controlled start-up (thermal expansion)
UT, MT
All conventional alloys for process heaters and boilers; 50Cr-50Ni family show improved resistance
Blend or change fuel source; Burner design/management; Low excess oxygen; Alloy upgrade to 50Cr-50Ni For hangers/supports
VT; UT For loss of thickness
Primarily CS; 300 SS highly resistant
Proper operation; Avoid buildup of HSAS; Design should control local pressure drop to minimize flashing; Avoid oxygen inleakage; Remove solids and hydrocarbons; Corrosion inhibibitors
VT and UT thickness internal; UT scans or profile RT For external; Corrosion coupons
CS, low alloys, 300 SS and duplex SS
Selection of insulation type; Maintain coatings and insulation
Strip insulation; VT, UT, IR, etc.
CS, low alloys, and copper alloyed Al
Surface prep and proper coating
VT and UT
Copper alloys with aqueous ammonia and/or ammonium compounds; CS in anhydrous ammonia
Copper - zinc content below 15%, 90-10CuNi and 70-30CuNi nearly immune, prevent ingress Copper - monitor pH, ECT or VT on of air, upgrade to 300 SS or Ni tubes For cracking; CS - WFMT, AET, alloys; CS - PWHT or addition or External SWUT water (0.2%), weld < 225 BHN, prevent inaress of oxvaen
CS, all grades of SS, copper, Al, titanium and Ni base alloys
Design process inlet < 135°F; Operation; Chemical treatment; Maintain water velocities; Avoid ERW tubes
pH; Oxygen content; Outlet temps; EC/IRIS tubes
Primarily CS; Some low alloy, 300 SS and copper based alloys
Oxygen scavenging treatment; Amine inhibitor treatment
Water analysis; Dearator cracking WFMT
Most common materials of construction
Treat water with biocides; Maintain flow velocities; Empty hydrotest water; Maintain coatinqs
VT; Measure biocide residual; Operating conditions indicate Fouling; Foul smelling water
Many commonly used materials
All metals with the exception of most noble metals; SEE Table 4-4 for Galvanic Series
Keep metal with low melting MT or PT For cracks, RT For mercury point away from other metal; deposits inside tubes Grind out cracks not acceptable Design; Differing alloys not in intimate contact; Coatings
Visual and UT Thickness
All alloys; Stress levels and number Good design; Material MT, PT, SWUT For cracks; Vibration of cycles to failure vary by material selection; Minimize stress risers monitoring
Carbon steels, low alloys, 300 SS and 400 SS; Ni based alloys more resistant
All engineering materials
Titanium alloys
Carbon steel, cast iron, and ductile iron
All; No known alloy immune under all conditions
Change in color to dull gray; Hardness testing (400 - 500 BHN); Check 300 SS Alloy change to 30% - 80% Ni For magnetism; Metallography; ECT; PT, RT, or UT For cracking in advanced stages Design; Supports and vibration dampeners; Stiffeners on small bore; Branch sizing
Visual/Audible signs of vibration
No titanium in known hydriding services such as amine or sour water; Use all titanium if ECT; Metallography; Crush/Bend test galvanic coupling may promote hydriding Most effective coatings and cathodic protection; Special backfill may help to lesser degree Protective layer of sulfur (usually as H2S); Material selection For specific application; Al diffusion treatment
Structure to soil potential; Soil resistivity; VT, guided UT, Pressure testing Compression wave UT For heater tubes; RT For pitting/thinning; VT if ID is accessible
No issue For newer steels with Mostly pre-1980's carbon steels enough Al For deoxidizer; BOF with large grain size and C-0.5 Mo better than older Bessemer; low alloy steel Pressurization sequence; PWHT or "Butter"
None
304L satisfactory For concentration 100% and temp Order of increasing resistance: CS, < 120°F ; 316L required 120°F 304L SS, 316L SS, and Alloy 20 225°F; 316L and Alloy 20 effective at concentrations up to 85% at boiling temps
RT or UT Thickness; Sample Iron in water; Corrosion coupons
Material selection; Velocity < Order of increasing resistance: CS, 30 fps; Recovery ovhd temps at 304L, 316L and Alloy C276 least 30°F > dew point
Carbon steels and low alloy steels
RT or UT Thickness; Corrosion coupons
Appearance Most often uniform thinning but may be localized; Sulfide scale will usually cover the surface
Blistering, HIC "stepwise cracking", SOHIC stacked arrays, SSC through thickness potentially
Noticeable deformation may be observed; May have significant bulging before final fracture occurs
Uniform loss in thickness°From the process side with an iron sulfide scale
Intergranular; Quite localized; Typically next to welds, but may be in base metal
Localized corrosion, pitting, or flow induced grooving in high velocity areas
General loss in thickness with potential For high localized rates; Low velocities may have localized under-deposit corrosion
Possible Fouling or corrosion
General uniform thinning, localized corrosion or underdeposit attack
Intergranular and adjacent to iron carbide areas in CS; Some blistering may be visible to the naked eye
General thinning; Usually covered on the outside surface with an oxide scale Cracks propagate transverse to the stress and usually dagger-shaped, transgranular, and oxide filled; May stop and restart; May be axial or circumferential, or both, at the same location; General thinning; Localized corrosion or underdeposit attack can occur Cracking, spalling or lift-off from the substrate, softening or general degradation from exposure to moisture; Erosive services: washed away or thinned
N/A
N/A
N/A
"spider web"; Predominantly intergranular, parallel to weld in adjacent base metal but can occur in the weld or HAZ Localized metal loss as grooves in a boiler tube or thinned areas under insulating deposits; Localized loss in thickness; Pits, grooves, gullies, waves, rounded holes and valleys; Often with a directional pattern "spider web"; Parallel to weld in adjacent base, but also in weld or HAZ; Predominantly intergranular Surface cracking on ID primarily in HAZ, but also in weld or adjacent to HAZ; Typically parallel to weld, but in weld, either transverse or longitudinal
"spider web"; Branched, transgranular, and may have "crazecracked" appearance
In advanced stage may be a volumetric increase
Can initiate sub-surface, but in most cases is surface breaking; Higher strength steels cracking is often intergranular
Open burst with edges drawn to a near knife-edge
Surface initiating cracks may appear as “craze" cracks
Sharp-edged pitting but may have a gouged appearance in rotational components
Widespread or localized; Damaged areas will be soft and easily gouged with a hand tool
"fishmouth" Cracks typically straight, nonbranching, with no plastic deformation; Limited intergranular cracking
Cracking particularly at welds or areas of high restraint
N/A
N/A
Intergranular and can be surface breaking or embedded General but attacks CS HAZ rapidly; Hydrogen grooving in low flow
Localized general or severe thinning of CS; May be accompanied by cracking due to hydrogen stress cracking, blistering and/or HIC/SOHIC damage
General wastage often with broad, shallow pits
Cracks at the toe of weld in the HAZ of the ferritic material
Surface breaking intergranular cracks
Often a color change or deep etched appearance; May be uniform through the cross-section or localized Localized thinning and/or pitting; May be deep pitting and grooving in areas of turbulence
"rabbit ears"; Transgranular but not branched, often multiple parallel cracks
"alligatorhide"
General uniform thinning, localized corrosion or localized underdeposit attack
May be highly localized; Loose, flaky scale covering the corroded component General or localized; Normally a distinctive iron oxide (red rust) scale Forms
Cu: bluish corrosion products at surface cracks, single or highly branched, either trans or intergranular
General corrosion, localized underdeposit, pitting, MIC, SCC, Fouling, grooving along ERW tubes Oxygen: pitting anywhere in the system; CO2: smooth grooving Localized pitting under deposits or tubercles; Cup-shaped pits within pits Brittle cracks in an otherwise ductile material More active material can suffer generalized loss in thickness or crevice, groove or pitting corrosion
"clam shell" type fingerprint with concentric rings called "beach marks"
"needle-like" particles of iron nitrides
Crack initiating at a point of high stress or discontinuity
N/A
External thinning with localized losses due to pitting Low alloys can be uniform but usually small pits filled with crumbly residue; SS and high alloys local, deep, round pits
N/A
General or localized thinning of CS
General or localized corrosion of CS
Material
x x x
x x x
x x x
x x
x x
x x x
x x
x x x x x x
x x x
x x
x x
x
x x
x
catalytic reforming - ccr
>ambient <180 SSC <300
x x x
fcc light ends recovery
any cs & low alloy any any
500 600 800 >500 x x x >500 x x
fcc
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
10 100 200 300 400
delayed coker
ANY
Pr
crude unit / vacuum
No
Temperatur
x x x x
x
x x
x
x x
x x
x
x
x
x
x
x x
x
34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
x
x
x x x x x x
x
x x x
x x x
x
x
x
Process Unit
Visbreaker
x
x
x
x
x
Caustic Treating
Hydrogen Reforming Isomerization
Sulfur Recovery
Sour Water Stripper
Amine Treating HF Alkylation sulfuric acid alkylation
x x
x
x
x x x
x
x x x
x x x x x x
x x x x x
x x
x x x x x x
x x x x x x x x x x
hydroprocessing units catalytic reforming - fixed bed
x
x x x x
x
x x
x x x x x x
x
x x x x x
x x x x x x x x x x
x
x x
x x x x x
x
x
x x
x
x
x
x
x
x
x x
x x
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Damage Mechanism Sulfidation Wet H2S Damage Creep High Temp H2/H2S corr Polythionic Acid Cracking Naphthenic Acid Corrosion Ammonium Bisulfide Corrosion Ammonium Chloride Corrosion HCl Corrosion High Temperature Hydrogen Attack Oxidation Thermal Fatigue Sour Water Corrosion (acidic) Refractory Degradation Graphitization Temper Embrittlement Decarburization Caustic Cracking Caustic Corrosion Erosion / Erosion-Corrosion Carbonate SCC Amine Cracking Chloride Stress Corrosion Cracking Carburization Hydrogen Embrittlement Steam Blanketing Thermal Shock Cavitation Graphitic Corrosion (see Dealloying) Short term Overheating – Stress Rupture Brittle Fracture Sigma Phase/ Chi Embrittlement 885oF (475oC) Embrittlement
Softening (Spheroidization) Reheat Cracking Sulfuric Acid Corrosion Hydrofluoric Acid Corrosion Flue Gas Dew Point Corrosion Dissimilar Metal Weld (DMW) Cracking Hydrogen Stress Cracking in HF Dealloying (Dezincification/ Denickelification) CO2 Corrosion Corrosion Fatigue Fuel Ash Corrosion Amine Corrosion Corrosion Under Insulation (CUI) Atmospheric Corrosion Ammonia Stress Corrosion Cracking Cooling Water Corrosion Boiler Water / Condensate Corrosion Microbiologically Induced Corrosion (MIC) Liquid Metal Embrittlement Galvanic Corrosion Mechanical Fatigue Nitriding Vibration-Induced Fatigue Titanium Hydriding Soil Corrosion Metal Dusting Strain Aging Sulfate Stress Corrosion Cracking Phosphoric Acid Corrosion Phenol (carbolic acid) Corrosion Ethanol Stress Corrosion Cracking Oxygen-Enhanced Ignition and Combustion Organic Acid Corrosion Of Distillation Tower Overhead Systems
