API-RP-571-Damag-10

API RP 571 - Damage Mechanisms Spreadsheet

Damage Mechanisms

Graphitization

Description of Damage

It is a change in the microstructure of certin carbon steels and 0.5 Mo steels after long term operation in the 800 to 1100 F range may cause a loss in strength, ductility and/or creep resistance.

May cause a loss in strength and/or creep resistance. Softening (Spheroidization) (Spheroidization)

Temper Embrittlement

Strain Aging

reduction in toughness. This change causes an upward shift in the ductile-to-brittle transition temperature. (by Charpy impact testing)

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. temperature. This results in an increase in hardness and strength with a reduction in ductility and toughness

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 temeratur range 600 to 1100.

Temperature Range

Affected Materials

800°F - 1100°F; Graphitization Some grades of CS and 0.5Mo steels before Spheroidization < 1025°F

850°F - 1400°F; Spheroidization before Graphitization > 1025°F May Cause a loss in strength and or creep resistance.

CS and low alloys

Prevention

Inspection

Addition of 0.7% Cr

Full thickness sample metallography

Minimize exposure to elevated temps

Field metallography or removal of samples

650°F - 1100°F; Quicker at 900°F but more severe in longterm exposure at 850°F

Pressurization seque sequence nce - MPT of 350°F for older steels and 150°F newer; Primarily 2.25Cr; Older 2.25Cr manuf. Heat treat to 1150°F and cool rapidly for prior to 1972 particularly susceptible temporary reverse; Limit J and X factors.

Impact test sample blocks from original heat

Intermediate Temperature

No issue for newer steels with enough Mostly pre-1980’s carbon steels with Al for deoxidizer; deoxidizer; BOF better better than older older large grain size and C-0.5 Mo low Bessemer; Pressurization sequence; alloy steel PWHT or "Butter"

None

600°F - 1000°F

Alloys containing containing a ferrite phase; phase; 400 400 SS and Duplex SS

Use low ferrite or non-ferritic alloys; Heat treat to 1100°F and cool rapidly

Impact/bend test samples; Cracking during t/a or when below 200°F; Increase in hardness

Sigma Phase Embrittlement

1000°F - 1750°F

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

Brittle Fracture

Temperatures below ductile-tobrittle transition temp

CS and low alloys esp. prior to 1987; 400 SS also susceptible

885°F Embrittlement

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Material selection; Minimize pressure at None to minimize; Susceptible vessels ambient temperatures; temperatures; PWHT; "Warm" inspect for pre-existing flaws pre-stress hydrotest


Damage Mechanisms


Temperature Range

Affected Materials

Prevention

Inspection

Creep and Stress Rupture

SEE Table 4-2 for Threshold Temp: C.S. --> 700ºF C-1/2 Mo --> 750ºF 1.25Cr thru 9Cr --> 800ºF 304H --> 900ºF 347H --> 1000ºF

All metals and alloys

Minimize temperatures; Higher PWHT may help; Minimize hot spots in heaters

Combination of techniques; Tubes bulging, sagging, diametric growth

Thermal Fatigue

Temp swings exceeding 200°F

All materials of construction

Design and operation; Liner to prevent cold liquid from contacting hot surface

VT, MT/PT, SWUT for cracking

Short Term Overheating – Stress Rupture

Local overheating above design temperature

All fired heater tube materials and common materials of construction

Steam Blanketing

Short-term, high-temp failures.

CS and low alloys

Dissimilar Metal Weld (DMW) Cracking

> 510°F

Widely differing thermal expansion coefficients; Most common CS to Austenitic SS

Thermal Shock

Significant Temperature Differentials


Minimize flow interruptions, severe restraint, rain/fire water deluge; Review injection points; Thermal sleeves

Highly localized; MT/PT to confirm cracking only

Erosion/Erosion – Corrosion

N/A

All metals, alloys and refractories

Design; Erosion - harder alloys; Corrosion - corrosion r esistant alloys; Impingement plates; Tube ferrules

VT, UT, RT; Corrosion coupons; IR scans for refractory

Cavitation

More likely at temps approaching the boiling point of the liquid

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

Mechanical Fatigue

N/A

All alloys; Stress levels and number of cycles to failure vary by material

Good design; Material selection; Minimize stress risers

MT, PT, SWUT for cracks; Vibration monitoring

Vibration-Induced Fatigue

N/A

All engineering materials

Design; Supports and vibration dampeners; Stiffeners on small bore; Branch sizing

Visual/Audible signs of vibration

Refractory Degradation

N/A

Refractory materials

Selection; Design; Installation

VT during shutdown; IR online

Reheat Cracking

During PWHT or at elevated temps.

low alloys, 300 SS, and Ni base alloys; High Strength Low Alloys (HSLA)

Joint configurations in heavy walls; Minimize stress risers

UT and MT/PT for surface cracks; UT for embedded cracks

Galvanic Corrosion

N/A

All metals with the exception of most noble metals; SEE Table 4-4 for Galvanic Series

Design; Differing alloys not in intimate contact; Coatings

Visual and UT Thickness

Atmospheric Corrosion

Corrosion rates increase with temp up to about 250°F.

CS, low alloys, and copper alloyed Al

Surface prep and proper coating

VT and UT

Corrosion Under Insulation (CUI)

More severe 212°F - 250°F for CS

CS, low alloys, 300 SS and duplex SS

Selection of insulation type; Maintain coatings and insulation

Strip insulation; VT, UT, IR, etc.

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Minimize temperature excursions; Visual; IR monitoring; Tubeskin Burner management thermocouples Tube rupture quickly follows DNB; Visual for bulging on tubes and Burner management; BFW treatment burners Ni based fillers; 300 SS rods used in low Visual and MT/PT for OD cracks; UT temp location only; Pup piece with for ID cracks intermediate coefficient


Damage Mechanisms Cooling Water Corrosion Boiler Water Condensate Corrosion CO2 Corrosion

Flue-Gas Dew-Point Corrosion Microbiologically Induced Corrosion (MIC) Soil Corrosion

Caustic Corrosion


Temperature Range

Affected Materials

Prevention

Inspection

Design process inlet < 135°F; Process side > 140°F; Brackish CS, all grades of SS, copper, Al, Operation; Chemical treatment; pH; Oxygen content; Outlet temps; and salt water outlet > 115°F titanium and Ni base alloys Maintain water velocities; Avoid ERW EC/IRIS tubes tubes Primarily CS; Some low alloy, 300 SS Oxygen scavenging treatment; Amine Water analysis; Dearator cracking N/A and copper based alloys inhibitor treatment WFMT Cr > 12% (SS); Corrosion inhibitors; Increasing corrosion with Increase pH > 6; Operation problems; increasing temp up to dewpoint < CS and low alloys VT, UT, RT 400 SS and Duplex SS resistant; W ater 300°F analysis Sulfuric acid dewpoint < 280°F; Maintain temps > 280°F; Avoid 300 SS Hydrochloric acid dewpoint < CS, low alloys and 300 SS if chlorides present; Soda Ash wash to UT for wall loss; VT and PT for SCC 130°F; pH < 6 neutralize the acids Treat water with biocides; Maintain flow VT; Measure biocide residual; 0°F to 235°F; pH range 0 - 12 Most common materials of velocities; Empty hydrotest water; Operating conditions indicate fouling; (Any) construction Maintain coatings Foul smelling water Most effective coatings and cathodic Structure to soil potential; Soil Corrosion rates increase with Carbon steel, cast iron, and ductile protection; Special backfill may help to resistivity; VT, guided UT, Pressure increasing metal temperature iron lesser degree testing High solution strength caustic UT Scans, RT, Injection points, general corrosion of CS above Design; Adequate water flooding; Primarily CS, low alloys and 300 SS Boroscope steam generating 175°F and very high CRates Burner management; Dilution of caustic equipment above 200°F. Primarily copper alloys as well as Alloy 400 and cast iron

Difficult to predict; Addition of alloying VT (may change color but may require elements may help; CP or coatings may scale removal), Metallography, Loss of help "metallic ring"

Dealloying

N/A

Graphitic Corrosion

< 200°F in the presence of moisture or an aqueous phase

Oxidation

Oxidation of CS significant > 1000°F; 300 Series SS susceptible to scaling > 1500°F. SEE Table 4-6 for CR at elev. Temps

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

Sulfidation

> 500°F

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

Carburization

> 1100°F

Decarburization

Elevated temperatures

Metal Dusting

900°F - 1500°F

Difficult to predict; Internal Primarily gray cast iron, but also coatings/cement linings for internal nodular and malleable cast irons graphitic corrosion; external coatings or which tend to crumble when attacked CP in corrosive soils

Loss of "metallic ring"; Reduction in hardness

CS and low alloys, 300 SS and 400 Alloy selection (Si & Al oxidizers); Lower Hardness/Field metallography if SS, cast SS, Ni base alloys with temperatures and higher oxygen/sulfur process side accessible; RT, UT, MT significant Fe content and HK/HP partial pressures. for cracking in advanced stages alloys Control chemistry of gas phase; Cr and Field metallography; Hardness tests CS and low alloys Mo form more stable carbides for softening All; No known alloy immune under all conditions

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Protective layer of sulfur (usually as H2S); Material selection for specific application; Al diffusion treatment

Compression wave UT for heater tubes; RT for pitting/thinning; VT if ID is accessible


Damage Mechanisms

Fuel Ash Corrosion


Temperature Range

Affected Materials

Prevention

Metal temps above the melting point of liquid species: Blend or change fuel source; Burner Oil ash - melting points below All conventional alloys for process design/management; Low excess 1000°F possible; Waterwall heaters and boilers; 50Cr-50Ni family oxygen; Alloy upgrade to 50Cr-50Ni for corrosion - melting points 700°F; show improved resistance hangers/supports Coal ash - melting points 1030°F to 1130°F

Inspection

VT; UT for loss of thickness

Alloy change to 30% - 80% Ni

Change in color to dull gray; Hardness testing (400 - 500 BHN); Check 300 SS for magnetism; Metallography; ECT; PT, RT, or UT for cracking in advanced stages

Nitriding

> 600°F; Severe > 900°F

Carbon steels, low alloys, 300 SS and 400 SS; Ni based alloys more resistant

Chloride Stress Corrosion Cracking (Cl-SCC)

> 140°F

300 SS; Ni 8% - 12% most susceptible; Ni > 35% highly resistant, Ni > 45% nearly immune

Material selection; Low chloride water for hydrotest; Coatings under insulation; Avoid designs with stagnant areas where chlorides can concentrate

VT in some cases, PT (surface prep may be necessary), ECT, UT

Corrosion Fatigue

N/A


Reduce corrosion (inhibitors, material selection, coatings, BFW chemical control, etc.); PWHT; Controlled start-up (thermal expansion)

UT, MT

Caustic Stress Corrosion Cracking (Caustic Embrittlement)

Increasing temps increase likelihood and severity

CS, low alloys and 300 SS; Ni base alloys more resistant.

Ammonia Stress Corrosion Cracking

Any temperature

Liquid Metal Embrittlement (LME)

N/A

Hydrogen Embrittlement (HE)

Ambient - 300°F; Decreases with increasing temp; Not likely to occur above 160°F to 180°F

Amine Corrosion

Increases with increasing temps; Above 220°F can result in acid gas flashing and severe localized corrosion

Ammonium Bisulfide Corrosion (Alkaline Sour Water)

< 150°F

Ammonium Chloride Corrosion

< 300°F; May corrode well above water dewpoint of 300°F

PWHT at 1150°F for CS; Alloy upgrade WFMT, EC, RT, ACFM for crack to Ni based alloys; Design/operation of detection; PT not effective (ti ght, scaleinjection system; Water wash filled cracks); SWUT for crack depth equipment prior to steamout

Copper - zinc content below 15%, 9010CuNi and 70-30CuNi nearly immune, Copper alloys with aqueous ammonia prevent ingress of air, upgrade to 300 and/or ammonium compounds; CS in SS or Ni alloys; CS - PWHT or addition anhydrous ammonia water (0.2%), weld < 225 BHN, prevent ingress of oxygen Keep metal with low melting point away Many commonly used materials from other metal; Grind out cracks not acceptable Use lower strength steels; PWHT; Low hydrogen, dry electrodes, and preheat CS, low alloys, 400 SS, Precipitation for welding; Bake out at 400°F or higher; Hardenable SS, some high strength Controlled pressurization sequence; Ni base alloys. Protective lining, SS cladding, or weld overlay Proper operation; Avoid buildup of HSAS; Design should control local pressure drop to minimize flashing; Primarily CS; 300 SS highly resistant Avoid oxygen inleakage; Remove solids and hydrocarbons; Corrosion inhibibitors Symmetrical/balanced flow in and out of air cooled exchangers; Maintain CS; 300 SS, duplex SS, Al alloys and velocities 10 to 20 fps for CS, resistant Ni base alloys more resistant materials > 20 fps; Water wash injection and low oxygen All commonly used materials; Order of increasing resistance: CS, low Pitting resistant alloys more have alloys, 300 SS, Alloys 400, duplex SS, improved resistance; Limit chlorides; 800, and 825, Alloys 625 and C276 Water wash; Filming inhibitors and titanium. Page 4 of 12

Copper - monitor pH, ECT or VT on tubes for cracking; CS - WFMT, AET, or External SWUT

MT or PT for cracks, RT for mercury deposits inside tubes

MT or PT for surface cracks; UT may be helpful; RT not sensitive enough

VT and UT thickness internal; UT scans or profile RT for external; Corrosion coupons

Frequent UT and RT profile thickness; IRIS and ECT tubes; Monitor water injection

RT or UT Thickness; Monitor feed streams; Corrosion coupons may be helpful if salts deposit on the element


Damage Mechanisms Hydrochloric Acid (HCl) Corrosion

High Temp H 2/H2S Corrosion


Temperature Range

Affected Materials

Prevention

Upgrade CS to Ni base can help; Increases with increasing temp Remove chlorides (neutralize, water up to point where water All common materials of construction wash, absorb, etc.); Minimize carryover vaporizes of water and salts Use alloys with high chromium content; Order of increasing resistance: CS, > 500°F 300 SS are highly resistant at service low alloys, 400 SS, and 300 SS temps Monitor CS operating > 150°F for thickness; Minimize water, oxygen, sulfur and other contaminants in feed; Alloy 400 (solid or clad) used to eliminate blistering/HIC/SOHIC. PW HT to minimize possibility of SCC.

Inspection AUT or RT for thickness; Corrosion coupons; Check pH UT, VT and RT for thickness; Verify operating temps; Check process H 2S levels periodically

Hydrofluoric (HF) Acid Corrosion

Increase with increasing temp; High CRates observed > 150°F

Low alloys, 300 SS and 400 SS are generally not suitable; CS, Cu-Ni alloys, Alloy 400, an other Ni base alloys have been used in some applications

Naphthenic Acid Corrosion (NAC)

425°F - 750°F; Has been reported from 350°F - 800°F

CS, low alloys, 300 SS, 400 SS, and Ni base alloys

Phenol (Carbolic Acid) Corrosion

Minimal below 250°F; Rapid CRates above 450°F

Phosphoric Acid Corrosion

N/A

Sour Water Corrosion (Acidic)

N/A

Sulfuric Acid Corrosion

N/A

Order of increasing resistance: CS, 316L, Alloy 20, high Si cast iron, high Ni cast iron, Alloy B-2 and Alloy C276

Materials selection; Proper operation; Caustic wash to neutralize

UT or RT of turbulent zones and hottest areas; Corrosion coupons

Polythionic Acid Stress Corrosion Cracking (PASCC)

Sensitization occurs 750°F 1500°F

Sensitized austenitic SS; 300 SS, Alloy 600/600H, and Alloy 800/800H

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

Flapper disc sanding to remove deposits and PT

Amine Stress Corrosion Cracking

N/A

CS and low alloys

PWHT all CS welds; Material selection (clad or solid); Water wash non-PWHT CS prior to welding, heat treatment or steam out

Crack detection best with WFMT or ACFM; PT usually not effective; SWUT crack depths; AET

Wet H2S Damage (Blistering/HIC/SOHIC/SSC)

Blistering, HIC, and SOHIC ambient to 300°F or higher; SSC < 180°F

CS and low alloys

Hydrogen Stress Cracking HF

Aqueous HF environments

CS and low alloys

Carbonate Stress Corrosion Cracking

Generally no temperature ranges; However, > 200°F if CO 2 > 2% in gas scrubbing units

2% - 2.5% molybdenum shows improved resistance; Change or blend crudes; Inhibitors Material selection; Velocity < 30 fps; Order of increasing resistance: CS, Recovery ovhd temps at least 30°F > 304L, 316L and Alloy C276 dew point 304L satisfactory for concentration 100% and temp < 120°F ; 316L required Order of increasing resistance: CS, 120°F - 225°F; 316L and Alloy 20 304L SS, 316L SS, and Alloy 20 effective at concentrations up to 85% at boiling temps Material selection; 300 SS < 140°F; Cu Primari ly CS; SS, Cu alloys, and Ni and Ni resistant, but Cu vulnerable in base alloys usually resistant ammonia

CS and low alloys

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RT or UT Thickness; Monitor small bore piping, flange face corrosion, blistering/HIC/SOHIC

RT or UT Thickness; Monitor TAN, sulfur, Fe, and Ni contents RT or UT Thickness; Corrosion coupons

RT or UT Thickness; Sample Iron in water; Corrosion coupons RT or UT Thickness; Monitor pH of ovhd accumulators; Corrosion coupons

Coatings or alloy cladding; Water wash to dilute HCN or inject ammonium Monitor free water phase; Crack polysulfide's to convert to t hiocyanates; detection best with WFMT, EC, RT or HIC-resistant steels; PWHT can prevent ACFM; SWUT for crack sizing; AET SSC and help with SOHIC; Inhibitors PWHT; W eld hardness < 200 HB and no localized zones > 237 HB; CS with Carbon Equivalent < 0.43; B7M Bolts; Coatings or alloy cladding PWHT at 1150°F; Material selection; Coatings or alloy cladding; Water wash non-PWHT prior to steamout or heat treatment; Inhibitors

WFMT for cracks; Hardness testing -2

Monitoring of pH and CO 3 concentration; WFMT or ACFM for crack detection; SWUT for crack depth; AET


Damage Mechanisms


Temperature Range

High Temperature Hydrogen Attack (HTHA)

Exposure to hydrogen at elevated temperatures

Titanium Hydriding

> 165°F

Affected Materials

Prevention

Inspection

Alloys with Cr (> 5 Cr) and Mo or Order of increasing resistance: CS, Ctungsten and vanadium; Use a 25°F to 0.5Mo, Mn-0.5Mo, 1Cr, 1.25Cr, 50°F safety factor; 300 SS overlay 2.25Cr-1Mo, 2.25Cr-1Mo-V, 3Cr, 5Cr and/or roll bond clad material

UT using combination of velocity ratio and backscatter (AUBT); In-situ metallography; VT for blistering; WFMT and RT in advanced stages with cracking

No titanium in known hydriding services such as amine or sour water; Use all titanium if galvanic coupling may promote hydriding

ECT; Metallography; Crush/Bend test

Titanium alloys

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Appearance

N/A

N/A

N/A

N/A

N/A

Cracking particularly at welds or areas of high restraint Cracks typically straight, nonbranching, with no plastic deformation; Limited intergranular cracking

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Appearance

Noticeable deformation may be observed; May have significant bulging before final fracture occurs

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; "fishmouth" Open burst with edges drawn to a near knife-edge Cracks at the toe of weld in the HAZ of the ferritic material Surface initiating cracks may appear as “craze” cracks Localized loss in thickness; Pits, grooves, gullies, waves, rounded holes and valleys; Often with a directional pattern Sharp-edged pitting but may have a gouged appearance in rotational components “clam shell” type fingerprint with concentric rings called “beach marks” Crack initiating at a point of high stress or discontinuity Cracking, spalling or lift-off from the substrate, softening or general degradation from exposure to moisture; Erosive services: washed away or thinned Intergranular and can be surface breaking or embedded More active material can suffer generalized loss in thickness or crevice, groove or pitting corrosion General or localized; Normally a distinctive iron oxide (red rust) scale forms May be highly localized; Loose, flaky scale covering the corroded component Page 8 of 12


Appearance General corrosion, localized underdeposit, pitting, MIC, SCC, fouling, grooving along ERW tubes Oxygen: pitting anywhere in the system; CO 2: smooth grooving Localized thinning and/or pitting; May be deep pitting and grooving in areas of turbulence General wastage often with broad, shallow pits Localized pitting under deposits or tubercles; Cup-shaped pits within pits External thinning with localized losses due to pitting Localized metal loss as grooves in a boiler tube or thinned areas under insulating deposits; Often a color change or deep etched appearance; May be uniform through the cross-section or localized Widespread or localized; Damaged areas will be soft and easily gouged with a hand tool

General thinning; Usually covered on the outside surface with an oxide scale

Most often uniform thinning but may be localized; Sulfide scale will usually cover the surface

In advanced stage may be a volumetric increase N/A Low alloys can be uniform but usually small pits filled with crumbly residue; SS and high alloys local, deep, round pits

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Appearance

“alligatorhide”

"needle-like" particles of iron nitrides

"spider web"; Branched, transgranular, and may have "crazecracked" appearance "rabbit ears"; Transgranular but not branched, often multiple parallel cracks "spider web"; Predominantly intergranular, parallel to weld in adjacent base metal but can occur in the weld or HAZ Cu: bluish corrosion products at surface cracks, single or highly branched, either trans or intergranular Brittle cracks in an otherwise ductile material Can initiate sub-surface, but in most cases is surface breaking; Higher strength steels cracking is often intergranular

General uniform thinning, localized corrosion or localized underdeposit attack

General loss in thickness with potential for high localized rates; Low velocities may have localized under-deposit corrosion

Possible fouling or corrosion

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Appearance General uniform thinning, localized corrosion or underdeposit attack Uniform loss in thickness from the process side with an iron sulfide scale Localized general or severe thinning of CS; May be accompanied by cracking due to hydrogen stress cracking, blistering and/or HIC/SOHIC damage Localized corrosion, pitting, or flow induced grooving in high velocity areas General or localized corrosion of CS

General or localized thinning of CS

General thinning; Localized corrosion or underdeposit attack can occur General but attacks CS HAZ rapidly; Hydrogen grooving in low flow Intergranular; Quite localized; Typically next to welds, but may be in base metal 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 Blistering, HIC "stepwise cracking", SOHIC stacked arrays, SSC through thickness potentially

Surface breaking intergranular cracks "spider web"; Parallel to weld in adjacent base, but also in weld or HAZ; Predominantly intergranular

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Appearance Intergranular and adjacent to iron carbide areas in CS; Some blistering may be visible to t he naked eye

N/A

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API-RP-571-Damag-10

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