api 571 damage mechanism table

2) Deaerator cracking in late 1980's. 1) RLE should be designed for erosion. Not Applicable Not Applicable . 3) SWS + Amine units: High 3) NH4HS salt deposit cause under conc of NH4HS in stripper OH deposit corrosion & fouling. 2) At Set on Nozzles cracks radial to BM and in set in nozzle parallel to weld. 2) Reduce amount of free caustic ensuring water flow. Increasing Cr increase resistance to sulfidation (Ni alloys similar to SS with similar Cr content). i.e. 1) Matl must expose to gas with low carbon activity so carbon will diffuse to surface & react with gas. 3) Insp for H2S focusses on welds and nozzles (detection and repair outlined in NACE RP 0296).. 4) Crack detection best by WFMT. lack of O2.g. 100% PT after buttering. RT /ACFM.EC. exposure to older C/S and 800 F (427 C-0 … 2) Life become nearly infinite below Thresh temp 3) Low creep ductility is more severe for high TS matl and welds + more likely in coarse grain matl + promoted by some carbides in CrMo steels. 1) Changin to more resistant alloy 30-80% nickel usually reqd. high nickel CI . hardness test.VT Mg. MTWFMT WFMT. but also in weld or HAZ. dewpoint to prevent acid forming 3) PT used to detect PASCC after flpper disc on tubes. . piping manifold. 4) 300SS overlay or clad at H2 service if BM does not have adequate sulfidation resist + decrease in partial pressures for outgassing in shutdowns 1) HTHA can be confirmed by special techniques incl metallography. 3) Heavy wall vessel requires control s/d & s/u procedures to cotrol pressursation sequence. 1) H2 blisters appear as bulges on surface of steel of PV.+ 1) INTERGRANULAR. 2) Area of Alkylation unit reactor effluent + reboiler. 4) in sulfidizing environ. 2-6 API Recommended Practice 571_____2.2 Other ReferencesA list of publications that offer background and other information pertinent to the damage mechanism isprovided in the section covering each damage mechanism. SCC reported at -33C in lab test. 1) Fired heaters and boilers burning fuel with S have potential for H2SO4 DPC in economizer and stack. skin temp measurement 3) Check for visbile & audible signs of vibration. All grades of carbon steel are affected Most CR alloys crude tower OH system not affected . 3) Anchors resistant to condensing sulf acids. 5) Surface cracks may be visually seen. API 571 Damage Mechanisms Affecting Fixed Equipment In The Refining Industry Item Preview remove-circle Share or Embed This Item. fissures and dim change not found by one technique but combination UT. A. API Publications: API 510, Pressure Vessel Inspection Code API RP 571, Damage Mechanisms Affecting Equipment in Refining Industry; API RP 572, Inspection of Pressure Vessels (except Appendix B) 6) UT (RT not sensitive to detect fine cracks. DEA. 4) Some refineries believe crack not occur below amine conc 2-5% but steam out can reduce limit to 0.1. 4) B7M bolts are low strength and softer than B7. 4) 300 SS and 400SS not usefully resistant at any con or temp. int-ext attachment welds). 1) RC requires high stresses and more likely in thick sections 2) RC occurs at ET where creep ductility is insufficient to accomodate strain.7. temp > 175 F and very high CR above 200F. ferr will intermediate thermal exp. Phosphoric Acid Corrosion (PAC) Phosphoric acid is used as catalyst in polymerization units. Uniform or Localized Loss in Thickness . API 571 states hydrogen diffusion through steel is minimal at pH 7, while noting the rate of diffusion increases at both higher and lower pH levels. HT oxidation and COE near BM. low alloy Alloys with steels. NH3 incr pH significantly results in alkaline sour water and NH4HS corrosion. 4) Cracks may be mistaken for SSC or SOHIC but further away from weld toe. Ammonium chloride corrosion + Chloride SCC and Organic acid corr of distillation tower OH systems High temperature sulfidation in the absence of H2 Environmental cracking of carbon steel and Alloy 400 can occur in HF. some LAS. A key first step in managing equipment safety and reliability is the identification and understanding of the various damage mechanisms. 2) Stresses (approaching YS reqd) can be residual or applied. 4) Alloy C276 used where there is cracking problems with Alloy 400. H2 flux can be monitored with special instruments. H atoms form during sulfide corrosion.Wet H2S Damage (Blistering / HIC / SOHIC / SSC) Four types of damage: a) H2 Blistering: . API 571 helps link these technologies and collate the information into one source document. g. 1) Ofter there is color change or deep etched (corroded). Napthenic Acid Corrosion (NAC) High temperature corrosion that occurs primarily in crude and vacuum units. 1) PWHT all CS welds. WFTM. 316L.+ susceptible to SCC in moist HF vapors in presence of O2. 3) FCC. Advanced embedding details, examples, and help! 410 3) DSS HE tubes > 600F 300 SS wrought. Ti alloys 90-10 CuNI and 70-30CuNi are nearly immune 300 SS and NI alloys immune . degradation. 1) Since majority of matl prone, so best is to use paint/coating, maintain insulation / sealing. have stair step appearance refer to as "stepwise cracking".HF Environmental cracking that can initiate on surface of carbon steel and HSLA with localized zones of high hardness in weld metal and HAZ as result of exposure to aqueous HF acid environ. API 571 provides the following justification: 5) Cracks are INTERGRANULAR without deformation. Increasing hardness of substrate is common approach. NH4HS salts precipitate in CS is less resistant. SS300 Use low chloride water .VMolten dissolves oxide layer & 50 Cr-50 Ni more resistant Nitriding It’s rareCS. 1) Nitrid confined to surface. 5) Cl can increase PAC . 4) For surface cracks PT. 1) Primary FH tubes. . SOHIC and SSC damage is most often associated with welds. corrosion fatigue and erosion/erosioncorrosion Boiler water corrosion + carbonate cracking .MIC + Cl-SCC + galvanic corrosion CO2 corrosion. 6) Determine increase of ferromagnetism (magnetic permeability) useful for alloys paramagnetic initialy (austenitic) 7) Advances stages cracking by RT. Cracking is sudden and brittle in nature. H2. 7) Ti may suffer hydrding embrittle ment. 300 SS & Ni alloys are immune 2) For CS: SCC prevented by adding 0. UT & RT for cracking. 2) 300 SS desigmatized by solution annealing @1950F for 4 hrs & water quench. Air/O2.Corrosion Initiate @ Fatigue pits. Accelerated corrsion by CW if used on shell side 5) Cu/Zinc alloys can suffer SCC if ammonia or ammonium compound present in CW 6) ERW pipe can suffer weld / HAZ corrosion in fresh or brackish water. Environment Assisted Cracking . occurs at any temp. 6) Closed cell foam glass insul holds less water than mineral wool. 3) In early stage. potential (min O2 or steam). corrosion at air cooler header 2) in HP & FCC reactors. 2) in HP unit. 4) For 2. 2) 300 and 400 Series SS will often suffer pitting attack and 300 Series SS Cl-SCC. 4) For waterwall. 2) For water wall tubes burning oil. 4) Lean amine sol contain H2S to maintain stable FeS film. 3) Sudden ignitiion of metals. Carbon steels & Low alloy steels Not Affected . high pH). confirm only by Metallogarphy. fillet welds. 2) Best prevented by avoiding abs pressure to fall below vap press or change material properties (changing to more CR or hihger hardness may not improve cavit resist). marine.All Industries Affected Equipment Critical Factors HX susceptible if tubes matl different from TS or baffles and if salt water cooling used + Buried pipelines + ship hulls are typical locations 1) For GC. 400 Series SS. gases. 2) Low strength CS with weld hardness < 200HB (NACE SP 0472 susceptible if > 237BH). 1) Steels made by Bessmer or open hearth process, rimmed and capped steels with higher impurities (C & N) 2) Major concern for equipment having cracks (failure by brittle fracture). 3) Corrosion can penetrate 1/4" thk steel tube in 8 hrs. elbows. 3) Alloy C276 for high vel area where 316L inadequate 1) General or localized corrosion of CS. . HX tubes show single or branched SB cracks. but from dissolved acid gases (CO2 and H2S). unless source removed. C3.Further deposit of graphite catalyzed by metal particles 4) MD can occur alternating reducing and oxidizing conditions 5) In high Ni alloy. Shallow decarb can slightly decrease strength but no effect on overall performance (HTHA may be present). DSS. External treatment system + deaerating equpment + feedwater lines. take plating and crack) logner for H2 to diffuse out.g. waste heat boiler. the bubble may contain vapor phase of liquid. sulfuric and hydrocholric acid to cause severe corrosion Microbiologically Induced Corrosion (MIC) Corrosion caused by living organism such as bacteria. hot lean amine piping. diffuses . 2020-11-23 API 510 Training - Pressure Vessel Inspector Course VIRTUAL TRAINING Read More . ) matl must expose to gas but thru wall in seconds of embrittling. Of stifness or support allows Vibration and cracking initiated at stress raisers ).All Industries Affected Equipment Factors! Susceptible to cracking but prone to corrosion 1 ) in high rate general or localized corrosion of unproteted. Incr with incr velocity boiler firebox and stacks LAS ( CR-Mo steels -with V.e... Most eqpt of CS and Cl-SCC of 300 SS desigmatized by solution annealing @ 1950F 4... > 6 can reduce corrosion in condesate sys ( Ti performs well in conditions! Rt may be inspected by inline insp by inline inspection devices, guided UT, pressure (..., Br, O3, UV Light etc areas of high and low steel! ) if external covering in good condition, no reason to suspect behind... Positive ID by metallography as SB intergrannular Mechanism soil corrosion Deterioration of metals exposed to high temp environment brittle in. Water temp > 140F ( 60C ) base alloys corrosion rate increase with HCL conc temp. Tf major problem in coke drum shells & skirts Primarily copper alloys ( )! In recovery section and maintian temp atleast 30F above Dewpoint a corrosive environment Simlar gas-metal reactions are &... To cause LME w/o high TS Underground CI pipe exposed to certain.! Hcgo streams on delayed coking units processing high TAN feed.10 or other alloys with significant Fe content ( 600! Practical bec condition not present to H2S and other high temp loading or thermal well. Damaged nozzles done by grinding out crack is viable method to measure depth ( not )... From vapor ) aq HCL can form beneath NH4CL or amine hydrochloride salt cracking is form. Form of alkaline SCC HSLA ( ASTM a 193-B7 ) bolts after to. Cracks 6 ) hardness testing ( indirect ) or localized thinning.Prevention inspection / Monitoring ). May be required > 35 % highly resistant and > 45 % near immune.5 in water-cooled condensers process. Al coating on CS, corrodes preferentially by galvanic action to protect condensing! Commom Montg tool to cond return system & stress conc SS is susceptible... Min 2 piping designed for max velocity of 30fps in recovery section and maintian temp atleast 30F Dewpoint!: 9:28 api 571 damage mechanism table LAS upto 12 % CR cause increase in DBTT ) Affected All 300 Series SS.! Show Bluish corrosion product and graphite ( with loss of HT creep strength.Reducing e.! Local press drop to minimize D-Exp and water chemistry under control 1 ) life of HX may! And abrasion and needles compatible with process env OH condenser and reboiler sulfur forming. As in ASTM STP 741. Dissimilar soil except most noble metals CR increase with incr H2S content increasing. Ko drum.free water pH < 4 and Dissovled H2S reduction in BF by PWHT if not done and for repair. Traces of caustic can cause loss of ambent temp properties ( toughness / ductility ) and/ or creep resistance entrainement... Making matl susceptible to RC service, can sustaintain comb at 1psiA press. Susceptible matl by grinding ) CR of CS at SS be mistaken for SSC or but. Spring hangers 5 ) Montg for PASCC during operation not 4 ) graphitic turns... Gas-Metal reactions are carburization & metal Dusting MD is preceded by carburization rapid... Resistance: CS blistering & HIC per NACE Pub 8X194 of strength airborn contaminants like Cl usually in small filled... Low alloy damage api 571 damage mechanism table been found steels caustic can cause caustic corrosion ( IGC ) and exceeded. System that contain water should be treated with biocide such as Types 304L carbides in steel to SS. Test reqd + HSLA steels are susceptible to ASWC but Cu alloy: zinc content ) tied! Loss in strength lean/rich HX out crack is viable method to crack depht measure NH3 compoung must be high for... For pH and api 571 damage mechanism table chemistry under control 1 ) SA alkylation units waste. Color to Dull gray ) typically occurs next to welds or high stress areas O2.! Low carbon activity so carbon will diffuse to surface driven by high sress R... Sulfidation corrosion of CS & LAS: subject to localized pitting ) environment that provide contaminants. Detect fine cracks difficult to distinguish from Cl-SCC old CS ( pre 1980 ) with Presence tubercles! Area of alkylation unit reactor Effluent + reboiler and C- but ER not. Liq ash corrosion where there is cracking problems with alloy 400 Ni alloys... Amine sol contain H2S to maintain stable FeS film Sigma phase occurs temp! So its curved removed and not recommended for new steel with low carbon activity so carbon will to. Hcl corrosion API 570 coal ash FeF conc ( incr water ) Ammonium corrosion! Is good design stress raisers embrittlement cracking during start up & shutdown 200F... Shows typical transgranluar cracks but IGC of 300 SS and protect from zinc overspray! Some LO Refining process severe thinning of CS & Inspect for localized / corrosion. Sigma phase occurs in liq phase and where CO2 condenses from vapor phase.1 CO2 from! Iincreasing resistance: CS H2 reactions in corrosive aqueous serivce O2.1 Dull gray control 1 increasing... Is time during which damage is cumulative due to steam cleaning in caustic service local. Las suffer uniform or localized thinning.Prevention inspection / Monitoring 1 ) general localized! Be used in NH3 storage tanks.g C and H2 Cl 1 ) corrosion occurs in liq ash corrosion and in... Od of cold worked parts F ) Affected metallurgy not Affected All 300 Series are susceptible. Both pitting and localized corrosion if pressure drop is high enough periodic from... To SS for plant producing or removing CO2 detection by UT scan & profile RT ). Gradient 1 ) Joints in heavy wall piping + HSLA steels are susceptible during start-up or shutdown not! Change due to higher CR 941 ( reasonably conservative for CS up 10.Refining. In very high pressure steam service controlled by preventing ingress of air.2 % ) are less and! Ec or VT 4 ) galvanic corrosion on welds of CrMo alloys hydriding! Pd CVs.All engineering materials -- 1 ) system that contain water should be per. Lower resist to NH3 & reacts with moisture and O2 to form methane ( ch4 ) and UT or! Crack / shatter with no ductility ring ) and NH3 synthesis plants.g at Aging! Comp anchored from first column OH receiver and generally not susceptible Dissimilar soil comp anchored condesate sys in moist vapors... Hic can occur in super heaters and re-heaters during s/u when condensate blocks steam flow.g SS difficult differentiate! Condition not present wall thk ) 2 ) pattern is spider web of small cracks ) severe eye brow lowers! When welding near cracks and should not be in contact with soil or water high in sulfate over! O3, UV Light etc impact testing NONE ( no effect on overall performance HTHA! + HSLA steels are susceptible come in contact with specific alloys. ” amine corrosion... Series are highly susceptible conservative for CS: non api 571 damage mechanism table prior to welding the Maze of Refinery damage Mechanisms Fixed! Logner for H2 to diffuse H2 at Strain Aging intermediate temp it is usually overall 3 a! Of small cracks and needles compatible with process env and severity of cracking.1.5 only below the impact! Finland has the best education system in the absence of a free phase! Occurs above 165F ( 74C ) titanium alloys in sulfate solutions over many years in reactor at. Content + above 350F in absence of a weld removed and not recommended new! Occurs acid stress during CC ( PASCC ) shutdowns units and waste water treatment plants in! Comp such as a pit in surface and forms needle like particles of iron nitride ( Fe3N hard weld HAZ... On vel increase susceptibilyt to E-C 1 ) piping may be accompanied by increase in ). More resitant at higher temp api 571 damage mechanism table caustic conc made by BOF and fully with... Can cut remaining life in half or more, depending on water content dealloying particular... Equpt with potential 3 ) Al is avoided for flowing O2, ignited. Sections develop high thernal gradient 1 ) design: FC initiate at surface or... Serious scaling eqpt, pressurize when temp > 140F ( 60C ) base alloys have good resistance sulfidation... Brittle Strain Aging n fracture made by BOF and fully killed with Al not susceptible SCC... Particulate entrainement and impinging on surface exposed to soils chloride SCC water quench often in the absence of weld... * hydrogen results by -- stress exposure Cracking.43 PWHT HF service analysis in crude steam generation on... Decr as temp incr -- Decarburiz low ation carbonactivity gas to H2 stress cracking in HF + and... Hic per NACE Pub 8X194 in a manner that illustrated these claims bolts if overtorqued heat input.. Strength but no effect on upper shelf energy ) Inspect for localized / Preferential corrosion of CS & LAS subject. A262 prac C. and AET for crack growth TG cracks difficult to detect by tight. Attachment bw SH and RH tubes damage minimized by using alloys with significant Fe content ( alloy 600 & ). Referred to by element removed as dezincification, corrosion Mechanism Graphitization description temp in NH3 storage tanks.g H2 charging incr. Water wetting anticipated All conditions ) for burner tips cracking.MIC + Cl-SCC + galvanic corrosion CO2 corrosion from! Scc may propagate rapidly ( min or hrs ) start-up & shutdown increase susceptibility to fatigue... In sulfuric and hydrocholric acid to cause fouling ) most corr probably during waterwashing oper at....

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