Module-2 : Damage Mechanisms

- Review on Periodic table & iron carbon phase diagram.

- Why corrosion & materials basics are must to act successful corrosion and asset integrity professionals?

- Factors affecting corrosion leading to various type of damage mechanisms.

- Why each equipment has its unique damage mechanisms?

- Why , there are unlimited types of damage mechanisms?

- Why corrosion is a complex problem?

- How corrosion is created by scale formation and prevented by scale?

- scope of module -2 : Corrosion & Metallurgical Degradation Damage Mechanisms , its identification, detection & monitoring and control /mitigation in refineries / petrochemicals & oil & gas installations both offshore & onshore.

- Solidification of metals/alloys from liquid to solid.

- Review of Fe-C phase diagram.

- Fe-Cr-Ni ternary diagram with alloys used in Oil & Gas & Power industries.

- Cs and Cr-Mo / Cr- Mo - V steels chemical compositions.

- Different type of stainless steels.

- Role of alloying elements in each type of austenitic stainless steels.

- Isothermal Fe-Cr-Ni ternary diagram at 650 deg. C and evolution of sigma phase  and behavior of carbon atom.

- Why preheating / pwht  required in thick section of weldments of carbon steels?

- How in creep range exposure of alloy steel results changes in microstructure & mechanical properties. ?

- why over & under tempering should be avoided and how to predict ?

- How grain size contributes to strengthening and  is governed by time and temperature in austenite region

- How the segregation of P, Sb, Sn, As  on GBs causes the temper embrittlement?

- Impact of alloying on eutectoid  temperature & eutectoid point.

- Carbide & non carbide forming elements in periodic table.

- How atomic size and electro negativity govern the carbide forming tendency of alloying in Fe-C  phase diagram?

- Relative carbide forming tendency of elements in periodic table.

- How  Mo causes temper embrittlement & how to avoid it?

- How titanium is better strengthener than vanadium at high temperature?

- Impact of Mn , Mo, Cr & Ti addition on Fe-C phase diagram.

- Relative impact of carbides , nitrides & borides of alloying elements in precipitation hardening of steels.

- Impact of alloying elements on hardness of low carbon steels.

- Solution & precipitation strengthening by interstitial & substitutional elements in steels.

- Impact of grain size on yield strength of steel.

- Why thick section of mild steels can't be hardened by precipitation hardening.

- Impact of alloying elements in CS and how the hardenability of mild carbon steel gets improved by alloying?

-What's widmanstatten's ferrite , when and why it appears in microstructure of weld and HAZ in steels.

- How the change in morphology of vanadium carbide during reheating of P91 steel causes type IV cracking?

- ISPESL simplified Neubauer classification of creep damages for remaining life based on optical & SEM micrographs.

- What's alpha prime and why industrial application of duplex stainless steels limits below 280deg. C.

- Relative susceptibility of 2304, 2205 and 2507 to sigma phase embrittlement,

- Basics of aqueous corrosion of metals & alloys.

- How corrosion is governed by electronegativities of interacting atoms of elements in alloys and environment?

- How nature of scale govern  the corrosion rate of metals / alloys.

- what's corrosion : why metal and alloys corrode?

- Type of corrosion : uniform / General corrosion & Localised corrosion.

- Types of localised corrosion: macroscopic & microscopic corrosion

- Corrosion allowance Vs. localized corrosion

- Basics of corrosion mechanisms in atmosphere & hydrocarbon pipelines.

- Corrosion drivers : Oxidizing agents & stimulating agents of corrosion .

- Difference in corrosion by chloride (HCl) & SO2..

- How nature of oxides govern the corrosion of metals & alloys?

- Mechanism of oxidation corrosion.

- ISO definition of corrosion : oxidation & reduction reaction causing aqueous corrosion.

- Different forms of corrosion : Active dissolution & passivity.ISO definition of Genral / uniform corrosion.

- Selective corrosion due to selective dissolution.

- Localised corrosion: main forms of localized corrosion- inter-granular corrosion, pitting corrosion & crevice corrosion.

- Environmentally affected cracking : SCC, Corrosion fatigue, strain induced corrosion cracking & hydrogen embrittlement.

- Erosion corrosion

- Cavitation corrosion

- MIC

- Main factors affecting corrosion

- Environmental factors : bulk liquid & surface film environment- main parameters like pH, oxydising species, temperature and presence of deleterious solutes.

- CMMDM : how damage mechanisms expertise is mandatory for RBI in all steps : what to inspect, where to inspect , how to monitor and how to control mitigate corrosion?

- AIM of RBI : Risk reduction rather than cost reduction.

- Classification of damage mechanisms.

- Next session on API 571: Damage mechanisms in static assets of refineries as per latest edition march'2020.

- thank you : raise your questions through Udemy Q & A 

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Why metals  & alloys corrode and degrade in service?

- NACE definition of corrosion.

- Consequence of corrosion

- How corrosion degradation follows the law of nature? reverse to extractive metallurgy.

- Thermodynamically : Corrosion is oxidation of metal but governed by cathodic reaction.

- Atmospheric corrosion of carbon steel.

- Crevice corrosion : Greatest hidden  enemy of engineering structures either due to poor design & poor maintanace.

- Corrosion Mechanism  in sea water : Redox reaction.-

- Rate of corrosion on offshore  platform Engineering structures.

- Corrosion drivers : Oxidizing agents & stimulating agents.

- Why nitrogen purging in idling equipment?

- How SRBs are oxidizing agents causing corrosion but biofouling is stimulating factor expediting corrosion.

- What's the driving force for atmospheric corrosion to happen?

- Under support atmospheric crevice corrosion in piping.

- Atmospheric  under insulation  corrosion on SS 304 tank roof plates.

- Corrosion under fire proofing in LPG horten sphere : How we ignore corrosion on site?

- What's rust (Fe2O3.nH2O).

- What makes rusting , a slow but self supporting spontaneous chemical oxidation reaction?

- Iron - Oxygen reaction mechanism for corrosion to happen: Whether corrosion can happen without water (wetness).

- Periodic table explanation  : How corrosion occurs based on electronegativity of metal with environment?

- Q & A on corrosion based on periodic table : atomic size and electronegativity of elements involved.

- How corrosion is a naturally occurring process and controlling it is a challenge to corrosion expert.?

- Understanding corrosion : why metal corrode?

- What are the factors that affect corrosion?

- Offshore & onshore corrosion in oil & gas : external & internal corrosion.

- Type of Localized Corrosion in stainless steel.

- Type of Localized Corrosion in CS & Low alloy steels.

- Pitting corrosion of stainless steels.

-Material selection for creep resistance & cryogenic service.

- Factors affecting corrosion rate.

- Corrosion diagram for two different type of stainless steels.

- Stainless steels electrochemical corrosion diagram.

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Opportunities & Challenges in Grade P91 (Part -1)

- Role of P91 in power industries.

- Difference in P9 & P91 material.

- Agenda (Part 1) : Manufacturing  & requirement in grade P91.

- History of P91 .

- Application s of grade P91: Super heater tube and Headers & steam piping 540 to 610 deg. C.

- Chemical composition of Grade 91 material.

- Why this material prone to catastrophes?

- Main drivers of grade 91 material : creep strength & steam oxidation/corrosion resistance.

- History of material in power industries.

- Chemical composition & function of alloying elements in grade P91 material.

- Grade 91 : steam oxidation resistance.

- Grade 91: hot corrosion resistance

- Grade 91 : heat treatment (NT ): Compliance to heat treatment condition.

- Formation of delta ferrite and why / how to avoid it?

- Calculated equilibrium diagram for grade 91 material.

- Why normalizing temperature range at 1060 - 1080 deg. C.

- Why cooling rate 0.1 deg. C /sec (minimum ) in normalizing treatment.

- P91 CCTTT curve  for normalizing . Why to avoid ferritic nose?

- Why tempering in temperature range of 760-780 deg. c.

- Why hardness to be controlled above 225 HV10 & below 265 HV10.

- How we get combination of good ductility & good strength (better toughness) in grade 91 .

- what's over & under tempering in P91 and why & how it is to be avoided?

- How formation of precipitates take place in diffusion controlled tempering heat treatment of P91 after normalizing.

- How time and temperature controlled diffusion governed by Larsen & Miller parameter(LMP)

- Relative Precipitates stability in grade 91 during heating : M23C6, Laves (FeMo2), M(CN) & MN

- Microstructures of grade 91 material after NT heat treatments.

- Microstructure (TEM) : after NT heat treatment of grade 91 material.

- Mechanical properties of grade 91 material .

- Hot tensile properties of grade 91 material.

- Effect of tempering on mechanical properties in grade 91 steel.

- Creep properties of grade 91 material.

-Why a good data base is important?

- Why extra-plotted creep data are not reliable in P91?.

- Evolution of microstructure in P91/P911 & P92 materials.

- Progressive microstructural degradation in grade  P91 steel.

- Microstructural degradation in Grade P91/(2 and Gr 122.

- Changes during microstructural evolution in grade 91 steels.

- Grade 91: distribution of precipitates.

- In-service microstructural evolution in grade 91 at 550 deg. C after 115,000 hrs of exposure.

- Evolution of precipitates with time at 600 deg. C  in grade 91 material.

- Evolution of M23C6 & MX at 600 deg. C after 104, 000 hrs of exposure.

-Evolution of MX at 650 deg. C after 115,000 hrs exposure.

- Z phase precipitate at 600 deg. C after 104,000hrs exposure,

- Conclusion : Challenges & opportunity in grade 91 material in power industries.

- Thank you for your passion and patience listening me. 

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Brittle Fracture

- Case Study of spherical tank rupture during testing.

- What's brittle fracture ?

- Material affected by brittle fracture.

- Why austenitic stainless steel & Nickel base alloys don't suffer by DBTT ?

- Morphology of damages by brittle fracture.

- Mitigating brittle fracture.

- Monitoring the extent of damage by brittle fracture.

- Ductile &  brittle fracture.

- Charpy V notch (CVN) toughness test.

- Which materials exhibit DBTT resulting brittle fracture.

- Lesson from Titanic & liberty ships : Design strategy : stay above DBTT to avoid brittle fracture.

- Fracture surface under tensile & shear load.

- How flaws act as stress concentrators ?

- Why surface crack are more insidious than internal defects.

- Modes of fracture operating on cracks.

- When fast fracture will occur ?

- Designing against the crack growth.

- Case study : compressed air tank.

- Fatigue Mechanism causing brittle fracture.

- Creep & type of creeps?

- Estimating the rupture time to creep rupture through Larson miller parameter.

- Opportunities & Challenges in grade 91 material

- Manufacturing of grade 91 pipe & tubes.

- Heat Treatment : Key point for grade 91 material.

- CCT diagram & Normalising treatment in grade 91 material.

- Tempering treatment why soaking temperature range 750- 780 deg. C.

- Heat treatment during manufacturing of grade 91 tube & pipe.

- Optical & TEM micrographs of grade 91 in NT condition.

- Influence of the pipe wall thickness on tensile strength : indicating good hardenability of grade 91 material.

- NDT of grade 91 pipe/tube as ASTM STD.

- Ultrasonic test for rolling defects, cracks , rolling defects (lamination) and wall thickness.

- Hardness requirement of grade 91 as per ASTM .

- How the limit 190-250 HB or 196 to 265 HV finalised for acceptance of material.?

- How to measure hardness of grade 91 material.?

- Why insitu hardness measurements are challenging in grade P91 material?

- Focus on welding: Typical heating cycle for grade 91 material.

- Influence of several PWHT on hardness.

- Influence of several PWHT on yield strength & tensile strength.

- What are the risk in PWHT due to overheating?

- Influence of chemical composition on AC1 temperature.

- Conclusion on welding

- Right Profile of welding in weldolet .

- Pipe / tube materials for super heaters & reheaters in fossils fired power plant.

- Chemical composition of P91/p911/p92 and its service temperature.

- Chemical & mechanical requirement of P91 in all weld metal.

- Chemical composition of filler material in GTAW/SMAW/SAW.

- Why we get best mechanical properties in GTAW.

- Impact of Ni & C content on toughness.

- Continuous cooling transformation diagram for grade 91 material.

- P91 heat control during welding &  PWHT condition.

- Influence of PWHT condition on Hardness.

- End crater cracks at SMAW welding in grade 91 steel.

- SMAW weld metal & mechanical properties of P91 material.

- Temperature limits of headers and piping system used by HPE under the aspects of design temperature according to EN12952.

-Fracture locations of cross weld sample P911/ SMAW at 650 deg. C , 70 MPa , 4295 hrs.

- Coefficient of thermal expansion lowest with grade 91 material.

- Development of steel for power generation boilers. P22 > P91>P92

- B9 grade filler  for P91 steel.

- AWS specifications for grade -91 material.

- Difference in microstructure of weld with B9 & 9Cb filler.

- Proper PWHT temperature for grade 91 material.

- TIPS for successful welding of grade 91 steels.

- Remedies to cold delayed cracking.

- Preventing hot solidification cracks in grade 91 welding.

- Dissimilar joints with grade 91 materials : PWHT temperature & filler wire

- Problem in grade 91 welding

- Arc strike

- Fit up bridges

- preheating

-Inter pass temperature

- Hydrogen Bake out

- External & transport load

- PWHT immediately after welding

- Lifting devices

- Hardness testing not simple.

- Hardness testing method : Pin brinnel / MIC 10.

First part- Sigma Embrittlement damage mechanism in Duplex/ super duplex  Stainless steels

- Opportunities and threats in 2205

- Degradation of duplex / super duplex stainless steels during reheating.

- Why DSS/SDSS are not allowed to operate above 250 deg. C temperature?

- Alert on application of duplex stainless steels.

- Origin of sigma phase formation mechanism.

- Why sigma phase formation lead to sigma embrittlement.

- Why DSS/SDSS have better strength than austenitic & ferritic stainless steels?

- Mystery of degradation   : Deterioration of mechanical & corrosion resistance properties in DSS/SDSS .

- How Sensitization & secondary phases affects the pitting resistance of DSS/SDSS.

- PREN & CPT in DSS/SDSS.

- Why 316 replaced by 2205 in offshore application?

- Microstructure of duplex stainless steel.

- How 2205 DSS is superior to 316 ASS.?

- Technical issues with duplex & super duplex stainless steel.

- Additional tests for duplex / super duplex stainless steels.

- Causes and consequences of sigma phase embrittlement.

- Remedial measures to avoid sigma embrittlement.

- Modern 22 % duplex stainless steel needs no PWHT.

- Why additional mechanical / metallurgical tests specified for duplex / super  stainless steels?

- Impact testing of duplex stainless steels.

- Corrosion testing : A 923 test method C & ASTM G48 test.

- Metallographic Examination as per ASTM E 562

- Case Study: Metallurgical degradation in super duplex steel tubing welded to forging in subsea pipeline.

- Case study: Pipe / weld neck flange cracking in 14" dia super duplex stainless steel (832750) spool embrittlement in high corrosive fluid of FPSO.

II-  Brittle Fracture Damage Mechanism   

- Is your plant vulnerable to brittle fracture?

- What's the brittle fracture?

- DBTT for old vs new steels.

- Brittle fracture initiate from crack like defects.

- Factors affecting DBTT.

- How to study the fracture surface to find out the cause of brittle fracture?

- Titanic disaster : start point of DBTT damage mechanism

DAMAGE MECHANISM : THERMAL FATIGUE

- difference in SCC & Fatigue

- different type of thermal fatigue viz: mechanical, corrosion & thermal fatigue.

- How SCC is aggravated by different type of fatigue.

- Thermal fatigue and affected materials.

- Thermal fatigue monitoring & its control.

- Critical factors affecting thermal fatigue.

- Affected units & equipment by thermal fatigue.

- Morphologies of thermal fatigue damages.

- Prevention / mitigation of thermal fatigue through design & operation control by avoiding swinging in temperature.

- Inspection & monitoring thermal fatigue damages.

Damage Mechanism : Corrosion Fatigue

- What's Corrosion Fatigue ?

- Why corrosion fatigue is much severe than normal mechanical fatigue ?

- How to distinct Fatigue & Corrosion Fatigue ?

- Steps in Fatigue failure & how the severity of fatigue aggravated in corrosive environment on S - N curve.

- Critical Factors affecting corrosion fatigue.

- Affected units & equipment by corrosion fatigue.

- Morphology of fracture surfaces in corrosion fatigue failure.

- Corrosion fatigue preventive & mitigating measures.

- Case study : Corrosion fatigue failure of a 5 " ND API5D drill pipe on a offshore platform.

Galvanic Corrosion & Atmospheric Corrosion Damage Mechanisms

- What's the role of Damage Mechanisms in managing the integrity of in-service assets .

- What are the damage mechanisms?

- CML fixing need the knowledge of damage mechanisms in RBI

- Selection of NDT techniques need knowledge of damage mechanism.

- NDT methods & their applications.

- RBI need right data & right analytics of damage mechanisms.

- Corrosion drivers in electrochemical wet corrosion: Oxidizing agents & stimulating agents.

- Morphologies of different type of corrosion.

- Varying morphologies in pitting corrosion.

- Statistics of corrosion mechanisms

Galvanic corrosion Damage Mechanism :

- Galvanic series

- Galvanic corrosion due to mix up of material.

- Affected equipment by galvanic corrosion

- Appearance & morphology of galvanic corrosion

Atmospheric Corrosion:

- What makes rusting a slow but spontaneous chemical reaction.

- Mechanisms of atmospheric corrosion.

- Why cathodic reaction is the governing reaction in atmospheric corrosion.?

- How cathodic protection & coating prevent atmospheric corrosion?

- Thermodynamic of rusting reaction on metal surface in atmospheric oxidation.

- What's the source of Eact (activation energy for oxidation to happen and sustain.?

- Why rusting initiation is a slow process?

- Factors affecting atmospheric rate of corrosion .

- How & why  the corrosion rate increases  in saline / marine environment in presence of H2S & SRBs?

- Why the corrosion rate increases inside the crevice and under deposit.?

- Prevention of atmospheric corrosion.

- Pitting corrosion in carbon steel.

- How crevice corrosion is the greatest enemy of metal?

- Why the corrosion rate inside the crevice goes on increasing exponentially in saline environment?

- Crevice corrosion causing rupture of pipe under support/clamp in saline environment offshore.

- Fast corrosion rate under the scales loaded with salts in heavily  corroded pipeline offshore platforms.

- Increased atmospheric corrosion of piping laid on the ground.

- Why difficult to find the remaining thickness on the heavily externally corroded pipelines ?

- External erosion corrosion of pipe due to fall of rain water  accumulated in structure .

- Under support & under clamp crevice corrosion on offshore piping.

- Under support crevice corrosion biggest challenge in managing the integrity of ageing assets.

- Corrosion in critical zoneof above ground petroleum storage tank : A challenge in managing the integrity of storage tank.

- offshore :Corrosion by sea water.

- Atmospheric corrosion challenges in an offshore rig.

- Why splash zone structures  are more critical to atmospheric corrosion in offshore?

- Under insulation atmospheric corrosion in SS304 tank on the roof.

- Condensate piping external atmospheric corrosion and internal vapor space corrosion resulting catastrophes in offshore platform.

- Damp & wet Corrosion

- Affected units / equipment by atmospheric corrosion.

- morphology of atmospheric corrosion.

- Prevention / mitigation of atmospheric corrosion,

- Inspection & monitoring of atmospheric corrosion.

- Corrosivity of atmosphere at different locations.

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Environmentally affected stress corrosion cracking

- Type of EASCC

- Fracture Mechanics of Environmentally affected stress corrosion cracking.

Chloride Stress Corrosion Cracking (CSCC) & Chloride Pitting Corrosion (CPC)

- How Chloride Stress Corrosion  Cracking take place

- Why Chloride Corrosion Cracking gives surprizes?

- Why Austenitic Stainless steels are widely even though they are susceptible to CSCC & Pitting Corrosion and PTASCC.

- Why Chloride stress corrosion cracking require the tensile stress above specific threshold limit of specific ASS.

- How 1 ppm chloride in wet aqueous solution can cause CSCC.

- Why different stainless steels have different resistance to CSCC.

- Why austenitic stainless steels suffer most by CSCC SS 316/317 steel resist CSCC.

- Why ferritic & martensitic stainless steel don't suffer with CSCC?

- When duplex stainless steels becomes susceptible to CSCC under high chloride stress condition?

- CSCC accelerated with increase in temperature due to evaporation of water enriching chloride concentration.

- When austenitic stainless steels suffer with pin type pitting & tunneling type decay of metal?

- Chloride stress corrosion cracking in austenitic stainless steels.

- Impact of chloride on SS 316 : Catastrophic CSCC & Catastrophic Pitting Type Corrosion.

- How small anode /large  cathode  area ratio increase the corrosion rate in CR alloys?

- Why we get electric lightening bolt type cracking geometry in CSCC?

- Why we get pinhole type pitting & tunneling type decay in CR SS 316 material.?

- Q & A :Increase your tacit skill through tacit thinking.

- What's the characteristic of CSCC?

- How can we mitigate CSCC ?

- Preventing CSCC in refineries & petrochemicals.

- How prevention of PTASCC by passivation prevent the CSCC too?

- How Aluminum  foil under insulation prevent CSCC of austenitic stainless steels?

- How use of SS 316 prevent CSCC in Amine regeneration & Sulfur Recovery Unit?

- Why Chloride Stress Cracking gives surprizes?

- Why 304 austenitic stainless steel totally stopped in Saudi & Saudi Aramco?.

- How austenitic stainless steel internal cladding can avoid the catastrophic failure , which may occur in full ASS?

- How in molten sulfur tank bottom , SS 304 cladded CS plate provide more integrity than full SS 304 plate?

- Preventing CSCC Austenitic stainless steels are not recommended for components where water is likely to evaporate or condense out.

- Why some times CSCC shows mix cracks of intergranular & trans-granular in austenitic stainless steels?

- Innovation: SCC of roll bonded cladding stops at the weld around the nozzle without propagating around in the base Carbon steel metal .   

- Synergistic effect of chlorides & oxygen on SCC of 304 ASS both without sensitization & with sensitization.

- Photograph of CSCC in 316 tube.

- CSCC in heat exchanger tube

- CSCC under insulation

- Detect the signature of CSCC : A real case study of CSCC on internal surface of   SS 304 deaerator vessel.

- Difference in caustic embrittlement & chloride stress corrosion cracking.

- Effect of temperature on severity of CSCC.

- Why austenitic stainless steels are affected by CSCC?

- Effect of chloride, oxygen content , pH, temperature& stress (PWHT) on CSCC.   

- Factors that influence the rate of severity of CSCC.

- Appearance & morphology of CSCC damages.

- How chloride are detrimental to SS 316?

- What are the three mandatory conditions for CSCC to occur? 

- Why SS 316/317 follow the pitting corrosion pattern , quite small on the surface but very large decay inside the metal.?

- Piston rod failure & remedy?

- Case study :  Failure investigation of ASS 321 charge heater tube failed in refinery.

- Case study : cracking of duplex stainless steel tube in heat exchanger due to poor design.

- Case study : Catastrophic failure of dia 2" SS 316 line in marine environment.

- Case study : Chloride stress corrosion cracking crevice in 303 austenitic stainless steel PIN coupling.

- Case study : Effect of chloride, temperature , oxygen & cold work on CSCC in SS 316 plate type exchanger.

- What's the difference in CSCC of SS316 & 25Cr duplex stainless steel.?

Polythionic Acid Stress Corrosion Cracking (PTASCC) : A kind of Environmentally Affected Stress Corrosion Cracking

- What's Polythionic Acid Stress Corrosion Cracking (PTASCC).

- Corrosion of Flare stack tip : PTASCC due to  Corrosive H2SxOy & MOC: Nickel Base Alloy Inconel 625 & 825.

- Internal & External PTASCC of Austenitic Stainless steels grades heater tube.

- Micrographs exhibiting PTASCC.

- Mitigation of PTASCC through passivation as per NACE RP 170, Use of stabilized grades & Low carbon grades austenitic stainless steels.

- Why SS 347 is more resistant to PTASCC than SS 321?

- My experiences in preventing PTASCC in heater tubes in refineries.

- Why stabilized grades austenitic stainless steels must be procured in both solution annealed and then stabilization heat treatments condition.?

- Why 4 hrs soaking temperature needed for stabilization treatment of stabilized grade stainless steels?

- What's knife line attack and how it can be avoided in stabilized grades stainless steels by stabilization heat treatment after welding.?

- Question & Answer : try the answers to these questions.

- Preventing sensitization through stabilization treatment after welding SS 321/ SS 347.

- Why PTASCC occurs during shutdown and not during operation but failures mostly occurs during restart of the unit.

- Equipment / Components & piping susceptible to PTASCC in FCCU.

- Mitigating PTASCC Through: Dry Air Purging during idling/sd, Soda Ash Passivation as per NACE -RP-170 both internally & externally, use of low carbon and stabilized grade austenitic stainless steels.

- Impact of carbon content & ageing time on Chromium Carbide precipitation (sensitization ) of austenitic stainless steels.

- Detection of IGC susceptibility of austenitic stainless steels welds by ASTM A262 practice to avoid PTASCC in service.

- Three conditions required for PTASCC.

- Materials affected by IGC.

- Pictorial depiction of sensitization in austenitic stainless steel.

- Sensitization in SS 304 weld HAZ in temperature range 500-800 deg. C.

- What's the mechanism of PTASCC and why it is intergranular?

- Austenitic stainless steel has the twinned grain boundaries and why they are eliminated in sensitization?

- Precipitation reactions in type 304 & 347 austenitic stainless steels and how addition of titanium and columbium stabilized the austenitic stainless steel and prevent the sensitization.

- Why sensitization is not significant below 510 deg. C to any extent of ageing time. ?

- Minimizing the effects of IGC in ASS.

- What are super austenitic stainless steels grade, why are they not susceptible to PTASCC.

- Stabilized grade stainless steels 321, 347, 20Cb3 & 316 Ti .

- Knife line attack , how it takes place in stabilized grade stainless steels and poses the problem of PTASCC in service in sensitization range ?

- Why additional stabilization heat treatment needed during both manufacturing & site welding of stabilized grade austenitic stainless steels.

- Case Study : IGCC in 304H waste heat recovery unit (WHRU) duct in in offshore environment.

- Polythionic acid stress cracking in nickel base alloy 600 on dished head near weld.

- Affected units and equipment by PTASCC in refineries and petrochemical by PTASCC.

- Appearance & Morphology of PTASCC affected damages.

- Why IGC test as per ASTM A262 practice  is must in all grade austenitic stainless steels even with stabilized grade if the stabilization heat treatment is ignored during welding.

- Inspection & monitoring of PTASCC affected components.

- Why inspection & monitoring is the challenge in austenitic grade stainless steels.?

Environmentally Affected Stress Corrosion Cracking: Alkaline Stress Corrosion Cracking: Caustic Gouging & Cracking

-Introduction to ASCC

- How even 50 ppm of NaOH can cause caustic corrosion & Cracking?

- How duplex stainless steels are better than austenitic stainless steels at high temperature upto 200 deg.C.

- type of Caustic Corrosion: caustic gouging & caustic cracking

- Mitigation of Alkali stress corrosion cracking.

- Why low strength material SA516 Gr60 carbon steel as MOC for caustic storage / vessels are considered better than high strength material .

- Major contributing factors for  caustic  in refineries & petrochemicals.

- Unit & Equipment affected by caustic corrosion in Refineries.

- Appearance & morphology of Damages in Caustic Corrosion

- Prevention & mitigation of caustic corrosion

- Inspection & monitoring due to caustic gouging.

- Caustic corrosion of steam header due to caustic injection.

- Caustic gouging in Boiler tube.

Caustic Stress Corrosion Cracking: Intergranular with Oxides filled cracks

- Why cold worked & welded components are affected by caustic stress corrosion cracking?

- Materials susceptible to caustic cracking.

- Factors affecting caustic stress corrosion cracking.

- How 50 ppm caustic solution can cause caustic cracking in hot service.

- How PWHT minimise the susceptibility of caustic stress corrosion cracking.

- Affected units/equipment in refineries & petrochemicals .

- Appearance & morphology of caustic corrosion cracking.

- Prevention & mitigating measures against caustic cracking of materials.

- Why the caustic corrosion cracking surfaces look like spider web?

- Prevention & mitigating measures for caustic stress corrosion cracking.

- Affected units/ equipment by caustic stress corrosion cracking.

- Inspection & monitoring of caustic cracking.

- Caustic Soda Service Graph : for selection of materials in caustic service wrt caustic concentration & temperature.

- NACE Caustic Soda Service Graph : Questions & Answers

-  Selection of austenitic stainless steel in caustic service.

- How PREN (Pitting Resistance Equivalent Number) governs the selection of stainless steels in caustic service.

- Risk of stress corrosion cracking in austenitic stainless steels.

- What's the impact of chloride on caustic cracking of austenitic stainless steels?

- How SS 316 provide better resistance to caustic cracking than SS 304 if chloride as an impurity are present in caustic.

- Caustic Corrosion & cracking on incoloy 825 caustic injection quill. 

Sour Water Corrosion & Cracking

- Introduction : H2S Corrosion

- Why Corrosion Becomes Complex Due to Varying Corrosives & their varying content in varying operating conditions?.

- Why Corrosion Can be better understood through periodic table.?

- Role of metallic , covalent and ionic bonding in governing the metallic properties and corrosion of metals & alloys.

- Role of electronegativity, atomic size , melting point & ionization energy.

- Wet Electrochemical Corrosion Drivers.

- Interaction of H2S with material at elevated and low temperature.

-Why sour water corrosion accelerated in presence of chloride & CO2.?

- What's the mechanism of wet H2S corrosion and cracking at low temperature?

- Why Oxygen & H2S scavengers are injected in Oil & Gas pipelines?

- Sour water Corrosion (Bell Curve)

- Effect of pH on sour water corrosion.

- Why sour water corrosion is more severe in Oil & Gas exploration?

- Wet H2S cracking Mechanisms.

- How hydrogen damages occur in sour water .

- How presence of cyanide in hydrocarbon line increase the severity of H2S corrosion cracking?

-   When and under what condition , hydrogen damages  HSC, SSC, HIC, Blistering, SOHIC, SWC occur in sour water service?

- What's hydrogen embrittlement?

- Where hydrogen resides in the steel lattice and causes Hydrogen Embrittlement?

- How hydrogen make the failure of the metal faster?

- Sulfide Stress Cracking = HE + Corrosion Fatigue + SCC

- NACE : Selection of Material -User / Operator's responsibility

- NACE / Manufacturers not responsible for any failure , only operator is responsible.

- NACE Changes : Affecting only carbon steel alloys.

_ Regions of environmental severity for CS/LAS : Four region of severity from 0 to 3.

Changes : affecting only the CRAs :

- New environmental restriction for alloys (part 3 A 1.3)

- Deletion of previously approved materials

- Corrosion resistant alloy (part 3 : clause A1.1)

- Equipment user application guide for MR0175 ISO 15156.

Cracking Mechanisms:

- What chemicals causes corrosion of steel by aqueous H2S.

- Sour water corrosion & Hydrogen cracking mechanisms.

- Picture showing morphology of HIC, SWC, HSC/SSC, Hydrogen Blistering.

- Sensitization , SCC & IGC.

- In H2S , worst damage occurs at room temperature , why?

- Discussion on wet H2S cracking : HIC & SOHIC

- What's the difference in  HIC  & SOHIC and why SOHIC is more dangerous than HIC?

- Preventive measures for hydrogen damages.

Damaging Mechanisms & Test Methods:

- Morphologies of damage mechanisms in sour service

- NACE definition of HIC

- NACE TM 028 4 -2003 - for acceptance of material for sour service.

- HIC test method as per TM 0284 .

- Definition as per NACE MR0175/15156

- NACE TM 0177  for SSC test

- SSC four point bend test

- SSC tensile test

- SOHIC definition as per NACE MR0175 as per NACE 0103   

Sour Water Corrosion & Testing

- SOHIC test arrangement as per NACE TM0103 /2003 .

- SOHIC test evaluation of cross section from the double beam specimen.

- Why normalized material are susceptible to SOHIC over Q&T material.

- MR0175 (ISO 15156) part I - General, Part II- Carbon & LAS , Part III- Corrosion resistant alloys

- HIC resistant material requirements.

- Requirement for homogenous crack resistant steel plates.

- Production route of HIC resistant material in manufacturing plant.

- Difference in corrosion fatigue and stress corrosion cracking (both IGC/TGC).

- Low temperature hydrogen embrittlement in CS & LAS in hydrocarbon sour service.

- Mechanism of hydrogen induced cracking.

- Why HIC detection by NDT techniques  proactively is difficult?

- Hydrogen damages inside the material due to sour service .

- Hydrogen embrittlement problem in cathodic protection in high strength material.

- Stepwise HIC cracking mechanism in X60 pipeline steel.

- Question & Answer

- Sulfide Stress Cracking (SSC)

- Why HSC/SSC more dangerous than CSCC ?

- Wet H2S damages (summary)

- Why SOHIC is more dangerous than HIC/Blistering.

- Morphology   of HIC/SWC damages.

- What is soft zone cracking?

- Sulfide Stress Corrosion Cracking Mechanism. 

- Sour gas service MR0175 (ISO 15156 ) predicting material behavior in presence of H2S, Chlorides, CO2, & O2 damage mechanism.

- Sulfide Stress Cracking in presence of chlorides in well fluid line.

- Case study : 5 % Nickel alloy steel exposed to H2S wet environment : Anodic Polarisation- First pitting & then cracking.

Cathodic polarization: HSC/SSC cracking with no pit.

- Why cathodic protection induce cathodic polarization resulting HSC/SSC.

- SCC vs. HSC/SSC

- Sour water (wet H2S corrosion)

- Hydrogen damages : Type & causes of metal embrittlement in aqueous H2S service.

- If it is clean steel, ductile metal with PWHT then one find no cracking in wet H2S service, why?

-How the hydrogen embrittlement can be avoided by heating , however the heating shall not be done above 315 deg. C why?

- Factors affecting Hydrogen embrittlement & effect on properties.

- How cyanide aggravate hydrogen damages?

- Hydrogen Stress Cracking in Oil & Gas.

- Interaction in HSC & HE.

- Relationship between H2S concentration & max. HAZ hardness or cracking threshold stress.

- Why proper hydrogen bake out procedure is required when equipment in hydrogen service are pressurized or cooled prior to shutdown.

- Tempering & PWHT temperature in high strength forging for sour service.

- Case Study: AISI 4130 forging welded or overlayed.

- Internal corrosion of well, well head piping to header, risers in crude oil service.

- Mechanism of Barnacle type corrosion in well tubing & casting.

- Hydrogen embrittlement during weld repair in wet H2S/H2 service.

- Why bake out required in repair of in-service equipment /piping in wet H2S cracking damages in carbon and low alloy steel.

- Pictorial presentation of wet H2S cracking damages in CS & LAS.

- What's are the requirement of HIC material.

Hydrogen Embrittlement (Case Studies), CORROSION DAMAGE MECHANISM : AMMONIUM BISULFIDE CORROSION,AMMONIUM CHLORIDE /AMINE SALT CORROSION

- Where Hydrogen resides in the metal causing hydrogen embrittlement (HE)

- Behavior  of hydrogen with stainless steels.

- Impact of solution annealing heat treatment & cold working on microstructure in austenitic stainless steel.

- Hydrogen embrittlement / HIC in Austenitic stainless steels.

- Case Study : Root cause analysis of leak during start up in SS 304 cold insulated cryogenic vertical vessel in a petrochemical plant.

- Sea water cathodic protection causing hydrogen embrittlement.

- Hydrogen embrittlement problem in cathodic protection : eight steps

- Case study : Comprehensive damage mechanism of hydrogen embrittlement of bolt fasteners in subsea pipeline.

- Why we use HIC resistant material in subsea?

- Factors affecting wet H2S damages (blistering, HIC, SOHIC , HSC /SSC)

. Environmental condition

. Affected material

. Effect of pH

. Effect of H2S partial pressure.

. Effect of temperature.

. Hardness of material.

- Why high strength steel in O&G are susceptible to SSC, first by pitting and then by cracking.?

- How occurrence of blistering / HIC / SOHIC are related to cleanliness of steel and not mechanical properties (hardness)?

- Effect of steel making on hydrogen damages in H2S sour service.

- What's dirty steel and why it is susceptible to HIC?

- Effect of PWHT:

. Why PWHT can't prevent blistering & HIC?

. How PWHT minimize the SSC & SOHIC damages.?

- Affected units / Equipment by hydrogen damages.

- Inspection & monitoring techniques for hydrogen damages in sour service.

. Why ACFM is used in offshore under water structure & piping for detection of cracking?.

- Selection of materials & its testing for NACE compliance in H2S sour service.

- NACE MR0175  (ISO 15156 I/II/III) & MR0103 for selection & acceptance of material but testing as per NACE -TM0284.

- NACE MR 0103 : material requirement for resistance to SSC & HIC/SOHIC/ Blistering / SWC.

CORROSION DAMAGE MECHANISM : AMMONIUM BISULFIDE CORROSION

- Alkaline sour water corrosion in presence of Ammonia (Bell Curve)

- Environmental factors causing Ammonium bisulfide corrosion.

- What's elemental sulfur and how its causes corrosion in alkaline sour service?

- Units/equipment affected by ammonium bisulfide corrosion.

- How cyanide accelerate the ammonium bisulfide corrosion?

- What's Kp factor and how its decide the occurrence of ammonium bisulfide corrosion?

- Ammonium bisulfide corrosion damages- location of damages.

- Ammonium bi-sulfide corrosion in hydrotreating units.

- Why Ammonium bisulfide corrosion is not a risk at temperature above 88 deg. C ? 

- Why Ammonium bisulfide corrosion is called Alkaline sour water corrosion?

- Affected material by Ammonium bi-sulfide corrosion?

- Affected equipment by Ammonium bisulfide corrosion.

CORROSION DAMAGE MECHANISM : AMMONIUM CHLORIDE /AMINE SALT CORROSION

- What's ammonium chloride corrosion and why it is more insidious than ammonium bisulfide corrosion?

- Material in order of increasing resistance to ammonium chloride corrosion.

- Why 300 series austenitic stainless steels are not used in NH4Cl service?

- Environmental factors affecting Ammonium chloride corrosion.

- Affected equipment by NH4Cl / Amine salt corrosion.

- NH4Cl/ NH4HS corrosion prevention by water wash in FCCU.

- Ammonium Bisulfide Corrosion mechanism in carbon steels.

- How Ammonium bi-sulfide corrosion is self terminating reaction?

- How presence of Cyanide accelerate the ammonium bisulfide / ammonium chloride corrosion?

- Ammonium Bisulfide Corrosion characteristics.

- Ammonium Bisulfide Corrosion Control Measures.

- Balance header configuration : design requirement to prevent ammonium bisulfide corrosion.

- Ammonium bi-sulfide corrosion prevention through material selection.

- Ammonium bi-sulfide corrosion in hydrocracker.

Alkaline Sour water corrosion: Amine Corrosion & Amine Stress Corrosion Cracking

- Natural & Unnatural combinations of Corrosion

- Risk assessment / Risk mitigation needs identification of natural & unnatural combinations.

- Design deficiencies in corrosion prevention & control.

- Design factors affecting corrosion of equipment /piping

. Environment

. Equipment design

. Metallurgy

. Geometry of equipment

. Geography

- Alkaline stress corrosion cracking (ASCC): Introduction

- Amine corrosion & Amine stress corrosion cracking

- Why all alkaline stress corrosion cracking suffer by intergranular cracking?

- Why equipment in lean amine cracking are more susceptible  to Amine stress corrosion cracking. ?

- Why equipment in rich amine suffer to under deposit pitting or erosion than cracking?

- Bell curve for sour water corrosion & alkaline sour water corrosion.

- Why sour water corrosion & amine corrosion is a serious concern in Oil & Gas exploration than in refineries & petrochemicals.?

- What's Alkaline sour water corrosion? How amine corrosion & amine stress corrosion cracking not due to amine but due to acid gases & corrosion products and type of amine?

- Problems in Amine Corrosion.

- Factors affecting amine corrosion , effect of pressure, velocity , purity of amine, type of amine.

- Why austenitic stainless steel 316 is accepted corrosion resistant material in amine service?

-  Amine corrosion monitoring: coupons, probes & iron counts in solution.

- Mitigation of alkaline stress corrosion cracking.

- How plant design, poor operating practices and contamination of amines are main causes of Amine corrosion & cracking?

-Why MEA is causes more amine corrosion &  cracking than DEA.? 

Environmentally Affected Stress Corrosion Cracking: Liquid Metal Embrittlement (LME) Damage Mechanism

- What's Liquid Metal Embrittlement?

- Characteristics of LME

- Impact of LME on Mechanical Properties

- LME is specific in certain Liquid Metal- Solid Metals combinations.

- LME need wettability & limited solubility of liquid metal  in the solid metal .

- Impact of  impurities in Zinc expedite the LME

- Liquid metal which forms intermetallic compounds with solid metal does not cause the LME

- Impact of metallurgy on LME: Alloying Additions.

- Liquid - solid metals couples causing liquid metal embrittlement.

- Mechanism behind LME

- When & how LME occurs?

- Liquid metal zinc embrittlement on austenitic stainless steel mechanism.

- Liquid metal embrittlement by zinc in galvanized steel.

-Practical experiences of LME

-Prevention & mitigation of LME

- 3 stages of liquid metal embrittlement

- LME Mechanism : Liquid zinc over solid austenitic stainless steels.

- LME liquid metal of solid Aluminium by Gallium (Ga).

-LME due to cadmium plating over steel screw used in casing of gas turbine.

- LME by liquid copper over austenitic stainless steel.

- LME of liquid Bismuth over solid copper.

- Hot tensile test results of steel showing the impact of temperature & strain rate.

- Effect of zinc coating on press hardening steel on stress strain curve.

- Fundamental mechanism and factors affecting LME.

- Mercury Embrittlement

- Case Study : 2004 Skida gas processing plant  , Algeria  LNG gas explosion due to LME of Liquid Mercury Attack on Aluminium Cold Box Exchanger in LNG service.

- Liquid copper on steel causing LME.

-LME susceptibility of galvanized welded structure of high strength steels.

- What causes liquid metal zinc embrittlement  over steel , whether the pure liquid zinc or the impurities found in the liquid metal zinc?   

Damage Mechanism : Dealloying & Graphitic Corrosion

- What's dealloying : Selective leaching or Parting or Selective Corrosion

- Dezincification : Selective leaching of Zinc from Brass.

- Why As & Sn are added in brass , how addition As & Sn prevent dezincification in Admiralty brass.

- Type of dezincification.

- Uniform dezincification .

- Type of dealloying : Dezincification & Graphitization

- Mechanism of dezincification : three stages

- Prevention & Mitigation of dezincification. : 1. Use of 1% Tin to 70/30 brass , 2. Use of Monel & Cupro-Nickel alloy

-  Affected materials by dealloying

- Factors affecting dealloying.

- Affected units & equipment.

- Appearance & morphology of damages.

- Prevention / mitigation : dealloying

- Cross section of silicon brass alloy C87500 pump impeller exhibiting de-zincification in fire water line.

Damage Mechanism: Graphitic Corrosion

- De-aluminfication , decarburization, de-cobaltification, de-nickelification.

- Preventive measures: use alloy not susceptible to grain boundary depletion.

- What's graphitic corrosion?

-Affected materials by graphitic  corrosion .

- Affected units/equipment by graphitic corrosion

- Appearance / Morphology of damage.

- Inspection & monitoring: Why Acoustic technique (loss of metallic sound)

- Prevention & mitigation of graphitic corrosion.

- Gray iron pipe that failed due to graphitization.

- Characteristics of graphitization

- type of cast irons.

- Gray iron vs nodular iron

- graphite  corrosion of gray cast iron .

- Why nodular cast iron is better than gray cast iron from graphitic corrosion point of view?

- Case Study: Thermal fatigue of cast iron causing graphitization.     

Damage Mechanism: Microbiologically Influenced Corrosion (A type of EASCC)

Why it is called Microbiologically Influenced Corrosion (MIC): Bacteria are not causing the corrosion directly  but are creating the environment which causes the corrosion of metal.

-Thermodynamics of Corrosion

- 3 bad actor of degradation of metals & alloys.

- Importance of MIC control & prevention

- Risk of MIC : BP2006 -trans-Alaskan pipeline spills & 2015 NG leak in USA due to MIC

- What's MIC & MID.?

- What are SRB(Sulphate reducing bacteria)  & IRB (Iron reducing bacteria)/IOB (Iron Oxidizing Bacteria), How they can expedite the MIC corrosion?

- Electrochemical wet corrosion : How IRB expedite the MIC corrosion by SRB?

-What is Clostridia and how it can cause the corrosion (HIC) without SRB ?

- How clostridia causes the health problem?

- Series & Parallel Corrosion Reactions.

- Why in parallel corrosion reactions , corrosion is difficult to control ?

- Parallel corrosion reactions by aerobic & anaerobic bacteria in pipeline.

- Corrosion Prevention & Control .

- Types of Micro-organisms :

. Aerobic & Anaerobic bacteria

. Planktonic bacteria

. Sessile bacteria 

. Biofilms

- 5 steps: Microbiologically Influenced Corrosion.

- MIC in Fire water lines : What causes MIC corrosion.

- MIC at the root of weld in SS 316 due to root weld  undercut.

- How to identify MIC corrosion on the bottom of steel tank.

- MIC corrosion in piping .

. What's red rust

. Why MIC is predominant on thread area in waterline.

- MIC mechanism : exhibiting , how SRB & IRB together expedite corrosion?

- Combined effect of SRB & IRB in MIC fire water line.

- Parameters that influence microbiological corrosion

- Mechanism of MIC corrosion in Offshore structure.

= Tubercle : Biological & Chemical reactions outside & inside the tubercle.

- MIC : Biological effects causing corrosion of steel.

- MIC drivers : Differential oxygen concentration inside and outside the mound.

- How the progress of tubercle related with the depth of corrosion.

- How presence of chlorides in water catalyse the MIC corrosion.

- How biofouling expedite the corrosion?

- Metal deterioration by metabolic activity by IRB & SRB & mitigating measures.

Case Study : MIC in impiggable section of high pressure water pipeline.

- How chlorides & SRB causes the pinhole type pitting corrosion in SS 316.

- MIC in heat exchanger tube,

- Major factors causing MIC

- External corrosion on heat exchanger tube.

- Equipment piping affected by MIC.

- How to monitor MIC?

- Prevention & Control of MIC.

Case study : SCC & MIC of a riser control line SS 316 fitting in offshore.

Case Study :  MIC pitting corrosion in 410 martensitic stainless steel valve body.

Case Study : MIC in 3275 super duplex stainless steel .hydraulic lines.

Case study : MIC failure of type 316L sea water pipeline.

- Tackling the MIC issues : require to change in the mindset

. MIC means SRB- not true

. Higher the SRB counting -higher the MIC : not true

. If there is no sulphate then there is no SRB : Not true

- Culturing is the best option to confirm MIC: not true

- Practical experience sharing

. what increases the risk of MIC

. Abbreviations 

EASCC: Damage Mechanism :High Temperature Hydrogen Attack (HTHA)

_ Difference in HTHA & HE.

- What's HTHA?

- Affected Materials by HTHA. (Why resistance to HTHA increases by increasing Cr & MO alloying addition in steels?

- Affected units in refineries, fertilizers & power plants by HTHA

- Factors affecting HTHA.

- Why damages during incubation period can't be detected by NDT?

- 4 stages of damage in HTHA.

- What care shall be taken in selecting the base metal for corrosion resistant cladded vessels?

- How to reduce the risk of HTHA in cold wall designed equipment ?

- Modified nelson curve in API 941.

- Why the various changes occur in nelson curve diagram?

-  Reliability of design based on nelson curve for equipment processing hot hydrogen or mixture of hydrogen & hydrocarbon.

- API RP 941 , its application & limitations.

- Inspection & Monitoring HTHA damage

- Impact of PWHT on resistance to HTHA

- API 580/581 on HTHA

Case Study : NHT exchanger shell failure in Tesoro refinery due to HTHA

. Chemical Safety board findings on NHT exchanger shell failure in Tesoro refinery.

. Why HTHA occurred in NHT exchanger?

. What went wrong : poor operation & procedure.

. What went wrong : poor safety culture

. What went wrong ? Use of carbon steel in place of Cr-Mo steel

. Q & A

. Flange leakages & complacency.

. NHT heat exchanger flange leakage issues and actions.

. Q & A

. Why can't a gasket be reused?

. Conclusion on NHT exchanger shell failure .

- Interaction of CS with hydrogen causing HTHA.

- Why HTHA damages are irreversible?

- Equipment & components susceptible to HTHA.

- Nelson Curve.

- HTHA prevention & Control.

- Avoid HTHA failure in existing equipment,

- Conclusion: Inherently safer design & material are  only way to avoid HTHA since its proactive detection is difficult.

- What's the difference in HTHA & HIC ?

- Why HTHA , is a concern of design & operation?

- Why proactive detection of HTHA is difficult?

- Why RTJ gasket in hydrogen in SS 321 line caused the tragedy on overtightening.?

- Further discussion on NHT exchanger shell failure.

- Why HTHA occurred in HTHA?

- Catastrophic heat exchanger failure: Root cause analysis

- note to designers:

- How stainless steel make the material immune to HTHA?

-How HTHA cracking is caused by dissolve hydrogen and prevented by PWHT in CS / LAS?

- Why HTHA cracking is intergranular and follows lines of high localised stress/hardness.?

- Why hydrogen attack can occur at CS & LAS welds in hydrogen service at temperature > 260 deg. C.

- Why API RP 941 modified?

- HTHA life assessment methodology  : HTHA screening & HTHA combined Damage method.

- Reducing the Risk of Failures : Study of Ammonia plant with failure case study.

. What happened in causing failure in hydrogen headers suffered with multiple failure.

. HTHA damage assessment & mitigation

. Material upgradation plan

. HTHA prevention & control : Materials control & procedure practices

. HTHA prevention- Inspection Practices

- Thank you   

Damage Mechanism: Cooling Water Corrosion

- Uniform & Localized Corrosion

- Why Corrosion Allowance plays no significant role in avoiding the failure on a/c of severe  localized corrosion.?

-  What's the hidden cause of catastrophes

* Dependency on corrosion allowance instead using inherently safer design & robust metallurgy.

* Lack of awareness of localized corrosion dynamics.

- Localized under deposit / crevice corrosion is several times faster than uniform corrosion.

- Why it is difficult to predict the real corrosion rate in localized corrosion?

- Water Corrosion in CS : Pitting, Under Deposit Corrosion, Erosion Corrosion, Tuberculation, Microbiologically Influenced Corrosion & Galvanic Corrosion.

- Why control on deposits, velocity, SRB & IRB counts and dissolved  Oxygen required to prevent water corrosion?

- Drivers of Corrosion: Oxidizing factors causing corrosion & stimulating factor expediting factors.

- How making the oxide film by oxygen & subsequently breaking the film by chlorides expedite corrosion?

- Selection of metallurgy for cooling water service.

- Various design, operating & maintenance factors affect corrosion in cooling water.

- How localized corrosion gives surprizes resulting catastrophes.

- Under Deposit Corrosion

* Under Deposit Corrosion (UDC) -one of the main cause of localized corrosion.

* Factors expediting UDC.

- Microbiologically Influenced Corrosion : Biological effects causing corrosion in offshore structures.

- Erosion - Corrosion : Cyclic corrosion if the velocity is higher than critical velocity for a specific material in a specific environment.

- Why erosion corrosion does not affect stainless steels?

- Galvanic Corrosion

- Tuberculation

- Cooling water corrosion in refineries

* Cooling water sources

* Tube Metallurgy of coolers in Cooling water service.

* Corrosion mechanisms in cooling water CS exchanger

* Effect of water velocity in cooling water exchanger corrosion: Impact of high & low velocity of cooling water.

* Corrosion of brass tube in cooling water cooler.

- Al brass is cost effective proposal in cooling water service.

- Titanium Gr.2/ Gr4. are excellent choice in sea water cooled exchangers.

- Cupro- Nickel exchanger  Metallurgy for CW service.

-  Aluminum Brass ferrules  with Cupronickel tube metallurgy in cooling water cooled exchanger

- Internal Coating of tubes in cooling water exchangers

- How to control corrosion in sea water cooled Titanium  Gr.2 & Gr.4 cooler offline & online.?

- Why Titanium tube cooler in sea water can't be used above 135 deg. C .

- Why duplex / Super duplex stainless in refineries and Titanium gr.2 / gr.4 tube coolers on offshore O&G fail?

- Effect of dissolved salts on cooling water corrosion in coolers & piping.

- Why 300 series austenitic stainless steels have limited use in cooling water service?

- What's the role of corrosion inhibitors in controlling cooling water corrosion?

- Types of corrosion in cooling water.

- What's the impact of oxygen on cooling water corrosion through make up water.

- Oxygen impact on corrosion during idling & shutdown of cooling water coolers & piping network.

- What's the way forward for selection of tube metallurgy in highly corrosive cooling water ? 

Damage Mechanism : Creep & Creep Cracking

Introduction

- What's Creep?

- Why Creep Can Cause Both Bulging and /or  Cracking.

- Effect of Creep on Ductile to Brittle Transition Temperature (DBTT)

- How creep is affected by operating temperature, Ageing, Operating Pressure (Throughput) & Thermal Shocks.

- Four stages of Creep .

- Creep Design Life Of Component.

- How Creep Damages affected by Noncompliance of Integrity Operating Window?

- How creep damages affects the remaining life of equipment?

- Creep Degradation Damage Mechanism through Grain boundaries Creep micro voids & microcracks  formation.

- Creep Damages as a function of PWHT, operating temperature & Ageing.

- Effect of increasing throughput (loading) on Creep life .

- Effect of increasing throughput on the design life.

- Creep Degradation through Spheroidization (  Degree of creep degradation as per ISPES) in Carbon & low alloy steel.

- Creep Degradation through Micro voids/ micro cracks formation in Cr-Mo alloys /special alloys .

- Expended life fraction & Creep Damage  Correlation as per Neubauer's Classification.

- Why in hard high strength  material , creep cracking predominates the bulging.

- In what condition creep cracking occur in thin lip or thick lip fish mouth opening  mode?

- In-situ Metallography : best tool for analysing in-service creep damages . What are the limitations?

- For creep degradation monitoring , one shall use both optical & scanning electron microscopy (SEM) .

- Various monitoring methods for monitoring the initial to advanced stage creep damages.

Creep Damages in P91 Material

- Introduction

- What's type IV cracking in P91 weld HAZ?

- Mechanism of type IV cracking degradation .   

- Type IV cracking : Most serious problems of power plants.

- How can you avoid cavities in HAZ of P91 Weldment after PWHT.?

- Evolution of fine Grain HAZ  (FGHAZ) microstructure in as welded  condition , after PWHT and after creep test.

- Why to prefer induction heating for PWHT in P91/p92  weld joints and must for thicker components?

- Why to avoid fabricated Tee, Lateral Connections & Miters in P91/92 materials?

- P91: major step during fabrication (material selection final assembly)

- P91 : Metallurgical pitfalls.

- Why multiple weld repair (more than once) not permitted in P91 weldments?

Damage:  Mechanisms: Ammonia Cracking , High Temperature Corrosion (Oxidation Corrosion, High Temperature Flue Gas Sulfidation   Corrosion, Fuel Ash Corrosion , High Temperature Sulfidic Corrosion, High Temperature Sulfidic Corrosion in presence of Hydrogen, High Temperature Naphthenic Acid Corrosion.

Damage Mechanism: Ammonia Cracking

- What's Ammonia Cracking.

- Types of Ammonia Cracking.

- Sources of Ammonia , Occurrence of Ammonia cracking in equipment / units in refineries.

- Prevention & mitigation of ammonia cracking.

Damage Mechanism : High Temperature Corrosion (without water)

- Dry Corrosion without water as electrolyte.

- Introduction to High temperatures Corrosion.

- Why high temperatures corrosion is more insidious than low temperature corrosion in hydrocarbon industries.?

- Classification of high temperature corrosion.

Damage Mechanism: Oxidation : Low temperature (wet) & High temperature (Dry) Oxidation Corrosion

- Why metal corrode ?

- Why Oxidation corrosion is a threat to life & environment ?

- Wet electrochemical Oxidation Corrosion mechanism.

- Dry  electrochemical oxidation corrosion mechanism.

- High temperature flue gas corrosion by oxygen  (Air) & H2S.

- Why sulfidation corrosion in nickel base alloy is dangerous than oxidation by air.

- Why Cr-Mo resist the sulfidation corrosion while nickel base alloy suffered more corrosion at elevated temperature.

- How Aluminium addition in austenitic stainless steels and nickel alloys increase their corrosion resistance in flue gas environment bearing H2S at high temperature.

- Scaling resistance temperature for different alloys used in refineries & petrochemicals.

- Factors affecting high temperature oxidation.

- Affected units / areas in refinery & petrochemicals by oxidation.

- Prevention / mitigation of oxidation damages.

- Inspection & monitoring of oxidation damages.

Damage Mechanism : Fuel Ash Corrosion

- Introduction to fuel ash corrosion.

- What's low temperatures & high temperatures fuel ash corrosion?

- Fly ash erosion corrosion sulfur dew point corrosion.

- Fuel Ash Corrosion (Catastrophic Oxidation )

- Q & A (Fuel ash corrosion

- Mechanism of fuel ash corrosion

- Factors affecting fuel ash corrosion.

- Fuel Gas Corrosion Prevention & Control

Damage Mechanism : Sulphidic Corrosion : Below dew point, above dew point, & above 230 deg. C.

- What's High Temperature Sulphidic Corrosion (H2S gas  attack on metal  above 230 deg. C.)?

- High temperatures sulfidic corrosion without the presence of hydrogen.

- High Temperature Sulphidic Corrosion  & McConomy  curves (Corrosion rate Vs Temperature for CS, Cr-Mo A stainless steels alloys.

- Corrosivity of sulphur compound in crude oil.

- Mitigating high temperature sulphidation corrosion.

- Role of integrity operating window & Cr-Mo alloy in controlling high temperature corrosion.

Damage Mechanism : Sulfidic Corrosion in presence of hydrogen

- Why chrome Molybdenum alloys don't control high temperatures corrosion in presence of hydrogen?.

- Why severity of sulfidic corrosion increases in presence of hydrogen?

- API -RP 941 -2016 for HTHA

- Modified Cooper Gorman Curves for high sulfidic corrosion rate  in presence of hydrogen.

- Modified Cooper Gorman curves for CS, C-1/2 MO, Cr-Mo alloys and Austenitic stainless steel.

- Why austenitic stainless steel is resistant to high temperature sulfidic corrosion in presence of hydrogen?

Damage Mechanism : Naphthenic Acid Corrosion (at Low temperature & Elevated temperature)

-Why naphthenic acid corrosion is severe at high temperature.?

- Low temperature & high temperature naphthenic acid corrosion.

- Understanding the mechanism of high temperature naphthenic acid corrosion.

- Units and equipment affected by naphthenic acid corrosion .

- Why Naphtheinc acid is more predominant in crude distillation and occurs less in FCCU, Coker & Hydrpfinishing & Hydrocracker units.

- Temperature range & corrosivity of naphthenic acid corrosion.

- Naphthenic acid corrosion reaction with steels.

- Unit and equipment affected by naphthenic acid corrosion

- Corrosivity of naphthenic acid corrosion.

- How to control & prevent Naphthenic acid corrosion.?

- Characterising naphthenic acid.

- Summary of naphthenic acid corrosion & its mitigation

Damage Mechanisms: Creep & Creep Cracking

- Introduction : Creep

- What's Creep & Creep Cracking

- Creep Curve : stages of creep

- Creep , Design life, RLA & Life Extension of Ageing Assets

- Metallurgical Changes in Microstructure

- Toughness as a function of Temperatures & Ageing

- Effect of loading (throughput ) on Creep Damages

- ISPES: Microstructure evaluation of Ferritic Steel (Degree of Spheroidization)

- Micro-voids  formation on Brain Boundaries (Neubauer's Classification

- Creep Voids formation damages Mechanism in Cr-Mo alloys

- Creep voids morphologies & linking and micro cracks formation( as per  Neubauer's Classification.

- Expended life fraction & creep damage correlation.

- Thin lip / thick life creep cracking

- Insitu- Metallography : best tool to predict the creep damages.

- In Creep what decide the  thick lip or  thin lip type failure.

- In-situ Metallography & its role in analysing creep damages.

- Why SEM /TEM is required for estimating the creep damages along with  optical metallography.?

- Lab methods for estimating creep damages.

- Creep Damages in P91

- Microstructure development in HAZ in P91 causing type IV cracking.

- Creep Damages during creep test

- Type IV cracking in P91 : Damage in Power Plant

- How to avoid cavity in HAZ of P91?

A Case Study on RCA of premature failure of HP 40 modified Hydrogen Reformer tube .

Introduction

- What're HP modified Alloys?

- How HP modified permit lesser thickness & its advantages?

- Mechanism of high temperature creep resistance in micro- alloyed HP 40 modified tube

- Role of Secondary carbide in Micro-alloyed HP40

- Impact of Niobium & titanium on secondary carbide morphology.

- Advantage of HP40 modified alloys over HP40 & HK40.

- Tube wall thickness calculation through Larson Miller Parameter .

- Tube skin temperature , creep resistant alloys & design life.

- Steam methane reformer schematic process flow diagram.

- Damage mechanisms in reformer tube

* Overheating causing creep  &  creep cracking damages.

* Thermal Cycling : Interruptions & No. of shutdowns

* Tube bending / Bowing

* Thermal Shocks

* Stress Corrosion Cracking : on top portion of tube due to CSCC

Root Cause Analysis of Premature failure of tube:

Observations:

* Visual examination

* Local Bulging: Loss of Strength

* Sample from failed Tubes : A, B, C & ( D1 & D2 - from failed location)

* Chemical Composition of failed tube

* Minimum sound wall thickness: reduction at failed location

* Metallography Examination

* Metallurgical Degradation in microstructures : noticed on C & D1 & D2.

* Damages were localized confined to lower part of tube on failed spot.

* Calculated temperature of exposure during failure : 1049 deg. C

Root Cause Analysis : Discussion & Conclusion: Overheating

* Probable causes of overheating

What are the options if single tube leaking

* Pigtail nipping

Way forward to sustain in ageing reformer heater:

- How  Metallography (Nondestructive - insitu & Destructive in lab ) along with LP & RT can provide the solutions to poor reliability in ageing heater?

- why Creep & Metallurgical degradation detection in reformer tube through metallography & LPT.& RT is most reliable?

- Factors affecting tube wall skin temperature .

- Why measurement of skin temperature in lower part of the heater is not possible by any techniques including thermography?

- Why periodic health monitoring of reformer tubes required to avoid its catastrophic failure?

- Why reformer tubes are cast structure rather than wrought.?

- History of materials of reformer tubes.

- Why metallurgy upgrades of reformer tube to micro-alloyed HP40 modified.

- Effect of titanium & Yttrium micro alloying additions.

-Why  Metallography indicators are better & most reliable indicators for FFP?

- Five level of creep damages.

-  Creep cracks in weld.

- Creep cracks are governed by temperature & hoop stresses.

In- service  microstructural evolutions in in reformer tube

* HP40 VS HP40-Nb

* Why coarser grains material are preferred for creep resistance?

* Modified HP40 - Nb :  Virgin VS Ageing tube

* Modified HP40: Nb & HP 40: Nb-Ti  in ageing condition

* Why titanium addition give better life than Niobium stabilized?

* Whether oxides can provide better stability than carbides?

* Outlet pigtails & Manifold metallurgy requirement.

* Why Inco alloy 800 for outlet pigtail & manifold?

* Factors affecting tube skin temperature.

Damage assessment of reformer tubes :

* why analytical NDT methods are not reliable?

* Why combination methods of NDT & destructive test for better reliability.

Qualitative tests : 5 levels of creep damages for RLA as per Neubauer's approach.

Damage mechanisms in hydrogen reformer

Radiation tube : Micro-alloyed modified HP 40 -Nb-Ti

- Creep

- Creep in welds

- Creep buckling & bowing

- Carburization (metal dusting)

Outlet Pigtail : Inco alloy : 800

* Creep

* Carburization

* Low cycle high temperature creep fatigue

Outlet Header (Inco alloy )

* Creep

* Low cycle high temperature creep fatigue

RCA : Discussion & Conclusion     

A Case Study on RCA of premature failure of HP 40 modified Hydrogen Reformer tube .

Introduction

- What're HP modified Alloys?

- How HP modified permit lesser thickness & its advantages?

- Mechanism of high temperature creep resistance in micro- alloyed HP 40 modified tube

- Role of Secondary carbide in Micro-alloyed HP40

- Impact of Niobium & titanium on secondary carbide morphology.

- Advantage of HP40 modified alloys over HP40 & HK40.

- Tube wall thickness calculation through Larson Miller Parameter .

- Tube skin temperature , creep resistant alloys & design life.

- Steam methane reformer schematic process flow diagram.

- Damage mechanisms in reformer tube

* Overheating causing creep  &  creep cracking damages.

* Thermal Cycling : Interruptions & No. of shutdowns

* Tube bending / Bowing

* Thermal Shocks

* Stress Corrosion Cracking : on top portion of tube due to CSCC

Root Cause Analysis of Premature failure of tube:

Observations:

* Visual examination

* Local Bulging: Loss of Strength

* Sample from failed Tubes : A, B, C & ( D1 & D2 - from failed location)

* Chemical Composition of failed tube

* Minimum sound wall thickness: reduction at failed location

* Metallography Examination

* Metallurgical Degradation in microstructures : noticed on C & D1 & D2.

* Damages were localized confined to lower part of tube on failed spot.

* Calculated temperature of exposure during failure : 1049 deg. C

Root Cause Analysis : Discussion & Conclusion: Overheating

* Probable causes of overheating

What are the options if single tube leaking

* Pigtail nipping

Way forward to sustain in ageing reformer heater:

- How  Metallography (Nondestructive - insitu & Destructive in lab ) along with LP & RT can provide the solutions to poor reliability in ageing heater?

- why Creep & Metallurgical degradation detection in reformer tube through metallography & LPT.& RT is most reliable?

- Factors affecting tube wall skin temperature .

- Why measurement of skin temperature in lower part of the heater is not possible by any techniques including thermography?

- Why periodic health monitoring of reformer tubes required to avoid its catastrophic failure?

- Why reformer tubes are cast structure rather than wrought.?

- History of materials of reformer tubes.

- Why metallurgy upgrades of reformer tube to micro-alloyed HP40 modified.

- Effect of titanium & Yttrium micro alloying additions.

-Why  Metallography indicators are better & most reliable indicators for FFP?

- Five level of creep damages.

-  Creep cracks in weld.

- Creep cracks are governed by temperature & hoop stresses.

In- service  microstructural evolutions in in reformer tube

* HP40 VS HP40-Nb

* Why coarser grains material are preferred for creep resistance?

* Modified HP40 - Nb :  Virgin VS Ageing tube

* Modified HP40: Nb & HP 40: Nb-Ti  in ageing condition

* Why titanium addition give better life than Niobium stabilized?

* Whether oxides can provide better stability than carbides?

* Outlet pigtails & Manifold metallurgy requirement.

* Why Inco alloy 800 for outlet pigtail & manifold?

* Factors affecting tube skin temperature.

Damage assessment of reformer tubes :

* why analytical NDT methods are not reliable?

* Why combination methods of NDT & destructive test for better reliability.

Qualitative tests : 5 levels of creep damages for RLA as per Neubauer's approach.

Damage mechanisms in hydrogen reformer

Radiation tube : Micro-alloyed modified HP 40 -Nb-Ti

- Creep

- Creep in welds

- Creep buckling & bowing

- Carburization (metal dusting)

Outlet Pigtail : Inco alloy : 800

* Creep

* Carburization

* Low cycle high temperature creep fatigue

Outlet Header (Inco alloy )

* Creep

* Low cycle high temperature creep fatigue

RCA : Discussion & Conclusion 

Corrosion & Metallurgical Degradation Damage Mechanisms & its control through design , Metallurgy Selection and Integrity operating window in hydrogen reformers.

- Introduction : Why reformer tubes degradation is the burning problem?

- Why managing the integrity of reformer tubes is difficult and ignored?

- Components of reformer heater & process flow diagram.

- Importance of reformer in refinery .

- Reformer tube design.

- Reformer tube material degradation in  HP40 modified alloy : Evolution of Primary carbides & Secondary carbides.

- Operator's requirement :

How to maximize tube life ?

How to avoid failures by IOW?

How to meet exigencies if tube fail ?

- Historical development in reformer tube metallurgy.

- Comparison of various reformer tube metallurgies.

- Manufacturing of reformer tubes.

- Microstructural changes in virgin & ageing tubes.

- Creep Damage mechanism of reformer tube.

- Why creep voids & creep microcracks in reformer tube start from mid wall?

- 3 stages of creep cracks propagation.

- Most common damage mechanisms affecting the integrity of reformer tubes.

- Why creep cracks are generally longitudinal in reformer tubes?

- Why creep cracks are radial along the height.?

- Why creep crack in welds  are circumferential? 

- Inspection & monitoring of hydrogen reformer tubes.

- NDT & Destructive test.

- Why managing the integrity in ageing reformer tubes need combination of NDT & destructive testing.?

- NDT techniques limitation & capabilities.

- Why Tube Diameter measurement for estimating is not reliable?

- Why Ultrasonic attenuation method is  not reliable?

- Categories of creep damages in reformer tubes

- Application of eddy current & its limitations in monitoring the creep damages.

- Application of metallurgical test (Insitu & Lab metallography both optical & SEM) for ensuring the integrity of reformer tubes.

- Why accelerated creep test are not reliable?

- LOTIS: its merits & demerits.

- Conclusion on NDT techniques and way forward to health monitoring of reformer heater tubes.

- Case study on RCA of premature failure of reformer heater tube  in steam methane reformer in fertilizer plant.

-Advantages of HP40 modified alloys over HP40 & HK40.

- Tube skin temperature, creep resistant alloys & design life.

- Steam methane reformer PFD.

- Damage Mechanisms in reformer tube

* Over heating

* Operating condition & Condition of catalyst.

- Effect of over heating on the life of reformer tubes.

- Thermal cycling

- Tube Bending/ bowing- Thermal Shocks

- Stress Corrosion cracking

- What are the option if single tube leaking?

- What's the way forward to sustain with ageing reformer heater?