Hydrogen Sulfide Cracking.pdf

CORROSION ENGINEERING SECTION

Large-Scale Wet Hydrogen Sulfide CrackingPerformance: Evaluation of Metallurgical,Mechanical, and Welding Variables

M.S. Cayard and R.D. Kane*

ABSTRACT

The serviceability of welded steel equipment in wet hydrogensulfide (H2S) service was studied. Large-scale exposure testswere conducted using a steel pressure vessel containingvarious welded test plates. Effects of variables includingsteel base plate composition, metallurgical processing,welding, applied stress, and orientation were examined.Particular attention was given to large-scale behavior vsbehavior for small-scale laboratory test specimens under anapplied tensile stress; performance of conventional carbonsteels (CS) vs advanced CS designed for enhanced resis-tance to hydrogen-induced cracking (HIC); and theinterrelationship of stress, welding, and plate orientation onsusceptibility to wet H2S cracking. Results provided insighton the role of steel quality and microstructure in susceptibil-ity of CS to HIC, stress-oriented hydrogen-induced cracking(SOHIC), and sulfide stress cracking (SSC).

KEY WORDS: blistering, carbon steel, hydrogen-inducedcracking, hydrogen sulfide, microstructure, plate orientation,stress-oriented hydrogen-induced cracking, sulfide stresscracking, welding

INTRODUCTION

Refinery equipment in wet hydrogen sulfide (H2S)service is characterized by exposure to aqueous pro-cess environments containing H2S. Systematicinspection programs conducted by petroleum compa-nies have shown wet H2S refinery processes can

CORROSION–Vol. 53, No. 3

Submitted for publication February 1995; in revised form, June1996.

* CLI International, Inc., 14503 Bammel-N. Houston, Suite 300,Houston, TX, 77014.

0010-9312/97/00005© 1997, NACE I

provide conditions for hydrogen charging of steeland widespread cracking of carbon steel (CS) equip-ment.1-2 Results of operating experience surveys andtechnical investigations have described situationswhere CS equipment exposed to wet H2S environ-ments may be susceptible to cracking viahydrogen-induced cracking (HIC), stress-orientedhydrogen-induced cracking (SOHIC) and/or sulfidestress cracking (SSC).3-6 In some cases, cracking hasbeen found to be minimal, resulting in no significanteffect on equipment integrity or serviceability. Inother cases, widespread cracking has initiatedand/or cracks have propagated to a degree where theintegrity or serviceability of equipment was impacted.

Prior to the initiation of the present study, theMaterials Properties Council, Inc., (MPC) organized aresearch program on wet H2S cracking of steels spon-sored by more than 20 major petroleum refiningcompanies, steel manufacturers, and equipmentfabricators. This program was aimed at developmentof screening procedures for evaluation of steels; de-termination of the influence of metallurgicalprocessing and welding variables; and better under-standing of the roles of stress, environmentcomposition, and temperature. Data were collectedusing standard small-scale laboratory tests such asthe NACE Standard TM0177 tensile test,7 the NACEStandard TM0284 HIC test8 and the double-beamtest developed during the MPC program.9 The datahas provided valuable fundamental information thathas improved awareness of causes of wet H2S crack-ing and of potential solutions in terms of newconstruction, repair, and remediation of existing

2277/$5.00+$0.50/0nternational


FIGURE 1. Schematic of the large-scale wet H2S test vessel.

equipment. However, there was a desire to validatefindings and conclusions of that program and to ex-plore the complex interrelations of variables that canaffect actual behavior of large-scale equipment usedin wet H2S refinery service.

The present study, organized by the RefiningDepartment of the American Petroleum Institute (API)and MPC, was conducted to provide information re-garding serviceability of welded steel equipment inwet H2S service. Situations exist in refinery opera-tions where it is necessary to assess the fitness ofequipment for continued service vs repair or replace-ment because of wet H2S damage. Such anassessment requires information regarding the na-ture of wet H2S crack propagation and operationalconditions that may affect wet H2S damage and theability to use nondestructive methods to assess thedegree of cracking in the operating equipment.

The present study addressed these issuesthrough a series of large-scale vessel tests designedto extrapolate small-scale tests to actual service con-ditions. A larger, more comprehensive researchreport also has been prepared.10-11

EXPERIMENTAL

Test Vessel and Window SpecimensThe large-scale exposure tests were conducted

with a fabricated steel vessel 36 in. (90 cm) in nomi-nal outer diameter and 6 ft (1.8 m) long that wasdesigned and fabricated in accordance with ASMEBoiler and Pressure Vessel Code, Section VIII, Divi-sion 1 requirements.12 The test used a novelapproach involving test specimens or “windows” fab-ricated from steel plates, welds, fittings, andattachments using typical practices used in con-struction and maintenance of refinery pressurevessels. These windows were welded into a vessel

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used to contain a pressurized wet H2S test media(Figure 1). With the exception of the test window, theentire inner-diameter (ID) surface of the vessel wascoated to protect the remainder of the vessel fromdamage and to maximize the ratio of solution volumeto surface area of the exposed steel.

Each window specimen measured ≈ 2 ft by 2 ft(0.6 m by 0.6 m) and typically contained a 2-ft (0.6-m)longitudinal weld and a 1-ft (0.3-m) girth or circum-ferential weld. The various test windows containedCharpy notches and low-heat input weld beads(< 10 kJ/in.) to assist in initiating cracking.

Materials Experiments were performed using the windows

comprised of conventional, low-sulfur conventional,“HIC-resistant,” and ultralow-sulfur advanced steels.All of the steels tested were tested previously in thesmall-scale laboratory test program (i.e., identicalheats). Basic attributes of each of these steels were:

Conventional Steels –– Conventional steels arecommercially produced steels either hot rolled ornormalized (e.g., ASTM A 516-70).13 They generallyhave moderate to high levels of impurities, particu-larly sulfur (i.e., ≥ 0.010 wt% sulfur). Also, theygenerally have high susceptibility to HIC in mosthydrogen-charging environments, even under moder-ate exposure conditions.

Low-Sulfur Conventional Steels — Low-sulfurconventional steels are commercially produced steelscontaining lower than normal levels of sulfur (i.e.,0.003 wt% to 0.010 wt%). They may exhibit improvedmechanical properties over conventional steels buttypically have not been processed specifically to ex-hibit high resistance to HIC. These steels still mayshow significantly high susceptibility to HIC, even inmoderate service environments.

HIC-Resistant Steels –– The term “HIC-resistant”is used by manufacturers and users to denote aconventional grade of steel (e.g., ASTM A 516-70)that has been processed metallurgically to enhanceits resistance to HIC. Such processing typically in-cludes reduction of sulfur to an ultralow level (i.e.,≤ 0.002 wt% sulfur), a normalizing heat treatment tomodify the hot-rolled microstructure, and possiblycalcium addition to produce sulfide shape control.These steels typically have improved resistance toHIC compared to conventional steels. However, theystill may show some degree of susceptibility to HICand SOHIC in severe wet H2S service conditions.

Ultralow-Sulfur Advanced Steels — Ultralow-sulfur advanced steels are those made by modernsteelmaking and processing techniques. Thesesteels typically have ultralow levels of sulfur (e.g.,≤ 0.002 wt% sulfur) and low carbon equivalents com-pared to conventional steels of comparable tensilestrengths (i.e., ASTM A 516-70). Steels in this cat-egory currently are made to ASTM A 841 by

CORROSION–MARCH 1997


TABLE 1Environmental Staging

H2S Acetic CurrentNo. Conc. Solution Acid HCl Density

Stage Days (ppm) pH (wt%) (wt%) ( µA/cm 2)

1(A) 5 325 4.4 – – –2(A) 6 2,100 4.2 – – –3 1 2,100 4.2 0.05 – –4(A) 5 2,100 4.1 0.50 – –5(A) 7 2,100 4.2 0.50 – 556 3 2,100 4.2 0.50 – 1457(A) 6 2,100 2.9 0.50 0.02 1458(A,B) 11 2,100 3.0 0.50 – 145

(A) An automated ultrasonic testing (AUT) scan was conducted at theconclusion of the stage. Pressure was maintained at 500 psig to550 psig throughout the first seven stages.

(B) Solution was removed and the exposed surface of the window wascleaned. A new batch of NACE Standard TM0177 solution wasadded immediately. Pressure varied from 500 psig to 850 psigduring Stage 8.

thermomechanically controlled processing (TMCP)and/or accelerated cooling techniques.14 Also, theyhave reduced carbon levels compared to conventionalsteels, resulting in ferritic/bainitic microstructureswith little or no microstructural banding. Thesesteels show almost complete resistance to HIC, butsome heats are subject to SOHIC under severe wetH2S service conditions.

ENVIRONMENTAL CONDITIONS

As with the previous small-scale laboratory testprogram, the test solution for the majority of thelarge-scale tests was the NACE Standard TM0177-90, Method A solution (0.5 wt% glacial acetic acid,5.0 wt% sodium chloride [NaCl] in distilled water).The solution was saturated with H2S and maintainedat a H2S concentration of ≈ 1,600 ppm to 2,100 ppmthroughout the test. No depletion in H2S concentra-tion was observed during the tests due to the highratio of solution volume to exposed steel surfacearea.

This environment was not typical of refining en-vironments, which tend to be alkaline. However,previous studies have shown that the TM0177 solu-tion produces similar levels of hydrogen charging andresultant damage as produced in alkaline solutions.15

In addition, the TM0177 solution is easier to handleexperimentally and is more stable.

For some tests, additional cathodic charging wasused to produce very severe hydrogen-charging con-ditions (i.e., two to three times the normal TM0177solution level). One test involved slowly increasingthe severity of the test environment in several stagesby deceasing the pH and increasing the H2S concen-tration. Details of the environment used in thisexperiment are summarized in Table 1.

All of the tests were conducted at room tempera-ture. Test duration ranged from < 4 days forconditions of rapid failure to 5 weeks for the stagedand prolonged experiments. The test pressure wasapplied hydrostatically. Operating pressures in therange of 0 psig to 850 psig (0 MPa to 5.9 MPa) wereexamined. The solution pH on all but one exposure(detailed in Table 1) ranged from 2.7 at the initiationof the test to 3.5 at test completion.

General TerminologyAs used in discussing the program results, the

following terms are defined as:Crack Length Ratio —␣ The crack length ratio

(CLR) provides a measure of the material’s resistanceto HIC as defined in NACE Standard TM0284-87.CLR is determined by summing the lengths of eachcrack array, dividing by the section width, and multi-plying by 100 to express it as a percentage.

Crack Thickness Ratio —␣ The crack thicknessratio (CTR) also provides a measure of the material’s


resistance to HIC as defined in NACE StandardTM0284-87. CTR is determined by summing thethicknesses of each crack array, dividing by the sec-tion thickness, and multiplying by 100 to express itas a percentage.

Longitudinal-Transverse (LT) Section —␣ A longitu-dinal-transverse (LT) section is a metallographicsection in which the perpendicular to the polishedface is parallel to the longitudinal or rolling direction.

Transverse-Longitudinal Section ␣ —␣ A transverse-longitudinal (TL) section is a metallographic sectionin which the perpendicular to the polished face isperpendicular to the longitudinal or rolling direction.

Banding Index ␣ —␣ The banding index (BI) repre-sents a quantitative measurement of a material’sdegree of microstructural banding or orientation. Thestereological procedures required are described inASTM E 1268.16

RESULTS

Large-Scale vs Small-Scale BehaviorIn general, observations of material behavior

were consistent with findings of the previous small-scale laboratory testing in the MPC Wet H2S ResearchProgram.17 Results of the present study validated theprevious wet H2S cracking test methods and showedtheir applicability to refinery wet H2S environments.

Cracking Resistance of Base MetalResults of the present study indicated the HIC-

resistant and ultralow-sulfur advanced steelsgenerally had fewer HIC indications than the conven-tional and low-sulfur conventional steels exposed tothe NACE Standard TM0177 solution environment atboth the standard TM0177 hydrogen-charging condi-tions and at very severe hydrogen-charging

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FIGURE 2. Comparison of base metal CLR values obtained for thevarious steels evaluated.

FIGURE 3. Comparison of base metal CTR values obtained for thevarious steels evaluated.

conditions (i.e., two to three times standard TM0177levels, as observed by automated ultrasonic testing[T-scan] and metallographic sectioning).

Based on the data obtained via metallographicsectioning, the base metal CLR was plotted as a func-tion of steel type, sulfur content, and BI. CLR servesas an indicator of the severity of in-plane crackingassociated with HIC. As shown in Figure 2, CLRdeceased with a corresponding decease in sulfur

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content and BI. While two data points were not avail-able to complete the spectrum, a strong correlationwas clear. The maximum CLR (83%) was observed inthe conventional A 516-70 steel possessing a sulfurcontent of 0.017 wt% and BI of 0.60. The minimumCLR (0%) was observed in the ultralow-sulfur TMCPsteel possessing a sulfur content of 0.001 wt% andBI of 0.20.

The severity of through-wall cracking was evalu-ated as a function of sulfur content and BI. CTRserves as an indicator of the severity of through-wallcracking associated with HIC. Figure 3 shows thebase metal CTR as a function of steel type, sulfurcontent, and BI. The maximum base metal CTR val-ues observed deceased with a corresponding decreasein sulfur content and BI. The maximum resistance tocracking was observed in the A841 TMCP steel with asulfur content of 0.001 wt% and BI of 0.20.

The above trends only represent the behavior ofthe base metal away from welds at stress levels rang-ing from 60% to 80% of the specified minimum yieldstrengths.

Additional factors that may control the depth ofin-plane and through-wall cracking in the base metalof steels exposed to wet H2S environments includethe differences in threshold hydrogen concentrationsto produce cracking in the various steels and thenatural hydrogen concentration gradient in the steelresulting from the ID exposure of the vessel to thewet H2S environment. The hydrogen concentration inthe steel is a maximum at the ID surface exposed tothe test solution resulting from the hydrogen charg-ing produced by the sulfide corrosion reaction. At theouter-diameter (OD) surface, the hydrogen concen-tration is zero because there is no barrier to theegress of hydrogen from the steel on this surface.

The depth to which base metal cracking canoccur in the steel is dependent upon the hydrogengradient through the wall of the vessel. Once thehydrogen concentration becomes less than thethreshold hydrogen concentration to produce crack-ing, the cracks will tend to arrest unless the drivingforge (i.e., stress or hydrogen concentration) is in-creased further. Results of this program showed thethreshold hydrogen concentration to produce basemetal cracking in the low-sulfur conventional, HIC-resistant, and ultralow sulfur advanced steels ishigher than for conventional steels. Therefore, thedepth of cracking is restricted to varying degrees. Therelationship is not simply linear but is complicatedby changes in cracking susceptibility through thethickness of the material caused by microstructuraldifferences such as centerline segregation or band-ing.

Cracking Resistance at WeldmentsThe behavior of the steels at areas of high re-

sidual tensile stress, such as at weldments or areas



FIGURE 4. Results of constant load tests under hydrogenationshowing time to failure as a function of sulfur content. (Reprinted bypermission: Met. Trans. A. 10A [1979]: p. 1,691).

FIGURE 5. Comparison of absolute through-wall cracking observedfor the various steels evaluated.

containing local stress concentrations, may in manysituations produce more severe cracking with respectto SOHIC. Figure 4, obtained from the literature,18

shows the effect of sulfur content on the time-to-failure of line pipe steels under various levels ofapplied tensile stress. It indicates the susceptibilityto through-wall cracking, as determined by time tofailure, increases with deceasing sulfur content, par-ticularly at higher applied stress levels. Therefore,the lower sulfur content, while deceasing susceptibil-ity to HIC, may under very severe environments andhigh applied or residual tensile stress produce anincreased susceptibility to SOHIC.

In these large-scale tests, exposure to verysevere hydrogen-charging conditions (i.e., two tothree times the standard TM0177 levels, did pro-duce substantial SOHIC adjacent to the welds inall materials, including the ultralow-sulfur ad-vanced steels. Figure 5 compares the through-wallcrack penetration observed at the standardTM0177 hydrogen-charging and very severe hydro-gen-charging conditions. All of the values representcracking along the longitudinal seam weld atlow-heat input weld bead locations, except theHIC-resistant steel in the standard TM0177 envi-ronment, which corresponded to the longitudinalweld only. At the standard TM0177 hydrogen-charging conditions, a decease in through-wallcrack penetration was observed with a decease insulfur content and decease in BI. The HIC-resistantand ultralow-sulfur advanced steels tested in thestandard TM0177 solution showed lower suscepti-bility to through-wall cracking by SOHIC thanconventional steels based on absolute crackdepths. SOHIC was produced to a maximum of 8%of the wall thickness in these steels. However,under the very severe conditions of hydrogencharging, no relationship was observed betweenthe sulfur content, BI, and through-wall crack pen-etration. Through-wall cracks were observed topenetrate ≈ 30% to 50% in the low-sulfur conven-tional, HIC-resistant, and TMCP steels.

These data suggested that deceased levels ofsulfur content and decreased microstructural band-ing in low-sulfur conventional, HIC-resistant, andTMCP steels reduce their susceptibility to HIC andSOHIC compared to conventional steels. However, invery severe hydrogen-charging environments, thesesame steels, irrespective of sulfur content or degreeof microstructural banding, may be just as suscep-tible to SOHIC at weldments as conventional steels.Therefore, to optimize cracking resistance in wet H2Srefinery equipment, it appears that issues related toall wet H2S cracking mechanisms (i.e., HIC, SOHIC,and SSC) should be addressed and the limitations ofthe specific CS identified. Alternative methods suchas the use of stainless steel-clad vessels may be moreappropriate for very severe environments.


Cracking Associated with Low-Heat Input WeldsThrough-thickness cracking resulting from

SOHIC was found to occur predominantly in theheat-affected zone (HAZ) of the base metal adjacentto the weld rather than in the bulk plate material.Where low-heat input welds (i.e., single pass weldsmade with heat input < 10 kJ/in.) were tested with-out post-weld heat treatment (PWHT), an increase insusceptibility to SOHIC was observed. Based on CTR

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values measured on the ID 1/3-section, the longitu-dinal fabrication weld, in combination with thelow-heat input weld, was ≈ 8 times more severe thanthat observed for the fabrication weld alone. Thisincrease was explained by two factors: the locallyhigh hardness that can produce a stress concentra-tor resulting from SSC and the locally high residualtensile stress that also can exist in the area of thelow-heat input weld.

Many instances of cracking were observed wherelow-heat input welding initiated cracks on the ID ofthe vessel as a result of SSC. However, the extent ofsubsequent crack propagation varied as a function ofsteel type. In conventional steels, SOHIC generallywas limited to a region within the HAZ of the basemetal adjacent to the weld. However, in the HIC-resistant A516-70 and A841 TMCP steels, crackgrowth extended beyond the HAZ.

Cracking of Hard Weld DepositIn one experiment, the test window was fabri-

cated using a procedure which produced a hard weldmetal deposit. Rockwell hardnesses were in the rangeof HRC 22 to 30. Complete through-wall crackingwas observed that was confined completely to theweld metal. Crack propagation by SSC was rapid atrelatively low levels of internal vessel pressure (i.e.,400 psig), and resulted in loss of pressure in the testvessel within 4 days. This was the only case in thepresent study where a complete through-wall crackwas obtained. Complete through-wall cracking wasnot observed in other tests even where substantialamounts of HIC and SOHIC (i.e., up to 60% of thewall thickness were noted) and high levels of internalvessel pressure (i.e., 850 psig) were combined withsevere hydrogen-charging conditions during exposure.

Relationship of Stress, Welding,and Plate Orientation

Metallographic evaluations in conventional steelsconducted on LT sections resulted in more severeSOHIC indications at weldments than for similarevaluations on TL sections. This effect appears to berelated to the orientation of the weld maximum ten-sile stress and rolling direction of the steel. When themaximum tensile stress direction was perpendicularto the welding direction and the plate rolling direc-tion, CTR values tended to be higher. Values of CTRwere consistently greater than those at welds wherethe welding direction was perpendicular to the platerolling direction and parallel to the direction of maxi-mum tensile stress, as was the case for the girthweld in the window specimen.

DISCUSSION

Results of this study indicated several funda-mental and important aspects of wet H2S cracking of

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CS. There are three distinct mechanisms of wet H2Scracking: HIC, SOHIC, and SSC. Based upon thisstudy, susceptibility to HIC in low-strength steelswas increased by an increase in sulfur content and/or microstructural banding. HIC was observed prima-rily in the base material and exhibited a higherin-plane as opposed to through-wall cracking compo-nent (i.e., CTR/CLR ratio is low).

In contrast, susceptibility to SOHIC in low-strength steels increased with a decrease in sulfurcontent. Hence, SOHIC may be more commonly ob-served in HIC-resistant and advanced steels. Oncesulfur was reduced, in-plane growth of HIC was lim-ited, which increased the tendency of crack growththrough-wall. With reduced sulfur content, micro-structural banding became an important variablesince the banding produced alternate sites for initia-tion. Increased microstructural banding or a higherbanding index reduced the distance required forthrough-thickness link-up between bands and led toan increased susceptibility to SOHIC. SOHIC wasobserved predominately in the HAZ region of the basemetal and was found to initiate at the tips of HICarrays or SSC in the HAZ region and/or stress con-centrations associated with weldments. Contrary toHIC, SOHIC produced a high CTR to CLR ratio.

SSC differs from HIC and SOHIC in that it isbrittle cracking produced by a form of hydrogenembrittlement under the combined action of tensilestress and aqueous corrosion in the presence of H2S.No direct relationship between SSC susceptibility,sulfur content, or microstructural banding was ob-served. SSC susceptibility was governed primarily bylocal hardness and/or microstructure. SSC wasfound to occur primarily in the HAZ regions ofweldments and in the weld deposit when certain con-ditions of hardness and microstructure were met.

CONCLUSIONS

❖ Observations of material behavior found using thelarge-scale test methodology were consistent withfindings of laboratory testing previously conductedusing small-scale specimens in the MPC Wet H2SResearch Program. Results of the present study vali-dated the wet H2S cracking test methods previouslydeveloped and showed their applicability to refinerywet H2S environments.❖ Susceptibility of the base metal to in-planecracking associated with HIC deceased with a corre-sponding decease in sulfur content and decease ofmicrostructural banding. This was observed at thestandard TM0177 hydrogen-charging and at verysevere hydrogen-charging conditions (i.e., two tothree times standard TM0177 levels).❖ Susceptibility of the base metal to through-wallcracking associated with HIC also deceased with acorresponding decease in sulfur content and decease



of microstructural banding. This was observed at thestandard TM0177 hydrogen-charging and at verysevere hydrogen-charging conditions (i.e., two tothree times standard TM0177 levels).❖ The threshold hydrogen concentration to producebase metal cracking in the low-sulfur conventional,HIC-resistant, and ultralow-sulfur advanced steels ishigher than for conventional steels.❖ The absolute through-wall crack penetration ob-served at weldments exposed to the standardTM0177 hydrogen-charging conditions deceased witha decease in sulfur content and decease in micro-structural banding. However, under very severehydrogen-charging conditions, the low-sulfur conven-tional, HIC-resistant, and TMCP steels exhibitedthrough-wall crack penetrations ranging from ≈ 30%to 50% irrespective of the sulfur content or degree ofmicrostructural banding. This indicates that thesesteels may be just as susceptible to SOHIC atweldments as conventional steels when exposed tosevere environments.❖ Low-heat input welds (i.e., single pass welds madewith heat input < 10 kJ/in.) applied adjacent to thelongitudinal welds were found toincrease the pres-ence of SOHIC significantly in the HAZ of theadjacent base metal.❖ Cracking initiating as SSC in localized hard zonesin weld HAZ on the exposed surface of conventionalsteels was found to propagate into the softer basemetal via SOHIC but only to the extent of the HAZ.Cracking initiating as SSC in localized hard zones inweld HAZ on the exposed surface of HIC-resistantand TMCP steels also was found to propagate viaSOHIC. However, in these steels, the cracks generallypropagated beyond the extent of the HAZ into theadjacent softer base metal.❖ When hard weld deposits (i.e., > 22 HRC) wereused in the test window fabrication, completethrough-wall failure occurred rapidly (< 4 days) viaSSC.❖ Maximum susceptibility to SOHIC at weldments inCS vessels was determined to occur when the direc-tion of maximum tensile stress was perpendicular tothe welding and plate rolling direction

ACKNOWLEDGMENTS

The authors acknowledge funding support of theMaterials Properties Council, Inc., and the Refining


Department of the American Petroleum Institute.DNV Industry, Inc., provided the nondestructiveevaluation services and data analysis, and ChicagoBridge and Iron assisted in fabrication of the wet H2Slarge-scale test vessel. The authors acknowledge thetechnical contributions of R.J. Horvath and M.Prager.

REFERENCES

1. W.A. Bonner, H.D. Burnham, “Air Injection for Prevention ofHydrogen Penetration of Steel,” 11th Ann. NACE Conference,Chicago, Illinois, March 1955 (Houston, TX: NACE, 1955).

2. R.D. Merrick, “Refinery Experiences with Cracking in Wet H2SEnvironments,” paper no. 190, CORROSION/87 (Houston, TX:NACE, 1987).

3. R. Kane, et al., “Review of-Hydrogen Induced Cracking of Steelsin Wet H2S Refinery Service,” Proc. Int. Conf. Interaction ofSteels with Hydrogen in Petroleum Industry Pressure VesselService (New York, NY: Materials Properties Council, Inc.,1989).

4. NACE Committee T-8-16, Survey of Wet H2S Refinery Experi-ence (Houston, TX: NACE International, in press).

5. R.D., Merrick, M.L. Bullen, “Prevention of Cracking in Wet H2SEnvironments,” CORROSION/89 (Houston, TX: NACE, 1989).

6. F. Perdieus, “Reinspection of Previously Cracked Vessels,” Proc.2nd Int. H2S Materials Conf. (Houston, TX: CLI International,Inc., 1992).

7. NACE Standard TM0177-90, “Laboratory Testing of Metals forResistance to Sulfide Stress Cracking in H2S Environments”(Houston, TX: NACE, 1990).

8. NACE Standard TM0284-87, “Evaluation of Pipeline Steels forResistance to Stepwise Cracking” (Houston, TX: NACE, 1987).

9. R.D. Kane, M.S. Cayard, “Test Procedures for the Evaluation ofResistance of Steels to Cracking in Wet H2S Environments,”paper no. 519, CORROSION/94 (Houston, TX: NACE, 1994).

10. “Research Report on Characterization and Monitoring of Crack-ing in Wet H2S Service,”, API Publication 939, October 1994(Washington, CD: American Petroleum Institute, 1994).

11. “Research Report on Characterization and Monitoring of Crack-ing in Wet H2S Service,” WRC Bulletin 396, November 1994(New York, NY: Welding Research Council, 1994).

12. ASME Boiler and Pressure Vessel Code, Section VIII, Division 1,“Rules for Construction of Pressure Vessels” (New York, NY:ASME, 1995).

13. ASTM A 516, “Pressure Vessel Plates, Carbon Steel, for Moder-ate- and Lower-Temperature Service” (Philadelphia, PA: ASTM,1995).

14. ASTM A 841, “Steel Plates for Pressure Vessels, Produced bythe Thermo-Mechanical Control Process (TMCP)” (Philadelphia,PA: ASTM, 1995).

15. R.D. Kane, D. Abayarathna, “Characterization of HydrogenCharging Severity in Simulated Wet H2S Refinery Environ-ments,” 2nd Int. Conf. Interaction of Steels with Hydrogen inPetroleum Industry Pressure Vessel and Pipeline Service (NewYork, NY: Materials Properties Council, Inc., 1994).

16. ASTM E 1268, “Assessing the Degree of Banding or Orientationof Microstructures” (Philadelphia, PA: ASTM, 1995).

17. R.D. Kane, M.S. Cayard, “Evaluation of Advanced Plate Steelsfor Resistance to HIC and SOHIC in Wet H2S Environments,”2nd Int. Conf. Interaction of Steels with Hydrogen in PetroleumIndustry Pressure Vessel and Pipeline Service (New York, NY:Materials Properties Council, Inc., 1994).

18. M. Iino, Metall. Trans 10A (1979): p. 1691-1697.

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Hydrogen Sulfide Cracking.pdf