1、Avoiding Environmental Cracking in Amine UnitsAPI RECOMMENDED PRACTICE 945THIRD EDITION, JUNE 2003REAFFIRMED, APRIL 2008Avoiding Environmental Cracking in Amine UnitsDownstream SegmentAPI RECOMMENDED PRACTICE 945THIRD EDITION, JUNE 2003REAFFIRMED, APRIL 2008SPECIAL NOTESAPI publications necessarily
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13、erican Petroleum InstituteFOREWORDAPI publications may be used by anyone desiring to do so. Every effort has been made bythe Institute to assure the accuracy and reliability of the data contained in them; however, theInstitute makes no representation, warranty, or guarantee in connection with this p
14、ublicationand hereby expressly disclaims any liability or responsibility for loss or damage resultingfrom its use or for the violation of any federal, state, or municipal regulation with which thispublication may conict.Suggested revisions are invited and should be submitted to the Director, Standar
15、dsDepartment, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005,standardsapi.org.iiiCONTENTSPage1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 REFERENCES . . . . . . . . . . . . . . . .
16、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 Referenced Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2 Referenced Codes and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、 . . . . 12.3 Other Codes and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.4 Selected Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 DEFINITIONS. . . . . . . . . . . . . . . . . . . . .
18、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.1 Amine Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19、 . . . . . . . . . . 24.2 Problems in Amine Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 GUIDELINES FOR CONSTRUCTION MATERIALS AND FABRICATION OF NEW EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、. . . . . 45.1 Construction Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.2 Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 INSPECTION AND REPAIR OF EXISTING EQUIPM
21、ENT . . . . . . . . . . . . . . . . . . . 76.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76.2 Inspection Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76.3 Eq
22、uipment and Piping that Should be Inspected . . . . . . . . . . . . . . . . . . . . . . . . . . 86.4 Examination Procedures and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86.5 Repair of Damaged Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、. . . . . . 106.6 Postweld Heat Treatment of Undamaged or Repaired Equipment . . . . . . . . . . . 10APPENDIX A CRACKING MECHANISMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13APPENDIX B CONSIDERATIONS FOR CORROSION CONTROL . . . . . . . . . . . . . 19APPENDIX C REQUEST FOR N
24、EW INFORMATION CONCERNING PROB-LEMS WITH ENVIRONMENTAL CRACKING IN AMINE UNITS. 23Figures1 Process Flow Diagram of a Representative Amine Unit . . . . . . . . . . . . . . . . . . . . . 3A-1 Sulde Stress Cracking in an Existing Hardened Heat-Affected Zone of a Weld. 13A-2 Hydrogen Blisters near the I
25、D Surface of a Carbon Steel Flange . . . . . . . . . . . . . 14A-3 Stepwise Hydrogen-Induced Cracking (HIC) in a Carbon Steel Specimen . . . . 14A-4 Stress-Oriented Hydrogen-Induced Cracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14A-5 Alkaline Stress Corrosion Cracking in the Vicin
26、ity of a Weld. . . . . . . . . . . . . . . . 15A-6 Alkaline Stress Corrosion Cracking in a Pipe Weld in MEA Service . . . . . . . . . . 16A-7 Alkaline Stress Corrosion Cracking in an Elbow in DEA Service . . . . . . . . . . . . 17A-8 Intergranular Alkaline Stress Corrosion Cracking in DEA Service. .
27、 . . . . . . . . . . 17v1Avoiding Environmental Cracking in Amine Units1 ScopeThis recommended practice discusses environmentalcracking problems of carbon steel equipment in amine units.Stress corrosion cracking of stainless steels in amine units isbeyond the scope of this document although there ha
28、ve beenisolated reports of such problems. This practice does provideguidelines for carbon steel construction materials includingtheir fabrication, inspection, and repair to help assure safe andreliable operation. The steels referred to in this document aredened by the ASTM designation system, or are
29、 equivalentmaterials contained in other recognized codes or standards.Welded construction is considered the primary method of fab-ricating and joining amine unit equipment. See 3.1 and 3.2 forthe denitions of weld and weldment.This document is based on current engineering practicesand insights from
30、recent industry experience. Older amineunits may not conform exactly to the information containedin this recommended practice, but this does not imply thatsuch units are operating in an unsafe or unreliable manner. Notwo amine units are alike, and the need to modify a specicfacility depends on its o
31、perating, inspection, and maintenancehistory. Each user company is responsible for safe and reli-able unit operation.2 References2.1 REFERENCED PUBLICATIONSThe following publications are referenced by number inthis recommended practice.1. H. W. Schmidt et al., Stress Corrosion Cracking inAlkaline So
32、lutions, Corrosion,1951, Volume 7, No. 9, p.295. 2. G. L. Garwood, What to Do About Amine Stress Cor-rosion, Oil and Gas Journal,July 27, 1953, Volume 52,p. 334.3. P. G. Hughes, Stress Corrosion Cracking in an MEAUnit, Proceedings of the 1982 U.K. National CorrosionConference, Institute of Corrosion
33、 Science and Technol-ogy, Birmingham, England, 1982, p. 87. 4. H. I. McHenry et al., Failure Analysis of an AmineAbsorber Pressure Vessel, Materials Performance,1987.Volume 26, No. 8, p. 18.5. J. Gutzeit and J. M. Johnson, Stress Corrosion Crack-ing of Carbon Steel Welds in Amine Service, MaterialsP
34、erformance, 1986, Volume 25, No. 7, p. 18.6. J. P. Richert et al., Stress Corrosion Cracking of Car-bon Steel in Amine Systems, Materials Performance,1988, Volume 27, No. 1, p. 9.7. A. J. Bagdasanian et al., Stress Corrosion Cracking ofCarbon Steel in DEA and ADIP Solutions, MaterialsPerformance,199
35、1, Volume 30, No. 5, p. 63. 8. R. J. Horvath, Group Committee T-8 Minutes, Sec.5.10Amine Units, Fall Committee Week/93, September29, 1993. NACE International.9. R. N. Parkins and Z. A. Foroulis, The Stress Corro-sion Cracking of Mild Steel in MonoethanolamineSolutions (Paper 188), Corrosion/87,NACE
36、Interna-tional, Houston, 1987.10. H. U. Schutt, New Aspects of Stress CorrosionCracking in Monethanolamine Solutions (Paper 159),Corrosion/88,NACE International, Houston, 1988.11. M.S. Cayard, R.D. Kane, L. Kaley and M. Prager,Research Report on Characterization and Monitoring ofCracking in Wet H2S
37、Service, API Publication 939,Amer-ican Petroleum Institute, Washington, D.C., October 1994.12. T. G. Gooch, Hardness and Stress Corrosion Crack-ing of Ferritic Steel, Welding Institute Research Bulletin,1982, Volume 23, No. 8, p. 241.13. C. S. Carter and M. V. Hyatt, Review of Stress Corro-sion Crac
38、king in Low Alloy Steels with Yield StrengthsBelow 150 KSI, Stress Corrosion Cracking and Hydro-gen Embrittlement of Iron Base Alloys,NACEInternational, Houston, 1977, p. 524.2.2 REFERENCED CODES AND STANDARDSThe following codes and standards are directly referenced(not numbered) in this recommended
39、 practice. All codes andstandards are subject to periodic revision, and the most recentrevision available should be used.APIAPI 510Pressure Vessel Inspection Code: Mainte-nance Inspection, Rating, Repair, andAlterationAPI 570Piping Inspection Code: Inspection, Repair,Alteration, and Rerating of In-S
40、ervice Pip-ing SystemsRP 572Inspection of Pressure VesselsRP 574Inspection Practices for Piping SystemComponentsRP 579Fitness-for-ServiceRP 580Risk-Based InspectionRP 582Welding Guidelines for the Chemical, Oil,and Gas Industries Publ 2217AGuidelines for Work in Inert ConfinedSpaces in the Petroleum
41、 Industry2 API RECOMMENDEDPRACTICE945NACE International1RP0472Methods and Controls to Prevent In-Ser-vice Environmental Cracking of CarbonSteel Weldments in Corrosive PetroleumRefining EnvironmentsNACE No. 2/ Near-White Metal Blast CleaningSSPC-SP 102.3 OTHER CODES AND STANDARDSThe following codes a
42、nd standards are not referenceddirectly in this recommended practice. Familiarity with theseis recommended because they provide additional informationpertaining to this recommended practice. All codes and stan-dards are subject to periodic revision, and the most recentrevision available should be us
43、ed.ASME2B31.3Process PipingBoiler and Pressure Vessel Code, Section VIII, Rules forConstruction of Pressure Vessels, and Sec-tion IX,Qualication Standard for Weldingand Brazing Procedures, Welders, Brazers,and Welding and Brazing OperatorsASTM3E 10Standard Test Method for Brinell Hardnessof Metallic
44、 MaterialsNACE InternationalMR0103Materials Resistant to Sulfide StressCracking in Corrosive Petroleum RefiningEnvironmentsTM0177Laboratory Testing of Metals for Resis-tance to Specific Forms of EnvironmentalCracking in H2S EnvironmentsTM0284Evaluation of Pipeline and Pressure Ves-sel Steels for Res
45、istance to Hydrogen-Induced Cracking2.4 SELECTED BIBLIOGRAPHYThe following selected publications provide additionalinformation pertaining to this recommended practice. D. Ballard, How to Operate an Amine Plant, Hydrocar-bon Processing, 1966, Volume 45, No. 4, p. 137. E. M. Berlie et al., Preventing
46、MEA Degradation, Chem-ical Engineering Progress, 1965, Volume 61, No. 4, p. 82.K. F. Butwell, How to Maintain Effective MEA Solutions,Hydrocarbon Processing, 1982, Volume 61, No. 3, p. 108.J. C. Dingman et al., Minimize Corrosion in MEA Units,Hydrocarbon Processing, 1966, Volume 45, No. 9, p. 285.R.
47、 A. Feagan et al., Experience with Amine Units, Petro-leum Refiner, 1954, Volume 33, No. 6, p. 167.R. J. Hafsten et al., API Survey Shows Few Amine Corro-sion Problems, Petroleum Refiner, 1958, Volume 37, No. 11,p. 281.G. D. Hall, Design and Operating Tips for EthanolamineGas Scrubbing Systems, Chem
48、ical Engineering Progress,1983, Volume 62, No. 8, p. 71.A. L. Kohl and F. C. Riesenfeld, Gas Purification(4th ed.),Gulf Publishing, Houston, 1985.N. R Liebenmann, Amine Appearance Signals Condition ofSystem, Oil therefore, it is not recommended. It should be noted thatthe allowable variation in the
49、chemical composition of steelscan be considerable, even within the same grade. In conjunc-tion with welding variables, this can produce high hardnessesin heat-affected zones that might not be adequately softenedby normal PWHT. Each situation should be evaluated todetermine whether the proposed PWHT is adequate. Investigations have shown that inadequate heated bandwidth can result in residual stresses of up to 172 MPa (25 ksi)after heat treatment. The residual stresses are highest withlarge diameter piping, due to higher internal con
