1、Use of Duplex Stainless Steels in the Oil Refining IndustryAPI TECHNICAL REPORT 938-C THIRD EDITION, FEBRUARY 2015Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewe
2、d.Neither API nor any of APIs employees, subcontractors, consultants, committees, or other assignees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibilit
3、y for any use, or the results of such use, of any information or process disclosed in this publication. Neither API nor any of APIs employees, subcontractors, consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights.API publications may be
4、 used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability
5、 or responsibility for loss or damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may conflict.API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publicatio
6、ns are not intended to obviate the need for applying sound engineering judgment regarding when and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices.Any manufacturer marking equ
7、ipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such products do in fact conform to the applicable API standard.Users of t
8、his Technical Report should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein.All rights reserved. No part of this work may be reproduced, translated, stored in
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11、against liability for infringement of letters patent.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standardsapi.org.iiiContentsPage1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Normative References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Terms, Definitions, and Acronyms . . . . . . . .
13、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.1 Terms and Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.2 Acronyms . . . . . . . . . . .
14、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Metallurgy of DSSs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
15、4.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.2 Solidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16、 . . . . . . . . . . . . . . . . . . . . 94.3 Problems to be Avoided During Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.4 Low and High Temperature Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、 . . . . . . . . . . . . . . . . . . . 104.5 Hardness Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Potential Environment-Related Failure Mechanisms . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . . . . . . . . . . . . . . . . . 145.1 Chloride Pitting and Crevice Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145.2 Corrosion in Seawater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . 165.3 Chloride Stress Corrosion Cracking (CSCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175.4 Hydrogen Stress Cracking (HSC)/Sulfide Stress Cracking (SSC) . . . . . . . . . . . . . . . . . . .
20、 . . . . . . . . . . . . . 195.5 Ammonium Bisulfide Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215.6 Naphthenic Acid Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21、. . . . . . . . . . . . . . . . . . . 225.7 475 C (885 F) Embrittlement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Material Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、. . . . . . . . . . . . . . . . . . . . . . . . . . . . 246.1 Typical Specification Requirements for Wrought Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246.2 Welded Versus Seamless Tubing and Piping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、 . . . . . . . . . . . . . . . . . . 276.3 Use of Integrally Finned Tubing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276.4 Use of Twisted Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286.5 Duplex SS Castings and HIP Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296.6 Duplex SS Used as a Cladding Material . . . . . . . . . . . . . . . . . . . . . . . . . . .
25、. . . . . . . . . . . . . . . . . . . . . . . . . . 297 Fabrication Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297.1 Typical Specification Requirements . . . . . . . . . . . . . . . . . . . . . . . . .
26、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297.2 Typical Welding Processes and Filler Metals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307.3 Dissimilar Metal Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317.4 Ferrite Measurements vs. Austenite Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317.5 Cold Working and Hot and Cold Bending. . . . . . . . . . . . . . . . . . . . .
28、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327.6 Tube-to-tubesheet Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327.7 Post-Fabrication Cleaning . . . . . . . . . . . . . . . . . . . . . . .
29、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337.8 NDE Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337.9 Hydrostatic Testing . . . . . . . . . . . .
30、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347.10 Coating Requirements and Risk of CUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348 Examples of DSSs Applications
31、 within Refineries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Annex A (informative) Example of Special Material Requirements for DSSs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Annex B (informative) Example of Special Welding Procedure Qu
32、alification Requirements for DSSs . . . . . . 46Annex C (informative) Example of Special Welding and Fabrication Requirements for DSSs . . . . . . . . . . . . . 47Annex D (informative) Example of a Duplex SS Casting Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48An
33、nex E (informative) Example of a Hot Isostatically-pressed (HIP) Duplex SS Material Specification . . . . . . 53vContentsPageBibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
34、Figures1 Comparison of the Proof Stress and Pitting Resistance (based on PREN of the bulk chemistry) of Duplex and Austenitic SS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Possible Precipitations in DSSs . . . . .
35、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Effect of Weld Metal Oxygen Content on the Toughness of the Weld . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Compilation of Hardness Data for a Range of Duplex Parent Mater
36、ials and Weldments Showing the Best-fit Line and ASTM E140 Conversion for Ferritic Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135CPT for 2 % Cr, Super and Hyper DSSs Alloys Compared to Austenitic SS Alloys in 6 % FeCl3, ASTM G48 Test Method A. . . . . . . . . . . . . .
37、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 CPTs at Various Concentrations of Sodium Chloride (at +300 mV vs. SCE, Neutral pH) . . . . . . . . . . . . . 157 CPTs and CCTs for 22 % Cr and Super DSSs Compared to Austenitic SS Alloys in AST
38、M G48 Tests. . 168 CSCC Resistance of DSSs Alloys Compared to Austenitic SS Alloys in Oxygen-bearing Neutral Chloride Solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 Results of SCC Tests of 22
39、% Cr and 25 % Cr DSSs Alloys Compared to Austenitic SS Alloys in Constant Load Tests in 40 % CaCl2, 1.5 pH at 100 C with Aerated Test Solution . . . . . . . . . . . . . . . . . . 1810 Impact Energy Curves for Alloys Aged at 300 C and 325 C: a) Quench Annealed S32750; b) 45 % Cold Worked S31803 C = (
40、F 32)/1.8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2511 Embrittlement of UNS S32304, S32205, and S32507 after Long Time Annealing . . . . . . . . . . . . . . . . . . . 26Tables1 Chemical Compositions of Commonly Used DSSs and Other Alloys . . . . .
41、. . . . . . . . . . . . . . . . . . . . . . . . 22 ASME and ASTM Specifications for DSSs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Mechanical Properties of Various Duplex and 316L SSs . . . . . . . . . . . . . . . . . . . . . . . . . .
42、 . . . . . . . . . . . . . . 44 Partitioning of Elements of Various DSS Grades (% in ferrite/% in austenite). . . . . . . . . . . . . . . . . . . . . . . 95 ASME Code Maximum Allowable Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 Estima
43、ted H2S Partial Pressure Limits for DSS in Production Services Based on Literature, Laboratory and Experiential Data (KPa psi). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 Successful Service Experience with DSS in Production Sour Services . . .
44、 . . . . . . . . . . . . . . . . . . . . . . . 218 Partitioning of Alloying Elements Between Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Welding Consumables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
45、. . . . . . . . . . . . . . . . . . . . . . 3110 Case Histories of DSS Uses Reported in NACE International Refin-Cor . . . . . . . . . . . . . . . . . . . . . . . . . . 3511 Case Histories of DSSs Uses Reported by Other Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
46、. 3912 Summary List of DSSs Refinery Applications to Date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43D.1 Impact and Corrosion Test Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50D.2 Welding
47、 Consumables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51viIntroductionDuplex stainless steels (DSSs) are finding increasing use in the refining industry, primarily because they often offer an economical comb
48、ination of strength and corrosion resistance. These stainless steels (SSs) typically have an annealed structure that is generally half ferrite and half austenite, although the ratios can vary from approximately 35/65 to 55/45. Most refinery applications where DSSs are used are corrosive, and DSSs or
49、 other higher alloys are required for adequate corrosion resistance. However, some plants are also starting to consider DSS as a “baseline” material1. These plants are using DSS in applications where carbon steel may be acceptable, but DSSs have been shown to be more economical, considering their higher strength and better long-term reliability. DSSs are often used in lieu of austenitic SS in services where the common austenitics would have problems with chloride pitting or chloride stress corrosion cracking (CSCC). Higher alloyed DSSs like super duplex and hyper duplex are
