1、Technical Report on Temperature Derating on API Flanges Under Combination of Loading API TR 6AF1 SECOND EDITION, NOVEMBER 1998 American Petroleum Institute Helping You Get The Job Done RightsM Technical Report on Temperature Derating of API Flanges Under Combination of Loading . Exploration and Prod
2、uction Department API TR 6AF1 SECOND EDITION, NOVEMBER 1998 American Petroleum Institute Helping You Get The Job Done Right:. STD*API/PETRO TI? bAFL-ENGL L758 W 0732270 Oh13378 23t3 W SPECIAL NOTES MI publications necessarily address problems of a general nature. With respect to partic- ular circums
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14、ght 0 1998 American Petroleum Institute STD.API/PETRO TR bAFJI-ENGL 1778 M 0732270 Ob13377 L74 m FOREWORD This Technical Report is under the jurisdiction of the AH Subcommittee on Valves and Wellhead Equipment. The first edition was issued as an API Bulletin in 1991, was reaffirmed in 1997 with edit
15、orial changes, and was reissued as a Technical Report. American Petroleum Institute (MI) Technical Reports are published to provide informa- tion for which there is broad industry need but which does not constitute either Specifica- tions or Recommended Practices. Any Technical Reports may be used b
16、y anyone desiring to do so, and a diligent effort has been make by MI to assure the accuracy and reliability of the data contained herein. How- ever, the Institute makes no representation, warranty or guarantee in connection with the publication of an Technical Reports and hereby expressly disclaims
17、 any liability or responsi- bility for loss or damage resulting from its use, for any violation of any federal, state, or municipal regulation with which an API publication may conflict, or for the infringement of any patent resulting from the use of this population. Suggested revisions are invited
18、and should be submitted to the director of the Exploration and Production Department, American Petroleum Institute, 1220 L Street, N.W., Washing- ton, D.C. 20005. iii CONTENTS Page . 1 SCOPE 1 2 REFERENCES 1 3 INTRODUCTION TO RATING CHARTS 1 3.1 Introduction and Scope . 1 3.2 Material Categories 2 3
19、.3 Flange Combined Load Capacities 2 3.4 Use of Rating Charts . 4 4 AXISYMMETRIC FINITE ELEMENT ANALYSIS 7 4.2 Finite Element Modeling 7 4.3 Assumptions 9 4.4 Material Categories . 10 4.6 Analysis Results 12 4.1 Introduction 7 4.5 Load Cases 10 5 FLANGE COMBINED LOAD CAPACITIES 17 5.1 Introduction .
20、 17 5.2 Allowable Stress Criteria . 17 5.3 Leak Criteria 18 5.4 Stress Linearization . 18 5.5 Load Rating Methodology. . 18 5.6 Results . 19 5.7 Use of Rating Charts 22 6 CONCLUSIONS AND RECOMMENDATIONS 24 6.2 Conclusion 24 6.1 Summary . 24 6.3 Recommendations 24 APPENDIX A MATERIAL CATEGORY A 25 AP
21、PENDIX B MATERIAL CATEGORY B . 101 APPENDIX C MATERIAL CATEGORY C . 175 APPENDIX D MATERIAL CATEGORY D . 211 APPENDIX E MATERIAL CATEGORY E . 247 APPENDIX F MATERIAL CATEGORY F . 253 Figures 1 Typical Combined Load Capacity Results 5 2 Load Capacity Results to Use with Example Problems 6 3 Typical F
22、inite Element Meshes . 8 as a Function of Wind Speed and Temperature 10 5 Load Conditions for Makeup and Pressure . 12 6 Load Conditions for Tension and Bending Moment 13 4 Convection Coefficients for Air Blowing Across a 1-Ft Diameter Cylinder V Previous page is blank Page 7 8 9 10 11 12 13 14 15 L
23、oad Conditions for Thermal and Thermal Stress Analysis 13 Typical Stress Intensity Contour Plots for Makeup and Pressure Load Conditions 71/16“ 10. O00 6BX Flange 14 Typical Stress Intensity Contour Plots for Tension and Bending Moment Load Conditions 14 Typical Contour Plots for Thermal Analysis Lo
24、ad Conditions 7/16“ 10. 000 6BX Flange . 15 Typical Stress Intensity Contour Plots for Makeup and Pressure Load Conditions 2l/16“ 2. O00 6B Flange . 15 Typical Stress Intensity Contour Plots for Tension and Bending Moment Typical Contour Plots for Thermal Analysis Load Conditions 2l/16“ 8. 000 6B Fl
25、ange 16 Typical Combined Load Capacity Results . 23 Load Conditions 2l/16“ 2. O00 6B Flange 16 Load Capacity Results to Use with Example Problems . 23 Tables 1 List ofMaterials . 3 2 Derated Values of Material Properties 4 3 Listof Materials 11 4 Derated Values of Material Properties . 11 5 API Phys
26、ical Properties and Material Types 19 6 Controlling Criteria Identification Numbers 21 Technical Report on Temperature Derating of API Flanges Under Combination of Loading 1 Scope This report is a continuation to the report on the capabili- ties of flanges under combined loadings (PRAC 86-21)2 which
27、 resulted in the publication of API Bulletin 6AF! Included herein is an in-depth look into the effect of elevated temperatures on API flanges. The results in this report are analytical and assume a tem- perature gradient across the flange as stated in this report. When the flange is insulated on the
28、 outside surface, the allow- able loads will be higher. Additional finite element models of five new flanges in API 6A, Sixteenth Edition, 1989, which were not in the 1986 Fifteenth Edition, used as a basis for the earlier work, were developed for the combined loading of bolt makeup, internal pressu
29、re, tension and bending moment. The API materials were then grouped into four material categories. A thermal analysis was performed (using all 63 axisymmetric finite ele- ment models of PRAC 86-212 and the 5 new models) to determine the temperature gradient and resulting thermal stresses at steady s
30、tate for all four material types at design bore temperatures of 350F and 650F. The post-processor program of PRAC 86-212 (calculating the maximum moment capacity for various levels of pressure and tension based on superposition) was partly modified to include thermal effects and produce separate rat
31、ing curves on the same chart, based on the leak or loss of preload (on the ring joint) criterion and the stress criteria. The stress criteria used were of two types: a) ASME Section VIII, Division 2, allowable stress categories for the flange with the basic mem- brane stress allowable established by
32、 APL and h) allowable bolt stresses as established by API. The results of this post- processing are presented in plots of pressure vs. allowable moment for various tension levels. These new rating charts were developed at two elevated temperatures for all four material categories in Appendices A, B,
33、 C, and D respectively. See Section 4 for details of the axisymmetric analysis and As in the previous report PRAC 86-21*, this report does not address the actual gasket contact loads required to make a seal. This report utilizes the leak or loss of preload (on the ring joint) criterion as in Bull 6A
34、F4 (PRAC 86-21 j and Bull 6AF25 (PRAC 88-21)6 and not the leakage criteria in report PN 90-2 1 . Section 5 for details of the load capacity calculations. 2 References This Technical Report references the following research reports and publications: 1 1. Temperature Derating of API Flanges Under Comb
35、ina- tions of Loading, PRAC 89-2 1, by Andreas T. Katsousnas, Joe R. Fowler, Stress Engineering Services, Inc., Report pre- pared for API, December 1989. 2. Cupubilities ofAPl Flanges Under Combinations of Loading, PRAC 86-21, by K. C. Walker, Joe R. Fowler, Stress Engineering Services, Inc., Report
36、 prepared for API, October 1987. 3. API Specification 6A, Specification for Wellhead and Christmas Tree Equipment, Sixteenth Edition, October 1, 1989. 4. API Bulletin 6AF, Capabilities ofAPI integral Flanges Under Combination of Load, First Edition, April 1, 1989. 5. API Bulletin 6AF2, Capabilities
37、of API Integral Flanges Under Combinations of Loading, First Edition, January 1, 1993. 6. Capabilities of API Integral Flanges Under Cornbina- fions of Loading, PRAC 88-21, by G. A. Ghoneim, K. H. Haverty, Veritas Marine Services (USA), Inc., Report pre- pared for API, December 1990. 7. Sealability
38、of API R, RX, while derating at elevated temperatures was applied according to Table 1 (derated from ambient temperature yield at 72F). The properties for both bolts and flanges, as well as the yield strength of bolts, were derated according to the ASME Boiler and Pressure Vessel Code (see Table 2).
39、 3.3 FLANGE COMBINED LOAD CAPACITIES The plotted results for the combined load capacity of each flange analyzed in this project are given in Appendices A, B, C, and D. The rating charts for each material category are presented in a separate Appendix. The results for each category are arranged in the
40、 same order as found in API 6A, first at 350F and then at 650F. The 6B flanges are first, fol- lowed by 6BX flanges. For each flange style the results are given in order of increasing diameter within each working pressure rating. (Thus, the 211/4“ 2,000 psi 6B flange is before the 2l/16“ 3,000 psi 6
41、B flange; and the 11“ 5,000 psi 6B flange is before the 263/4“ 2,000 psi 6BX flange.) For the first two material categories (Appendices A and B) combined load ratings were determined for each flange with two different bolt makeup stresses. The first rating was deter- mined for bolts made up to 52.5
42、ksi, and the second rating was done for a makeup stress of 40 ksi. The two plots are given on the same page to help evaluate the effect of a reduced preload on a flanges bending capacity. For each. of the first two material categories, two separate sets of plots are provided at 350F and at 650F. For
43、 the last two material categories (Appendices C and D) combined load ratings were determined for each flange with only one bolt makeup stress. The rating charts were deter- mined for bolts made up to 42.5 ksi. Therefore, the charts for the two temperature ratings are provided in the same plot. Bolt
44、makeup is taken as half the yield strength of the bolts. To assist the user in better understanding the rating charts, a table of controlling criteria has been established (see Table 6). Each identification number corresponds to a separate stress condition. Also included in the table is ID=l 1, whic
45、h denotes leaknoss of preload. The controlling capacity curve with ID=11 is shown in the rating charts with a continuous line. Therefore, only the identification of the controlling stress criteria will be shown in the rating charts. When studying these results, one should keep in mind that for a par
46、ticular flange the moment capacity based on leak/loss of preload criteria is assumed to not be affected by temperature variations; thus no difference exists between material catego- ries or between temperatures within a material category. This assumption was made because, in general, the thermal bou
47、nd- ary conditions chosen result in the flanged-joint preload increasing, due to temperatm. This increase, if accounted for, would allow higher moments for the leak criterion. However, if STD.API/PETRO TR bAFL-ENGL L998 m 0732270 Ob13404 3bL m TEMPERATURE DERATING ON API FLANGES UNDER COMBINATION OF
48、 LOADING 3 Table 1-List of Materials Derating Factors Material Category Flange Bolts 350F 650F A Carbon and Low Alloy Steels 4130 CR-% Mo B Martensitic, Ferritic and Precipitation 410SS Hardening Stainless Steels I3 Cr C Austenitic and Duplex Stainless Steels Ferralium-255 S-32550 D Carbon and Low A
49、lloy Steels 4130 Cr% Mo SA 193 B7 or 0.85 0.75 SA 193 B7M Cr-h Mo SA 193 B7 or 0.85 0.75 SA 193 B7M Cr- /S Mo SA 453 Gr 660 0.80 0.73 (A286) 26Ni- 15Cr-2Ti SA 453 Cr 660 0.85 0.75 (A286) the thermal boundary condtions are not as severe, then accounting for thermal preload increase is unconservative. On the other hand, leak/loss of preload is affected by bolt makeup. In addition, when primary loads (without makeup) control, the moment capacity-based on stress criteria-is the same for any material category with the same flange material (compare material categories A and D at e
