1、 Standard Test Method Evaluation of the Carburization of Alloy Tubes Used for Ethylene Manufacture This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone, w
2、hether he or she has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE standard is to be construed as granting any right, by implication or otherwise, to manufactur
3、e, sell, or use in connection with any method, apparatus, or product covered by letters patent, or as indemnifying or protecting anyone against liability for infringement of letters patent. This standard represents minimum requirements and should in no way be interpreted as a restriction on the use
4、of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE assumes no responsibility for the interpretation or use of this standard by other par
5、ties and accepts responsibility for only those official NACE interpretations issued by NACE in accordance with its governing procedures and policies which preclude the issuance of interpretations by individual volunteers. Users of this NACE standard are responsible for reviewing appropriate health,
6、safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE standard may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and
7、/or operations detailed or referred to within this standard. Users of this NACE standard are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any exis
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10、ications by contacting the NACE FirstService Department, 15835 Park Ten Place., Houston, TX 77084-5145 (telephone +1 281-228-6200). Revised 2014-03-08 Revised 2006-03-10 Reaffirmed 2002-09-10 Approved 1998-06-26 NACE International 15835 Park Ten Place Houston, Texas 77084-5145 +1 281-228-6200 ISBN 1
11、-57590-058-0 2014, NACE International NACE TM0498-2014 Item No. 21235 TM0498-2014 NACE Internatioal i _ Foreword This NACE standard establishes a standard test procedure for pack bed carburization of alloys used for ethylene manufacture. The pack bed carburization procedure is specified in this stan
12、dard because it is simple to perform. The test specimen geometry chosen reflects the intent of the procedure to be used for evaluation of carburization of furnace tube alloys intended for ethylene manufacture. This standard also establishes two recommended methodscombustion analysis and chemical etc
13、hingfor measuring the relative carburization of alloys for tubes intended for service in ethylene manufacture, or for assessing the performance of these tubes after service. Application procedures for the two methods are defined in detail. The combustion analysis method is preferred because it is qu
14、antitative. The chemical etching method is simpler and less expensive, but is only semiquantitative. Other methods considered and the reasons they are not recommended are discussed in Appendix A (nonmandatory). The carburization measurement methods in this standard may be used independently from the
15、 pack bed carburization procedure when assessing the condition of tubes after service or when other carburization procedures have been performed. This standard is intended to assist designers, operators, producers, fabricators, users, and testing laboratories in the selection of furnace tube alloys
16、used for ethylene manufacture. This standard was originally prepared in 1998 by Task Group T-5B-11, a component of Unit Committee T-5B on High-Temperature Materials Performance. It was reaffirmed in 2002 by Specific Technology Group (STG) 37, “Process IndustryHigh Temperature.” It was revised in 200
17、6 by Task Group (TG) 124 to include a standard pack bed carburization procedure. It was revised in 2014 by TG 124. TG 124 is administered by STG 37. This standard is issued by NACE International under the auspices of STG 37. In NACE standards, the terms shall, must, should, and may are used in accor
18、dance with the definitions of these terms in the NACE Publications Style Manual. The terms shall and must are used to state a requirement, and are considered mandatory. The term should is used to state something good and is recommended, but is not considered mandatory. The term may is used to state
19、something considered optional. _ TM0498-2014 ii NACE International _ Evaluation of the Carburization of Alloy Tubes Used for Ethylene Manufacture Contents 1. General 1 2. Definitions 1 3. Test Specimens for the Pack Bed Carburization Procedure 2 4. Carburizing Media . 2 5. Pack Bed Containment Vesse
20、l 2 6. Carburizing Temperature 3 7. Carburizing Procedure 3 8. Carburization Measurement and Reporting 4 9. Combustion Analysis Measurement Method 4 10. Chemical Etching Measurement Method . 7 References 8 Bibliography 9 Appendix A (Nonmandatory): Other Carburization Measurement Methods . 11 FIGURES
21、 Figure 1: Schematic of pack bed containment vessel 3 Figure 2: An uneven magnetic response line. 5 Figure 3: A relatively uniform magnetic response line is shown by this distribution of magnetic particles. 6 Figure 4: Four sections of internally finned tubing etched to show the degree of carburizat
22、ion . 7 _ TM0498-2014 NACE International 1 _ Section 1: General 1.1 This standard was developed to address a need for a standardized method to test the relative carburization of various furnace tube alloys used for ethylene manufacture. MTI(1)Publication No. 521provides definitive guidelines for dev
23、eloping standard carburization testing methods for broader applications, and procedures for measuring the test result, but does not specify a standard method. This NACE standard defines a standard pack bed carburization procedure and standard methods for measurement of the relative carburization of
24、alloy tubes intended for use in ethylene manufacture. 1.2 The pack bed carburization procedure is specified because of its ease of application. Gas carburization procedures require a more complex apparatus. This procedure is designed so that alloys may be carburized without the use of expensive or c
25、omplicated laboratory equipment. The user of this procedure is cautioned that the pack bed carburization procedure does not duplicate the carburizing conditions in the furnace tubes used for ethylene manufacture. However, it has been shown to be a reliable procedure that produces a standard carburiz
26、ing environment suitable for the evaluation of the relative carburization of alloys. 1.3 Tubular segments are specified as the test specimens to ensure that the test specimens have similar macrostructures, microstructures, and geometry to those typically used in furnaces for ethylene manufacture. A
27、standard reference test specimen shall be used for each set of carburization exposures. The reference test specimen shall be alloy UNS(2)N08810 (alloy 800H). 1.4 Carburization data for proprietary alloys and for standard alloys such as UNS J94204 have generally been developed by tube suppliers. Beca
28、use of variations in testing and measuring methodologies, attempts to compare carburization data from one supplier to another for specific temperature ranges have not always provided consistent results. Standardization of the carburization procedure and measurement methods allows data from different
29、 suppliers to be compared. Furthermore, by using a standard reference alloy with each set of exposures, differences in test severity between suppliers are apparent. This ensures a standard method is used to rank the carburization of alloys used for ethylene manufacture and provides a means to evalua
30、te any disparities involved in interpreting supplier carburization data. 1.5 The carburization procedure and measurement methods established by this standard should not be inferred to provide any information regarding the possible consequences of carburization in general or for any particular furnac
31、e design. Nor should they be inferred to provide a basis for projecting the remaining service life of partially or fully carburized tubes. The test results should not be used for direct extrapolation to actual service in ethylene manufacturing plants. It is the responsibility of the user of this sta
32、ndard to determine the applicability of the data. 1.6 Users of carburization data determined by these methods are responsible for developing their own criteria for applying the data to their needs. In addition to the carburization test results, other relevant material properties should be considered
33、 in evaluating the suitability or relative performance of a given tube alloy for service in ethylene manufacture. 1.7 The evaluation of mechanical properties and the extent to which they might be affected by various degrees of carburization are not within the scope of this standard. 1.8 This standar
34、d does not purport to address all the safety concerns associated with this carburization procedure. It is the responsibility of the user of this standard to establish appropriate safety and health practices. _ Section 2: Definitions 2.1 Carburization is the absorption and diffusion of carbon in iron
35、 or an iron-based alloy in contact with a suitable carbonaceous environment at elevated temperature. (1)Materials Technology Institute (MTI), 1215 Fern Ridge Parkway, Suite 206, St. Louis, MO 63141-4405. (2)Unified Numbering System for Metals and Alloys (UNS). UNS numbers are listed in Metals & Allo
36、ys in the Unified Numbering System, 10thed. (Warrendale, PA: SAE International and West Conshohocken, PA: ASTM International, 2004). TM0498-2014 2 NACE International _ Section 3: Test Specimens for the Pack Bed Carburization Procedure 3.1 Test specimens shall be tube segments and shall have an outsi
37、de diameter (OD) between 75 and 100 mm (3.0 to 4.0 in). The length of the test specimen shall be a minimum of 75 mm (3.0 in). 3.2 The wall thickness of the test specimens shall be 9.53 1.59 mm (0.375 0.0625 in). 3.3 The internal bore of the test specimen shall be machined to a 3.18 m (0.125 mil) roo
38、t mean square (RMS) maximum surface finish. The internal surface shall be free of defects, machining oils, and lubricants. The intent is for the test specimen to have an internal surface condition that corresponds to the internal surface condition of an alloy furnace tube typically used in ethylene
39、manufacture. 3.4 The reference test specimen shall have an OD of 75 to 100 mm (3.0 to 4.0 in). It shall be wrought alloy UNS N08810 (alloy 800H) tube, in accordance with ASTM(4)B4072bright annealed or mill annealed, and pickled. The internal surface shall not be machined, but shall be clean and free
40、 of oils and lubricants. The use of the reference test specimen allows comparison between data sets from different sources. 3.5 Test specimens shall not be preoxidized or pretreated prior to carburizing. 3.6 A minimum of two test specimens per alloy shall be tested at each test temperature. Unexpose
41、d materials from the same heat shall be retained for reference. _ Section 4: Carburizing Media 4.1 Carburizing media shall be a solid carbon, coke-based granular type with a granule size of 6.4 to 8.4 mm (0.25 to 0.33 in), with ash content of less than 15%, fluxing (activator) agent content of less
42、than 10%, and sulfur content of less than 0.15%. _ Section 5: Pack Bed Containment Vessel 5.1 The test specimen shall be positioned on a bottom plate with its longitudinal axis vertical and capped with a top plate, effectively closing each end, to form a containment vessel for the carburizing media,
43、 as shown in Figure 1. 5.2 The top and bottom plate material shall be selected to maintain structural integrity and resist deformation for the duration of the carburizing procedure. 5.3 After the test specimen is positioned on the bottom plate, any gaps between the test specimen and the bottom plate
44、 shall be filled with aluminosilicate refractory paste. 5.4 After assembly of the test specimen and bottom plate, the carburizing media shall be packed firmly to completely fill the internal volume of the test specimen. 5.5 The top plate shall then be placed on the test specimen. Any gaps between th
45、e test specimen and the top plate shall be filled with aluminosilicate refractory paste. 5.6 The containment vessel shall not be airtight, as this would effectively create a pressurized vessel upon heating, but it shall not have any openings larger than 1 mm (0.04 in). 5.7 A calibrated thermocouple
46、shall be firmly attached to the middle of the test specimen OD using heat-resistant wire. (4)ASTM International (ASTM), 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. TM0498-2014 NACE International 3 Figure 1: Schematic of pack bed containment vessel, showing top and bottom pl
47、ates. The entire internal volume shall be firmly packed with carburizing media. A thermocouple shall be placed on the test specimen OD to ensure that the carburizing temperature is maintained. _ Section 6: Carburizing Temperature 6.1 One of the following standard carburizing temperatures for this class of furnace tube alloys shall be mutually agreed upon between the users of this standard procedure (e.g., purchaser, supplier). 1,000 C (1,832 F) 1,050 C (
