1、Identification, Repair, and Mitigation of Cracking of Steel Equipment in Fuel Ethanol ServiceAPI BULLETIN 939-E SECOND EDITION, AUGUST 2013Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regu
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16、s published annually by API, 1220 L Street, NW, Washington, DC 20005.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standardsapi.org.iiiContentsPage1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Normative References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Terms, Definitions, Acronyms, an
18、d Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.1 Terms and Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.2 Acronyms and Abbreviation
19、s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Background on SCC in Fuel Ethanol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.1 Description of Fuel
20、Ethanol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.2 Relevant Standards for Fuel Ethanol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.3 Supply
21、 Chain for Fuel Ethanol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.4 Significance of SCC in Fuel Ethanol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、. 74.5 Factors Related to SCC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Guidelines for Fabrication of Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、 . . . . . 135.1 Materials of Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135.2 Tank Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、. . . . . . . . . . . . . . . . . . . 155.3 Fabrication of Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155.4 Fabrication Guidelines to Minimize SCC . . . . . . . . . . . . . . . . . . . . . . . . . .
25、. . . . . . . . . . . . . . . . . . . . . . . . . . 165.5 Specific Guidelines for Minimizing SCC in Various Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165.6 Guidelines for PWHT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、. . . . . . . . . . . . . . . . . . . . . . . 175.7 Organic Coatings for Internal Protection of Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 Inspection of Existing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27、 . . . . . . . . . . . . . . . . . . . . . 196.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196.2 Inspection Intervals. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196.3 Inspection After Leakage Caused by SCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.4 Initial Inspection Without Leakage . . . . . . . . . . . . . . .
29、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.5 Examination Procedures for Identification of SCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 Repair of SCC Damaged Equipment . . . . . . . . . . . . . . . . . .
30、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237.2 Assessment of Fitness-for-service and Risk .
31、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237.3 Temporary Repair by Clamps and Patches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237.4 Crack Repair. . . . . . . . . . . . . . . . . . . .
32、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247.5 Stress Relief Heat Treatment Applied to Piping and Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247.6 Coatings . . . . . . . . . . . . . . . . . . . . . .
33、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 Monitoring of Fuel Ethanol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258.1 Sampling and Analysis
34、 of Fuel Ethanol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258.2 Methods for Monitoring and Testing for Corrosion and SCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Annex A (informative) Listing of Reported
35、Cases of SCC in Fuel Ethanol and Remedial Measures. . . . . . . . . 26Annex B (informative) Form to Submit New Information on SCC in Fuel Ethanol Systems. . . . . . . . . . . . . . . . 32Annex C (informative) Examples of Typical SCC in Fuel Ethanol . . . . . . . . . . . . . . . . . . . . . . . . . .
36、 . . . . . . . . . . . 34Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42vContentsPageFiguresC.1 SCC in Steel Tank Bottom . . . . . . . . . . . . . . . . . . . . . . . . . .
37、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34C.2 SCC in Steel Air Eliminator Vessel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35C.3 Leak in Piping Resulting from a Crack Adjacent to the Weld . .
38、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36C.4 Characteristics of SCC in Steel Exposed to Fuel Ethanol, Showing Multiple Crack Initiations and Through-thickness Propagation in Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36C.5 SCC in St
39、eel Tank Bottom Showing Highly Branched, Intergranular Cracks at 100X . . . . . . . . . . . . . . . 37C.6 SCC in Steel Metallographically Prepared with Grain Boundary Etch at 500X . . . . . . . . . . . . . . . . . . . . . 37C.7 SCC in Steel Pipe from a Loading Rack Supply Line . . . . . . . . . . .
40、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38C.8 Cracking of Another Pipe Sample from Same Situation as Noted in the Previous Figure. . . . . . . . . . . . 39C.9 SCC of Steel Piping in a Fuel Ethanol System Return Line/Tank Transfer Line . . . . . . . . . . . . . . . . . . . . 40C
41、.10 Same SCC Incidence Shown in Previous Figure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Tables1 Quality Specification for Fuel Ethanol per ASTM D4806 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Generally Comp
42、atible and Incompatible Polymeric Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15vi1Identification, Repair, and Mitigation of Cracking of Steel Equipmentin Fuel Ethanol Service1 ScopeUsage of fuel ethanol as an oxygenate additive in gasoline blends is increasing bo
43、th in the United States and internationally. This document discusses stress corrosion cracking (SCC) of carbon steel tanks, piping, and equipment exposed to fuel ethanol as a consequence of being in the distribution system, at ethanol distribution facilities, or end user (EU) facilities where the fu
44、el ethanol is eventually added to gasoline. Such equipment includes but is not limited to: storage tanks, piping and related handling equipment, and pipelinesthat are used in distribution, handling, storage, and blending of fuel ethanol. However, data for pipelines in ethanol service is limited and
45、caution should be used when applying guidelines from this document that have been derived mainly from applications involving piping and tanks in ethanol storage and blending facilities. SCC of other metals and alloys is beyond the scope of this document, as is the corrosion of steel in this service.
46、It is realized that SCC of steel in fuel ethanol is a topic where knowledge of the subject is actively growing through documentation of recent experience and through research in progress. This document deals with handling of cracks in existing equipment and reduction of SCC occurrence in new equipme
47、nt as a result of exposure to fuel ethanol per ASTM D4806 (or other international specifications), ethanol fuel blends, and pipeline transmixes involving fuel ethanol and conventional hydrocarbon fuels (gasoline, diesel, or jet fuel). It includes guidelines for carbon steel construction materials, i
48、ncluding their fabrication, inspection, and repair to help assure safe and reliable operations. This document is based on current engineering practices and insights from recent industrial experience and research. Older equipment may not conform exactly to the information contained herein, but this d
49、oes not imply that such equipment is being operated in an unsafe or unreliable manner. It is also recognized that facilities may vary and may need to be modified depending on specific operating conditions, inspection, and maintenance experience. Each user company is ultimately responsible for its own safe and reliable operations.The steels referred to in this document are defined by the ASTM or API designation systems or equivalent steel grades contained in other recognized codes or standards. Welded construction is considered the primary method of fabrication in equipment exposed to f
