1、Guidelines for Avoiding Sulfidation (Sulfidic) Corrosion Failures in Oil RefineriesAPI RECOMMENDED PRACTICE 939-C FIRST EDITION, MAY 2009Guidelines for Avoiding Sulfidation (Sulfidic) Corrosion Failures in Oil RefineriesDownstream SegmentAPI RECOMMENDED PRACTICE 939-C FIRST EDITION, MAY 2009Special
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16、Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, D.C. 20005, standardsapi.org.iiiContentsPageIntroduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、 . . . . . . . . . . . . . . . . . . . vii1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Normative References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Definitions and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Basics of Sulfidati
20、on Corrosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Location of Sulfidation Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Effects
21、of Process and Material Variables on Corrosion Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.2
22、H2-free Sulfidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.3 H2/H2S Corrosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、 . . . . . . . . . . . . . . . 97 Practical Guidelines for Avoiding Sulfidation Corrosion Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107.1 For Existing Units and Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . . . 107.2 New and Replacement Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 Limitations of Current Knowledge Base. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25、. . . . 159Incidents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Annex A (informative) Failure Experience Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、. . . . . . . . . . . . 17Annex B (informative) Sulfidation Corrosion Prediction Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Annex C (informative) Corrosion Data for Carbon Steel Piping with Higher and Lower Si Contents . . . . . . . . 31Bibliography . . . .
27、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Figures1 NPS 8 Carbon Steel Piping Failed Due to Sulfidation Corrosion (H2Free) . . . . . . . . . . . . . . . . . . . . . . . . . 42 Corroded Car
28、bon Steel Sight Glass Nipple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 FCC Fractionator Bottoms Carbon Steel Piping Operating at 150 psig (1 MPa) and 650 F to 700 F (340 C to 370 C). . . . . . . . . . . . . . . . . . . . . . . . . . . .
29、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 FCC Fractionator Bottoms Carbon Steel Piping Shown in Figure 3 Operating at 150 psig (1 MPa) and 650 F to 700 F (340 C to 370 C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Summary of Reported Fai
30、lures by Type, Number of Reported Instances, and Percentage of the Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16B.1 Modified McConomy Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31、. . . . . . . . . . . . . . . . . . . . . . . . . . . 21B.2 Modified McConomy Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21B.3 Couper-Gorman H2/H2S Curves for Carbon Steel for Both Gas Oil and Naphtha. . . . . .
32、. . . . . . . . . . . . . 22B.4 Couper-Gorman H2/H2S Curves for 1.25Cr Steel for Both Gas Oil and Naphtha. . . . . . . . . . . . . . . . . . . . 23B.5 Couper-Gorman H2/H2S Curves for 2.25Cr Steel for both Gas Oil and Naphtha . . . . . . . . . . . . . . . . . . . . 24B.6 Couper-Gorman H2/H2S Curves f
33、or 5Cr Steel for Both Gas Oil and Naphtha . . . . . . . . . . . . . . . . . . . . . . 25B.7 Couper-Gorman H2/H2S Curves for 7Cr Steel for Both Gas Oil and Naphtha . . . . . . . . . . . . . . . . . . . . . . 26B.8 Couper-Gorman H2/H2S Curves for 9Cr Steel for Both Gas Oil and Naphtha . . . . . . . .
34、. . . . . . . . . . . . . . 27B.9 Couper-Gorman H2/H2S Curves for 12Cr Steel (Same for Both Gas Oil and Naphtha). . . . . . . . . . . . . . . 28B.10 Couper-Gorman H2/HH2S Curves for 18Cr Steel (Same for Both Gas Oil and Naphtha) . . . . . . . . . . . . . 28B.11 Corrosion Rate in H2S/High H2Partial P
35、ressureAll Vapor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29vContentsPageB.12 Corrosion Rate in H2S/High H2Partial PressureLiquid Shifted by a Factor of 6 Lower vs Vapor . . . . 29B.13Corrosion Rate in H2S/H2VaporLow H2Partial Pressure (High H2Partial PressureAll Vapor
36、 Curves Adjusted by Experience) . . . . . . . . . . . . . . . . . . . . . . . . . . . 30C.1Corrosion Rate vs Si Content for FCC Slurry Carbon Steel Piping Failure (Operating Conditions: 150 psig and 650 F to 700 F) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32C
37、.2Corrosion Rate vs Si Content for FCC Slurry Piping Failure (Operating Conditions: 1 MPa and 340 C to 370 C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33C.3Corrosion Rate vs Si Content for Various H2-free Services. . . . . . . . . . . . . . . . . . . . . .
38、. . . . . . . . . . . . . . . 34C.4Corrosion Rate vs Si Content for Various H2-free Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34viIntroductionSulfidation corrosion, also often referred to as sulfidic corrosion, of piping and equipment within the refining indus
39、try continues to be a significant cause of leaks leading to equipment replacements, unplanned outages, and incidents associated with large property losses and injuries. The objective of this recommended practice (RP) is to provide practical guidance to inspectors, maintenance, reliability, project,
40、operations and corrosion personnel on how to address sulfidation corrosion in petroleum refining operations. This document is intended to provide a better understanding of sulfidation corrosion characteristics. Examples of failures are discussed to highlight the common causes. An overview of the two
41、 mechanisms of sulfidation corrosion (with and without H2present) and the methods used to control and inspect for sulfidation corrosion are summarized. The data herein is a compilation of information extracted from published technical papers, industry information exchanges (NACE and API) and contrib
42、utions from several owner/operators. Some refining companies have developed proprietary methods to predict sulfidation corrosion and these were not made available as part of this effort. Common refinery units in which essentially H2-free sulfidation corrosion occurs are the crude/vacuum, fluid catal
43、ytic cracker, coker, and visbreaker units. Hydroprocessing and hydrocracking units experience H2-free sulfidation corrosion in their feed and distillation sections. They experience sulfidation in the presence of hydrogen in their reaction sections. This sulfidation in the presence of H2is typically
44、referred to as H2/H2S corrosion. Included in this RP are: background to the degradation mechanism, the most common types of incidents and damage observed, root causes of sulfidation corrosion, methods to predict and monitor the corrosivity of systems, materials selection for new and revamped process
45、es, inspection and nondestructive examination (NDE) methods used for detecting sulfidation corrosion. Materials and corrosion specialists should be consulted for additional unit-specific interpretation and application of this RP.vii1Guidelines for Avoiding Sulfidation (Sulfidic) Corrosion Failures i
46、n Oil Refineries1 ScopeThis recommended practice (RP) is applicable to hydrocarbon process streams containing sulfur compounds, with and without the presence of hydrogen, which operate at temperatures above approximately 450 F (230 C) up to about 1000 F (540 C). A threshold limit for sulfur content
47、is not provided because within the past decade significant corrosion has occurred in the reboiler/fractionator sections of some hydroprocessing units at sulfur or H2S levels as low as 1 ppm. Nickel base alloy corrosion is excluded from the scope of this document.While sulfidation can be a problem in
48、 some sulfur recovery units, sulfur plant combustion sections and external corrosion of heater tubes due to firing sulfur containing fuels in heaters are specifically excluded from the scope of this document. 2 Normative ReferencesThe following referenced documents are indispensable for the applicat
49、ion of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced doucment (inlcuding any amendments) applies.API 510, Pressure Vessel Inspection Code: Maintenance Inspection, Rating, Repair, and Alteration API 570, Piping Inspection Code: Inspection, Repair, Alteration, and Rerating of In-service Piping Systems API Recommended Practice 571, Damage Mechanisms Affecting Fixed Equipment in the Refining IndustryAPI Recommended Practice 578, Material Verification Program for New and Existin
