1、Damage Mechanisms Affecting Fixed Equipment in the Refining IndustryAPI RECOMMENDED PRACTICE 571SECOND EDITION, APRIL 2011Damage Mechanisms Affecting Fixed Equipment in the Refining IndustryDownstream SegmentAPI RECOMMENDED PRACTICE 571SECOND EDITION, APRIL 2011Special NotesAPI publications necessar
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18、ington, DC 20005, standardsapi.org.iiiv TABLE OF CONTENTS SECTION 1 1-1 1.1 Introduction 1-3 1.2 Scope 1-3 1.3 Organization and Use 1-4 1.4 References 1-4 1.5 Definitions of Terms 1-4 1.6 Technical Inquires 1-4 SECTION 2 2-1 2.1 Standards 2-3 2.2 Other References . 2-6 SECTION 3 3-1 3.1 Terms 3-3 3.
19、2 Symbols and Abbreviations 3-4 SECTION 4 4-1 4.1 General 4-3 4.2 Mechanical and Metallurgical Failure Mechanisms 4-3 4.2.1 Graphitization . 4-3 4.2.2 Softening (Spheroidization) 4-7 4.2.3 Temper Embrittlement . 4-10 4.2.4 Strain Aging 4-14 4.2.5 885F (475oC) Embrittlement . 4-16 4.2.6 Sigma Phase E
20、mbrittlement 4-19 4.2.7 Brittle Fracture 4-27 4.2.8 Creep and Stress Rupture . 4-32 4.2.9 Thermal Fatigue 4-39 4.2.10 Short Term Overheating Stress Rupture 4-46 4.2.11 Steam Blanketing . 4-51 4.2.12 Dissimilar Metal Weld (DMW) Cracking . 4-54 4.2.13 Thermal Shock 4-63 4.2.14 Erosion/Erosion Corrosio
21、n 4-65 4.2.15 Cavitation 4-70 4.2.16 Mechanical Fatigue 4-74 4.2.17 Vibration-Induced Fatigue . 4-81 4.2.18 Refractory Degradation . 4-84 4.2.19 Reheat Cracking . 4-87 4.2.20 Gaseous Oxygen-Enhanced Ignition and Combustion 4-93 4.3 Uniform or Localized Loss of Thickness . 4-101 4.3.1 Galvanic Corros
22、ion 4-101 4.3.2 Atmospheric Corrosion . 4-105 4.3.3 Corrosion Under Insulation (CUI) . 4-108 4.3.4 Cooling Water Corrosion . 4-117 4.3.5 Boiler Water Condensate Corrosion 4-120 4.3.6 CO2Corrosion . 4-124 4.3.7 Flue-Gas Dew-Point Corrosion . 4-128 4.3.8 Microbiologically Induced Corrosion (MIC) . 4-1
23、30 4.3.9 Soil Corrosion . 4-136 4.3.10 Caustic Corrosion 4-140 4.3.11 Dealloying . 4-143 4.3.12 Graphitic Corrosion . 4-147 4.4 High Temperature Corrosion 400F (204C) . 4-153 4.4.1 Oxidation . 4-153 4.4.2 Sulfidation . 4-159 4.4.3 Carburization 4-166 vi 4.4.4 Decarburization 4-169 4.4.5 Metal Dustin
24、g 4-172 4.4.6 Fuel Ash Corrosion 4-175 4.4.7 Nitriding . 4-180 4.5 Environment Assisted Cracking 4-184 4.5.1 Chloride Stress Corrosion Cracking (Cl-SCC) . 4-184 4.5.2 Corrosion Fatigue 4-193 4.5.3 Caustic Stress Corrosion Cracking (Caustic Embrittlement) 4-199 4.5.4 Ammonia Stress Corrosion Cracking
25、 4-206 4.5.5 Liquid Metal Embrittlement (LME) 4-210 4.5.6 Hydrogen Embrittlement (HE) . 4-215 4.5.7 Ethanol Stress Corrosion Cracking (SCC) 4-220 4.5.8 Sulfate Stress Corrosion Cracking . 4-227 SECTION 5 5-1 5.1 General 5-3 5.1.1 Uniform or Localized Loss in Thickness Phenomena 5-3 5.1.1.1 Amine Cor
26、rosion 5-3 5.1.1.2 Ammonium Bisulfide Corrosion (Alkaline Sour Water) 5-9 5.1.1.3 Ammonium Chloride Corrosion . 5-13 5.1.1.4 Hydrochloric Acid (HCl) Corrosion 5-16 5.1.1.5 High Temp H2/H2S Corrosion 5-19 5.1.1.6 Hydrofluoric (HF) Acid Corrosion 5-23 5.1.1.7 Naphthenic Acid Corrosion (NAC) . 5-31 5.1
27、.1.8 Phenol (Carbolic Acid) Corrosion 5-35 5.1.1.9 Phosphoric Acid Corrosion 5-37 5.1.1.10 Sour Water Corrosion (Acidic) . 5-39 5.1.1.11 Sulfuric Acid Corrosion 5-41 5.1.1.12 Aqueous Organic Acid Corrosion 5-45 5.1.2 Environment-Assisted Cracking . 5-49 5.1.2.1 Polythionic Acid Stress Corrosion Crac
28、king (PASCC) 5-49 5.1.2.2 Amine Stress Corrosion Cracking . 5-55 5.1.2.3 Wet H2S Damage (Blistering/HIC/SOHIC/SSC) 5-60 5.1.2.4 Hydrogen Stress Cracking - HF 5-70 5.1.2.5 Carbonate Stress Corrosion Cracking (ACSCC) 5-72 5.1.3 Other Mechanisms . 5-83 5.1.3.1 High Temperature Hydrogen Attack (HTHA) .
29、5-83 5.1.3.2 Titanium Hydriding 5-90 5.2 Process Unit PFDs 5-94 ANNNEX A . A-1 A.1 Introduction . A-3 A.2 Inquiry Format . A-3 1-1 SECTION 1 INTRODUCTION AND SCOPE 1.1 Introduction 1-3 1.2 Scope 1-3 1.3 Organization and Use 1-4 1.4 References 1-4 1.5 Definitions of Terms 1-4 1.6 Technical Inquires 1
30、-4 This page intentionally left blank. Damage Mechanisms Affecting Fixed Equipment in the Refining Industry 1-3 _ 1.1 Introduction The ASME and API design codes and standards for pressurized equipment provide rules for the design, fabrication, inspection, and testing of new pressure vessels, piping
31、systems, and storage tanks. These codes do not address equipment deterioration while in service and that deficiencies due to degradation or from original fabrication may be found during subsequent inspections. Fitness-For-Service (FFS) assessments are quantitative engineering evaluations that are pe
32、rformed to demonstrate the structural integrity of an in-service component containing a flaw or damage. The first step in a fitness-for-service assessment performed in accordance with API 579-1/ASME FFS-1 is to identify the flaw type and the cause of damage. Proper identification of damage mechanism
33、s for components containing flaws or other forms of deterioration is also the first step in performing a Risk-Based Inspection (RBI) in accordance with API RP 580. When conducting an FFS assessment or RBI study, it is important to determine the cause(s) of the damage or deterioration observed, or an
34、ticipated, and the likelihood and degree of further damage that might occur in the future. Flaws and damage that are discovered during an in-service inspection can be the result of a pre-existing condition before the component entered service and/or could be service-induced. The root causes of deter
35、ioration could be due to inadequate design considerations including materials selection and design details, or the interaction with aggressive environments/conditions that the equipment is subjected to during normal service or during transient periods. One factor that complicates an FFS assessment o
36、r RBI study for refining and petrochemical equipment is that material/environmental condition interactions are extremely varied. Refineries and chemical plants contain many different processing units, each having its own combination of aggressive process streams and temperature/pressure conditions.
37、In general, the following types of damage are encountered in petrochemical equipment: a) General and local metal loss due to corrosion and/or erosion b) Surface connected cracking c) Subsurface cracking d) Microfissuring/microvoid formation e) Metallurgical changes Each of these general types of dam
38、age may be caused by a single or multiple damage mechanisms. In addition, each of the damage mechanisms occurs under very specific combinations of materials, process environments, and operating conditions. 1.2 Scope This recommended practice provides general guidance as to the most likely damage mec
39、hanisms affecting common alloys used in the refining and petrochemical industry and is intended to introduce the concepts of service-induced deterioration and failure modes. These guidelines provide information that can be utilized by plant inspection personnel to assist in identifying likely causes
40、 of damage; to assist with the development of inspection strategies; to help identify monitoring programs to ensure equipment integrity. The summary provided for each damage mechanism provides the fundamental information required for an FFS assessment performed in accordance with API 579-1/ASME FFS-
41、1 or an RBI study performed in accordance with API RP 580. The damage mechanisms in this recommended practice cover situations encountered in the refining and petrochemical industry in pressure vessels, piping, and tankage. The damage mechanism descriptions are not intended to provide a definitive g
42、uideline for every possible situation that may be encountered, and the reader may need to consult with an engineer familiar with applicable degradation modes and failure mechanisms, particularly those that apply in special cases. 1-4 API Recommended Practice 571 _ This document incorporates informat
43、ion gathered from major incidents in the refining industry and is intended to be consistent with applicable API documents as well as other related best-industry standards and practices. It is intended to provide guidance to inspection personnel but should not be considered the final technical basis
44、for damage mechanism assessment and analysis. 1.3 Organization and Use The information for each damage mechanism is provided in a set format as shown below. This recommended practice format facilitates use of the information in the development of inspection programs, FFS assessment and RBI applicati
45、ons. a) Description of Damage a basic description of the damage mechanism. b) Affected Materials a list of the materials prone to the damage mechanism. c) Critical Factors a list of factors that affect the damage mechanism (i.e. rate of damage). d) Affected Units or Equipment a list of the affected
46、equipment and/or units where the damage mechanism commonly occurs is provided. This information is also shown on process flow diagrams for typical process units. e) Appearance or Morphology of Damage a description of the damage mechanism, with pictures in some cases, to assist with recognition of th
47、e damage. f) Prevention / Mitigation methods to prevent and/or mitigate damage. g) Inspection and Monitoring recommendations for NDE for detecting and sizing the flaw types associated with the damage mechanism. h) Related Mechanisms a discussion of related damage mechanisms. i) References a list of
48、references that provide background and other pertinent information. Damage mechanisms that are common to a variety of industries including refining and petrochemical, pulp and paper, and fossil utility are covered in Section 4.0. Damage mechanisms that are specific to the refining and petrochemical
49、industries are covered in Section 5. In addition, process flow diagrams are provided in 5.2 to assist the user in determining primary locations where some of the significant damage mechanisms are commonly found. 1.4 References Standards, codes and specifications cited in the recommended practices are listed in Section 2. References to publications that provide background a
