Expert contributors to this book provide a wealth of insider knowledge and engineering expertise that complements their explanations and advice. Case Studies from areas such as pipelines, tankers, packaging and chemical processing equipment ensure that the reader understands the practical measures that can be put in place to save money, lives and the environment.
- Introduces the reader to the effects of environmental degradation on a wide range of materials, including metals, plastics, concrete, wood and textiles
- Describes the kind of degradation that effects each material and how best to protect it
- Includes case studies that show how organizations, from small consulting firms, to corporate giants design and manufacture products that are more resistant to environmental effects
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Handbook of Environmental Degradation of Materials
By Myer Kutz
ElsevierCopyright © 2012 Elsevier Inc.
All rights reserved.
Analysis of Failures of Metallic Materials Due to Environmental Factors
Corrosion and Metallurgical Consultancy Centre, Mumbai, India
1.1 Introduction 3
1.2 Classification of Failures 3
1.3 Analysis of Failures 5
1.4 Case Histories of Environmental-Related Failures 6
1.5 Conclusions 31
In a Handbook of Environmental Degradation of Materials, inclusion of the chapter "Analysis of Failures Due to Environmental Factors" assumes great importance. This is because unless the failures are analyzed in a systematic, detailed manner, the main causative factor arising from the environment cannot be determined. If such determination is not made and appropriate remedial measures are not implemented, there is no guarantee that the failure would not repeat itself on the replaced structure, column, vessel, pipe, tube, and so forth. This chapter presents certain case studies of recent failures, analyzed by the author, attributable to environmental factors. All the case studies are concerned with process equipment used in chemical process industries and made of metallic materials, carbon steel, stainless steel or nickel base alloy.
1.2 Classification of Failures
The word "failure" in chemical process equipment denotes unexpected unsatisfactory behavior of the equipment leading to non-functioning with respect to desired operation within the design life period of the equipment. Such behavior is often referred to as "premature failure." The causative factors can be classified into two main categories:
1.2.1 Material/Manufacturing-Related Causes
These causes arise from defects in material of construction (MOC) of the equipment and the fabrication steps through which the material was shaped and processed to arrive at the desired equipment. This chapter will not discuss this category of causes.
1.2.2 Environment-Related Causes
These causes arise from the environment to which the equipment is exposed during service, both the internal chemical process medium and the external medium, such as the prevailing atmosphere, insulation, and so forth. The operation-related causes are closely linked to the environment in that failures arise if the actual operating conditions fall short of or exceed the specified limits.
1.2.3 Environment-Related Categories
The environmental factors can be further classified into five categories, as follows:
1. Deviations within the chemical composition of the fluid being handled in the chemical process, such as the following:
Condensation occurring within the vapor phase
Concentration of aggressive species suddenly increasing
2. Unexpected impurities present within the fluid being handled, such as the following:
Chloride and oxygen in boiler feed water
Sulfur in petroleum crude
3. Operating temperatures different from those designed and specified
Exceedingly high temperatures leading to creep, oxidation, sulfidation, etc.
4. Operating pressures different from those designed and specified, such as high pressures in autoclaves and boilers
5. The environment external to the process equipment becoming aggressive, such as marine and humid atmospheres attacking uninsulated external surfaces of the equipment
Insulations becoming wet and corrosive
1.2.4 Environmentally Induced Failures
The environmentally induced failures in process equipment can be also classified into the following, based on the final appearance or mode in which the failure presents itself:
1. High temperature failures (temperatures higher than the boiling point of the process medium to which the equipment is exposed)
f. Plastic deformation—yielding, warping, sagging, bowing, etc.
2. Ambient temperature failures (temperatures less than the above-mentioned boiling point)
a. Corrosion in its various forms
General uniform corrosion
Stress corrosion cracking (including hydrogen-related cracking)
Erosion corrosion by high velocity and by slurry movement
b. Overload mechanical failure
3. Low temperature failures (temperatures lower than ambient, including sub-zero)
a. Brittle mechanical failures at temperatures lower than ductile brittle transition temperature (DBTT)
1.3 Analysis of Failures
This chapter presents a few case studies illustrating some of the above-listed environmental factors leading to premature failures of chemical process equipment. Each failure has been analyzed by the author to the extent the case merits, so as to arrive at the actual cause of the failure and to make appropriate recommendations to avoid the repetition of the same failure in the future.
The detailed failure analysis involves roughly the following steps.
1.3.1 SITE Visit
Site visits are for the following purposes:
Inspect the failed equipment and also the nearby upstream and downstream equipment to the extent accessible.
Closely examine the failed area and record relevant features.
Obtain representative cut samples containing the failed spots and the failure features, and also samples from typical unfailed areas. Cutting of samples may not be possible and/or may not be necessary in many cases. Detailed records of the appearance of the failure must be relied upon in such cases, and at times such records are themselves sufficient. If necessary, non-destructive tests such as radiography, ultrasonic, or dye-penetrant tests need to be performed on the equipment in position at the failed locations.
Obtain representative samples of scales, deposits, corrosion products, etc. in loose or adherent contact with the inside surface (process side) of the equipment.
Thoroughly discuss with plant personnel the design, material of construction, specified and operating service conditions, and operational/inspection history of the failed equipment. The service conditions would include the chemical compositions of the fluids being handled, and the equipment's design, operating temperatures, and pressures. Variations in these factors over a meaningful period of time prior to the failure should also be noted.
1.3.2 Testing of Samples
Some of the more frequently used tests are listed below, but not all of these need to be performed. Depending upon the merit of each case, select from the following:
Non-destructive tests like radiography, ultrasonic, dye-penetrant, etc.
Chemical and/or X-ray diffraction analysis of both the metal and deposit samples
Mechanical tests—strength, ductility, hardness, toughness, etc.
Microscopic examination (optical and/or scanning)
The purpose of the tests is to trace the progress of the failure mode, to check the nature and purity of the metal and deposit samples, to determine whether any unusual impurity has been present in the medium, and to verify whether the equipment conforms to the stated specification under which it was designed, fabricated, and put to use.
1.3.3 Analysis, Interpretation, and Diagnosis of the Failure
The site observations and sample test results should be analyzed as a whole package. If necessary, support from published literature should be obtained. All these should be viewed together, with the aim of arriving at the right diagnosis and the root cause of the failure.
1.3.4 Submission of Failure Analysis Report
The report should contain the following:
Statement of why the said failure analysis was necessary, verifying that the failure was premature
Factual summary of the site observations and discussions
Actual sample test results
Interpretation, discussion and analysis of all the input information
Diagnosis of the failure
Explanation of all the observed symptoms using the stated diagnosis
Easily implementable, practical recommendations to prevent similar failures in the particular site
1.4 Case Histories of Environmental-Related Failures
This section deals with the actual case studies conducted by the author. In the presentation of each case study, the environmental factor that was responsible for the failure is discussed in detail. In all the cases, the material and manufacturing quality of the equipment were checked during the failure analysis procedure, and were found to be not responsible for any failures. Hence, the material and manufacturing quality of the equipment are not discussed here.
1.4.1 Failure of A Natural Gas Feed Preheater in a Fertilizer Plant
A fertilizer plant producing ammonia and urea uses natural gas (NG) as the feedstock. The waste heat from the primary reformer is used to heat various streams for different purposes. One such purpose is to preheat the feedstock NG from ambient temperature to some elevated temperature prior to different processing steps. The preheating is done in a set of parallel coils. The coils are made of seamless pipes of low-alloy steel conforming to ASTM Specification A-335/P-11, a chromium-molybdenum alloy steel containing 1.0–1.5% Cr, 0.44–0.65% Mo and 0.05–0.15% C. The pipes are of size 4.5 in. outside diameter (OD) and 6.03 mm wall thickness (WT). The pipes failed by leaking at several places after about 23 months of operation, and this was considered a premature failure.
Excerpted from Handbook of Environmental Degradation of Materials by Myer Kutz. Copyright © 2012 Elsevier Inc.. Excerpted by permission of Elsevier.
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Table of ContentsPart I: Analysis 1. Analysis of Failures of Metallic Materials due to Environmental Factors 2. Laboratory Assessment of Corrosion 3. Modeling of Corrosion Processes 4. Lifetime Predictions
Part II: Types of Degradation 5. Electrochemical Corrosion 6. Localized Corrosion 7. High-Temperature Oxidation 8. Weathering of Plastics 9. Chemical and Physical Aging of Polymers 10. Thermal Degradation of Plastics 11. Environmental Degradation of Reinforced Concrete 12. Biofouling and prevention, and biodeterioration and biodegradation of materials 13. Material Flammability 14. Fire Retardant Materials
Part III: Protective Measures 15. Cathodic Protection 16. Thermal Protective Clothing 17. Wood Protection 18. Materials Selection for Environmental Degradation Prevention
Part IV: Surface Engineering 19. The Intersection of Design, Manufacturing, and Surface Engineering (updated to include new coatings: (biomimetic, nanostructured and conductive polymers) 20. Nanostructured Surfaces and Nanomaterial Coatings 21. Protective Coatings for Aluminum Alloys 22. Anti-Corrosion Paints 23. Thermal and Environmental Barrier Coatings 24. Thermay Spray Coatings 25. Paint Weathering Tests 26. Coatings for Concrete Surfaces: Testing and Modeling 27. The importance of intrinsic defects in the protective behavior of coatings 28. Plastics Additives for Environmental Stability
Part V: Industrial Applications 29. Degradation of Spacecraft Materials 30. Cathodic Protection for Pipelines 31. Tanker Corrosion 32. Barrier Packaging Materials 33. Corrosion prevention and control programs for chemical processing equipment