DOCSLIB.ORG

High Temperature Corrosion and Corrosion Protection Part 3: High Temperature Corrosion and Corrosion Protection of the Boilers in Waste to Energy Plants

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
High Temperature Corrosion and Corrosion Protection Part 3: High Temperature Corrosion and Corrosion Protection of the Boilers in Waste to Energy Plants [Seminar] Lecture on Fundamental Aspects of High Temperature Corrosion and Corrosion Protection Part 3: High Temperature Corrosion and Corrosion Protection of the Boilers in Waste to Energy Plants Manabu NOGUCHI*, and Hiroshi YAKUWA** Abstract One of the characteristics of incinerators is that the waste used as fuel contains chlorine in high concentration. The chlorine reacts with alkaline metal, etc., to form a chloride, which is deposited as ash adhesion on boiler heat transfer tubes and the like. When this adhered ash melts, the corrosion environment is significantly deteriorated. In addition, the soot blow used to remove the adhered ash promotes the destruction of the corrosion scale and accelerates the metal loss of the heat transfer tubes. The ash adhesion behavior depends on temperature, and chloride is concentrated where the exhaust gas temperature is high, deteriorating the corrosion environment. Accordingly, a good understanding of the adhesion behavior and an appropriate design for the corrosion environment are required in order to prevent the corrosion of heat transfer tubes. This paper explains the metal loss behavior mainly due to the influence of ash adhesion, and also describes examples of corrosion behavior and corrosion protection in the actual plants. Keywords: High temperature corrosion, Chlorination, Molten salt, Waste to Energy Plant, Superheater, Boiler, Ash adhesion, Predication of corrosion rate 1. Introduction 2. Boilers for waste-to-energy plants Parts 3 and 4 of this lecture discuss high-temperature 2.1 Characteristics of waste-to-energy plants corrosion associated with incinerators. This part Figure 3-11) shows an example of a waste-to-energy focuses on boilers used in waste-to-energy plants, and plant. The plant shown in the figure uses a grate-type the next part, on other equipment. incinerator, a typically used incinerator at present. While thermal power plants practically use steam at Other than this type of incinerator, there are fluidized 600 °C or higher, in waste-to-energy plants, the steam bed furnaces, gasification melting furnaces, etc. The temperature is around 400 °C, which is significantly combustion method varies depending on the incinerator lower than the former. Waste-based power is a type. However, any type of incineration system is significant social need as renewable energy, and almost the same in configuration basically. Waste fed efficient power generation is also required. However, into the pit is burned in the incinerator. The heat is high-temperature corrosion of the heat transfer tubes recovered by the boiler, economizer, etc. Then the is a technical problem, which makes it difficult to use exhaust gas is purified using environmental measures higher-temperature, higher-pressure steam. This part such as exhaust gas treatment and dust removal, and of the lecture explains corrosion of boilers in waste-to- is discharged from the smokestack. energy plants and corrosion protection. In addition to a large amount of ash, waste contains chlorine and sulfur, which act as oxidizers; the amount of chlorine is much larger than that of sulfur, which is the prominent characteristic of waste2). Chlorine reacts * Ebara Enviromantal Plant Co., Ltd. with alkali metals or heavy metals to form chlorides. ** Technologies, R&D Division Ebara Engineering Review No. 253（2017-4） ─ ─1 Lecture on Fundamental Aspects of High Temperature Corrosion and Corrosion Protection Part 3: High Temperature Corrosion and Corrosion Protection of the Boilers in Waste to Energy Plants Flow of waste High-pressure steam header Flow of flue gas Flow of air Steam condenser Flow of ash and dust Steam turbine Flow of steam generator Chemical silo Condensate Flow of water tank Boiler Recycled Economizer water To atmosphere Waste crane Bag filter Superheater Deodorization Desuperheater unit Waste hopper Incinerator Stack Secondary blower Induced draft fan Drying stoker From other Platform Post-combustion stoker incinerators Combustion Forced draft Refuse stoker fan feeder Collected dust conveyor Weighing scale From other incinerators Collected dust and ash handling system Fallen ash conveyor Ash conveyor To the final landfill site Air preheater Input bunker Storage bunker Ash Solidified bunker material pit Fig. 3-1 Flowchart of a waste-to-energy plant1) Then, ash containing such chlorides flies from the other hand, in the superheater, ash adhesion greatly incinerator to the following equipment, adhering to the varies depending on the area, in general. Ash adhesion heating surface of the boiler. In general, to minimize is maximized at the superheater entrance (d). In some such ash adhesion, the exhaust gas is turned 180° at cases, adhering ash grows in a comb-like shape toward the bottom of the boiler to detach adhering ash, with a the upstream of the gas flow. Toward the downstream superheater installed in the third path of the boiler. of the gas flow, however, the amount of adhering ash Figure 3-2 shows an example of ash adhering to the gradually decreases with almost no adhering ash boiler of an actual incineration system for industrial observed at the superheater exit (f) in many cases. Ash waste. Adhering ash is partially removed from the adhesion may not only decrease the heat transfer upper area (a) of the water tube of the boiler. However, efficiency of boilers but also cause gas blockage in a no significant difference in appearance is observed superheater. Therefore, it is usual that adhering ash is among the upper, middle, and lower areas. On the periodically removed during operation using soot blowing which blows steam or the like. Tube side 2.2 Characteristics of adhering ash Gas side Water tube Adhering of ash affects corrosion of incinerators in particular. The composition of adhering ash is not constant and is often different between the gas side Flue gas and the water tube side. The photo of ash adhering to (a) Upper area (f) SH the water tube (shown in Figure 3-2 (a) to (c)) indicates that a hard cream-colored substance like a crispy rice SH bar is observed on the gas side. However, inside the (b) Middle area SH (e) above substance, there is a light green dense substance, inside which there is a reddish brown corrosion SH product covering the surface of the water tube. The ash adhering to the superheater (shown in Figure 3-2 (c) Lower area (d) Boiler diagram (d) to (f)) is not as clear as the ash that adheres to the ：Sampling locations SH：Superheater water tube, but the properties of gas side and the tube Fig. 3-2 Example of ash adhering to the boiler of an actual waste-to-energy plant side are different. Except the ash in Area (f), where the Ebara Engineering Review No. 253（2017-4） ─ ─2 Lecture on Fundamental Aspects of High Temperature Corrosion and Corrosion Protection Part 3: High Temperature Corrosion and Corrosion Protection of the Boilers in Waste to Energy Plants Table 3-1 Analysis results of adhering ash3) Water tube Superheater Location Collected (a) (b) (c) (d) (e) (f) ash Side Tube Gas Tube Gas Tube Gas Tube Gas Tube Gas Whole N＝11 Na 5.79 2.75 5.36 2.38 6.00 3.46 15.18 1.42 1.83 1.60 3.51 0.96 Al 1.61 2.56 2.32 2.99 4.01 4.80 2.49 2.59 2.69 2.96 2.60 4.12 Si 2.03 2.40 1.97 2.11 2.02 1.90 5.37 6.22 5.52 6.88 5.85 20.62 S 8.43 12.18 8.74 12.68 11.90 12.60 2.53 3.31 5.55 3.43 5.62 2.17 Cl 12.81 5.16 13.35 4.52 4.40 3.71 23.06 14.32 14.29 11.48 10.25 2.69 K 6.41 0.82 8.66 1.13 6.64 3.37 5.73 2.33 2.67 1.90 3.01 1.16 Ca 6.59 28.46 7.46 26.60 12.37 20.24 21.06 30.44 27.72 29.01 19.96 15.43 Cu 7.69 1.31 8.56 1.60 5.79 3.81 3.98 3.26 7.24 2.37 7.16 0.61 Zn 2.39 1.23 2.38 1.24 2.25 1.81 2.00 1.71 1.78 1.79 2.46 0.70 Pb 22.18 0.09 14.86 0.09 6.85 0.73 0.73 0.31 0.21 0.18 2.86 0.14 Endothermic 344 ℃ 678 ℃ 361 ℃ 658 ℃ 466 ℃ 518 ℃ 527 ℃ 562 ℃ 534 ℃ 536 ℃ N.D. peak pH 6.2 10.13 5.81 9.82 6.78 8.56 amount of adhering ash is small, we identified the ash area. The higher the exhaust gas temperature becomes, collected at each location as the gas side one or the the higher concentration heavy metal chlorides, tube side one, and analyzed them. Table 3-13) shows the especially Pb, tend to have. On the other hand, as well analytical results. The ash on the gas side contained as Ca, S tends to be more concentrated mainly in the almost no component of heat transfer tubes, such as Fe. ash adhering to the water tube on the gas side. It is On the other hand, the ash on the tube side contained considered that S is concentrated as Ca sulfate in the a large amount of corrosion products and up to nearly areas where the exhaust gas and surface temperatures 50 % of the heat transfer tube components. For this are high. reason, these values removed Fe, Cr, and Ni and As described above, the temperature range of converted to 100 %. The table also shows the results of concentration varies depending on the compound, and analysis on the (collective) ash taken from the chlorides, which have a significant effect on corrosion, equipment following the boiler, which is considered to are likely to be more concentrated in the areas where have passed through the boiler.
Load more

Recommended publications
  • Introduction to Corrosion Your Friendly TSC Corrosion Staff
    Introduction to Corrosion Your Friendly TSC Corrosion Staff: Daryl Little Ph.D. Materials Science & Engineering [email protected] 303-445-2384 Lee Sears Ph.D. Materials Science & Engineering [email protected] 303-445-2392 Jessica Torrey Ph.D. Materials Science & Engineering [email protected] 303-445-2376 Roger Turcotte, PE, CPS Materials Engineer [email protected] 303-445-2383 What is Corrosion? CORROSION IS DEFINED AS THE DETERIORATION OF A MATERIAL AND/OR ITS PROPERTIES CAUSED BY A REACTION WITH ITS ENVIRONMENT. Why is Corrosion a Major Concern? First and Most Important- Public Safety! • June 28, 1983: Mianus River Bridge, Greenwich, CT (TIME photo archive) • Northbound 3-lane section of I-95 bridge collapsed, killing 3 people • “Pin and Hanger” design was compromised when pin was displaced due to extensive corrosion of load-bearing components, amplified by salt from road maintenance. • Inadequate maintenance procedures were also cited as a contributing factor. • Subsequent to this failure, extensive inspections were conducted on this type of bridge across the country, and design modification were made to prevent catastrophic failures of this kind. First and Most Important- Public Safety! • April 28,1988, Aloha Airlines 737 Accident • 18 feet of cabin skin ripped off, resulting in the death of a flight attendant and many injuries • Attributed to corrosion fatigue Reclamation Case Study- Folsom Dam • Spillway gate No. 3 was damaged beyond repair, but no flooding occurred. • Replacement of No. 3 and repair of other gates cost ~$20 million and required 40% drainage of reservoir • Cause of failure: Increasing corrosion at the trunnion pin-hub interface raised the coefficient of friction and, therefore, the bending stress in the strut and the axial force in the brace exceeded limits.
    [Show full text]
  • Of the Periodic Table
    of the Periodic Table teacher notes Give your students a visual introduction to the families of the periodic table! This product includes eight mini- posters, one for each of the element families on the main group of the periodic table: Alkali Metals, Alkaline Earth Metals, Boron/Aluminum Group (Icosagens), Carbon Group (Crystallogens), Nitrogen Group (Pnictogens), Oxygen Group (Chalcogens), Halogens, and Noble Gases. The mini-posters give overview information about the family as well as a visual of where on the periodic table the family is located and a diagram of an atom of that family highlighting the number of valence electrons. Also included is the student packet, which is broken into the eight families and asks for specific information that students will find on the mini-posters. The students are also directed to color each family with a specific color on the blank graphic organizer at the end of their packet and they go to the fantastic interactive table at www.periodictable.com to learn even more about the elements in each family. Furthermore, there is a section for students to conduct their own research on the element of hydrogen, which does not belong to a family. When I use this activity, I print two of each mini-poster in color (pages 8 through 15 of this file), laminate them, and lay them on a big table. I have students work in partners to read about each family, one at a time, and complete that section of the student packet (pages 16 through 21 of this file). When they finish, they bring the mini-poster back to the table for another group to use.
    [Show full text]
  • The Corrosion of Iron and Its Alloys
    UNIVERSITY OF ILLINOIS LIBRARY Class Book Volume ^ M rlO-20M -r - 4 'f . # f- f f > # 4 Tjh- |fe ^ lINlN^ ' ^ ^ ^* 4 if i i if i^M^'M^i^ H II I li H : : \ ; . tNP* i rHt . ; ^ * 41 W 4s T »f 4 ^ -f 4. f -4- * i 4 4 : * 1- 1 4 % 3**:- ->^> A 4- - 4- + * ,,4 * 4" T '* * 4 -f- ± f * * 4- 4 -i * 4 ^ 4* -f + > * * + 1 f * 4 # * .-j* * + * ^ £ - jjR ^^MKlF^ f ^ f- + f v * IT :/^rV :,HH':,* ^ 4 * ^ 4 -f- «f f 4- 4 4 ,,rSK|M| ; * 4 # ; || II I II II f || .- -fr 4* , «g* 4 I. ^ vmiM 4- THE CORROSION OF IRON AND ITS ALLOYS BY RUSSELL SAMUEL HOWARD THESIS FOR THE DEGREE OF BACHELOR OF SCIENCE IN CHEMISTRY IN THE COLLEGE OF SCIENCE OF THE UNIVERSITY OF ILLINOIS Presented June, 1910 UNIVERSITY OF ILLINOIS June 1 1910 THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Russel Samuel Howard ENTITLED The Corrosion of Iron and It s Alloys IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF Bachelor of Scienc e In Chemistry Instructor in Charge Approved: HEAD OF DEPARTMENT OF 167529 Digitized by the Internet Archive in 2013 ^ttp://archive.org/details/corrosionofironiOOhowa CORROSION OF IRON AND ITS ALLOYS. In nature everything is subject to deterioration, varying from those substances decomposed by light to those only decomposed by the strong- est agents. The deterioration of metals as effected by alloying is the sub- ject of this paper and perhaps .no subject is of more vital importance to the builder and interest to the chemist than this one of corrosion.
    [Show full text]
  • INFLUENCE of Ph on the LOCALIZED CORROSION of IRON
    BNL 39687 MIT/BNL-86-6 INFORMAL REPORT INFLUENCE OF pH ON THE LOCALIZED CORROSION OF IRON MIT/BNL-86-6 BNL—39687 DE87 010452 R. Webley and R. Henry Consultants: H. Isaacs and G. Cragnolino June 1986 BROOKHAVEN STATION SCHOOL OF CHEMICAL ENGINEERING PRACTICE MASSACHUSETTS INSTITUTE OF TECHNOLOGY R.O. SPROULL. DIRECTOR F.J. HRACH, ASSISTANT DIRECTOR DEPARTMENT OF APPLIED SCIENCE BROOKHAVEN NATIONAL LABORATORY ASSOCIATED UNIVERSITIES. INC. UPTON, LONG ISLAND, NEW YORK 11973 UNDER CONTRACT NO. DE-AC02-76CH00016 WITH THE UNITED STATES DEPARTMENT OF ENERGY MASTER DISTRIBUTION OF TMiS DOCUMENT IS UNLIMITED DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, nor any of their contractors, subcontrac- tors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or use- fulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency, contractor or subcontractor thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency, contractor or subcontractor thereof. ABSTRACT The influence of pH on the pitting corrosion of iron in chloride and sul- fate solutions was determined using two artificial pit apparatuses to obtain the pH near the surface of the pit bottom.
    [Show full text]
  • The Effects and Economic Impact of Corrosion
    © 2000 ASM International. All Rights Reserved. www.asminternational.org Corrosion: Understanding the Basics (#06691G) CHAPTER 1 The Effects and Economic Impact of Corrosion CORROSION is a natural process. Just like water flows to the lowest level, all natural processes tend toward the lowest possible energy states. Thus, for example, iron and steel have a natural tendency to com- bine with other chemical elements to return to their lowest energy states. In order to return to lower energy states, iron and steel frequently combine with oxygen and water, both of which are present in most natu- ral environments, to form hydrated iron oxides (rust), similar in chemi- cal composition to the original iron ore. Figure 1 illustrates the corro- sion life cycle of a steel product. Finished Steel Product Air & Moisture Corrode Steel & Form Smelting & Rust Refining Adding Giving Up Energy Energy Mining Ore Iron Oxide (Ore & Rust) Fig. 1 The corrosion cycle of steel © 2000 ASM International. All Rights Reserved. www.asminternational.org Corrosion: Understanding the Basics (#06691G) 2 Corrosion: Understanding the Basics The Definition of Corrosion Corrosion can be defined in many ways. Some definitions are very narrow and deal with a specific form of corrosion, while others are quite broad and cover many forms of deterioration. The word corrode is de- rived from the Latin corrodere, which means “to gnaw to pieces.” The general definition of corrode is to eat into or wear away gradually, as if by gnawing. For purposes here, corrosion can be defined as a chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its proper- ties.
    [Show full text]
  • Metal Contamination of Drinking Water from Corrosion of Distribution Pipes
    Environmental Pollution 57 (1989) 167-178 Metal Contamination of Drinking Water from Corrosion of Distribution Pipes Ibrahim A. Alam & Muhammad Sadiq Water Resources and Environment Division, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia (Received 24 February 1988; revised version received 22 September 1988; accepted 26 September 1988) A BS TRA C T The objectives of th& study were to evaluate metal contamination of drinking water resulting from the corrosion of distribution pipes and its significance to human health. A community in Dhahran, which is served from its own desalination facilities, was chosen for this study. About 150 drinking water samples were collected and analyzed for metal concentrations using an inductively coupled argon plasma analyzer. It wasjbund that copper, iron and zinc in the drinking water increased during its transportation from the desalination plant to the consumers. This increase was related to the length and material of distribution pipes. Concentrations of copper and zinc were increased during overnight storage of water in the appliances. Metal concentrations found in this study are discussed with reference to human health. INTRODUCTION Drinking water in Saudi Arabia is mainly obtained by desalting seawater or ground water. After desalination, the finished water is generally mixed with ground water, disinfected, pH adjusted, and transported through the distribution network to the consumers. Drinking water supplies contain variable amounts of metals (Bostrom & Wester, 1967; Durum, 1974; Andermann & Shapir, 1975). Several of these 167 Environ. Pollut. 0269-7491/89/$03'50 O 1989 Elsevier Science Publishers Ltd, England. Printed in Great Britain 168 lbrahim A.
    [Show full text]
  • Corrosion of Carbon Steel in Marine Environments: Role of the Corrosion Product Layer
    corrosion and materials degradation Review Corrosion of Carbon Steel in Marine Environments: Role of the Corrosion Product Layer Philippe Refait 1,*, Anne-Marie Grolleau 2, Marc Jeannin 1, Celine Rémazeilles 1 and René Sabot 1 1 Laboratoire des Sciences de l’Ingénieur pour l’Environnement (LaSIE), UMR 7356 CNRS-La Rochelle Université, Av. Michel Crépeau, CEDEX 01, F-17042 La Rochelle, France; [email protected] (M.J.); [email protected] (C.R.); [email protected] (R.S.) 2 Naval Group Research, BP 440, CEDEX 50104 Cherbourg-Octeville, France; [email protected] * Correspondence: [email protected]; Tel.: +33-5-46-45-82-27 Received: 5 May 2020; Accepted: 30 May 2020; Published: 3 June 2020 Abstract: This article presents a synthesis of recent studies focused on the corrosion product layers forming on carbon steel in natural seawater and the link between the composition of these layers and the corrosion mechanisms. Additional new experimental results are also presented to enlighten some important points. First, the composition and stratification of the layers produced by uniform corrosion are described. A focus is made on the mechanism of formation of the sulfate green rust because this compound is the first solid phase to precipitate from the dissolved species produced by the corrosion of the steel surface. Secondly, localized corrosion processes are discussed. In any case, they involve galvanic couplings between anodic and cathodic zones of the metal surface and are often associated with heterogeneous corrosion product layers. The variations of the composition of these layers with the anodic/cathodic character of the underlying metal surface, and in particular the changes in magnetite content, are thoroughly described and analyzed to enlighten the self-sustaining ability of the process.
    [Show full text]
  • Enghandbook.Pdf
    785.392.3017 FAX 785.392.2845 Box 232, Exit 49 G.L. Huyett Expy Minneapolis, KS 67467 ENGINEERING HANDBOOK TECHNICAL INFORMATION STEELMAKING Basic descriptions of making carbon, alloy, stainless, and tool steel p. 4. METALS & ALLOYS Carbon grades, types, and numbering systems; glossary p. 13. Identification factors and composition standards p. 27. CHEMICAL CONTENT This document and the information contained herein is not Quenching, hardening, and other thermal modifications p. 30. HEAT TREATMENT a design standard, design guide or otherwise, but is here TESTING THE HARDNESS OF METALS Types and comparisons; glossary p. 34. solely for the convenience of our customers. For more Comparisons of ductility, stresses; glossary p.41. design assistance MECHANICAL PROPERTIES OF METAL contact our plant or consult the Machinery G.L. Huyett’s distinct capabilities; glossary p. 53. Handbook, published MANUFACTURING PROCESSES by Industrial Press Inc., New York. COATING, PLATING & THE COLORING OF METALS Finishes p. 81. CONVERSION CHARTS Imperial and metric p. 84. 1 TABLE OF CONTENTS Introduction 3 Steelmaking 4 Metals and Alloys 13 Designations for Chemical Content 27 Designations for Heat Treatment 30 Testing the Hardness of Metals 34 Mechanical Properties of Metal 41 Manufacturing Processes 53 Manufacturing Glossary 57 Conversion Coating, Plating, and the Coloring of Metals 81 Conversion Charts 84 Links and Related Sites 89 Index 90 Box 232 • Exit 49 G.L. Huyett Expressway • Minneapolis, Kansas 67467 785-392-3017 • Fax 785-392-2845 • [email protected] • www.huyett.com INTRODUCTION & ACKNOWLEDGMENTS This document was created based on research and experience of Huyett staff. Invaluable technical information, including statistical data contained in the tables, is from the 26th Edition Machinery Handbook, copyrighted and published in 2000 by Industrial Press, Inc.
    [Show full text]
  • Corrosion Glossary C
    Corrosion Glossary calcareous coating or deposit clad metal A layer consisting of a mixture of A composite metal containing, two calcium carbonate and magnesium or more layers that have been hydroxide deposited on surfaces bonded together. The bonding may being cathodically protected because have been accomplished by co- of the increased pH adjacent to the rolling, co-extrusion, welding, protected surface. diffusion bonding, casting, heavy calomel electrode chemical deposition, heavy An electrode widely used as a electroplating, or explosive cladding. reference electrode of known cleavage potential in electrometric Splitting (fracture) of a crystal on a measurement of acidity and crystallographic plane of low index. alkalinity, corrosion studies, cleavage fracture voltammetry, and measurement of A fracture, usually of polycrystalline the potentials of other electrodes. metal, in which most of the grains See also electrode potential, have failed by cleavage, resulting in reference electrode, and saturated bright reflecting facets. It is calomel electrode. associated with low-energy brittle calorizing fracture. Imparting resistance to oxidation to cold cracking an iron or steel surface by heating in A type of weld cracking that usually aluminum powder at 800 to 1000 ºC occurs below 203 ºC (400 "F). (1470 to 1830 ºF). Cracking may occur during or after carbonitriding cooling to room temperature, A case hardening process in which a sometimes with a considerable time suitable ferrous material is heated delay. Three factors combine to above the lower transformation produce cold cracks: stress (for temperature in a gaseous example, from thermal expansion atmosphere of such composition as and contraction). hydrogen (from to cause simultaneous absorption of hydrogen-containing welding carbon and nitrogen by the surface consumables), and a susceptible and, by diffusion, create a micro.structure (plate martensite is concentration gradient.
    [Show full text]
  • Drinking Water Problems: Corrosion Mark L
    E-616 7/12 Drinking Water Problems: Corrosion Mark L. McFarland, Tony L. Provin, and Diane E. Boellstorff* orrosion is one of the most common problems affecting domestic water Csupplies. Chemical processes slowly dissolve metal, causing plumbing pipes, fixtures and water-using equipment to deteriorate and fail. Corrosion can cause three types of damage: • The entire metal surface gradually thins and red stains appear in iron or steel plumbing systems or blue-green stains in copper and brass plumbing systems (Fig. 1). Figure 2. Pinhole leaks in copper tubing caused by internal corrosion. • Deep pits appear that can penetrate pipe or tank walls. This type of corrosion may not add significant amounts of iron or copper to the water, but can eventually perforate a pipe or tank, and cause potentially major water damage to a home or business (Fig. 2). • Copper or other metals oxidize in a process similar to the rusting of steel. It often reduces water flow through supply lines Figure 1. Corrosion at a connection on a water heater and destroys water valves and other water indicated by the blue-green color. control surfaces, creating leaks inside and outside of valves and faucets. This type of Professor and Extension Water Quality Coordinator, Professor and corrosion is not necessarily caused by water Extension Water Testing Laboratory Director, Assistant Professor and chemistry, but by exposure to soil or other Extension Water Resources Specialist, Texas AgriLife Extension Service, The Texas A&M System corrosive environments. What health problems Two common tests can determine if water is likely to be corrosive: the Langelier Saturation can corrosion cause? Index (LSI) and the Ryzner Stability Index (RSI).
    [Show full text]
  • Characteristics and Applications of High Corrosion Resistant Titanium Alloys
    NIPPON STEEL & SUMITOMO METAL TECHNICAL REPORT No. 106 JULY 2014 Technical Report UDC 669 . 295 . 018 . 8 Characteristics and Applications of High Corrosion Resistant Titanium Alloys Hideya KAMINAKA* Masaru ABE Satoshi MATSUMOTO Kinichi KIMURA Hiroshi KAMIO Abstract In this paper, the characteristics of TICOREX and SMIACE TM which corrosion resist­ ance is enhanced by the addition of small amount of platinum group elements, and the ap­ plications of the alloys to various corrosive environment are outlined. TICOREX is a fine TM Ti2 (Ni1­xRux) phase precipitated Ti alloy, and SMIACE is a Pd solid solution alloy of the α­Ti phase. Both alloys exhibit an excellent corrosion resistance because low hydrogen over­ potential of platinum group element makes alloy’s corrosion potential more noble and the surface passive film more stable. TICOREX has an economical advantage due to addition of Ru, the cheapest platinum group element, but are not suitable for severe processing due to precipitation of fine compounds. On the other hand, SMIACE TM has an excellent workabil­ ity and processing into complex shapes, because Pd is solid­soluted and the precipitates are not present. Two type corrosion­resistant titanium alloys can be proposed appropriately de­ pending on whether the use needs workability or economical benefit. These alloys have been applied to heat exchange gas cooler of seawater, refining autoclave inner wall materials, salt production plant, brine electrolyzer, etc., and the further expansion in the future is expected. 1. Introduction uniform corrosion resistance of the Gr.7 titanium alloy to non-oxi- Commercial pure titanium forms a very stable passive film on its dizing acids have been greatly improved, compared to those of pure surface, and therefore exhibits better corrosion resistance than stain- titanium, the material is costly because of the addition of about less steel and Ni-based alloys in neutral chloride and oxidizing acid 0.15% Pd within the platinum group of elements.
    [Show full text]
  • How Zinc Protects Steel
    3. Corrosion – Mechanisms, Prevention, and Testing GalvInfoNote How Zinc Protects Steel 3.1 REV 1.2 DEC 2017 Introduction Steel sheet is a very versatile product. It comes in many sizes and types, and is applied to many end uses including steel buildings, automotive panels, signs, and appliances. The low cost, strength and formability of steel sheet are some reasons for its widespread use. Unfortunately it is prone to rusting, a phenomenon that causes the surface to become unsightly and, over time, may contribute to product failure. For this reason, steel is protected by a variety of methods ranging from internal alloying, e.g., stainless steel, to coating with metallic coatings and/or paints. Corrosion is an electrochemical process that, in the case of steel sheet, oxidizes the iron in the steel and causes the sheet to become thinner over time. Oxidation, or rusting, occurs as a result of the chemical reaction between steel and oxygen. Oxygen is always present in the air, or can be dissolved in moisture on the surface of the steel sheet. During the rusting process, steel is consumed during the corrosion reaction, converting iron to corrosion products. In the case of most low-carbon steel sheet products, iron oxide (rust) develops on the surface and is not protective because it does not form as a continuous, adherent film. Instead, it spalls, exposing fresh iron to the atmosphere that, in turn, allows more corrosion to occur. This aspect of steel sheet behaviour is very undesirable, both aesthetically and from the aspect of service life. Eventually, often sooner than desired, steel sheet corrodes sufficiently to unduly shorten its service life, i.e., loss of structural strength, or perforation and intrusion of water.
    [Show full text]