Handbook of Hot-dip Galvanization E-Book

• Herausgeber: Wiley-VCH
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 587

Veröffentlichungsjahr: 2011

Beschreibung

Hot-dip galvanization is a method for coating steel workpieces with a protective zinc film to enhance the corrosion resistance and to improve the mechanical material properties. Hot-dip galvanized steel is the material of choice underlying many modern buildings and constructions, such as train stations, bridges and metal domes.

Based on the successful German version, this edition has been adapted to include international standards, regulations and best practices. The book systematically covers all steps in hot-dip galvanization: surface pre-treatment, process and systems technology, environmental issues, and quality management. As a result, the reader finds the fundamentals as well as the most important aspects of process technology and technical equipment, alongside contributions on workpiece requirements for optimal galvanization results and methods for applying additional protective coatings to the galvanized pieces.

With over 200 illustrated examples, step-by-step instructions, presentations and reference tables, this is essential reading for apprentices and professionals alike.

Leseprobe

Table of Contents

Cover

Related Titles

Title page

Copyright page

Preface to the Third German Edition

Acknowledgment

Preface to the Second German Edition

List of Contributors

1 Corrosion and Corrosion Protection

1.1 Corrosion

1.2 Corrosion Protection

Appendix 1.A

2 Historical Development of Hot-dip Galvanizing

3 Surface-preparation Technology

3.1 As-delivered Condition

3.2 Mechanical Surface-preparation Methods

3.3 Chemical Cleaning and Degreasing

3.4 Rinsing of the Parts

3.5 Pickling

3.6 Hot-dip Galvanizing Fluxes

Standards

Lifting Devices

4 Hot-dip Galvanizing and Layer-formation Technology

4.1 Process Variants

4.2 Layer Formation in Hot-dip Batch Galvanizing Between 435 °C and 620 °C

4.3 Liquid-metal-induced Embrittlement (LME)

4.4 After-treatment

5 Technical Equipment

5.1 Preliminary Planning

5.2 Layout Variants of Plants

5.3 Pretreatment Plant

5.4 Drying Furnaces

5.5 Galvanizing Furnaces

5.6 Galvanizing Kettle

5.7 Zinc Bath Housings

5.8 After-treatment

5.9 Unloading Area

5.10 Crossbeam Return

5.11 Crane Units

5.12 Filtration Plants

5.13 Semiautomatic Galvanizing Lines for Small Parts

5.14 Galvanizing Furnace with Ceramic Trough

5.15 Automatic Galvanizing Line for Small Parts

5.16 Pipe Galvanizing Line

5.17 Application of Vibrators

5.18 Energy Balance

5.19 Commissioning and Decommissioning of a Hot-dip Galvanizing Kettle, Kettle Change, Method of Operation

6 Environmental Protection and Occupational Safety in Hot-dip Galvanizing Plants

6.1 Rules and Measures Concerning Air-pollution Control

6.2 Measures for the Control of Air Pollution

6.3 Measuring Systems

6.4 Waste and Residual Materials

6.5 Noise

6.6 Occupational Safety

6.7 Practical Measures for Environmental Protection

7 Design and Manufacturing According to Hot-dip Galvanizing Requirements

7.1 General Notes

7.2 Requirements Regarding Surface Quality of the Basic Material

7.3 Dimensions and Weights of Material to be Galvanized

7.4 Containers and Tubular Constructions (Hollow Bodies)

7.5 Steel Profile Constructions

7.6 Steel Sheet and Steel Wire

7.7 Constructions of Hot-dip Galvanized Semifinished Products

7.8 Avoidance of Distortion and Crack Formation

7.9 Welding Before and After Hot-dip Galvanizing

7.10 Hot-dip Galvanizing of Small Parts

7.11 Reworking and Repair of Zinc Coatings

7.12 Hot-dip Galvanizing of Cast Materials

7.13 Local Avoidance of Zinc Adherence

7.14 Standards and Guidelines

7.15 Defects and Avoiding Defects

8 Quality Management in Hot-dip Galvanizing Companies

8.1 Why Quality Management?

8.2 Important Criteria

8.3 Structure of the QM System according to DIN EN ISO 9001 : 2000

8.4 Short Description of QM Elements Sections 4–8

8.5 Introduction of QM Systems

8.6 Trends

Acknowledgment

9 Corrosion Behavior of Zinc Coatings

9.1 Corrosion – Chemical Properties

9.2 Corrosion Caused by Atmosphere

9.3 Corrosion through Water

9.4 Corrosion in Soils

9.5 Corrosion Resistance to Concrete

9.6 Corrosion in Agricultural Facilities and Caused by Agricultural Products

9.7 Corrosion through Nonaqueous Media

9.8 Corrosion Protection Measures at Defective Spots

9.9 Examination of Corrosion Resistance and Quality Test

10 Coatings on Zinc Layers – Duplex-Systems

10.1 Fundamentals, Use, Main Fields of Application

10.2 Definitions of Terms

10.3 Protection Period of Duplex-Systems

10.4 Special Features of the Constructive Design of Components

10.5 Quality Requirements for the Zinc Coating for Protective Paint Layers

10.6 Surface Preparation of the Zinc Coating for the Protective Paint

10.7 Coating Materials, Protective Paint Systems

11 Economic Efficiency of Hot-dip Galvanizing

12 Examples of Use

12.1 Building Construction

12.2 Civil Engineering

12.3 Traffic Engineering

12.4 Sport/Leisure

12.5 Plant Engineering

12.6 Mining

12.7 Energy Supply

12.8 Agriculture

12.9 Component Parts/Fasteners

12.10 Environmental Protection

12.11 Handicraft

12.12 Art

12.13 Continuous-sheet Galvanizing

12.14 Conclusion

13 Appendix

Appendix A Defect Occurrence on Zinc Coatings and at Hot-dip Galvanized Workpieces

13.1 Requirements for the Zinc Coating

13.2 Assessment Criteria for Hot-dip Galvanized Coatings on Steel Structures

13.3 Major Defects in the Zinc Coating or at the Hot-dip Galvanized Workpiece

Appendix B Information Centers in the Federal Republic of Germany

Appendix C Hot-dip Galvanizing Companies in Germany as of 15/8/2005 Source: Institut für Feuerverzinken GmbH

Appendix D Worldwide Galvanizing Associations

Index

Related Titles

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The Editors

Dr. Peter Maaß

Fabrikstr. 17a

04178 Leipzig

Germany

Dr. Peter Peißker

Dahlienstr. 5

04209 Leipzig

Germany

Translation

Christine Ahner

Translate Economy

Freiherr-von-Eichendoff-Str. 8/l

88239 Wangen

Germany

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Library of Congress Card No.: applied for

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

Bibliographic information published by the Deutsche Nationalbibliothek

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© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Boschstr.12, 69469 Weinheim

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ISBN: 978-3-527-32324-1

ISBN: 978-3-527-63689-1 (epub)

ISBN: 978-3-527-63691-4 (mobi)

Preface to the Third German Edition

As the second German edition of the “Handbuch Feuerverzinken”, published in 1993, has been out of print for some time, a third, completely revised edition became necessary. With its publication we would like to thank all authors, some of them new to this edition, for their valuable contributions.

The following modifications and additions have been made:

In the revision the new Euro- and ISO standards are considered, in particular DIN EN ISO 1461.The chapter on surface preparation technology now covers new processes that take into account the trend towards environmentally friendly technologies.The layer formation technology is explained on an entirely new footing, based on the investigations of the Institute for Corrosion Protection, Dresden, and the Institute for Steel Engineering, Leipzig, and includes high temperature galvanization.The chapters on technical equipment, design and manufacturing according to hot-dip galvanizing requirements as well as on occupational safety and quality management have been updated.The commercially important method of powder coating is now covered in the sections on the post-treatment of zinc coatings.All chapters take into account the vastly expanded range of hot-dip galvanized products, e.g., truck frame parts.After eight years of intense discussions with the responsible government departments, trade associations and the IG Metall (Industrial Union of Metal Workers) the method of hot-dip galvanization, since August 2005, has been integrated into the job description of a Surface Coating Specialist. Therefore, for the first time, a Germany-wide recognized trade for hot-dip galvanization specialists exists.

We hope that the third edition of the “Handbuch Feuerverzinken” will continue to meet interest in the professional circles and will constitute a ready reference for the hot-dip galvanization industry.

Critical remarks conducive to the book’s content will be much appreciated. We would like to thank the publisher Wiley-VCH, notably Dr. Ottmar and Dr. Münz, who sympathetically supported us in our wish to publish this third edition and unbureaucratically also undertook some of the editors’ work.

Peter Maaß

Peter Peißker

Leipzig,

December 2007

Acknowledgment

The publisher wishes to thank Philip G. Rahrig, Executive Director of the American Galvanizers Association (AGA), USA, Werner Niehaus, former President of Voigt & Schweitzer, Inc., USA, and Barry P. Dugan of Horsehead Corp., USA, for their support in reviewing the translation. Philip G. Rahrig and Murray Cook, Director of the European General Galvanizers Association (EGGA), UK, kindly provided the lists of the AGA and EGGA member associations that are reproduced in Appendix D.

Preface to the Second German Edition

Hot-dip galvanization was invented in 1742 by the French chemist Paul Jacques Malouin, but first found wide-spread use in 1836 after a patent on its practical application was issued to the French chemist Stanislas Sorel. Decades of alchemy and chemistry combined with craftsmanship led the way to a productive, efficient and modern industry.

The increasing importance of structural engineering with its varied application fields on the one hand and the demands for low-maintenance or maintenance-free corrosion protection on the other hand have spurred the development of process technology and installation engineering of hot-dip galvanization.

The essential groundwork on the topic was laid in the landmark publication “Das Feuerverzinken” (Hot-dip Galvanization) by Prof. Bablik, the eminent expert of process technology, published in 1941. The book “Das Feuerverzinken”, the first German edition of “Handbuch Feuerverzinken” by the editors, published in 1970, and its second edition will provide readers and practitioners with the possibility to gain an understanding of the historical and technological development of hot-dip galvanization and will hopefully help to bring it to fruition in practical applications.

Corrosion and corrosion protection, notably hot-dip galvanization, are nowadays integral parts of quality management of products and of environmental protection because corrosion is caused by environmental influences. By limiting and preventing corrosion, hot-dip galvanization as a prime method of corrosion protection helps to

protect natural resourcesconserve valuesincrease the quality of livingenhance security.

If reference books could be written by few individual authors in the past, the sheer complexity of process technology and installation engineering necessitates a joint effort of an assembly of experts from various disciplines. Critical remarks conducive to the book’s content will be much appreciated. We thank the publisher which supported us in every respect.

Peter Maaß

Peter Peißker

Leipzig, July 1993

List of Contributors

Dipl.-Ing. Hans-Jörg Böttcher

Düsseldorf (Chapters 4 and 9)

Ing. Werner Friehe

Mühlheim (Chapter 9)

Dr. Gunter Halm

Dorsten (Chapter 8)

Dipl.-Chem. Lothar Hörig

Leipzig (Chapter 3)

Dr. Dietrich Horstmann

Erkrath (Chapter 9)

Dipl.-Ing. Mark Huckshold

Düsseldorf (Chapter 7)

Dipl.-Ing. Jens-Peter Kleingarn

Düsseldorf (Chapter 11)

Dr. Rolf Köhler

Haan (Sections 6.1 to 6.3)

Dr. Carl-Ludwig Kruse

Dortmand (Chapter 9)

Dr. Peter Maaß

Leipzig (Chapters 1, 2, 11, 12, and 13)

Dipl.-Ing. Jürgen Marberg

Düsseldorf (Section 6.4 to 6.7, and Chapter 7, 8 and 12)

Dipl.-Ing. Rolf Mintert

Hagen (Chapter 5)

Dr.-Ing. Peter Peißker

Leipzig (Chapter 3 and 5)

Ing. Gerhard Scheer

Rietberg (Chapter 7)

Dipl.-Chem. Andreas Schneider

Leipzig (Chapter 10)

Dr. Wolf-Dieter Schulz

Leipzig (Section 3.6, and Chapters 4 and 9)

Prof. Dr. Wilhelm Schwenk

Duisburg (Chapter 9)

Dipl.-Chem. Marc Thiele

Dresden (Chapter 4)

Dr. Christian Kaßner

Hattingen (Chapter 6)

Dipl.-Ing. Rolf Mintert

Halver (Chapter 5)

1

Corrosion and Corrosion Protection

Peter Maaß

1.1 Corrosion

1.1.1 Causes of Corrosion

All materials or products, plants, constructions, and buildings made of such materials are subject to physical wear during use.

A general overview of different kinds of wear caused by mechanical, thermal, chemical, electrochemical, microbiological, electric, and radiation-related impacts is shown in Figure 1.1.

Figure 1.1 Types of wear of materials.

The technical and economic mastering of physical wear is difficult, since several causes are intertwined and mutually influence each other. The interaction with certain media of the environment results in undesired reactions of the materials that trigger corrosion, weathering, decaying, embrittlement, and fouling.

While mechanical reactions lead to wear, chemical and electrochemical reactions cause corrosion. Such processes emanate from the materials’ surfaces and lead to modifications of the material properties or to their destruction. According to DIN EN ISO 8044, corrosion is defined as:

“Physical interaction between a metal and its environment which results in changes of the metal’s properties and which may lead to significant functional impairment of the metal, the environment or the technical system of which they form a part.”

Note: This interaction is often of an electrochemical nature.

From this definition, included in the standard, further terms are derived:

Corrosion system: A system consisting of one or several metals and such parts of the environment that affect corrosion.Corrosion phenomenon: Modification in any part of the corrosion system caused by corrosion.Corrosion damage: Corrosion phenomenon causing the impairment of the metal function, of the environment or of the technical system of which they form a part.Corrosion failure: Corrosion damage characterized by the complete loss of operational capability of the technical system.Corrosion resistance: Ability of a metal to maintain operational capability in a given corrosion system.

When unalloyed or alloyed steel without corrosion protection is exposed to the atmosphere, the surface will take on a reddish-brown color after a short time. This reddish-brown color indicates rust is forming and the steel is corroding. In a simplified way, the corrosion process of steel progresses and is chemically based on the following equation:

(1.1)

(1.2)

The corrosion processes begins when a corrosive medium acts on a material. Since (energy-rich) base metals recovered from naturally occurring (low-energy) ores by means of metallurgical processes tend to transform to their original form, chemical and electrochemical reactions occur on the material’s surface.

Two kinds of corrosion reactions are distinguished:

chemical corrosion Corrosion excluding electrochemical reaction,electrochemical corrosion Corrosion including at least one anodic and one cathodic reaction.

1.1.2 Types of Corrosion

Corrosion does not only occur as linear abrasion, but in versatile forms of appearance. According to DIN EN ISO 8044, important variants for unalloyed or alloyed steel are:

Uniform surface corrosion General corrosion occurring on the entire surface at nearly the same rate.Shallow pit corrosion Corrosion with locally different abrasion rates; caused by the existence of corrosion elements.Pitting corrosion Local corrosion resulting in holes, that is, in cavities expanding from the surface to the inside of the metal.Crevice corrosion Local corrosion in connection with crevices occurring in or immediately adjacent to the crevice area, which has developed between the metal surface and another surface (metal or nonmetal).Contact corrosion (aka dissimilar metal corrosion) Occurs at contact surfaces of different metals; the acceleratedly corroding metal area is the anode of the corrosion element.Intergranular corrosion Corrosion in or adjacent to the grain boundaries of a metal.

The standard mentioned above describes altogether 37 types of corrosion. These types of corrosion result in corrosion phenomena.

1.1.3 Corrosion Phenomena

EN ISO 8044 defines corrosion phenomena by corrosion-causing modifications in any part of the corrosion system.

Major corrosion phenomena are:

Uniform surface attack A form of corrosion where the metal material is almost uniformly removed from the surface. This form is also the basis for the calculation of the mass loss (g m−2) or the determination of the corrosion rate (µm y−1).Shallow pit formation A form of corrosion with irregular surface attack forming pits with diameters much larger than their depth.Pitting A form of corrosion with crater-shaped or surface-excavating pits or pits resembling pin pricks. The depth of the pitting spots usually exceeds their diameter.

It is very difficult to differentiate between shallow pit formation and pitting.

1.1.4 Corrosive Stress

According to DIN EN ISO 12944-2: All environmental factors enhancing corrosion (see Figure 1.2).

Figure 1.2 The reduction of SO2 pollution in Germany over the last 20 years led to decisive reductions of the zinc-removal values (cf. Table 1.1).

1.1.4.1 Atmospheric Corrosion

The corrosion rate in the atmosphere is insignificant as long as the relative humidity on the steel surface does not exceed 60%. The corrosion rate increases, especially with inadequate ventilation,

With increasing relative humidity.With condensate occurring (surface temperature < dew point).In the presence of precipitation.With increasing pollution of the atmosphere which may affect the steel surface and/or be deposited on it. Pollutants are gases, including sulfur dioxide, salts, chlorides, and sulfates. In connection with humidity, deposits like soot, dusts, salts, etc., on steel surfaces accelerate corrosion.

Temperature also, influences the corrosion process. The following criteria are decisive for the evaluation of the corrosive stress:

climatic zone;cold climate;moderate climate;dry climate;warm, humid climate;sea climate;local climate.

Local climate is defined as what is prevailing within the radius of the object (up to 1000 m). The local climate and the pollutant content are the basis for the classification of atmospheric types.

atmospheric types;room atmosphere;rural atmosphere;urban atmosphere;industrial atmosphere;marine atmosphere;microclimate.

The microclimate is the climate immediately at an individual component part. The local conditions, such as influences of humidity, dew-point shortfalls, local humidification and its duration, especially in connection with pollutants occurring at the location, have a significant impact on corrosion.

Table 1.1 shows the corrosive stress of atmospheric corrosion for different atmospheric types and corrosivity categories according to DIN EN ISO 12944-2.

Table 1.1 Corrosive stress – classification of environmental conditions acc. to DIN EN ISO 12944-2.

1.1.4.2 Corrosion in the Soil

The corrosion behavior is determined by soil conditions and electrochemical parameters, such as element formation with other component parts and the influence of alternating and direct current.

Corrosive stress is decisively determined by:

the composition of the soil;changes of the soil condition at the object due to deposits present in the soil;additional electrochemical factors.

For further details, see EN 12501-1.

1.1.4.3 Corrosion in Water

Major conditions for corrosive stress in water are:

the composition of the waters, such as oxygen content, kind and amount of dissolved substances in fresh water, brackish water and salt water;mechanical stress;electrochemical factors.

DIN EN ISO 12944-2 distinguishes between the underwater zone, the intermediate (fluctuating level) zone, the splash zone and humid zone.

1.1.4.4 Special Corrosive Stress

Corrosive stress at the location, in the application area or through production-related influences is a special load that has a decisive impact on corrosion. Mainly, chemical stress is concerned, like operation-related emissions (acids, alkaline solutions, salts, organic solvents, aggressive gases, and dusts and others). However, special stresses may also be mechanical stress, temperature stress and combined stresses – contemporaneous presence of mechanical and chemical stress, and all enhance corrosion.

1.1.4.5 Avoidance of Corrosion Damages

The following basic determinations are required for the avoidance of corrosion damage:

determination of the corrosion exposure of the product, the plant, the structure or the building;knowledge of the service life: period of time in which the corrosion system meets the requirements for functionality (EN ISO 8044);knowledge of the protection period: expected service life of a coating system up to the first parts replacement (EN ISO 12944-1).

The determination of the corrosion exposure is relatively difficult since both the influence of the climatic zones, the local climate, the atmospheric types and the microclimate need to be taken into account. A corrosion protection corresponding to the service life has to be determined in order to minimize the expenses for costly repetitive maintenance measures.

1.2 Corrosion Protection

1.2.1 Procedures

All methods, measures, and procedures aimed at the avoidance of corrosion damages are called corrosion protection. Modifications of a corrosion system in so far as corrosion damages are minimized.

Figure 1.3 gives an overview.

Figure 1.3 Methods, measures, and procedures of corrosion protection (von Oeteren, Korrosionsschutz-Fibel).

1.2.1.1 Active Procedures

Active corrosion protection helps reduce or avoid corrosion by means of manipulation of the corrosion process, corrosion protection-related material selection, project engineering, design and manufacturing. But it is also a significant precondition for the effectiveness of passive corrosion-protection procedures. The following aspects are surveyed in this respect:

Design-Engineering Requirements

The basic design-engineering requirements of the corrosion-protection-related design of steel structures are defined in the DIN EN ISO 12944-3:

corrosion protection of steel structures by protective paint systems;basic rules for protective coating;EN ISO 14713;protection of iron and steel structures against corrosion – zinc and aluminum coatings.

In the figurative sense, they also apply to other products, unless these contain precise requirements determined in the respective DIN. In his engineering work, the design engineer has to consider the corrosive stress triggered by the corrosion types and phenomena. He has to depict a design engineering solution that is expected to provide an efficient protection period with optimal quality.

Here, essential aspects are:

Materials used Knowledge of their properties and corrosion behavior are required.Surface design Preference to components with small corrosion-prone surfaces.Profiles used Preference to profiles forming the smallest number of edges. The angle profile ranks before the U-profile, the U-profile before the I-profile.Component arrangement Components and structures have to be arranged in a way to prevent or minimize the impact of aggressive media and to ensure an unimpeded circulation of air.Component joining The joining of components preferably requires smooth, closed surfaces. Fasteners require the same corrosion protection as the constructions, or an equivalent one with regard to the protection period.Manufacturing requirements The application of a passive corrosion-protection procedure entails the consideration of manufacturing criteria already in the design phase.The determination of a corrosion-protection procedure results, inter alia, in the demand for a design compatible with coating, hot-dip galvanizing, sputtering, enameling and galvanizing.Maintenance-related requirements The corrosion protection design has to allow for the possibility of efficient maintenance measures. Since the service life of components, constructions, products, plants and buildings differs from the protection period of the corrosion protection, repeated protection measures are usually required.

1.2.1.2 Passive Procedures

In passive corrosion protection, corrosion is prevented or at least decelerated through the isolation of the metal material from the corrosive agent by the applied protective layers. The technical preconditions of a corrosion layer are:

the protective layer has to be pore-free;it must adhere firmly to the base material;it must be resistant to external mechanical stress;it must possess a certain ductility; andit must be corrosion resistant.

Essential preconditions for the effectiveness of corrosion-protection coatings are:

Surface preparation to achieve the surface preparation degree Sa 2,5 or Sa 3 (blasting) or Be (pickling),Quality-oriented corrosion protection design.

Figure 1.4 shows the logical structure of DIN EN ISO 12944.

Figure 1.4 Short logarithm for the specification of coating systems according to DIN EN ISO 12944.

An overview of the procedures of passive corrosion protection is given in Figure 1.5 and Table 1.3 shows the available methods for protecting steel against corrosion with zinc.

Figure 1.5 Overview of passive corrosion-protection procedures (von Oeteren, Korrosionsschutz-Fibel).

This is the first time that the protection period has been defined in years (cf. Table 1.2).

Table 1.2 Protection period for coating systems according to DIN EN ISO 12944-1 and -5.

Protection periodClassYearsShort2–5Medium5–15Long>15

The protection period for a coating system chosen in dependence on the corrosive stress is regarded to be the expected service life until the first repairs. Unless otherwise agreed, the first replacement of parts for reasons of corrosion protection will be necessary as soon as the coating system has reached the degree of rustiness Ri 3 acc. to ISO 4628-3. The protection period is no “warranty period”, but a technical term that may help the contractor determine a maintenance program.

Table 1.3 Corrosion-protection processes.

On steel products exposed to corrosive stress for decades

coatings such as paints, lacquers;metallic platings such as hot-dip platings, thermal-spray coatings;as well as the duplex system – hot-dip galvanizing plus coating.

are applied.

While Figure 1.5 gives an overview of passive corrosion methods, Table 1.4 shows corrosion-protection methods for steel with zinc.

Table 1.4 Important parameters for corrosion-protection methods for steel and zinc (Beratung Feuerverzinken).

Essential decision-making aids for the choice of a corrosion-protection method are:

important parameters of corrosion-protection methods for steel with zinc; (Table 1.4);advantages and disadvantages of different methods of metallic coating; (Table 1.5);limitation of use of the methods, determined by their characteristics (Table 1.6).

Table 1.5 Advantages and disadvantages of different metallic coating methods.

Table 1.6 Limitation of use of the methods determined by their characteristics (cf. Table 1.3)a).

1.2.2 Commercial Relevance

The demands placed on components, constructions, products, plants, and structures of steel are inter alia,

high operational reliability;long service life;good decorative design;high corrosion resistance;high performance; andhigh environmental compatibility.

Here, a permanent task is the reduction in material input, size, nonrecurring, and regular costs.

This goal determines the application of corrosion-protection methods as well as the development trend and direction of corrosion protection.

Corrosion protection is not considered an end in itself, but part of the product development, manufacturing and utilization, and sometimes even part of the base materials or semifinished products. In view of corrosion damages in the amount of 50 bn Euro the German economy sustains every year, exclusive of corrosion damages in the private sector, the implementation of the research findings on corrosion protection and their consequent application allow for annual reductions of approx. 15 bn Euro. The aim of the continuous information efforts is to achieve corrosion protection not as good as possible, but as good as required.

Decisive for the efficiency of corrosion protection is not the initial protection cost, but the annual or specific corrosion protection costs in consideration of the protection period of the respective corrosion protection system and the service life of the products.

More attention should be paid to the connection between product development, product quality, material handling, maintenance, environmental protection, and corrosion protection, which should take into account corrosion-damage protection in the planning and design phase – despite all influencing factors – as well as static safety against breakage, stability of buildings and operational safety regarding performance and service life.

1.2.3 Corrosion Protection and Environmental Protection

Corrosion has its roots in the environment. With the limitation and impediment of corrosion, corrosion protection relieves the environment in a number of ways and becomes a decisive measure for environmental protection. Yes, one can say “corrosion protection is environmental protection.”

The protection of steel against corrosion by means of hot-dip galvanizing or the duplex method is particularly effective, lasts for decades, and is efficient in comparison to other methods. Moreover, it is a convenient corrosion-protection method since the reduction in corrosion does not only impede the loss of steel as a material, but contributes to the saving of resources and the avoidance of waste. After its utilization, steel or hot-dip galvanized steel is 100% recyclable. The recycling of material is an important contribution to environmental protection.

From the environmental protection point of view, much importance is attached to corrosion protection ex works, as is practiced in the case of hot-dip galvanizing. The technology is measurable, testable and controllable. In former times, the hot-dip galvanizing industry polluted the environment, but new environmental protection laws and their acceptance by the galvanizing industry has contributed much to the industry’s considerable investments in housings, filtration plants, water pollution control, etc.

“Corrosion protection can only be sold as environmental protection by someone who does not ruin the environment himself.”

(Seppeler, K.: Feuerverzinken, Faszination der Zukunft – Magazine “Feuerverzinken” 18 (1989) 3, p. 34).

This leitmotif should be the aim of the industry’s policy, which includes image building and constant staff qualification.

Appendix 1.A

Basic Standards for Corrosion Protection of Steel Structures

Corrosion of metals and alloys

EN ISO 8044 Basic terms and definitions

DIN EN 150 12944 Coating material – Corrosion protection of steel structures by protective paint systems.

Part 1: General Introduction

Protection period of coating systems.General statement on health protection, work safety and environmental protection.

Part 2: Classification of environmental conditions

Corrosivity classes in the atmosphere.Categories of environmental conditions in water and soil.Special corrosive stress.

Part 3: Basic design rules

Treatment of crevices, composite construction.Measures against sediments and accumulation of water.Boxes and hollow construction elements.Edges, recesses, reinforcements.Avoidance of contact corrosion.Handling, transport and assembly.

Part 4: Surface types and surface pretreatment

Surface types and methods of surface pretreatmentSurface pretreatment qualities and their testing

Part 5: Coating systems

Basic types of coating materials.Example for coating systems in dependence of corrosivity class and assessed protection period.

Part 6: Laboratory tests for the evaluation of coating systems

Part 7: Execution and monitoring of the coating work

General statements on the execution of coating work.Methods for the application of coating materials.Monitoring of coating work, manufacturing of control surfaces.

Part 8: Development of specifications for new work and maintenance

DIN 55928 Corrosion protection of steel structures from corrosion by organic and metallic coatings

Part 8: Protection of supporting thin-walled building components from corrosion

Part 9: Composition of binders and pigments

Preparation of steel substrates before application of paints and related products – Surface roughness characteristics of blast-cleaned steel substrates

DIN EN ISO 8503

Part 1: Specifications and definitions for ISO surface profile comparators for the assessment of abrasive blast-cleaned surfaces

Part 2: Method for the grading of surface profiles of abrasive blast-cleaned steel – Comparator procedure

Part 4: Stylus instrument procedure

ISO 8501-1 and ISO 8501-2

Visual assessment of surface cleanliness (rust grades, preparation grades).

2

Historical Development of Hot-dip Galvanizing

Peter Maaß

The purpose of history is “to study the past in order to understand the present and to master the future” [1].

This shall be made clear by taking a closer look at the development of iron and steel, at the term “corrosion”, and at the discovery of zinc up to the invention of hot-dip galvanizing and its importance today.

The iron industry, and the steel industry that developed from it during the 18th century, is one of the most important and traditionally oldest manufacturing sectors. Since about 3000 year ago, the metal iron turned into the material basis of human culture and civilization, the end product made of iron and steel has greatly determined and still determines

technical progress;economic growth; andthe improvement of quality of life.

In England, the first molten steel was produced in the so-called crucible steel process already in 1740, but in Germany only at the beginning of the 19th century. The era of mass steel production, however, was heralded in 1855 by Henry Bessemer. And ever since the use of metallic materials, mankind has also been confronted with their destruction.

The term corrosion in its present-day meaning was first mentioned in a bibliographical reference. In a travelogue of the Caribbean Islands from 1667, the term “corroded” was used to describe the poor conditions of iron canons in a Jamaican fortress that were described as perforated by corrosion and looking almost like honeycombs [2].

In 1669 the term “corrosion” appeared for the first time in the description of an English spa written by J. Clanvill [3]. The report describes a strong attack of the hot bathwater on silver coins due to the mineral water containing complex sulfur compounds.

In China, India and Persia, zinc was already known in antiquity. The Greeks and Romans smelted carbonate-oxide zinc ores (Galmie) together with copper to get brass. In 1746, the German A.S. Marggraf succeeded in producing metallic zinc by heating zinc oxide with carbon under the exclusion of air. However, it was only in 1820 that this process gained industrial importance.

Hot-dip galvanizing was first proposed by the French chemist Malouin in 1741, when he discovered the possibility of coating iron and steel parts with liquid zinc. He described the process in the way it is still carried out today in wet galvanizing. Utilization on an industrial scale, however, was not possible at that time, since a low-cost process for the cleaning of iron or steel surfaces did not exist. In 1836, Stanislaus Sorel, an engineer working in Paris, was the first to succeed in the practical application of hot-dip galvanizing after he had discovered the pickling process for cleaning iron and steel surfaces. On May 10, 1837, he was granted a patent for the process of protecting ferrous and steel parts from corrosion through surface cleaning, and by immersion into molten zinc.

The significance of surface pretreatment, that is, the cleaning of iron and steel surfaces, for development of hot-dip galvanizing process is demonstrated in the following references:

In 1843, a report by the “French Marine Commission of Brest on the Galvanizing of Iron”, which reports on a pickling process preventing metal from being attacked [4].

“The removal of rust from iron requires great attention. It is indispensably necessary to completely remove rust from the iron exposed to the acid used; however, the acid attack on the surface of the iron must not be too strong, but attention must be paid to the right moment in which the iron should be withdrawn from the acid bath.”

Another report says [5]:

“It is no longer diluted sulfuric acid or hydrochloric acid that is used for the removal of rust, but the sour water of oil refineries, which due to its glycerin content, does not attack the metallic iron itself, but removes only the oxide on its surface”.

While research into corrosion and the principles of corrosion protection belong to the natural sciences, in particular to chemistry and metallurgy, corrosion protection has its roots in engineering, since corrosion protection is a technological process in the manufacturing of a metallic object or it is guaranteed to occur in the use of the object.

After 1820, the market was flooded with zinc and in 1826, the “Association for the Support of Trade Diligence” offered a prize for the discovery of a mass application of zinc. Where the first German railway line between Nuremberg and Fürth opened in1835, the rapid expansion of the route network triggered an enormous demand for iron and steel.

A method for the protection against rust had to be applied, for example in the early railroad sectors, which protected steel system components, for example, signal installation, workshops, station concourses against rapid deterioration. White lead and red lead had already been known, but were toxic and expensive. Zinc-white paints boosted the development of the paintwork industry, however, the zinc paints did not entirely fulfill the expectations of the railway with regard to corrosion protection [6]. Another method to protect iron against rust had already been known for a long time: the application of metallic coatings, above all, of tin. From an old handbook by F. Releaux [7] dating back 150 years it is cited:

“Therefore the idea of coating iron with zinc was obvious, since zinc reacts positively towards any other metal, which will be protected by its contact with zinc, while zinc itself is oxidized…That is why telegraph wires, rope wires, screws and nails, block clamps, sheet metals, cannon balls etc. are galvanized to a great extent.”

Around 1840, the first hot-dip galvanizing shops for sheet-metal products and objects like buckets, watering cans, bath tubs, wires and ferrous structures were established. Hot-dip galvanizing was carried out manually with tongs and racks, the galvanizing kettle was heated by charcoal, coal or coke. Heat and temperature control existed only to a limited extent; the operating supplies were home-made based on secret formulas [8]. Until approx. 1920, hot-dip galvanizing was carried out “in the form of most superstitious empiricism” [9], it could have even been called alchemy. According to Bablik [10], hot-dip galvanizing was more and more subject to scientific management, in particular up to 1940.

The progression from manual hot-dip galvanizing to the industrial development of this corrosion protection method during the last decades was characterized by external and internal developments.

External developments included, among others:

In the period between 1950 and 1990, global steel production increased from 192 m tons to 770 m tons.Steel construction developed in terms of quantity and quality. New types of steel, new fields of application and lightweight design placed higher demands on corrosion protection, as for example in the case of pylons, beams, greenhouses, factories, etc.The environmental pollution on the one hand, but also the growing environmental awareness on the other, placed higher demands on corrosion protection, not the least of which on hot-dip galvanizing.The corrosion awareness of the public, government officials, trade associations, as well as the private sector, has increased. However, information campaigns are still required, since it is an ongoing task.

Internal developments included, among others:

Basic research in the hot-dip galvanizing technology.Technological research, but also product-related and application-oriented joint research.Increase in kettle dimensions up to a length of 17.2 m.Change from liquid fuels to natural gas as energy sources and their controllability.Utilization of transport systems in accordance with the larger kettle dimensions and thus with higher unit weights.Utilization of auxiliary equipment, especially to control environmental emissions, as for example in the 1960s the peripheral edge dust suction facility and in the 1980s the enclosures at the galvanizing kettle.Public-relation measures of the national associations of hot-dip galvanizing companies as well as continuous qualification of their staff.

It was a long road from alchemy to a united Europe. This road from isolation and secrecy, to manual hot-dip galvanizing and, finally, to a modern, environmentally friendly industry is only possible through cooperation with organized associations working for the benefit of the economy and along with the companies of the hot-dip galvanizing industry involved. The integration of this industry in the steel industry, the metalworking industry and the trade as well as in their associations and institutions is thus another step ahead and should be further strengthened. Hot-dip galvanizing cannot be explained independently, but only in connection with products, plants and buildings.

For the further development of hot-dip galvanizing, the following considerations are required:

1. Since steel is the only material to be hot-dip galvanized, the hot-dip galvanized portion (continuous galvanized sheet or after-fabrication galvanizing) of the total production plays an important role in market-strategy related tasks:

2. In 1991, the German steel construction industry had a capacity of 2.5 million tons with a total value of 15.5 bn German Marks. With this, in 1991 the turnover of the German steel industry increased by 12% compared to 1990 [11].

3. Bablik’s principle regarding the duplex system, dating from 1941 [12] and often forgotten in the past, says: “Since the coat of paint prevents the zinc from being attacked, there will still be an excellently well paintable substrate after the paint has worn off. Therefore, hot-dip galvanizing and paint coating are today‘s most reliable and longest-lasting corrosion protection methods for steel constructions.”

The application of this system as the ideal method of passive corrosion protection for products with long service lives is an important challenge for the future – the more so as currently there is no alternative.

Since the issue of corrosion and corrosion protection is no longer limited to a circle of experts, but corrosion damages and their consequences are reported on all over the world today, it is also the task of the hot-dip galvanizing industry – not least because of its history of 265 years (proven in practice for 160 years) – to show and publish examples of corrosion resistance of hot-dip galvanized steel.

Art and Corrosion Protection in 1918

Hot-dip galvanized steel in art.

On behalf of the Johann Adam Johnen company from Erfurt, Heinrich Zille created 7 caricatures for advertising purposes – an amazing venture for this age. Zille as an “advertising manager” is rather unknown.

The pictures show typical products of hot-dip galvanizing of the past, produced by the wet-galvanizing method.

The pictures are shown in the Angermuseum in Erfurt. The photos are from Constantin Beyer, Weimar, and were published in the magazine “Feuerverzinken”, Vol. 4, December 1991.

References

1 Bemal, J.-D. (1961) Die Wissenschaft in der Geschichte, Deutscher Verlag der Wissenschaften, Berlin, p. 16.

2 Clanvill, J. (1665/72) Philos. Trans., I, 364 (abridged 1809).

3 (1843) Polytechnisches Zentralblatt, New Series, vol. 1, Leipzig, p. 308.

4 (1846) Bulletin du musee de J’Industrie, 11, 119; thereof: Polytechnisches Zentralblatt, New Series l, 960 (1847).

5 Greiling, W. (1950) Chemie erobert die Welt, Econ Verlag, p. 67.

6 Winterhager, H. (1977) Der Zinck – seine Benutzungsarten in Naturwissenschaft und Technik im Laufe der Zeiten. From: 25 Jahre (1951–1976) Gemeinschaftsausschuß Verzinken e. V., issue 1977, p. 34.

7 Releaux, F. (1836) Das Buch der Erfindungen, Gewerbe und Industrie IV: Die Behandlung der Rohstoffe, Verlag O. Spaner.

8 Kleingarn, J.P. (1975) Korrosionsschutz durch Feuerverzinken gestern, heute und morgen. Industrie-Anzeiger 97. Vol. 60 from 25/07/1975.

9 Bablik, H. (1941) Das Feuerverzinken, Julius Springer Publishing House, Vienna, Part III (Preface).

10 Bablik, H. (1941) Das Feuerverzinken, Julius Springer Publishing House, Vienna, Part III (Preface).

11 Goldbeck, O. (1992) Die Situation der deutschen Stahlbau-Industrie. Stahlbau Nachrichten, 3, 7.

12 Bablik, H. (1941) Das Feuerverzinken, Julius Springer Publishing House, Vienna, Part III p. 250.

13 Bablik, H. (1941) Das Feuerverzinken, Julius Springer Publishing House, Vienna, Part III p. 3.