Murat Saatcioglu PhD,P.Eng.
Professor and University Research Chair
Department of Civil Engineering
The University of Ottawa
Ottawa, ON
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Rapid Screening of Buildings for Seismic Retrofit Assessment Report
Murat Saatcioglu PhD,P.Eng.
Professor and University Research Chair
Department of Civil Engineering
The University of Ottawa
Ottawa, ON
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1. INTRODUCTION
1.1 General
Traditional fatigue analysis of welded components is based on the use of nominal stresses and catalogues of classified details. A particular type of detail is assigned to a particular fatigue class with a given S-N curve. Such a method is used in the IIW fatigue design recommendations (1). This nominal stress approach ignores the actual dimensional variations of a particular structural detail, which is an obvious drawback.
Moreover, the form of a welded component is often so complex that the determination of the nominal stress is difficult or impossible. This is true even if the finite element analysis (FEA) method is used for the stress analysis.
In the context of potential fatigue failure by crack growth from the weld toe or end, the structural hot spot stress approach goes one step forward. Here the calculated stress does take into consideration the dimensions of the detail. The resulting structural stress at the anticipated crack initiation site ('hot spot') is called the structural hot spot stress. Structural stress includes the stress concentrating effects of the detail itself but not the local non-linear stress peak caused by the notch at the weld toe. This notch effect is included in the hot spot S-N curve determined experimentally. This is reasonable because the exact geometry of the weld will not be known at the design stage. The variation in the local geometry of the weld toe is one of the main reasons for scatter in fatigue test results. By using the lower-bound characteristic S-N curve, lower bound quality of the weld toe is incorporated into the analysis. A single S-N curve should suffice for most forms of structural discontinuity, providing the weld toe geometry is always the same.
An obvious reason for introducing the structural hot spot approach is the availability of powerful computers and software, which make detailed FEA possible for most design offices. However, the approach is also a valuable tool for choosing the locations of strain gauges when validating design by field-testing prototype structures. Moreover, finite element analyses make it possible to produce parametric formulae in advance for easy estimation of structural stresses at various hot spots. The hot spot approach was first developed for fatigue analysis of welded tubular joints in offshore structures. Corresponding fatigue design rules were published by the American Petroleum Institute, the American Welding Society, Bureau Veritas, UK Department of Energy, etc. A review of this topic can be found in Ref. (2). There is now an increasing demand for application of the approach to be extended to all kinds of plated structures. Some progress has been made in doing this, but at present there are differences in the methods recommended for estimating the structural hot spot stress. The first general design rule to include the structural stress (referred to at the time as the geometric stress) approach was the European pre-standard ENV 1993- 1 - 1 (3) (Eurocode 3) but only limited guidance was given. Later, the International Institute of Welding (IIW) published new recommendations containing four fatigue design approaches, including the hot spot approach (1). A background document was also published focusing on definitions and the determination of stresses used in the fatigue analysis of welded components (4).
Subsequently, further research has led to improved procedures for determining the structural hot spot stress, particularly using FEA (5,6), and the provision of background fatigue test data from which to derive suitable design S-N curves (7-10). Furthermore, the ability to establish through-thickness stress distributions using FEA has enabled a method to be developed that uses this information to calculate the structural hot spot stress. Previously attention has focussed on use of the surface stress distribution, approaching the weld in question, and determination of the structural hot spot stress using an extrapolation procedure. Use of the through-thickness stress distribution instead should avoid the need for extrapolation.
The goal of the present document is to help design engineers and stress analysts to implement the structural hot spot stress approach in practice. Symbols and terms are defined as they are used but symbols are also defined in Appendix 1.
Practical examples of the application of the methods described are given in the form of Case Studies in Sections 6 and 7. Moreover, the document should serve as a reference when detailed guidelines for design are developed for particular welded products. The recommendations given here are intended for design of general welded structures subjected to fatigue loading. The document is mainly focused on plated structures, such as bridges, cranes, earth moving machinery, ship hulls, etc. Specific rules are already available for certain fields of application, including tubular structures (1 l), ship hulls (12,13) and pressure vessels (14).
In view of the scope of current experience and the availability of relevant fatigue test data, the recommendations presented in this document are only intended for plate thicknesses above 4 mm.
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EWM Welding consumables - The logical consequence
The whole world of welding technology from one single supply source:
• Unbeatable benefi ts for the users of EWM Welding consumables
• One point of contact for all system components
• Consultation and service for the whole process chain
• Accelerated availability and delivery times
The responsibility for the complete process chain is carried by one single system partner:
EWM!!
Certifi ed welding with EWM welding consumables
The complete spectrum of EWM welding consumables are produced to EWMs stringent specifi -
cations. Detailed analysis of every single production charge ensures perfectly consistent quality
and welding results.
Further to this, (we will take our solid wire as an example), , we control the winding, coating
quality, percentage of draw lubricants, feed/glide properties (also over long distances) and metallurgical
properties, just to mention a few of the factors effecting quality. All this to ensure the
best possible, reproducible process safety.
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Consumables for mild steels 5
Consumables for low-alloyed steels 87
Consumables for stainless and high-alloyed steels 187
Consumables for aluminium alloys 311
Consumables for nickel-based alloys 339
Consumables for copper-based alloys 365
Consumables for cast iron 381
Consumables for dissimilar materials 389
Consumables for hardfacing 411
Special products 457
Packaging and spool types 471
Storage and handling 481
Quick guide for the selection of welding consumables 485
General information and tables 499
Index 523
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Overview stainless steel consumables 4
Consumable selection by parent material 8
Covered electrodes for MMA welding 10
Solid wires for MIG/MAG welding 42
Welding of exhaust systems. 49
Wires for TIG Welding 50
Orbital-TIG – a great way to join pipes 57
Tubular cored wires for MIG/MAG welding 58
Construction of chemical tankers with cored wires 66
Fluxes for submerged arc welding 67
The stainless steel cladding process 75
Facts about Stainless Steels 76
Corrosion 81
Ferrite in weld metals 82
Joining of Dissimilar Steels 86
Storage and handling 90
Global manufacturing 91
page
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Every day, welders throughout the world encounter the initials OK on the consumables
they use. OK for Oscar Kjellberg, the founder of Esab AB. Oscar
Kjellberg first invented a new welding technique and followed it up with the
covered electrode. These inventions are the origins of Esab.
Oscar Kjellberg qualified as an engineer and worked for several years on
a couple of Swedish steamships. It was during this period at the end of the
1890s that he came across the problem for which there was no effective solution
at that time. The riveted joints on steam boilers often leaked. Attempts were
made to repair the leaking joints with nails which were forged to produce small
wedges which were then pushed into the joints. Simple electrical welding was
already in use, but Oscar Kjellberg had seen electrical welding repairs and the
results were poor, as there were still cracks and pores.
He realized, however, that the method could be developed and was
supported by the leading shipyards. Oscar Kjellberg set up a small experimental
workshop in the harbour in Göteborg.
In the shipyards of Göteborg, the method quickly attracted a great deal of
interest. It was obvious that it could provide tremendous benefits when welding
and repairing ships. Since then, this repair technique has been further
developed and implemented in other segments.
Today, Esab can offer repair and maintenance consumables for most materials
and welding processes.
In this handbook, you will find Esab Repair & Maintenance products and a
number of applications in which these products are used. The products shown
for each application are general recommendations and should only be used as
a guide.
For further product information, please refer to the ESAB Welding Handbook
or to your local Esab dealer.
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Presentation
Every day countless kilometres of steel pipelines are installed
worldwide for the most varied civil and industrial uses.
They form real networks comparable to a system of road networks,
which, although not so obvious, are definitely much more intricate and
carry fluids that have become essential for us.
To comply with technical specifications and fulfil the necessary safety
requisites, special materials and welding processes which have
evolved with the sector have been developed in recent years.
The main welding process used to install the pipelines is manual
welding with coated electrode, which, thanks to its ease and
versatility, is still the one most used.
However, to limit costs and increase welding productivity, particularly
on long routes, various constructors have adopted the semi-automatic
or completely automatic welding process with solid wire or wire
flux coated with gaseous protection.
This handbook describes both methods. Ample space has been
dedicated, in particular, to manual welding, with particular reference to
the operative practice and quality assessment, due to its considerable
use still today, but not neglecting more modern and productive
methods which will be increasingly used in future.
The presumption of this work is to be able to satisfy the most
demanding technician and welder, but, in particular, to supply each
user with useful information and a solid operative basis, as regards
the processes and filler materials and the welding equipment.
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Author: F. R. N. NABARRO-J. P. HIRTH | Size: 12.7 MB | Format:PDF | Quality:Original preprint | Publisher: Elsevier | Year: 2004 | pages: 603 | ISBN: 0-444-51483-X (volume)-0-444-85269-7 (set)-1572-4859
Preface
This is the first volume to appear under our joint editorship. While Volume 11 concentrated
on the single topic of dislocations and work hardening, the present volume spreads
over the whole range of the study of dislocations from the application by Kléman and
his colleagues of homotopy theory to classifying the line and point defects of mesomorphic
phases to Chaudhri’s account of the experimental observations of dislocations formed
around indentations.
Chaper 64, by Cai, Bulatov, Chang and Yip, discusses the influence of the structure of
the core of a dislocation on its mobility. The power of modern computation allows this
topic to be treated from the first principles of electron theory, and with empirical potentials
for more complicated problems. Advances in electron microscopy allow these theoretical
predictions to be tested.
In Chapter 65, Xu analyzes the emission of dislocations from the tip of a crack and its
influence on the brittle to ductile transition. Again, the treatment is predominantly theoretical,
but it is consistently related to the very practical example of alpha iron.
In a dazzling interplay of experiment and abstract mathematics, Kléman, Lavrentovich
and Nastishin analyze the line and point structural defects of the many mesomorphic phases
which have become known in recent years.
Chapter 67, by Coupeau,Girard and Rabier, is essentially experimental. It shows howthe
various modern techniques of scanning probe microscopy can be used to study dislocations
and their interaction with the free surface.
Chapter 68, by Mitchell and Heuer, considers the complex dislocations that can form in
ceramic crystals on the basis of observations by transmission electron microscopy and
presents mechanistic models for the motion of the dislocations in various temperature
regimes.
While the underlying aim of the study of dislocations in energetic crystals by Armstrong
and Elban in Chapter 69 is to understand the role of dislocations in the process of detonation,
it has the wider interest of studying dislocations in molecular crystals which are
“elastically soft, plastically hard, and brittle”.
Chaudhri in Chapter 70 discusses the role of dislocations in indentation processes,
largely on the basis of the elastic analysis by E.H. Yoffe. The special case of nanoindentations
is treated only briefly.
F.R.N. Nabarro
J.P. Hirth
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Forewords
The CuproBraze brazing handbook is a way to share the latest knowledge regarding the CuproBraze process. It deals with technical questions in general. The CuproBraze process is rather young and developments in different areas are still on-going. Therefore, all recommendations in the handbook should be seen as advice, sometimes better or other ways to success can be found. The handbook will be updated from time to time and if there are any questions or other matters which should be included, please contact editors.
The handbook is based on the original manuscript of Leif Tapper, who has retired when this edition comes out.
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Contents
1. General
1.1 Efficient heat exchangers
1.2 Technology development
1.3 Effects of annealing
1.4 Soldering and brazing
2. Copper alloys
2.1 Fin material
2.2 Tube material
2.3 Brass material for headers, side supports and similar applications
2.4 Strength at elevated temperatures
3. Filler materials
3.1 Brazing powder
3.2 Brazing foil
3.3 Brazing paste
4. Paste application
4.1 Paste on tubes
4.2 Paste on fin tips
4.3 Tube-to-header joints
5. Fabrication and assembly of components
5.1 Tube fabrication
5.2 HF-welded tubes
5.3 Folded tubes
5.4 Fins
5.5 Headers
5.6 Surface conditions
5.7 Brazing fixtures and assemblies
6. Brazing operation
6.1 Atmosphere
6.2 Temperature and time
7. Selecting a furnace
7.1 Batch furnace
7.2 Semi-continuous furnace
7.3 Continuous furnace
7.4 Heating source
7.5 Process emissions
8. Corrosion resistance
8.1 Cleaning after brazing
8.2 lnternal corrosion
8.3 External corrosion
8.4 Coatings
9. Special brazing processes
9.1 One shot brazing
9.2 Brazing of parts with internal turbulators (CAC)
9.3 Splitter fin together with CuproBraze
9.4 Brazing of steel parts
10 Quality check
10.1 Visual inspection in general
Reparability
11.1 Soldering
11.2 Re-brazing
11.3 Brazing with AgCu filler metals
12. Troubleshooting
13. Luvata Brazing Center
14. Getting started
14.1 Contacts
14.2 Web sites
14.3 Regular publications
14.4 Recent technical literature
15. CuproBraze in brief
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