Designing Weldments
Description
An important tool for professionals wishing to enhance their understanding or those who are new to the subject, Designing Weldments bridges that gap between structural engineers and a deeper understanding of the welding engineering within the structures.
In modern-day construction, welding is the primary method to join various members of any structure. Welds are required to meet various types of load in tension, compression, torsion, and perform in static or cyclic loading conditions. The weld has to be at least as strong as the parent metal to meet the demands of various stress working on the structure. It should meet the structural requirement, add value to the integrity of the structure, and prevent failures.
However, many design engineers lack even a fundamental insight or a basic understanding of essential welding processes and design requirements. Simply copying a few joint configurations in a drawing will not suffice. All-embracing and readable, Designing Weldments delivers a deeper understanding of many design factors that play a critical role in the design. The book clarifies welding design principles and applications. With this reference in hand, designers will have expert knowledge to consider very early on in the project, the implications of the choice of what type of weld to use for joining structural members, and how the component is made. The author explains the many welding techniques developed over the years, as well as some of which are still evolving.
The reader will also find in this book:
* Rules of thumb for saving time and money in the design phase of a project.
* An insider's view for choosing the proper welding approach to ensure the overall strength of a structure.
* Offers structural engineers a deeper understanding of the weld within their structures.
* Clarifies welding design principles and applications, limiting the necessity to redesign the structure.
Audience
The intended market for this book is professionals working on the infrastructural projects in shipbuilding, construction of buildings, bridges, offshore platforms, wind towers for renewable energy, and other structures that join plates, pipes, and pipelines in power plants, manufacturing, and repair.
More details
Other editions
Additional editions
Person
Ramesh Singh, MS, IEng, MWeldI, is registered as an Incorporated Engineer with the British Engineering Council UK and a Member of The Welding Institute, UK. He worked as an engineer for various operating and EPC organizations in the Middle East, Canada, and the US. Most recently, he worked for 10 years with Gulf Interstate Engineering, Houston, TX. He is now consulting in the field of welding, corrosion engineering, pipeline integrity, and related materials and corrosion topics. Ramesh is a graduate of the Indian Air Force Technical Academy, with diplomas in Structural Fabrication Engineering and Welding Technology. He has been a member and officer of the Canadian Standard Association and NACE and serves on several technical committees. He has worked in industries spanning aeronautical, alloy steel castings, fabrication, machining, welding engineering, petrochemical, and oil and gas. He has written several technical papers and published articles in leading industry magazines, addressing the practical aspects of welding, construction, and corrosion issues relating to structures, equipment, and pipelines. He recently authored Welding Processes Handbook (Wiley-Scrivener, 2021).
Content
List of Figures xi
List of Tables xv
Foreword xvii
Preface xix
1 Properties and Strength of Material 1
1.1 Introduction 1
2 Properties of Metals 3
2.1 Material Properties 3
2.1.1 Structure Insensitive Properties 4
2.1.2 Structure Sensitive Properties 4
2.1.3 Mechanical Properties 5
2.1.3.1 Modulus of Elasticity 5
2.1.3.2 Tensile Strength 6
2.1.3.3 Yield Strength 7
2.1.3.4 Fatigue Strength 7
2.1.3.5 Ductility 8
2.1.3.6 Elastic Limit 9
2.1.3.7 Impact Strength 10
2.1.3.8 Energy Absorption in Impact Testing 10
2.1.3.9 Transition Temperature for Energy Absorption 11
2.1.3.10 Transition Temperature for Lateral Expansion 11
2.1.3.11 Drop-Weight Tear Test (DWTT) 11
2.1.3.12 Fracture Toughness 11
2.1.4 Low Temperature Properties 14
2.1.4.1 Metal Strength at Low Temperature 16
2.1.5 Elevated Temperature Properties 16
2.1.6 Physical Properties 17
2.1.6.1 Thermal Conductivity 17
2.1.6.2 Coefficient of Thermal Expansion 17
2.1.6.3 Melting Point 17
2.1.7 Electrical Conductivity 18
2.1.8 Corrosion Properties 18
3 Design: Load Conditions 19
3.1 Design of Welds 19
3.2 Design by Calculations 20
3.2.1 Different Types of Loading 21
3.2.2 Tension 23
3.2.3 Compression 24
3.2.4 Bending 25
3.2.5 Shear 28
3.2.6 Torsion 29
3.2.7 Flat Sections 31
3.2.8 Round Cross Sectionals 32
3.2.9 Transfer of Forces 33
4 Design of Welds and Weldments 35
4.1 Introduction 35
4.1.1 Structural Types that Affect Weld Design 38
4.2 Full Penetration Welds 38
4.3 Partial Penetration Welds 39
4.4 Groove Welds 39
4.4.1 Definitions of Terms Applicable to Groove Welds 39
4.4.1.1 Effective Length 40
4.4.1.2 Effective Size of CJP Groove Welds 40
4.4.1.3 Effective Weld Size (Flare Groove) 40
4.4.1.4 Effective Area of Groove Welds 40
4.5 Weld Grooves 42
4.5.1 Square Groove Welds 42
4.5.2 Single Bevel Groove Welds 43
4.5.3 Double Bevel Groove Weld 43
4.5.4 Single-V-Groove Weld 43
4.5.5 Double-V-Groove Welds 44
4.5.6 Single or Double-J-Groove Weld 44
4.5.7 Single or Double-U-Groove Weld 44
4.6 Fillet Welds 44
4.6.1 Definitions Applicable to Fillet Welds 45
4.6.1.1 Effective Length (Straight) 45
4.6.1.2 Effective Length (Curved) 45
4.6.1.3 Minimum Length 45
4.6.1.4 Intermittent Fillet Welds (Minimum Length) 45
4.6.1.5 Maximum Effective Length 45
4.6.1.6 Calculation of Effective Throat 45
4.6.1.7 Reinforcing Fillet Welds 46
4.6.1.8 Maximum Weld Size in Lap Joints 46
4.6.1.9 Effective Area of Fillet Welds 46
4.7 About Fillet Weld 46
4.7.1 Filet Weld Defined and Explained 47
4.7.1.1 Single Fillet Welds 52
4.7.1.2 Double Fillet Welds 52
4.7.1.3 Combined Groove and Fillet Welds 52
4.8 Weld Design and Loading 54
4.8.1 Common Conditions to Consider When Designing Welded Connections 55
4.8.2 Marking the Fabrication and Construction Drawings 55
4.8.3 Effective Areas 57
4.8.4 Effective Area of Groove Welds 57
4.9 Sizing Fillet Welds 59
4.9.1 Effective Length of Straight Fillet Welds 59
4.9.2 The Determination of Effective Throat of a Fillet Weld 59
4.9.2.1 Fillet Welds Joining Perpendicular Members 59
4.9.2.2 Fillet Weld in Acute Angle 60
4.9.2.3 Fillet Welds That Make Angle Between 60 o and 80 o 60
4.9.2.4 Fillet Welds That Make Acute Angle Between 60 o and 30 o 61
4.9.2.5 Reinforcing Fillet Welds 61
4.9.3 Fillet Welds - Minimum Size 61
4.9.4 Maximum Weld Size in Lap Joints 62
4.9.5 Skewed T-Joints 63
4.9.5.1 T-Joint Welds in Acute Angles Between 80° and 60° and in Obtuse Angles Greater Than 100° 63
4.9.5.2 T-Joint Welds in Angles Between 60° and 30° 63
4.9.5.3 T-Joint Welds in Angles Less than 30° 63
4.9.5.4 Effective Length of Skewed T-Joints 64
4.9.5.5 Effective Throat of Skewed T-Joints 64
4.9.5.6 Effective Area of Skewed T-Joints 64
4.10 Fillet Welds in Holes and Slots 64
4.10.1 Slot Ends 64
4.10.2 Effective Length of Fillet Welds in Holes or Slots 64
4.10.3 Effective Area of Fillet Welds in Holes or Slots 64
4.10.4 Diameter and Width Limitations 64
4.10.5 Slot Length and Shape 65
4.10.6 Effective Area of Plug and Slot Welds 65
4.11 Designing Calculations for Skewed Fillet Weld 65
4.12 Treating Weld as a Line 66
4.12.1 Calculation Approach 67
4.12.2 Finding the Size of the Weld 67
4.12.3 Calculated Stresses 73
4.12.4 Stress in Fillet Welds 73
4.12.5 Joint Configuration and Details 74
4.12.6 Compression Member Connections and Splices 75
4.12.7 Where There is an Issue of Through-Thickness Loading on the Base Plate 75
4.12.8 Determining the Capacity of Combinations of Welds 75
4.12.9 Corner and T-Joint Surface Contouring 75
4.12.10 Weld Access Holes 75
4.12.11 Welds with Rivets or Bolts 76
4.12.12 Joint Configuration and Details 76
4.12.12.1 Groove Welds - Transitions in Thicknesses and Widths 76
4.12.12.2 Partial Length CJP Groove Weld Prohibition 76
4.12.12.3 Flare Welds, Flare Groove and Intermittent PJP Groove Welds 76
4.12.12.4 Joint Configuration and Details 77
4.12.12.5 Termination of Fillet Welds 77
4.12.12.6 Fillet Welds in Holes and Slots 78
4.13 Design of Tubular Connections 80
4.13.1 Weld Joint Design 82
4.13.2 Uneven Distribution of Load 88
4.13.3 Collapse 91
4.13.4 Lamellar Tear and Lamination 91
4.13.5 Fatigue 92
4.14 Design for Cyclic Loading 93
4.14.1 Improving Fatigue Performance of Welds, and Evaluation of S-N Curves for Design 105
4.14.1.1 Typical Weld Flushing Plan 107
4.15 Aluminum 107
4.15.1 Aluminum Alloys and Their Characteristics 108
4.15.1.1 Aluminum Alloys Series 1xxx 108
4.15.1.2 Aluminum Alloy Series 2xxx 109
4.15.1.3 Aluminum Alloy Series 3xxx 109
4.15.1.4 Aluminum Alloy Series 4xxx 109
4.15.1.5 Aluminum Alloy Series 5xxx 109
4.15.1.6 Aluminum Alloy Series 6xxx 110
4.15.1.7 Aluminum Alloy Series 7xxx 110
4.15.2 The Aluminum Alloy Temper and Designation System 110
4.15.3 Wrought Alloy Designation System 111
4.15.4 Cast Alloy Designation 111
4.15.5 The Aluminum Temper Designation System 112
4.16 Welding Aluminum 114
4.16.1 Aluminum Welding Electrodes 115
4.16.2 Electrical Parameters 115
4.17 Design for Welding Aluminum 116
4.17.1 Effect of Welding on the Strength of Aluminum and its Alloys 117
4.17.2 Effect of Service Temperature 119
4.17.3 Type of Weld Joints for Aluminum Welding 120
4.17.3.1 Butt Joints 120
4.17.4 Lap Joint for Aluminum Welding 121
4.17.5 Use of T-Joints in Aluminum Welding 121
4.18 Distribution of Stress in Aluminum Weld Design 122
4.18.1 Shear Strength of Aluminum Fillet Welds 123
4.18.2 Fatigue Strength in Aluminum Welds 123
4.19 Heat and Distortion Control 124
4.19.1 Angular Distortion 125
4.19.2 Longitudinal Distortions 126
5 Introduction to Welding Processes 131
5.1 Introduction 131
5.2 Shielded Metal Arc Welding (SMAW) 134
5.3 Gas Tungsten Arc Welding 139
5.4 Gas Metal Arc Welding 142
5.5 Flux Cored Arc Welding (FCAW) 145
5.6 Submerged Arc Welding (SAW) 145
5.7 Electroslag Welding (ESW) 146
5.8 Plasma Arc Welding 146
5.9 Stud Welding 146
5.10 Oxyfuel Gas Welding 147
5.11 Hyperbaric Welding 152
5.12 Application of Welding Processes 153
6 Welding Symbols 155
6.1 Introduction 155
6.2 Common Weld Symbols and Their Meanings 156
6.2.1 The Basic Structure of Welding Symbol 156
6.2.2 Types of Welds and Their Symbols 157
6.3 Fillet Welds 158
6.3.1 The Length of the Fillet Weld 159
6.4 Groove Welds 160
6.4.1 Square Groove Welds 161
6.4.2 V-Groove Welds 161
6.5 Bevel Groove Welds 162
6.5.1 U-Groove Welds 163
6.5.2 J-Groove Welds 163
6.5.3 Flare-V Groove Welds 164
6.5.4 Flare Bevel Groove Weld 164
6.6 Plug and Slot Welds 166
7 Structural Design and Welding Specifications, and Other Useful Information 169
7.1 Introduction 169
7.2 Structural Welding Codes 169
7.3 Useful Engineering Information 174
Index 201
2
Properties of Metals
Synopsis
This chapter discusses the properties of material, structure sensitive and structure insensitive properties are defined. How properties are determined for engineering applications. Behavior of metal in extreme environ conditions like heat and cold are introduced.
Keywords
Mechanical, physical, corrosion, modulus of elasticity, tensile strength, fatigue strength, cyclic loading, HAZ
2.1 Material Properties
Knowledge of the properties of the metal is an essential aspect of welding engineer's ability to be a good welding engineer. This knowledge allows the engineer to choose the most suitable material to improve upon the cost and functioning of the component being designed.
Various metals and non-metals are used in fabrication and construction, they all possess certain specific properties that differentiates them from others to be more desirable for the specific demands of the design to be an engineering material. All these metal properties are assessed and classed in three specific metal properties that are relevant to the engineering evaluations, for the suitability for the project.
Metal properties can be classified as,
- 1. Mechanical properties
- 2. Physical properties and
- 3. Corrosion properties.
These are the primary properties however they can also be classified on the basis of their nuclear and optic properties. Further they can be classified on the basis of, if these properties are structure sensitive, or structure insensitive etc. Some details of these properties given the Table 2.1 below.
Table 2.1 Properties of materials.
General group Structure-insensitive properties Structure-sensitive properties Mechanical Elastic moduli- Ultimate strength,
- Yield strength,
- Fatigue strength,
- Impact strength,
- Hardness,
- Ductility,
- Elastic limit,
- Damping capacity,
- Creep strength,
- Rupture strength.
Thermal conductivity,
Melting point,
Specific heat,
Emissivity,
Thermal evaporation rate,
Density,
Vapor pressure,
Electrical conductivity,
Magnetic properties,
Thermionic emission. Ferromagnetic properties Corrosion
- Electrochemical potential,
- Oxidation resistance
- Color,
- Reflectivity.
- Radiation obsorbtivity,
- Nuclear cross section,
- Wavelength of characteristic X-rays
The following is the discussion on these material properties.
2.1.1 Structure Insensitive Properties
These are well stablished and defined properties of a metal. These properties are standard from one piece of metal to another, from the engineering aspect they do not change. These properties are verifiable and can be tested for verification. These can be calculated, rationalized by consideration of the chemical compositions and crystallographic structure of metal.
2.1.2 Structure Sensitive Properties
These properties are dependent upon chemical and microstructural details of the metal. These chemical and microstructural details get altered through the manufacturing and processing history of the metal. Even the size of the sample can affect these properties. All mechanical properties of metal except the Elastic Moduli are Structure sensitive properties. And all the physical properties except the Ferromagnetic properties are Structure insensitive properties of the metal. Corrosion, Optical, and Nuclear properties are all structure insensitive properties.
Now we briefly discuss these properties as they apply to metals in engineering application.
2.1.3 Mechanical Properties
Mechanical properties of metals make them useful for engineering applications. These properties make them strong, playable, to form shape and still retain their strength. Metals possess a combination of properties like toughness, strength and ductility that vary from metal to metal this variation allows the choice of specific metal for specific needs of the structure. These properties of some metals like steel, and aluminum can be altered and improved to make them more suitable for specific objectives.
Through a combination of both alloy selection and heat treatment gives design engineers a selection of mechanical properties in metals to choose from. During the fabrication process too, the applied heat, joining methods like welding and brazing choice of filler metal for welding all affect metal's mechanical properties. Some of these properties are counter to each other; that is, if you increase one property the other may be lowered and vice versa. This leads to some compromises in selection process. This brings in the importance of fully knowing the properties of metals. To know the specific properties of metal in given condition and during its formation during fabrication it is essential to test and know exact properties of the material that is being used for design purpose.
In the following paragraphs a brief introduction to some of the mechanical properties is discussed.
2.1.3.1 Modulus of Elasticity
The ability of a metal to resist stretching (stain) under the stress is defined by the ratio of the two. This is called the Modulus of Elasticity and indicated by letter E. This is a constant value for specific metal. The Table 2.2 below gives Modulus of Elasticity values of some of the common engineering metals.
where;
Table 2.2 Modulus of elasticity of common engineering metals.
Metal Modulus of elasticity, psi Aluminum 9.0 × 106 Beryllium 42.0 Columbium 15.0 Copper 16.0 Iron 28.5 Lead 2.0 Molybdenum 46.0 Nickel 30.0 Steel, (Carbon and alloy steels) 29.0 Tantalum 27.0 Titanium 16.8 Tungsten 59.0The elastic modulus is a structure sensitive property, (see Table 2.1) is not changed by metal's gain size, cleanliness, by significant alloying, or by heat treatment. However, modulus of elasticity decreases with increasing temperatures, and the rate of change is not same for all metals.
The modulus indicates that, how much a beam would deflect elastically under the load, or a bar would elastically stretch, when loaded. In welding engineering the modulus is frequently used to determine the level of stress created in a piece of metal when it is forced to stretch elastically for a specific amount. In this case the stress (s) can be determined by multiplying the strain (?) by the modulus of elasticity (E) which is a constant for the given metal.
2.1.3.2 Tensile Strength
By far the most often used property is the metals' ability to sustain the load while it is put under tensile strain. During testing, it is determined by the sustained load at which the test specimen breaks or the metal has lost its elasticity and entered in the Plastic state and deformed. This value is divided by the cross-section of the specimen being tested to obtain the Ultimate Tensile Strength (UTS) of the metal under test. The Figure 2.1 below is the tensile test graph of typical mild steel, it indicates the key points of mechanical behavior during the testing.
Figure 2.1 A typical strain and stress diagram, describing various elements of tensile test.
2.1.3.3 Yield Strength
The yield strength of a metal is the load at which the metal transits from being elastic to plastic. This load is reached at a point called yield point, however it also transits and peaks at one point, where metal exhibits total plasticity and YIELDS to the applied load. Both these points are shown in the Figure 2.1 above.
Note that there is a line at 0.2 percent offset, this value of the yield is often the engineering yield value that is used for design calculations.
2.1.3.4 Fatigue Strength
When a metal structure is subject to repeat (a cyclic load) loading, the metal is subject to specifically more stringent conditions. The cyclic loading fatigues the metal structure and reduces the life of the structure, and ultimately fractures and fail. Fatigue strength is an important mechanical property to know about the metal and welds if cyclic loading is one of the demands of the designed structure. Metal's ability to sustain cyclic loading, for longer time of its design life is the Fatigue strength of that metal. Fatigue strength is a measures of load versus...
