تذكير بمساهمة فاتح الموضوع :احبتى فى الله
الى كل مهتم بعمليات اللحام اليكم هذا الكتاب المميز الا وهو
Welded Connections—
A Primer For Engineers
Table of Contents
1. INTRODUCTION ............................................... 1
1.1 IMPORTANCE OF WELDING ............................ 1
1.2 SCOPE OF WELDING ......................................... 1
1.3 WELDING-RELATED CODES AND
SPECIFICATIONS
1.3.1 AISC Specification for Structural
Steel Buildings ......................................... 1
1.3.2 AWS D1.1 Structural Welding
Code—Steel .............................................. 2
1.3.3 AISC Seismic Provisions for
Structural Steel Buildings ........................ 2
1.3.4 AWS D1.8 Structural Welding
Code—Seismic Supplement ..................... 3
1.3.5 AWS D1.3 Structural Welding
Code—Sheet Steel .................................... 3
1.3.6 Other AWS D1 Codes .............................. 3
2. WELDING AND THERMAL CUTTING
PROCESSES ........................................................ 5
2.1 INTRODUCTION ................................................. 5
2.1.1 Requirements for Welding ....................... 5
2.1.2 Arc Welding as Compared to Other
Welding Processes ................................... 6
2.1.3 Process Issues and Concerns for the
Engineer ................................................... 6
2.2 SMAW ................................................................... 8
2.2.1 Fundamentals ........................................... 8
2.2.2 Equipment ................................................ 8
2.2.3 Consumables ............................................ 9
2.2.4 Electrode Classification System .............. 9
2.2.5 Low-Hydrogen SMAW Electrodes ........ 10
2.2.6 Care and Storage of Low-Hydrogen
Electrodes .............................................. 10
2.2.7 Process Advantages/Limitations ............ 12
2.2.8 Applications ........................................... 12
2.3 FCAW .................................................................. 12
2.3.1 Fundamentals ......................................... 12
2.3.2 Equipment .............................................. 13
2.3.3 Consumables .......................................... 13
2.3.4 Electrode Classification ......................... 14
2.3.5 FCAW Advantages and Limitations ...... 15
2.3.6 FCAW-G Advantages and Limitations .. 16
2.3.7 FCAW-G Applications ........................... 16
2.3.8 FCAW-S Advantages and Limitations ... 16
2.3.9 FCAW-S Applications ............................ 16
2.3.10 FCAW-S Intermix Concerns .................. 16
2.4 SAW .................................................................... 17
2.4.1 Fundamentals ......................................... 17
2.4.2 Equipment .............................................. 18
2.4.3 SAW Consumables ................................ 18
2.4.4 Electrode and Flux Classification .......... 19
2.4.5 Flux Recovery ........................................ 20
2.4.6 Crushed Slag .......................................... 20
2.4.7 Process Advantages and Limitations ..... 20
2.4.8 Applications ........................................... 21
2.5 GMAW ................................................................ 21
2.5.1 Fundamentals ......................................... 21
2.5.2 Equipment .............................................. 21
2.5.3 Consumables .......................................... 22
2.5.4 Electrode Classification System ............ 22
2.5.5 Shielding Gas ......................................... 22
2.5.6 Modes of Transfer .................................. 23
2.5.7 Process Advantages and Limitations ..... 24
2.5.8 Applications ........................................... 25
2.6 ESW/EGW .......................................................... 25
2.6.1 Fundamentals ......................................... 25
2.6.2 Equipment .............................................. 26
2.6.3 Consumables .......................................... 26
2.6.4 Electrode Classification ......................... 26
2.6.5 Process Advantages and Limitations ..... 26
2.6.6 Applications ........................................... 27
2.7 GTAW .................................................................. 27
2.8 ARC STUD WELDING ...................................... 27
2.9 THERMAL CUTTING PROCESSES ................ 28
2.9.1 Oxyfuel Gas Cutting and Gouging ........ 29
2.9.2 Plasma Arc Cutting and Gouging .......... 29
2.9.3 Air Carbon Arc Gouging and Cutting .... 30
3. WELDED CONNECTIONS ............................ 31
3.1 JOINTS ................................................................ 31
3.2 WELD TYPES—GENERAL .............................. 31
3.3 COMPLETE JOINT PENETRATION (CJP)
GROOVE WELDS .............................................. 31
3.3.1 CJP Groove Weld Backing .................... 32
3.3.2 Single-Sided vs. Double-Sided Welds ... 34
3.3.3 Groove Weld Preparations ..................... 34
3.3.4 Spacer Bars ............................................ 34
3.4 PARTIAL JOINT PENETRATION (PJP)
GROOVE WELDS .............................................. 34
3.4.1 Effective Throats for PJP
Groove Welds ......................................... 35
3.4.2 Minimum PJP Groove Weld Sizes ......... 35
3.4.3 Restrictions on the Use of PJP
Groove Welds ......................................... 35
3.4.4 Required Filler Metal Strength
for PJP-Groove Welds ............................ 36
3.4.5 Flare-V and Flare-Bevel Groove
Welds ..................................................... 36
3.4.6 Single-Sided vs. Double-Sided Welds ... 36
3.4.7 PJP-Groove Weld Details ....................... 36
3.5 FILLET WELDS ................................................. 36
3.5.1 Minimum Size of Fillet Welds ............... 37
3.5.2 Maximum Size of Fillet Welds .............. 38
3.5.3 Minimum Fillet Weld Lengths ............... 38
3.5.4 Maximum Fillet Weld Lengths .............. 38
3.5.5 Intermittent Fillet Welds ........................ 38
3.5.6 Penetration in Fillet Welds ..................... 39
3.5.7 Longitudinal vs. Transverse
Fillet Welds ............................................ 39
3.5.8 Combined Longitudinal vs.
Transverse Welds ................................... 40
3.5.9 End Returns (Boxing) ............................ 40
3.5.10 Weld Termination (Fillet Welds) ............ 41
3.5.11 Fillet Welds and Fitup ............................ 42
3.6 PLUG/SLOT WELDS ......................................... 42
3.7 INTERACTION OF JOINT TYPES
AND WELD TYPES ........................................... 43
3.8 SELECTION OF WELD TYPES ....................... 43
3.9 WELD DETAILS ................................................ 45
3.9.1 Weld Tabs ............................................... 45
3.9.2 Weld Access Holes ................................. 45
3.9.3 Fillers ..................................................... 46
3.9.4 Welds and Mechanical Fasteners ........... 46
3.9.5 Strength of Welds in Combinations ....... 47
3.9.6 k-Area Detailing ..................................... 47
3.10 LAMELLAR TEARING AND
JOINT DETAILS ................................................. 48
3.11 REQUIRED FILLER METAL STRENGTH ...... 48
3.11.1 Matching Filler Metal ............................ 48
3.11.2 Undermatching Filler Metal .................. 48
3.11.3 Overmatching ........................................ 49
3.12 DETERMINING WELD STRENGTH ............... 50
3.12.1 CJP Groove Welds ................................. 50
3.12.2 PJP Groove Welds .................................. 50
3.12.3 Fillet Welds ............................................ 50
3.12.4 Plug/Slot Welds ...................................... 51
3.13 SPECIAL WELDS .............................................. 51
3.13.1 Arc Spot Welds (Puddle Welds,
Deck Welds) ........................................... 51
3.13.2 Repair Welds .......................................... 51
3.13.3 Seal Welds .............................................. 52
3.13.4 Tack Welds ............................................. 53
3.13.5 Temporary Welds ................................... 54
3.13.6 Compatibility of Weld Metals ................ 54
3.14 SPECIFIC REQUIREMENTS FOR
VARIOUS JOINTS ............................................. 54
3.14.1 Butt Joints .............................................. 54
3.14.2 Corner Joints .......................................... 54
3.14.3 T-Joints ................................................... 55
3.14.4 Lap Joints ............................................... 55
3.15 WELDING SYMBOLS ...................................... 55
3.16 SAMPLE CALCULATIONS .............................. 57
4. METALLURGICAL ISSUES .......................... 59
4.1 INTRODUCTION ............................................... 59
4.2 STEEL—PROPERTIES OF INTEREST ............ 59
4.3 DESCRIPTIONS OF STEEL GROUPS ............. 60
4.3.1 AWS D1.1 Prequalified Steels ............... 60
4.3.2 AWS D1.1 Approved Steels ................... 60
4.3.3 AWS D1.1 Unlisted Steels ..................... 60
4.3.4 AISC Specification Treatment of
Unidentified Steels ................................. 604.4 WELDING REQUIREMENTS FOR
SPECIFIC STEELS ............................................. 60
4.4.1 Weathering Steels .................................. 60
4.4.2 Quenched and Tempered Steels ............. 61
4.4.3 Historical (Obsolete) Steels ................... 62
4.5 WELDING NONSTRUCTURAL STEELS ....... 63
4.5.1 Anchor Rods .......................................... 63
4.5.2 Bolts and Nuts ........................................ 64
4.5.3 Stainless Steel to Steel ........................... 64
4.5.4 Cast Iron ................................................ 64
4.5.5 Wrought Iron ......................................... 65
4.5.6 Steel Castings ......................................... 65
5. WELD CRACKING .......................................... 67
5.1 INTRODUCTION ............................................... 67
5.2 SHRINKAGE AND RESTRAINT ...................... 67
5.2.1 Shrinkage ............................................... 67
5.2.2 Constraint ............................................... 67
5.3 TYPES OF WELD CRACKS ............................. 68
5.3.1 Centerline Cracking ............................... 68
5.3.2 Heat-Affected Zone Cracking ................ 72
5.3.3 Transverse Cracking .............................. 74
5.4 LAMELLAR TEARING ..................................... 75
5.5 REDUCING SHRINKAGE STRESSES ............ 77
5.6 REDUCING RESTRAINT ................................. 78
5.7 POST-WELDING STRESS REDUCTION
MEASURES ........................................................ 78
6. DISTORTION .................................................... 79
6.1 INTRODUCTION ............................................... 79
6.2 CAUSES OF DISTORTION ............................... 79
6.3 DISTORTION CONTROL ................................. 80
6.3.1 General ................................................... 80
6.3.2 Angular Distortion ................................. 81
6.3.3 Transverse Shrinkage ............................. 82
6.3.4 Longitudinal Shortening ........................ 82
6.3.5 Twisting ................................................. 83
6.3.6 Longitudinal Sweep or Camber ............. 83
6.3.7 Buckling and Warping ........................... 84
6.3.8 Rotational Distortion ............................. 84
6.4 SPECIALIZED DISTORTION CONTROL
MEASURES ........................................................ 85
6.4.1 Adding Restraint .................................... 85
6.4.2 Weld Placement ..................................... 86
6.4.3 Welding Sequence .................................. 86
7. WELDING PROCEDURE
SPECIFICATIONS ........................................... 89
7.1 INTRODUCTION ............................................... 89
7.2 WRITING WELDING PROCEDURE
SPECIFICATIONS .............................................. 89
7.3 USING WELDING PROCEDURE
SPECIFICATIONS .............................................. 89
7.4 PREQUALIFIED WELDING PROCEDURE
SPECIFICATIONS .............................................. 90
7.5 QUALIFIED WELDING PROCEDURE
SPECIFICATIONS .............................................. 91
7.6 EFFECTS OF WPS VARIABLES ...................... 92
7.6.1 Amperage ............................................... 92
7.6.2 Arc Voltage ............................................ 92
7.6.3 Travel Speed .......................................... 92
7.6.4 Wire Feed Speed .................................... 93
7.6.5 Electrode Extension ............................... 93
7.6.6 Contact Tip to Work Distance ................ 93
7.6.7 Electrode Diameter ................................ 93
7.6.8 Polarity ................................................... 93
7.6.9 Heat Input .............................................. 93
7.6.10 Preheat and Interpass Temperature ........ 94
7.6.11 Post-Heat ................................................ 94
7.6.12 Stress Relief ........................................... 94
8. WELD QUALITY ............................................. 95
8.1 INTRODUCTION ............................................... 95
8.2 TYPES OF WELD DISCONTINUITIES ........... 95
8.2.1 Planar Discontinuities—Weld and
Base Metal ............................................. 95
8.2.2 Volumetric Discontinuities—Specific
to the Weld ............................................. 97
8.2.3 Volumetric Discontinuities External to
the Weld ............................................... 100
8.2.4 Metallurgical Deficiencies ................... 1009. WELD INSPECTION ..................................... 101
9.1 INTRODUCTION ............................................. 101
9.2 VISUAL INSPECTION (VT) ........................... 101
9.2.1 Visual Inspection Before Welding ....... 101
9.2.2 Visual Inspection During Welding ....... 102
9.2.3 Visual Inspection After Welding .......... 102
9.3 NONDESTRUCTIVE TESTING —
GENERAL ........................................................ 102
9.4 PENETRANT TESTING (PT) .......................... 102
9.5 MAGNETIC PARTICLE INSPECTION (MT) 103
9.6 RADIOGRAPHIC INSPECTION (RT) ............ 104
9.7 ULTRASONIC INSPECTION (UT) ................. 104
10. SEISMIC WELDING ISSUES ....................... 107
10.1 INTRODUCTION ............................................. 107
10.2 SPECIFICATIONS AND CODES .................... 108
10.3 SEISMIC WELDING TERMINOLOGY ......... 108
10.4 SPECIAL CONNECTION DETAILS .............. 109
10.5 FILLER METAL REQUIREMENTS ............... 110
10.6 WELDER QUALIFICATION TESTS .............. 111
10.7 NONDESTRUCTIVE TESTING ..................... 111
11. FATIGUE CONSIDERATIONS .................... 113
11.1 INTRODUCTION ............................................. 113
11.2 STRESS RANGE .............................................. 113
11.3 CONNECTION GEOMETRY .......................... 116
11.4 COMPUTATIONS ............................................ 118
11.5 INSPECTION ISSUES ..................................... 119
11.6 SPECIAL FABRICATION/ERECTION
REQUIREMENTS ............................................ 119
12. SPECIAL WELDING APPLICATIONS ...... 121
12.1 WELDING ON ANCHOR RODS .................... 121
12.1.1 General ................................................. 121
12.1.2 Extending Anchor Rods ....................... 121
12.1.3 Welding Anchor Rod to Base Plates .... 121
12.2 WELDING ON COATED STEELS .................. 122
12.2.1 General ................................................. 122
12.2.2 Galvanized Materials ........................... 122
12.2.3 Testing .................................................. 122
12.2.4 Ventilation ............................................ 123
12.3 WELDING ON HEAVY SECTIONS ............... 123
12.4 WELDING ON HEAVILY RESTRAINED
MEMBERS ....................................................... 124
12.5 WELDING HSS ............................................... 125
12.5.1 Introduction .......................................... 125
12.5.2 Connections and HSS Member Size ... 126
12.5.3 Overall Configurations of HSS
Assemblies ........................................... 126
12.5.4 Cutting and Preparing Joints in HSS .. 126
12.5.5 Welding HSS ....................................... 127
12.6 WELDING AESS ............................................. 127
12.7 SHOP VS. FIELD WELDING .......................... 128
12.8 WELDING ON EXISTING STRUCTURES .... 128
12.8.1 General ................................................. 128
12.8.2 General Welding Precautions ............... 128
12.8.3 Welding on Members under Load ....... 129
12.8.4 Repair of Plastically Deformed Steel .. 129
12.9 HEAT SHRINKING .......................................... 130
13. THE ENGINEER’S ROLE IN
WELDED CONSTRUCTION ........................ 131
13.1 INTRODUCTION ............................................. 131
13.2 CONTRACT DOCUMENTS ............................ 131
13.2.1 Design Drawings ................................. 132
13.2.2 Static vs. Cyclic Loading ..................... 132
13.2.3 Inspection Requirements ..................... 132
13.2.4 Alternate Acceptance Criteria .............. 133
13.2.5 Notch Toughness Requirements .......... 133
13.2.6 Welding on Existing Structures ........... 133
13.2.7 Structural Details ................................. 134
13.2.8 Certification of Welding Materials ....... 134
13.3 APPROVALS .................................................... 134
13.3.1 Background .......................................... 134
13.3.2 New Materials and Processes .............. 135
13.3.3 Routine Items ....................................... 135
13.3.4 Practices Requiring Review ................. 135
13.3.5 Practices That May or
May Not Be Acceptable ....................... 136
13.4 UNEXPECTED CIRCUMSTANCES .............. 136
13.4.1 Background .......................................... 136
13.4.2 Base Metal Discontinuities .................. 13613.4.3 Fit-up and Alignment Problems ........... 137
13.4.4 Welding Problems ................................ 137
13.4.5 Post-Welding Corrections .................... 137
14. ECONOMY IN WELDING ........................... 139
14.1 INTRODUCTION ............................................. 139
14.2 SELECTION OF PROPER WELD TYPE ........ 139
14.2.1 CJP Groove Welds vs. Alternatives ..... 139
14.2.2 Fillet Welds vs. PJP Groove Welds ...... 140
14.2.3 Combination PJP/Fillet Weld Option ... 140
14.3 PROPER DETAILING OF WELDS ................. 141
14.3.1 Fillet Welds: Leg Size vs. Length ........ 141
14.3.2 Fillet Welds: Intermittent vs.
Continuous ........................................... 141
14.3.3 CJP Groove Welds: Single vs.
Double Sided ....................................... 142
14.3.4 CJP Groove Weld Details:
Included Angle vs. Root Opening ........ 142
14.3.5 CJP Groove Welds: V and
Bevel vs. U and J ................................. 145
14.3.6 PJP-Groove Welds: Single vs.
Double Sided ....................................... 145
14.3.7 Flare Groove Welds ............................. 146
14.3.8 Shop vs. Field Welding ........................ 146
14.3.9 Welded vs. Bolted Connections ........... 146
15. WELDING SAFETY ...................................... 147
REFERENCES .............................................................. 149
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