Pipe Welding Procedures
اسم المؤلف
Hoobasar Rampaul
التاريخ
المشاهدات
579
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Pipe Welding Procedures
Second Edition
by Hoobasar Rampaul
Contents
Forward iv
Preface v

  1. Introduction 1
  2. Essentials of Shielded Metal-Arc Welding Technology 10
  3. Heat Input and Distribution 14
  4. Reparation of the Pipe Joint 21
  5. Uphill Welding the Root Bead on Heavy-WallPipe
    (5GPosition) 31
  6. Welding the Rood Bead by the Gas Tungsten Arc
    Welding Process 57
  7. The Intermediate and Cover Passes 81
  8. Welding Thin-Wall Pipe 100
  9. Horizontal Pipe Welding (20) 136
  10. Welding Complicated Pipe Joints 158
  11. Introduction to Welding Metallurgy 170
  12. Distortion in Pipe Welding 198
  13. Pipe Welding Defects 207
  14. Fitting-UP Pipe 222
  15. Qualification of the Welding Procedure & the Welder 237
    I6.General Welding Safety
    Index
    Alignment, perpendicular pipe 235. 236
    vertical pipe, 234, 235
    Alloying elemenls in steel, 185- J88
    boron, 188
    carbon, 186
    chromium, 187
    cobalt, 188
    manganese. 186
    molybdenum, 187
    nickel, 187
    silicon, 186, 187
    titanium, 188
    tungsten, 188
    vanadium, 187
    Aluminum as a deoxidizer in steel, 188
    “Amperage,” 10
    Arc length, 12, 13
    Arc strike cracking, 207, 208
    Austenite, 180
    Bainite, 180, 181
    Base metal – Hiler metal combinations, 75-77
    Bend tests, 240-242
    Boron as an alloying element in steel. 188
    Brittleness, (def.) 174
    Carbon as an alloying element in steel, 186
    Cementite, [77,178
    Chromium as an alloying element in steel, 187
    Cleaning the joint surfaces, 23
    Coating, electrode. 12
    Cobalt as an alloying element in steel. 188
    Codes and standards, 8, 9
    Complicated pipe joints, full lateral joint in,162-165
    intennediate and cover passes in, 160, 161
    rool beads in, 158-160
    special precautions ill welding, 168
    T-joint with intersection at side, 166, 167
    T-joint with intersection on bottom, 166
    T-joint with intersection On top, 165
    welding, 158·169
    V-joint, 167
    Copper added to steel, 188
    Cover passes, in horizontal pipe welding, 148, 149
    in mUltilayer welding, 91-93
    in Otin·wall pipe welding, 122-23
    in welding complicated pipe joints, 160, 161
    Cracking, arc strike, 207, 208
    restraint, 52, 209·211
    underbead 208, 209
    Cryogenic services, 156, 157
    Current flow. 10
    Current setting in multilayer welding, 84-86
    Defects in pipe welding, 207-221
    Index
    Distortion in pipe welding, 198·206
    preventing, 206
    Distortion in welds, 193- J97
    Downhill pipe welding, 3-7
    of thin·wall pipe, 102·106
    heavy wall and large diameter, 126·128
    DUClility, (def.) 174
    Electric arc welding, basic concepts of, 10, II
    Electrode coating, 12
    Electrodes for GTAW process, 62,63
    Electrodes for multilayer welding, low-hydrogen, 93, 94
    Elements in steel, alloying, 185·188
    Fatigue, 174
    Faults and their prevention in welding, 211-216
    Ferrite, 177
    Fifth, sixth, and seventh passes
    pipe welding. 148, 149
    Fittmgs, pipe, 224
    Fitting-up pipe, 23, 24, 222-236
    Fit-up, pipe-to-pipe. 224-226
    poor, 45-49
    Flanges to pipe, welding, 226-230
    Flat welding the root bead, 4041
    45-degree elbows to pipe, welding, 231-233
    Full lateral joint in welding complicated
    pipe joints, 162-165
    Gas cylinders, safe handling of, 233, 234
    Gas tungsten arc welding (GTAW), 57-58
    welding the root bead by, 57·80
    Grain size, 182·184
    Grain structure, 175-177
    GTAW, equipment for, 59-63
    shielding gas for, 59, 61
    torch for, 62
    welding machine for. 59
    GTAW process,
    f;aution, 74, 80
    cover passes, 132-135
    depositing root bead, 128-129
    downhill pipe welding, 126-128
    electrodes for, 62, 63
    features of, 57
    filler passes, 129-132
    Heavy-wall pipe welding. 126-135
    making a tie-in in, 74, 75
    preparation of the weld joint in, 65
    procedure for welding the root bead in, 65-70
    pulse current, 72-74
    rool bead, 72·80
    second pass in, 72
    shielding the weld metal in, 63·65
    stop and restart in, 70, 71
    247Index
    Handling of gas cylinders, safe, 244
    Hardenability, 173
    Hardness. (def.) 114
    Heat distribution, 14, 15·20
    Heat input, 14, 15
    Heat withdrawal from weld zone, I5
    High temperature services, alloy steel in, I54-156
    Horizontal pipe welding, 8, 136-157
    coverp~esin, 148. 149
    fi fih, sixth, and seventh passes in, 148, 149
    making a tie-in in, 14 I
    of the root bead, 137-14Q
    ofthin·wall pipe, 104
    poor fit·up in, 141·143
    second pass in, 144·146
    stop and restart in, 140
    third and fourth passes in, 146-148
    using low·hydrogen electrodes, 143
    Hot pass in thin-wall pipe welding, 115-119
    1nelusions of slag, 212·214
    Incomplete penetration, 216
    inspecting the weld in uphill welding the rootbead,
    44-52
    intermediate and cover passes, in welding
    complicated pipe joints, 160, 161
    on heavy-wall pipe, 81·99
    intermediate passes, in multilayer welding, 86-89
    in thin-wall pipe welding, 119·122
    iron-carbon diagram, 181,182
    Keyhole, 27, 28
    in uphill welding the root bead, 33, 34
    Lack of fusion, 216
    Large diameter pipe welding, 126-135
    depositing root bead, 128-129
    downhill pipe welding, 126-128
    Lead added to steel, 188
    Low temperature serv ice, 156, I57
    Malleability, 174
    Manganese as an alloying element in steel, 186
    Martensite, 179
    Metallurgy, welding, 170-197
    Metals, properties of. I 70-174
    size changes in, 184, 185
    Metal transfer, 11, 12
    Molybdenum as an allOying element steel, 187
    Multilayer welding, 81·82
    current setting in, 84-85
    intermediate passes in, 86-89
    low-hydrogen eleclfodes for, 93, 94
    stop and restart in, 89-91
    the cover pass in, 91-93
    tie-in in, 91
    Multiple layers, 81-82
    Nickel as an alloying element in steel, 187
    9O-degree elbows to pipe, welding, 230, 231
    OXYllC\:tyJene welding, safety regulations for,
    245,246
    Pearlite, 178
    Perfect weld requirements, 239, 240
    Phosphorus in steel, 188
    Pipe fittings, 224
    Pipeline welding, outdoor, 104, 105
    Pipe parts to pipe, welding, 226-236
    Pipe-IO-pipe fit-up, 224·226
    Poor fit·up, in horizontal pipe welding, 141·143
    in thin-wall pipe welding, 124
    narrow root opening, 48, 49
    root face 100 thin, 49
    root face too wide, 49
    wide and narrow rool openings, 48, 49
    wide root openingI 4548
    Porosity, 215, 216
    Positions for pipe welding, basic, 1,2
    Precautions in welding complicated pipe joints, 168
    Preparation of the pipe joint, 21-30
    Preparation of the rool bead in multilayer
    welding, 82-84
    Preparation oflhe weldjoinl in GTAW pro-cess, 65
    Preparing pipe edges, 21·23
    Preventing distorticm in pipe welding, 206
    Prevention of welding faults, 211·216
    Procedures, bask pipe welding, 3-8
    for fitting-up pipe, 222
    qualifYing, 237
    Properties ofmetals, 170-1 74
    Pulse current, root bead, 72-74
    Qualification of the welding procedure and
    the welder, 237·242
    Relieving of stresses, 188, 189
    Requirements for a perfect weld, 239, 240
    Residual stresses and distortion in welds, 193-197
    Restart in uphill welding the rool bead, 37, 38
    Restraint cracking, 52, 209-211
    Rool bead, flat welding the, 40-41
    in complicated pipe joints, 158·160
    in uphill welding on heavy-wall pipe, 31-34
    vertical uphill welding of the, 38·39
    Root bead, GTAW process, 72·80
    pulse current, 72-74
    Root bead in multilayer welding, prepara-tion of
    the, 82·84
    Root bead in uphill welding, starting the. 34-36
    Root bead welding, summary of, 52-56
    thin-wall pipe, 103·108
    with low-hydrogen electrodes, 49-52
    248Index
    Safe handling of gas cylinders, 244
    Safety, general welding, 243-246
    Safely regulations for oxyacetylene welding, 245,246
    Second half of the pipe joint, welding the, 41
    Second pass in horizontal pipe welding, 144-146
    Shear stress, 172
    Shielded metal·arc welding. 10-13
    electrode, 94-99
    Shielding gas for GTAW process, 59, 61
    Shielding the weld metal in GTAW process, 63-65
    Silicon as an alloying element in steel, 186, 187
    Size changes in metals, 184, 185
    Slag inclusions, 212-214
    Spheroidite, 180
    Standards and codes, 8, 9
    Standard symbols designating welding posi-lions, 2
    Starting the root bead in uphill welding,34·36
    Steel, structural characteristics ot: 177-181
    Stop and restart, in GTAW process, 70, 71
    in hori7,Ontai pipe welding, 128, 129
    in multilayer welding, 89-91
    in thin-wall pipe welding, 114·115
    in uphill welding the root bead, 37, 38
    Stopping the weld, 28-30
    Strain, (def.) 172
    Strength, 172, 173
    ultimate tensile, 173
    yield, (def.) 173
    Stress, (def) 17I, 172
    shear, 172
    torsional, 172
    Stresses and distortions in welds, residual, 193-197
    Stress relieving, 188, 189
    Structural characteristics of steel, 177-181
    Structure of the weld, 189-193
    Structure sleel 78, 79
    Sulfur added to steel, 188
    Symbols designating welding positions, 2
    Tack welding, 25-27
    thin-wall pipe, 106-110
    Tees to pipe, welding, 234
    Tensile strength, ultimate, 173
    Tests, bend, 229-231
    Thin-wall pipe welding, 100-135
    cover pass in, 122·123
    downhill, 102·106
    horizontal, 104
    pass in, 115, II 6 joint tor, 105,106
    Thin-wall pipe welding, intermediate passes in,
    119-122
    poor fit·up in, 124
    preparation for the hot pass in, 115, 116
    preparation of the pipe joint for, 105, 106
    stop and restart in, 1114, 115
    tack welding, 106-110
    tie-ins in, 115
    uphill, 100, !OI
    welding the root bead in, 110·114
    with pipe axis at 45-degree POSilion,124-125
    Third and fourth passes in horizontal pipewelding,
    146-148
    Tie-in, in GTAW process, 72
    in horizontal pipe welding, 141
    in multilayer welding, 91
    in thin-wall pipe welding, 115
    procedure, 41-44
    TIG (tungsten inert gas) welding, 57-58
    Titanium as an alloying elemen! in sleel, 188
    T-joint, in welding complicated pipe joinIs, 164-167
    with intersection at side in welding com-plicated
    pipejoinls, 166,167
    wilh intersection on top in welding com-plicated
    pipejoints, 165
    Tools required for fitting-up pipe, 209-2 II
    Torch for GTAW process, 62
    Torsional stress, 172
    Toughness, (def.) 174
    Tungsten as an alloying element in steel, 188
    Ultimate tensile strength, 173
    Underbead cracking, 208, 209
    Undercutting, 211,212
    Uphill pipe welding, 7, 8
    wilh pipes in an angular (6G) position, 161,162
    Uphill welding the root bead, 36-38
    keyhole in, 34
    on heavy-wall pipe (50 position), 31-48
    vertical, 38-39
    UphHl welding thin-wall pipe, 100, 101
    Vanadium as an alloying element in steel, 187
    Venical uphill Welding of the root bead, 38·39
    Voltage, 10
    “Weaving,” 20
    Weld-affected zone, 190-193
    Weld repair, 217-221
    “Whipping.” 20, 28
    “Whipping and pllllSe,” 39
    Widmanstatten structure, 179
    Withdrawing heat from weld zOne, 15
    Yield strength, (def.) 173
    V-joint in welding complicated pipe joints

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