Advanced Welding Processes: Technologies and Process Control

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PROJECT: WELDING CODE : WELDING PROCESS EDGE PREPARATION JOINT TYPE JOINT POSITION DRAWING REFERENCE : : : : : JOINT DETAIL PASS SEQUENCE WELD PASS ELECTRODE FLUX DETAILS DESCRIPTION No. SIDE POS TYPE SIZE SPEC. GAS TEST PLATE IDENTIFICATION MARKED: WELDER: No. DATE: NOTES: Monitoring and control of welding processes 183 STICKOUT: SHIELD GAS: FLUX: ELECTRODE: WELDING PROCEDURE SPECIFICATION W.P.S. No.: AMPS CONSUMABLE/DETAILS Rev.: Page: APPROVALS CONTRACTOR: CLIENT: CERT. AUTH.: JOINT TOLERANCES DIMENSION AS DETAILED ROOT OPENING R ROOT FACE F GROOVE ANGLE OC GRADE: THICKNESS: RANGE QUAL.: MATERIAL SPECIFICATION PREHEAT: MAX. INTERPASS: P.W.H.T.: WELDING PARAMETERS VOLTS POL THERMAL TREATMENT SPEED VISUAL: M.T.: R.T.: U.T.: PREPARED BY: 10.2 Typical welding procedure specification sheet. INTER PASS TEMP Amendment of procedure. If the specified procedure fails to produce the required results, it may be necessary to repeat the process and amend the welding parameters. N.D.E. HEAT INPUT KJ/mm
184 Advanced welding processes Procedure qualification Formal qualification of the procedure involves completion of sample joints to the agreed WPS, often under the supervision of the client or an independent approval body. The welded joints are subjected to a specified selection of non-destructive and mechanical tests, the results of which are reported in a procedure qualification record (PQR) as shown in Fig. 10.3. The skill of the welder is often a major factor in determining the final weld quality. The welder’s skill may be assessed and ‘calibrated’ by means of a general approval process. [198] It may also be required to qualify a named welder to carry out a specific procedure. Procedure management Management of welding procedures using this technique involves: maintenance of procedure specification and qualification records; calibration of welding and ancillary equipment; and monitoring compliance with the specified procedure. Maintaining procedure records. Having established a satisfactory procedure and obtained procedure qualification, it is necessary to maintain a record of the parameters and techniques used and to control the issue of this information to the shop floor to enable consistent joint quality to be achieved. In many cases, this information will be required on an irregular basis particularly when small batches of fabrications are required. The welding procedure specification records will also be required when tendering for new projects, when preparing procedures for new work or when analysing production problems. A fabricator will quickly generate a large library of procedures and it is necessary to devise a suitable system for storage and retrieval. Many companies are now using computer database systems for procedure management in order to reduce duplication and improve access to procedure data. [199] Validity of parameters and calibration of equipment. The validity of the procedure will depend on the possibility of establishing the same operating conditions: when the process is used with the stated parameters, by a different operator in a different workplace using equipment and consumables of the specified type. If the parameters specified are ambiguous or ill-defined, the resultant weld may well be inferior to those prepared at the procedure development stage. For example in GMA welding when voltage is used as a control parameter, the voltage reported should be the arc voltage measured as near to the arc as possible. Open circuit (or no-load) values may be easier to measure, but are meaningless unless the static characteristics of the power source are also stated. In addition, since there may be a significant voltage drop in the
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Advanced welding processes i
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Advanced welding processes Technolo
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Contents Preface ix Acknowledgement
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Contents vii 10.4 Automated control
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Welding has traditionally been rega
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Acknowledgements I would like to ac
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1.1 Introduction Welding and joinin
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An introduction to welding processe
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Stage 1 Stage 2 An introduction to
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Slag deposit on weld surface An int
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∑ no heavy slag - reduced post-we
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Electro slag SAW multi wire SAW FCA
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Weld metal used (kg m -1 ) 40 35 30
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Advanced process development trends
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% consumed 70 60 50 40 30 20 10 Adv
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Advanced process development trends
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Mains input Power regulation Contro
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Welding power source technology 29
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Three-phase transformer Three-phase
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Mains input Welding power source te
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Off line storage Operator interface
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4.2.1 Improved toughness Filler mat
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Filler materials for arc welding 47
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Flat strip Solidified slag on weld
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Gases for advanced welding processe
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CVN impact energy (J) 200 150 100 5
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∑ argon plus 15-25% carbon dioxid
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25 23 21 19 17 15 13 11 9 7 20 18 1
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Ozone emission (ml min -1 ) 4 3 2 1
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Table 5.3 Continued Argon + 1 to 7%
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Advanced gas tungsten arc welding 7
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Power source Advanced gas tungsten
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Number of arc starts 35 30 25 20 15
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Water cooling 6.7 Dual-shielded GTA
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∑ low current: 0.1-15 A; ∑ inte
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Surface tension Surface tension Adv
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7.2.1 Globular drop transfer Metal
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Gas metal arc welding 103 projected
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Droplet forming 7.6 Drop spray tran
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Number of counts 100 80 60 40 20 0
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Metal cored Rutile Basic Self-shiel
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F d Fem F v F st F g 7.13 Balance o
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Gas metal arc welding 113 is the cu
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Stick out Dip transfer Pulse/spray
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Gas metal arc welding 117 V = M + A
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Voltage (V) 50 40 30 20 10 Gas meta
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Pulse current t p 7.23 Pulsed trans
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Gas metal arc welding 123 The mean
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Wire feed rate (m min -1 ) 11 10.5
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Gas metal arc welding 127 Improveme
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Gas metal arc welding 129 and a num
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Current (A) 500 400 300 200 100 0 G
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Page 148 and 149: Gas metal arc welding 135 otherwise
Page 150 and 151: High-energy density processes 137
Page 152 and 153: High-energy density processes 139 P
Page 154 and 155: Arc voltage 30 25 20 15 10 High-ene
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Page 158 and 159: Reflecting mirror Laser cavity Powe
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Page 162 and 163: Laser beam Gas lens Plasma control
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Page 166 and 167: High-energy density processes 153 M
Page 168 and 169: High-energy density processes 155 a
Page 170 and 171: High-energy density processes 157 l
Page 172 and 173: High-energy density processes 159 p
Page 174 and 175: 8.4.5 Practical considerations High
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Page 178 and 179: 9.1 Introduction 9 Narrow-gap weldi
Page 180 and 181: 6-16 mm Parallel-sided with backing
Page 182 and 183: Water cooling Main Shielding-gas po
Page 184 and 185: Narrow-gap welding techniques 171 T
Page 186 and 187: 9.7 ‘Twist arc’ narrow-gap GMAW
Page 188 and 189: GMAW torch The NOW process GMAW tor
Page 190 and 191: Narrow-gap welding techniques 177 T
Page 192 and 193: 10.1 Introduction 10 Monitoring and
Page 194 and 195: Monitoring and control of welding p
Page 198 and 199: TYPE TOUGHNESS TEST TYPE No. TEMP R
Page 204 and 205: Data RAM ADC I/O device Monitoring
Page 208 and 209: Current I(A) 150 140 130 120 110 Mo
Page 210 and 211: Table 10.5 Stability criteria Monit
Page 224 and 225: CCD camera Travel direction Torch M
Page 232 and 233: Welding automation and robotics 219
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Welding automation and robotics 233
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Table 11.1 Robot applications Weldi
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∑ evaluate alternatives; ∑ eval
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Option Manual metal arc Gas metal a
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Appendices Appendices 247
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Arc Metal arc Manual metal arc Resi
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Tensile strength Appendices 251 Des
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Appendices 253 Exx16 Basic low-hydr
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GMAW stainless steel c Wire feed sp
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Appendix 4 American, Australian and
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Appendices 259 Carbon Manganese ste
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Consumable type Features Applicatio
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Appendix 7 Plasma keyhole welding o
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References [1] British Standards In
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References 267 [40] Anon, 1989 ‘S
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References 269 [88] Boughton P and
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References 271 Century Conference (
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References 273 [178] Benn B, 1988
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References 275 [224] Philpott M L,
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References 277 [269] UK Patent 8411
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Activated TIG (A-TIG) 91, 97 adapti
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digital measuring systems 189-90 di
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high-frequency high-voltage arc ini
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current measurement 194-6 determina
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carbon dioxide 63-4, 64-6 chlorine
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