Welding procedure and techniques and types of welding

Welding procedures and training for welding

1. WELDING TECHNIQUE

2. COURSE CONTENTS

3. COURSE SCHEDULE

4. First welding process was discovered about 5800 years ago by a blacksmith Tubal-Cain. This was forged welding technique. In 1800, Frenchman Volta used bank of batteries to produce an electric arc. But it was unsuccessful. In 1865, Englishman Wilde was able to generate electric arc and welded small pieces of iron together. WELDING-General Concepts BRIEF HISTORY

5. In 1890, Baltic Shipyards used bare electrode first time for welding. But oxygen and other gases contamination produced exceedingly poor weld. In 1902, Swedish engineer Oscar Kjelberg devised a method of shielding molten weld metal. He used coated electrodes for the first time and set a foundation of welding technique which is still in use. BRIEF HISTORY WELDING-General Concepts

6. When two pieces of similar or different materials are joined together with the help of high temperature with or without filler material ; This can be achieved either by applying pressure or without it. This process is known as WELDING . WELDING-General Concepts WELDING DEFINITION

7. When two metals, which are not melted, are joined with a third metal, which has a melting point less than adjoining metals. Filler Metal: Eutectic Alloy, Tin Lead, Tin-zinc etc. WELDING-General Concepts SOLDERING APPLICATIONS Plumbing Electronics Jewelry Manufacturing

8. When two metals, which are not melted, are joined with a third metal, which has a melting point less than adjoining metals. Filler Metals: AL-718, CP 102, High Temp 080 etc. WELDING-General Concepts BRAZING APPLICATIONS Automotive industry HVAC Equipments

9. Soldering filler wire melting temperature is less than 450°C whereas brazing filler wire’s is above 450°C. WELDING-General Concepts DIFFERENCE BETWEEN BRAZING & SOLDERING Filler Wire Melting Point SOLDERING Tin-Lead 215°C Tin-Zinc 343°C BRAZING High Temp 080 855°C

10. The process of producing hole or cavity in a metal piece by using electric arc is called gouging. WELDING-General Concepts GOUGING Process is similar to welding but instead of conventional filler metal a high carbon electrode is used to remove metal.

11. Hand Held Screens Adjustable Helmets Clothing should be free from oil, grease or any flammable substance. Do not roll up sleeves. Cuffs, turn-ups on trousers, exposed long hairs and low cut shoes are places vulnerable for sparks, slag or globules of hot metal etc. WELDING PPEs SCREENING CLOTHING

12. SCREENING

13. CLOTHING WELDING PPEs Protect front of body from throat to knees with suitable apron / jacket. Use suitable leather gloves to protect wrists and hands. High cut safety leather shoes.

14. POWER SOURCE: Correctly connected and adequately earthed. CABLES: Insulation proper, clear of ladders, gangways and doors, do not allow traffic pass over it, disconnect from power source before joining/disconnecting cables. HOSES: Appropriate hoses, Connections leak proof, clear of gangways, doors and ladders, avoid being crushed by weights , kinks free etc. WELDING-SAFETY MEASURES PRE WELDING SAFETY MEASURES

15. LEADS: Properly insulated. Lead thimbles are properly connected. Avoid kinks. Return welding lead connected to only welded piece unless special procedures exist, return leads must be as short as possible and have sufficient current carrying capacity. Do not wrap welding leads around components, work table, scaffolding etc. WELDING-SAFETY MEASURES PRE WELDING SAFETY MEASURES

16. HOLDERS: Completely insulated holder when welding in confined space, difficulty to access weld, steels that may be hardened by accidental ‘arcing’. Avoid contact of partly insulated holder with metal parts causing stray flashes. When holder not in use secure it in insulated hook. WELDING-SAFETY MEASURES PRE WELDING SAFETY MEASURES

17. GAS CYLINDERS: Healthy condition, keep them away from welding arc, fitted with pressure regulator and calibrated gauge. WORKING AREA: Proper hot job enclosure, Neat and tidy, free from flammable materials, fire extinguisher available, properly ventilated etc. SCREENING: screen available to avoid exposure of arc light to others. WELDING-SAFETY MEASURES PRE WELDING SAFETY MEASURES

18. Ensure weld spatters and slag do not fall beyond hot job enclosure. Welder assistant should be wearing eye protective to avoid exposure of welding arc. WELDING-SAFETY MEASURES DURING WELDING SAFETY MEASURES

19. House keeping of working area. Barricading of welded components to avoid human contact. Disconnect power supply. Wrap up welding leads and power cables. WELDING-SAFETY MEASURES POST WELDING SAFETY MEASURES

20. TYPES OF WELDING

21. BASE METALS : Metals which are required to be welded. ELECTRODE/FILLER WIRE : Third Metal require to form weld joint or Metal rod require for arc production. WELD PUDDLE : Pool of molten metal. SLAG : Deposition of electrode coating on weld. TYPES OF WELDING WELDING GLOSSARY

22. Non-consumable electrode made up of tungsten. Shielding gas (inert) to cover weld puddle. Filler wire TYPES OF WELDING GAS TUNGSTEN ARC WELDING-GTAW Requirements

23. Electric arc is established by touching electrode with workpiece . As soon as arc is developed, operator maintains a constant gap of 1.5 to 3mm between electrode and workpiece . Arc ionizes inert gas and allows welding current to flow through it and causes base metal to melt. Then welder add filler wire in molten metal pool to achieve desire weld quality. TYPES OF WELDING GAS TUNGSTEN ARC WELDING-GTAW Operation

24. TYPES OF WELDING GAS TUNGSTEN ARC WELDING-GTAW

25. TYPES OF WELDING

26. Base metal positive. Electrode negative. Direct Current. Welding Speed is slow Can be employed on all types of weld geometries Highest quality root over wide range of thicknesses and weld geometries . TYPES OF WELDING PARTS OF GAS TUNGSTEN ARC WELDING-GTAW Salient Features

27. Consumable electrode. TYPES OF WELDING SHIELDED METAL ARC WELDING-SMAW Requirements Operation Electric arc is established by touching an consumable electrode with work piece. As soon as arc is established, operator maintains a gap between electrode and work piece. Electric arc melts base metals. Electrode flux provides shielding gas when melts and electrode core provides filler metal to have desire properties of weld joint.

28. Base metal negative Electrode positive Both DC and AC are source suitable Welding speed is greater than GTAW Can be employed on all types of weld geometries. Weld spatters Slag required to be grind off TYPES OF WELDING SHIELDED METAL ARC WELDING-SMAW Salient Features

29. TYPES OF WELDING SHIELDED METAL ARC WELDING-SMAW

30. This type of welding is done by machine and employs bare rod. Bare electrode is already place in machine which produces electric arc. A powder is showered by machine which covers molten pool to avoid contamination. After welding, burned flux is recovered again for reuse. TYPES OF WELDING SUBMERGED ARC WELDING-SMAW Operation

31. Very high thickness plates can be welded in quick time. In case of high pre heat temperatures and manual welding is not possible, this technique is very conducive. This welding can be only be applied for flat position. TYPES OF WELDING SUBMERGED ARC WELDING-SAW Salient Features

32. TYPES OF WELDING SUBMERGED ARC WELDING-SMAW

33. SUBMERGED ARC WELDING-SMAW

34. Electrodes and filler wires classification and their use is defined by American Welding Society (AWS). Moreover, weld joint inspection is also covered by AWS (B1.11). AWS publishes codes and guidelines for welding of structures (AWS D1.1), welding of carbon steels, alloy steels etc. AWS is being endorsed by ASME/ANSI. TYPES OF WELDING ELECTRODES & FILLER WIRES

35. TYPES OF WELDING ELECTRODES & FILLER WIRES ELECTRODES/FILLER WIRES FOR SMAW, GTAW & SAW SMAW E 7018 (Carbon Steel SFA 5.1) E 6010 (Carbon Steel SFA 5.1) E 9015 (Low Alloy Steels SFA 5.5) GTAW ER 70S-3 (Carbon Steel SFA 5.18) ER 80S B2 (Low Alloy SFA 5.28) ER 308 (Stainless Steel SFA 5.9) SAW EL 8 (Mild Steel SFA 5.17)

36. Take an example E-7018 TYPES OF WELDING ELECTRODES DECODING Electrode Tensile Strength ( Ksi ) Welding Position Type of Flux Coating Alphabet Shows Either Electrode (E) or Filler Wire (ER) First two numeric digit shows minimum tensile strength in Ksi

37. 1 All Positions (Flat, horizontal, vertical and over head positions) 2 Flat and horizontal positions 3 Flat position only TYPES OF WELDING ELECTRODES DECODING Third numeric digit shows ‘Welding Position’ Last numeric digit indicates type of flux and type of power supply required for electrode High Cellulose Sodium DC 1 High Cellulose Potassium AC or DC 8 etc. Iron Powder Low hydrogen AC or DC

38. E 308-16 TYPES OF WELDING ELECTRODES DECODING Corrosion Resistant Electrodes Alphabet Shows Either Electrode (E) or Filler Wire (ER) 308 shows 18% Cr and 8% Ni 1 shows suitable for all welding positions 6 shows suitable with both AC and DC

39. Electrodes and filler wires are available in number of sizes; TYPES OF WELDING ELECTRODES SIZES (Diameter of Core) DESCRIPTION SIZES (mm) ELECTRODES 1.6, 2.0, 2.5, 3.2, 4.0, 5.0, 6.0, 6.3, 8.0 FILLER WIRES 1.6, 2.4, 3.2, 6.0

40. WELDING ACCESSORIES ELECTRODE HOLDERS Electrode holder is used to hold and guide the electrode over the seam to be welded. A good holder should be light to reduce excessive fatigue while welding, receive and eject electrodes easily and be properly insulated. Some holders are fully insulated and some are semi insulated. Always connect holders firmly with power cables. A loose connection where the cable joins holder may overheat the holder. FULLY INSULATED SEMI INSULATED

41. Electrode holder is used to hold and guide the electrode over the seam to be welded A good holder should be light to reduce excessive fatigue while welding, receive and eject electrodes easily and be properly insulated. ELECTRODE HOLDERS WELDING ACCESSORIES

42. SEMI INSULATED Always connect holders firmly with power cables A loose connection where the cable joins holder may overheat the holder. WELDING ACCESSORIES ELECTRODE HOLDERS

43. WELDING ACCESSORIES SMAW-ELECTRODE HOLDERS

44. WELDING ACCESSORIES GTAW-ELECTRODE HOLDERS CAP TORCH BODY ALUMINA NOZZLES

45. WELDING ACCESSORIES POWER SUPPLIES WELDING TRANSFORMER WELDING RECTIFIER WELDING GENERATOR or CONVERTER WELDING INVERTER PORTABLE WELDING GENERATOR

46. WELDING ACCESSORIES WELDING TRANSFORMER Provides AC current with high amperes and less voltage is received for welding. Current regulator provided for adjusting current. There are three types of welding transformers i.e single phase, two phase and three phase.

47. WELDING ACCESSORIES WELDING RECTIFIER Welding rectifier can provide either AC or DC welding current. Rectifier operation is quieter. These machines offer greater efficiency then their counterparts.

48. WELDING ACCESSORIES WELDING GENERATOR It is just an electric dynamo which when driven by electric motor or auto engine produces electricity. These machines produces high DC current 72Volts. These machines are usually employed for heavy welding jobs.

49. WELDING ACCESSORIES ELECTRODE OVEN Electrodes absorbs moisture in open atmosphere. This causes porosity in weld metal and cracking in HAZ. When electrodes absorbs moisture; A white layer is formed over it. Its flux starts disintegrating during welding. Excessive spatter. Excessive rusting of core wire observes. Electrodes affected by moisture may be used after draying in oven for approximately an hour at 110 to 150°C.

50. It is a document describing welding procedures, which provides direction to the welder or welding operators for making sound and quality production welds as per the code requirements. WELDING PROCEDURE SPEC. Definition

51. WELDING PROCEDURE SPEC. Information Available in WPS Type of Welding Type of Weld Joint Base Metals Type of Filler Metal/Electrode Welding Position Preheat Requirement Postweld Heat Treatment Gas Characteristics Electrical Characteristics Welding Bead Technique Current and Speed Requirement Miscellaneous Details

52. WELDING PROCEDURE SPEC. Welding Joint Terminologies Fillet Weld/Joint Lap Weld/Joint Weld Root Filling Capping Butt Weld/Joint

53. Root Pass Hot Pass Fill Pass Cover/Capping Pass WELDING PROCEDURE SPEC.

54. WELDING PROCEDURE SPEC. Fillet Welding Joint Terminologies

55. WELDING PROCEDURE SPEC. Variations in Welding Joints

56. WELDING PROCEDURE SPEC. Welding Joint Positions

57. WELDING PROCEDURE SPEC. Welding Joint Positions

58. WELDING PROCEDURE SPEC. Welding Beads THERE ARE TWO TYPES OF WELD BEADS A weld bead is the result of a welding pass that deposits filler material. Stringer Bead Weave Bead DEPENDING ON HOW MUCH OSCILLATIONS WELDER USES

59. When the welder uses more oscillation while applying filler material, the result is weave bead. Employed when large amount of weld deposit required. WELDING PROCEDURE SPEC. Weave Bead

60. Stringer Bead WELDING PROCEDURE SPEC. When the welder uses very little oscillation while applying filler material, the result is stringer bead. Stringer beads are generally not very wide and can be used in any welding position.

61. WELDING PROCEDURE SPEC. Current Selection Electrode Size Welding Deposition Rate Type of Job Welder’s Skill

62. WELDING DISCONTINUITIES Discontinuity Discontinuities are interruptions in the desirable physical structure of weld. Defect When discontinuities reach to an extent that it poses danger to the fitness for purpose of a weld then it is called defect.

63. WELDING DISCONTINUITIES Classification of Welding Discontinuities DESIGN RELATED WELDING PROCESS RELATED METALLURGICAL

64. It includes problems related to Design detail. Choice of wrong type of weld joint for a given application. Undesirable changes in cross section WELDING DISCONTINUITIES Discontinuity-Design Related

65. WELDING DISCONTINUITIES Discontinuity-Welding Process Related Undercut Slag Inclusion Porosity Overlap Backing Piece Left On Shrinkage Voids Oxide Inclusions Lack of Fusion Lack of Penetration Craters Spatters Underfill Melt Through Arc Strikes

66. WELDING DISCONTINUITIES Undercut A groove melted into the base metal adjacent to the toe or root of a weld and left unfilled by weld metal. Remedial Measures Decrease current, travel speed and electrode diameter. Change electrode angle. Avoid weaving.

67. WELDING DISCONTINUITIES Slag Inclusion Non-metallic solid material entrapped in weld metal or between weld metal and base metal. Remedial Measures Decrease cooling rate. Increase temperature of weld puddle. Improve weld geometry.

68. WELDING DISCONTINUITIES Porosity Pores formed by gas entrapment during welding. Remedial Measures Remove rust, scale, paint, moisture etc. Eliminate moisture from flux or shielding gas. Provide sufficient shielding. Keep weld molten metal long enough to escape gases.

69. WELDING DISCONTINUITIES Overlap The protrusion of weld metal beyond toe, face or root of the weld. Remedial Measures Change electrode angle. Use higher travel speed. Use high welding current.

70. WELDING DISCONTINUITIES Backing Piece Left On Failure to remove material placed at the root of a weld joint to support molten weld metal. Remedial Measures Ensure proper removal of backing material.

71. WELDING DISCONTINUITIES Shrinkage Voids Cavity type discontinuity formed owing to shrinkage during solidification. Remedial Measures Slow cooling.

72. WELDING DISCONTINUITIES Oxide Inclusions Particles of surface oxides which have not melted and are mixed into the weld metal. Remedial Measures Clean joint and weld area thoroughly prior welding.

73. WELDING DISCONTINUITIES Lack of Fusion A condition in which fusion is less than complete. Remedial Measures Increase heat input. Improve joint geometry. Reduce travel speed Use proper electrode angle.

74. WELDING DISCONTINUITIES Lack of Penetration A condition in which joint penetration is less than required. Remedial Measures Increase heat input. Improve joint geometry. Reduce travel speed Use proper electrode angle.

75. WELDING DISCONTINUITIES Craters Depression at the termination of weld bead. Remedial Measures Fill crater before breaking arc. Employ backstepping technique.

76. WELDING DISCONTINUITIES Spatters Metal particles which are expelled during welding that do not form part of weld. Remedial Measures

77. WELDING DISCONTINUITIES Underfill Depression on the face of weld or root surface extending below the surface of the adjacent base metal. Remedial Measures To minimize underfill , voltage, travel speed and root opening should be reduced.

78. WELDING DISCONTINUITIES Arc Strike (Arc Burn) Discontinuities consisting of any localized re-melted metal, heat effected metal or change in surface profile of any part of weld or base metal resulting from arc. Remedial Measures Ensure proper handling of welding torch.

79. WELDING DISCONTINUITIES HI-LO (Misalignment) Misalignment of welding joint. Remedial Measures Careful while joint tacking. Ensure same Inside diameter of welded pipes etc.

80. WELDING DISCONTINUITIES Cracking Fracture type discontinuities. Remedial Measures Proper preheating. Proper post heating. Use proper electrode that has sufficient ductility. etc. Discontinuity-Metallurgy Related

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82. Standard Number † Title AWS A02.4 Standard symbols for welding, brazing, and non-destructive examination AWS A03.0 Standard welding terms and definitions AWS A05.1 Specification for carbon steel electrodes for shielded metal arc welding AWS A05.18 Specification for carbon steel electrodes and rots for gas shielded arc welding AWS B01.10 Guide for the nondestructive examination of welds AWS B02.1 Specification for Welding Procedure and Performance Qualification AWS D01.1 Structural welding (steel) AWS D01.2 Structural welding (aluminum) AWS D01.3 Structural welding (sheet steel) AWS D01.4 Structural welding (reinforcing steel) AWS D01.5 Bridge welding AWS D01.6 Structural welding (stainless steel) AWS D01.7 Structural welding (strengthening and repair) AWS D01.8 Structural welding seismic supplement AWS D01.9 Structural welding (titanium) AWS D08.1 Automotive spot welding AWS D08.6 Automotive spot welding electrodes supplement AWS D08.7 Automotive spot welding recommendations supplement AWS D08.8 Automotive arc welding (steel) AWS D08.9 Automotive spot weld testing AWS D08.14 Automotive arc welding (aluminum) AWS D09.1 Sheet metal welding AWS D10.10 Heating practices for pipe and tube AWS D10.11 Root pass welding for pipe AWS D10.12 Pipe welding (mild steel) AWS D10.13 Tube brazing (copper) AWS D10.18 Pipe welding (stainless steel) AWS D11.2 Welding (cast iron) AWS D14.1 Industrial mill crane welding AWS D14.3 Earthmoving & agricultural equipment welding AWS D14.4 Machinery joint welding AWS D14.5 Press welding AWS D14.6 Industrial mill roll surfacing AWS D15.1 Railroad welding AWS D15.2 Railroad welding practice supplement AWS D16.1 Robotic arc welding safety AWS D16.2 Robotic arc welding system installation AWS D16.3 Robotic arc welding risk assessment AWS D16.4 Robotic arc welder operator qualification AWS D17.1 Aerospace fusion welding AWS D17.2 Aerospace resistance welding AWS D18.1 Hygienic tube welding (stainless steel) AWS D18.2 Stainless steel tube discoloration guide AWS D18.3 Hygienic equipment welding