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Welding Processes

Welding Processes. Welding Process Knowledge - A Benefit to Inspectors. Helps spot problems Leads to better inspection Gains respect of welders Gains cooperation. Common Features of Welding Processes. Source of energy Source of shielding

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Welding Processes

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  1. Welding Processes

  2. Welding Process Knowledge - A Benefit to Inspectors Helps spot problems Leads to better inspection Gains respect of welders Gains cooperation

  3. Common Features of Welding Processes Source of energy Source of shielding Filler metal (optional) { autogenous or hetrogeneous}

  4. SMAW

  5. Functions of the Electrode Coating To provide a gas to shield the arc To produce a slag blanket to protect the hot weld metal from the air To improve the smoothness and stability of the arc Deoxidisers to cleanse the weld Adding alloying elements

  6. Types of coating 1- Cellulose - Organic compound cellulose - Limited amount of slag - used for all positions - E 6010 , E 6011

  7. Types of coating 2- Basic - Calcium carbonates - Low hydrogen content - E 7015 , E 7018 3- Rutile - Titanium dioxides - Heavy slag - E 6013, E 6024

  8. SMAW Electrode Identification System EX XX X-XEELECTRODEXXDeposite weld metal tensile strengthKsiXthe position

  9. Welding Positions

  10. Welding Positions

  11. Welding Positions

  12. Welding Positions

  13. Welding Positions

  14. Position Description 1 - used in all positions 2 - used in flat or horizontal fillets only 3 - not used at present time 4 - used for ‘downhill’ progression

  15. SMAW Electrode Identification System E X X X X-XXCoating/Operating Characteristics X Alloying elements percent

  16. Electrode Suffixes - 1 of 2

  17. Electrode Suffixes - 2 of 2

  18. Example of electrode classification E 7010 E 6013

  19. Electrode Coating ClassificationF #s F1 - EXX20, EXX24, EXX27 F2 - EXXX2, EXXX3, EXXX4 F3 - EXX10, EXXX1 F4 - EXXX5, EXXX6, EXXX8

  20. Low Hydrogen Electrodes Types end in a ‘5’, ‘6’, or ‘8’ Purchase in sealed, metal containers Store after opening in heated, vented oven Limit atmospheric exposure

  21. Stainless Steel Electrodes E308, E308L - Weld 304 and 304L E316, E316L - Weld 316 and 316L E309 - Weld Stainless to Carbon Steel

  22. SMAW Advantages Simple equipment Inexpensive Very portable Welds most alloys Less sensitive to wind & draft air Not required shielding gas

  23. SMAW Limitations • Relatively slow • Slag removal • Electrode storage considerations • Arc blow • It can not weld refractory materials ( tantalum, Mo, Cr, W ) or reactive materials ( Titanium,..

  24. SMAW Discontinuities Porosity Slag inclusions Spatter Incomplete joint penetration Incomplete fusion

  25. Gas Tungsten Arc Welding Equipment

  26. GTAW Nomenclature

  27. AWS Tungsten Electrode Classifications

  28. GTAW Filler Metals Carbon Steels ER70S-2, ER70S-3, etc. Stainless Steels ER308, ER308L, ER316, etc.

  29. Effect of DCEN Current on GTAW

  30. Effect of DCEP Current on GTAW

  31. Effect of AC Current on GTAW

  32. SHIELDING GASES ARGON - High density ( suitable in flat position ) - Weld all metal except reactive & refractory materials - High spatter - Recommended flow rate 7 : 16 L /min

  33. SHIELDING GASES Helium - Low density ( suitable in overhead position position ) - Good penetration - Recommended flow rate 14 : 24 L /min

  34. GTAW Advantages Good for thin materials High quality welds Good appearance Very clean No slag Autogeneous ( without filler metal )&heterogeneous

  35. GTAW Limitations Relatively slow Low tolerance for contamination Shielding gas expensive Purging gas expensive

  36. GTAW Discontinuities Porosity Incomplete fusion Incomplete joint penetration Tungsten inclusions

  37. Causes of Tungsten Inclusions • Contact between: • Tungsten and base metal • Tungsten and filler metal • Excess current • Excess tungsten extension • Improper tungsten tip grinding

  38. Submerged Arc Welding (SAW)

  39. SAW

  40. SAW Filler Metal Identification System Flux F XXX - E X X X FFlux XTensile strength X Heat Treatment X Impact Test Temperature

  41. SAW Filler Metal Identification System Flux F X X X - EXX X EElectrode X (Low, Medium, High - Mn%) XX (8 through 16 for chemistry)

  42. SAW Filler Metal Example F7A6-EM12K

  43. SAW Equipment

  44. SAW Advantages High deposition rate Deep penetration Mechanized process Not required black lenses Good for overlay of large areas Less smoke than SMAW

  45. SAW Limitations Flat or horizontal fillets only Extensive setup time Needs positioning equipment Arc not visible to operator Slag removal

  46. SAW Discontinuities Groove alignment Slag inclusions Porosity Incomplete fusion Cracking (W/D ratio)

  47. GMAW

  48. GMAW Equipment

  49. GMAW Nomenclature

  50. GMAW Electrode Identification System ERX XS – X EElectrode R Rod S Solid XXStregngth of deposite weld metal X Chemical Composition

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