CSWIP 3.2 notes

There are some highlights that I would like to share you should note in study book before prepare for learning. Most questions are unlike CSWIP 3.1, you must have about welding knowledge to take an examination, special in Scenario Questions.

Questions

PART 1: 30 General Questions

All general questions in 12 slides and additional welding processes without specification.

  • Welding processes, 1-2 questions
  • Weldability, 6-7 questions
  • Heat treatment, 2-3 questions
  • Destructive test, 2-3 questions
  • Symbols, 2-3 questions
  • NDT, 2-3 questions
  • WPS and welder qualification, 2-3 questions
  • Consumables, 2-3 questions
  • Welding defects, 3-4 questions

Part 2: 60 Scenario Questions

Approximately 20% questions related specification, you need to check in specification without NDT and Welding Symbols.

  • 12 questions – specification and drawings
  • 4 questions – joint design + drawings
  • 4 questions – fracture test
  • 12 questions – weldability (HICC, hot crack, lamellar)
  • 4 questions – weld repair
  • 4 questions – destructive test
  • 4 questions – stress and distortion
  • 4 questions – arc energy and heat input
  • 4 questions – wps and welder qualification
  • 4 questions – consumables
  • 4 questions – heat treatment

Part 3: 40 NDT Questions

Most questions refer to specification with conventional methods of MT, PT, UT, RT with specification, advantage/ disadvantage of each method.

Part 4: 10 Welding Symbol Questions

You need familiar with BS EN ISO 2553 rule, and join design.

Senior Welding Inspection - questions and answers at WIS10-30816.

Summary from study book

Heat treatment

Temperature are devided in two groups follows:

Temperature range Type of heat treatment
Upper Critical Temperature ( 880 – 920 deg. C ) Annualizing; Normalizing; Quenching
Lower Critical Temperature( <730 deg. C) Preheat; PWHT; Tempering; Recovery

Note: purpose and effective heat treatment see in study book.

  • Term “ local ” - heat treatment a partial equipment or weld joint; “ Global ” = heat treatment whole equipment.
  • PWHT soaking: decrease yield strength, decrease residual stress, and then increase yield strength (<100%).
  • PWHT effect: toughness increase, hardness decrease, residual stress decrease, tensile decrease, not completely remove residual stress.
  • Tempering: follows Quenching.

Welding consumable and welding process

A. MMA (111) process

  • Electrode type: Cellulose (0, 1), Rutile (2,3,4) Basic (5,6,8).
  • Cellulose never baking, Rutile only dry at 90 – 120 degree C; Basic shall be baked at 350 deg. C and then drying at 150 degree C before using.

B. TIG (141) process

  • Lowest hydrogen content.
  • Slope-in occurs tungsten inclusion, slope-out occurs cater crack (shrink crack).
  • Zirconiated electrode suitable for Aluminum , only AC current; Thoriated electrode suitable carbon steel.

C. MIG/MAG (131/135) process

  • Dip transfer for thin plate; give lack of fusion and spatters.
  • Pulse transfer for small weld pool and all positions.
  • Spray transfer for thick plate, flat, horizontal; give no spatter, less distortion.
  • Globular transfer given high distortion, only with CO2

D. SAW (121) process

  • Fusion: hydroscopic, restrict moisture, no baking
  • Agglomerate: sensitive moisture, baking before use, easy add more elements, good quality.
  • Given high deposit rate, less distortion, high dilution.

E. Current and Polarity DC EP

  • MMA, FCAW, MIG/MAG, SAW prefer, given highest penetration, narrow weld bead, lowest deposited metal.

F. Current and Polarity AC

  • Balance 50:50, weld bead normal, deposit weld metal normal.
  • Suitable with Aluminum and aluminum alloy.

E. Current and Polarity DC EN

  • TIG process, avoid tungsten inclusion.
  • Lower penetration, wide weld bead, highest deposit metal.

NOTES :

  • Avoid arc below by changing DC to AC.
  • Inverter changes DC to AC; Rectifier changes AC to DC.
  • MMA welding process and welding consumables are most suitable application to compare with other process.
  • MIG/MAG most used DCEP, MIG suitable with Al, Ni, its alloy, stainless steel.
  • Flat characteristic = constant voltage, current = wire feed speed, for automatic, semiauto, MIG, MAG, SAW (less than 1000A).
  • Drop characteristic = constant current, control arc length by welder, manual, for TIG, MMA.
  • Arc length = arc voltage = arc gap, effect to weld profiles; increase arc length > increase weld bead, decrease penetration, unstable arc, susceptible hydrogen entrap.
  • In SAW process: increase arc voltage > increase flux consumption; susceptible solidification crack (depth to width ratio >1.5), less dilution by change DCEP to DCEN (for cladding/surfacing).
  • Remember welding process number of 111, 121, 131, 135, 136

Weld Fracture

A. Ductile

  • Overloading.
  • Reduce area, plastic deformation (permanent deformation).
  • Surface roughness, torn surface, 45 degree shearing slip.

B. Brittle

  • Low temperature, occur at subzero temperature.
  • Fast at the speed of sound.
  • Flat, roughness, not torn.
  • Chevron mark, initiation point.
  • Crystalline appearance.
  • Stress

C. Fatigue

  • Cycle loading, load below yield stress, slow propagation.
  • Stress.
  • Surface smooth, beach mark, curve.
  • Initiation point from the defects.

Destructive test

  • Understanding term of “quantitative test” and “qualitative test” has detailed in the study book.
  • Definitions of each mechanical test such tensile, CVN, bending test …
  • Which method use for WPS qualification, such transverse tensile test, CVN, macro, micro, bend test, hardness test.
  • Which method use for welder qualification, such fillet weld fracture test, butt weld nick-break test (alternative RT).
  • Which method use for welding consumables, such all tensile test.

Tensile test

  • All tensile test for welding consumable to measure tensile, yield strength and elongation (gauge length 50 mm)
  • Transverse tensile test to measure tensile strength of weld joint.
  • Elongation determine: using gauge length for all tensile test; reduced cross section for transverse test and Z through thickness test.
  • Re, Rm, unit, elastic, plastic statement should note from study book.
  • Related TS, YS, Elongation and %C graphic should note from the study book.

Bending test

  • Diameter of former (typical 4T), if former (OD) less than 4T may cause wrongly results.
  • Bending test formed at 180 degree.
  • Side bend test for material >= 13 mm, face bend and root bend for material <13 mm (cap or root may be flushed to remove stress.

Hardness:

  • Why Rockwell diamond cone hardness test not allowed testing on product weld, because it made initiation point.

Impact test

  • Transition range definition should note from study book.
  • CTOD test measures material properties – toughness fracture (quantitative test type)

Macro and Micro test

  • Marco test to detect the defects (5x-10x magnification).
  • Micro test to detect defects and grain structure (100x – 1000x magnification)

Other

  • Advantage and disadvantage should note from study book.

Join Design

  • Single sided preparation (V, bevel) give high distortion, required high skill welder and more deposited weld metal.
  • Double sided preparation (V, U, bevel) and single sided (U, J) give less distortion and less deposited weld metal.
  • A U-, J-preparation susceptible solidification because of high depth to width ratio.
  • Set-on/in nozzle: susceptible lamellar tearing (after welding), difficult to UT, limits access from outside.
  • Set-out/through nozzle: not occur lamellar tearing, easy access both sides, easy UT
  • SAW very hard to weld with opening root gap.
  • Reduction of bevel angle may result in a risk of lack of fusion and would not compliant with the specification.

Weldability

Solidification cracks

  • Another name: is hot crack.
  • Factor effect: high tensile stress, sulphur, joint design (dept to width radio).
  • Single-U preparation are susceptible to hot cracks
  • Occur only on centerline of weld metal only, star crack (stop weld).
  • NDT method detect solidification crack: visual and both surface/volumetric.

HICC

  • Another name is cold cracking, HAZ crack.
  • Factor: CEV, Temperature, Stress, Hydrogen,
  • Occur on weld metal, HAZ (weld zone),
  • Austenitic stainless steel do not occur HICC.

Lamellar tearing

  • Other name is Step line appearance, occur on base metal only, underneath or subsurface, can’t detect by MT/PT, least effect RT (due to perpendicular with the beam), good detect by UT with 0-degree probe (straight, zero, normal probe).
  • Occur on T-Y-K or Conner joint only.
  • Lamellar tearing occurs only on set-on joint.

Factor and avoid cracking see in study book.

Repair

  • Do not confuse when weld joint subject to repair or cut-out.
  • Cut-out: crack defect, second repair, exceed 25% circumferential weld length.
  • Weld repair procedure must approve before commencing.
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nice, thanks for your sharing @Amsiz

very nice, thanks

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Thanks @JANSI @tinhaminhvt_ha.