1 Visual Inspection of Visual Inspection of Welds: Welds: The The Key to Successful Quality Assurance Key to Successful Quality Assurance Program Program Presented By: Presented By: Usman Basha Usman Basha Sr. Mech Inspector, YPIU Sr. Mech Inspector, YPIU September 16, 2003 September 16, 2003
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Visual Inspection of Welds:Visual Inspection of Welds: The The Key to Successful Quality Assurance Key to Successful Quality Assurance
Flow of PresentationFlow of Presentation Importance of Visual welding InspectionImportance of Visual welding Inspection
Welding ProcessesWelding Processes
Welding DefectsWelding Defects
Welding inspection ToolsWelding inspection Tools
ConclusionsConclusions
3
Visual InspectionVisual Inspection• Visual examination can be an invaluable tool.
• Excellent process control technique to help identify welder’s problems.
• Visual examination is a method for identifying surface flaws and imperfections.
• Quality control program
• It has been shown that a conscientious program of visual inspection occurring before, during, and after welding can result in discovery of the majority of all defects.
4
Prior to WeldingPrior to WeldingPrior to welding, some typical action items requiring attention by the visual inspector include:
1. Review drawings and specifications.
2. Check qualification of welders to be utilized.
3. Review materials and Equipment to be utilized.
4. Check fit-up and alignment of weld joints.
5. Check preheat, if required.
6. Check for calibration of power supplies of welding machines
5
Joint Fit-UpJoint Fit-Up
Items that may be considered prior to welding include:
1. Grove angle
2. Root openings
3. Joint alignment
4. Backing
5. Consumable insert
6. Joint cleanliness
7. Tack welds
8. Preheat & Stress
6
During WeldingDuring Welding Check amperage, voltage, polarity.Check amperage, voltage, polarity.
Cracks form in the weld and base metal when localized stresses exceed the ultimate strength of the material.
Cracks can be classified as either hot cracks or cold cracks.
Cracking associated with hydrogen embrittlement, commonly referred to as “delayed cracking.” Is a form of cold cracking. Hot cracks propagate along grain boundaries. Cold cracks propagate both along grain boundaries and through grains.
24
Cracks.Cracks.
• ROOT CRACKS• THROAT CRACKS• TOE CRACKS• UNDERBEAD AND HAZ CRACKS• CRATER CRACKS
25
Discontinuities - FusionDiscontinuities - Fusion
Molten weld metal running over un-melted base metal
Faulty electrode manipulation
Overlap - weld metal rollover
Incomplete fusion caused by:
26
UndercutUndercutUndercut creates a transition which should be evaluated for a reduction in cross section, and for stress concentrations or notch effect which fatigue is a consideration
Overlap Overlap is the protrusion of weld metal beyond the weld toe, or weld root.