8.1 State TWO factors that should be taken into account during oxy-acetylene welding to ensure quality welding - NSC Mechanical Technology Welding and Metalwork - Question 8 - 2019 - Paper 1
Question 8
8.1 State TWO factors that should be taken into account during oxy-acetylene welding to ensure quality welding.
8.2 State TWO causes of incomplete penetration durin... show full transcript
Worked Solution & Example Answer:8.1 State TWO factors that should be taken into account during oxy-acetylene welding to ensure quality welding - NSC Mechanical Technology Welding and Metalwork - Question 8 - 2019 - Paper 1
Step 1
State TWO factors that should be taken into account during oxy-acetylene welding to ensure quality welding.
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Answer
The correct flame for the work at hand is crucial for ensuring proper heating and melting of the materials.
Proper alignment of the welding torch and rod is necessary for achieving a high-quality weld.
Step 2
State TWO causes of incomplete penetration during arc welding.
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Answer
If the welding current is too low, it may not generate sufficient heat to achieve full penetration.
An incorrect welding angle can cause the arc to stray from the joint, resulting in incomplete penetration.
Step 3
State TWO precautions to eliminate the following welding defects: Slag inclusion.
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Use well-maintained consumables to ensure cleanliness and optimal welding conditions.
Ensure adequate shielding gas is used to protect the weld pool from contamination.
Step 4
State TWO precautions to eliminate the following welding defects: Centre-line cracks.
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Answer
Decreasing the current to reduce excess penetration can help avoid centre-line cracking.
Slowing travel speed during welding can prevent rapid cooling which contributes to this defect.
Step 5
Define porosity of a welded joint.
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Porosity refers to cavity-type pores (bubbles or gas pockets) formed by gas during the solidification of molten weld metal, which can compromise the integrity of the weld.
Step 6
Explain why non-destructive tests are preferred to destructive tests.
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Answer
Non-destructive tests allow for the evaluation of a weld's integrity without damaging the test specimen, enabling the assessment of internal and surface flaws while maintaining the usability of the welded joint.
Step 7
State TWO types of welding defects that are detected when conducting an ultrasonic test onto a welded joint.
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Answer
Internal flaws such as voids or inclusions within the weld can be detected.
Surface flaws, including cracks or lack of fusion, can also be identified through ultrasonic testing.
Step 8
Name THREE elements that should be inspected during the visual inspection process of a welded joint.
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Answer
The shape of the profile should be evaluated for uniformity and consistency.
Overlap and undercutting should be checked to ensure proper coverage.
The penetration bead must be inspected for completeness.
Step 9
Describe the steps to be followed when performing a nick-break test on a welded joint.
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Make a hack saw cut at both edges, through the center of the weld.
Place the specimen on two steel supports to allow the joint to be stressed.
Use a sledge hammer to break the specimen in the area of the cuts, exposing the weld metal for evaluation of fusion, slag inclusion, etc.
