5.1 State the purpose of purlins in roof trusses - NSC Mechanical Technology Welding and Metalwork - Question 5 - 2023 - Paper 1
Question 5
5.1 State the purpose of purlins in roof trusses.
5.2 Identify the weld symbols in FIGURES 5.2.1 to 5.2.4 below.
5.2.1
(FIGURE 5.2.1)
5.2.2
(FIGURE 5.2.2)
5.2.3
... show full transcript
Worked Solution & Example Answer:5.1 State the purpose of purlins in roof trusses - NSC Mechanical Technology Welding and Metalwork - Question 5 - 2023 - Paper 1
Step 1
State the purpose of purlins in roof trusses
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Answer
Purlins are horizontal members that provide support for the roof covering. They contribute to the rigidity and correct spacing of the rafters or structure, ensuring stability.
Step 2
Identify the weld symbols in FIGURES 5.2.1 to 5.2.4 below
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Answer
5.2.1: Site weld.
5.2.2: Surfacing.
5.2.3: U butt weld.
5.2.4: Seam weld.
Step 3
State ONE use of a strip template
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Answer
Strip templates are used for guiding the cutting or bending of longer sections of angle iron, ensuring accurate measurements.
Step 4
Calculate the mean diameter of the ring
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Answer
The mean diameter of the ring can be calculated using the formula:
extMeanDiameter=extInsideDiameter+extThickness
Substituting the given values:
extMeanDiameter=180extmm+12extmm=192extmm
Step 5
Calculate the mean circumference of the ring
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Answer
The mean circumference can be calculated using the formula:
extMeanCircumference=extπimesextMeanDiameter
Substituting the calculated mean diameter:
extMeanCircumference=extπimes192extmmextMeanCircumferenceext(approximately)=603.186extmm
Rounding to the nearest whole number: 603 mm.
Step 6
Fully describe the weld symbol and the meaning of EACH of the dimensions in the diagram
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Answer
The weld symbol shown in FIGURE 5.5 depicts a fillet weld on both sides, which indicates the area where the weld is applied. The dimensions indicate:
8 mm: Size of the weld.
50 mm: Length of the weld bead.
100 mm: Pitch or spacing between the welds.
Step 7
Label parts A–E in FIGURE 5.6
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What is the advantage of using lattice beams over a longer span?
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Answer
Lattice beams tend to be very rigid which provides excellent strength-to-weight ratios over long spans, reducing material usage while maintaining structural integrity.
