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
5.2.2
5.2.3
5.2.4
5.3 State ONE use of a... 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 play a critical role in roof trusses as they provide structural support by attaching the roof covering to the purlins while ensuring rigidity and proper spacing of the rafters or overall structure.
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 utilized to ensure accurate measurements and cuts for longer sections of angle iron.
Step 4
5.4.1 The mean diameter of the ring.
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Answer
The mean diameter can be calculated using the formula:
Mean Diameter = Inside Diameter + Thickness = 180 mm + 12 mm = 192 mm.
Step 5
5.4.2 The mean circumference of the ring (round off answer to the nearest whole number).
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Answer
The mean circumference is calculated with the formula:
Mean Circumference = π × Mean Diameter = π × 192 mm ≈ 603.186 mm.
Rounded off to the nearest whole number, the mean circumference is 603 mm.
Step 6
Fully describe the weld symbol in FIGURE 5.5 and give the meaning of EACH of the dimensions in the diagram.
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Answer
The weld symbol in FIGURE 5.5 indicates a fillet weld on both sides, with specific dimensions provided. The dimensions are as follows:
8 mm in size: This refers to the size of the weld bead.
Length of weld bead is 50 mm: This specifies the length of the weld.
Pitch of weld is 100 mm: This indicates the spacing between welds.
Step 7
Label parts A–E.
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Answer
The parts of the roof truss labeled A–E are as follows:
A: Purlins
B: Ridging
C: Roof covering
D: Rafter
E: Internal bracing member.
Step 8
What is the advantage of using lattice beams over a longer span?
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Lattice beams provide significant advantages for longer spans as they tend to be very rigid, offering reduced weight ratios. This structural efficiency allows for greater stability and support without excessive material use.
