428A Boilermaker Practice Quiz
Free · 193 Questions.

• Flammable vapour below 5 per cent of its lower explosive limit, with continuous monitoring
• Flammable vapour below 25 per cent of its lower explosive limit, tested once before entry
• Flammable vapour below 10 per cent of its lower explosive limit, tested each shift
• Flammable vapour below 50 per cent of its lower explosive limit, with a spark watch

Why: O. Reg. 632/05 s. 19(4) para. 3: hot work is allowed only if the flammable concentration is below 5 per cent of the LEL, oxygen is not above 23 per cent, the atmosphere is monitored continuously, the permit has hot-work provisions and a warning system and exit procedure exist.

• 40 kN
• 20 kN
• 34.6 kN
• 80 kN

Why: Each leg carries tension T = W / (2 x sin 30) = 40 / (2 x 0.5) = 40 kN. At low angles the tension in each leg is as large as the whole load, which is why the effect of sling angle must be planned for.

• 4.5 metres
• 3 metres
• 6 metres
• 7.5 metres

Why: The table in s. 188(2): 3 m for lines from 750 up to 150 000 V, 4.5 m for more than 150 000 V up to 250 000 V, and 6 m for more than 250 000 V. A 230 000 V line falls in the 4.5 m band.

• About 3 110 mm
• About 3 142 mm
• About 3 079 mm
• About 3 173 mm

Why: The plate length follows the mean diameter: OD minus one thickness = 990 mm. Circumference = pi x 990 = 3 110 mm. Using the outside diameter (3 142 mm) or the inside diameter (3 079 mm) gives the wrong length.

• Prior concurrence of an inspector (or the insurer) and a subsequent inspection
• A letter of intent sent to the supplier of the vessel before work starts
• A written estimate filed with the municipality before the work is done
• A completed hot work permit alone, signed by the owner's supervisor

Why: Section 7(3): no person shall repair a boiler, pressure vessel, fitting or piping without the prior concurrence of and subsequent inspection by an inspector or, where it is insured, the insurer. Subsection (5) excepts approved repair and self-inspection programs.