Question

1. when welding on metals plated with cadmium:

a) use a fully deoxidized filler metal to avoid porosity.
b) consult msds for safety procedures to follow.
c) general mechanical ventilation is adequate provided there are four complete air changes per hour.
d) a dust filter mask should be worn.

1. hydrogen sulphide gas (h₂s) found in oil and gas wells in concentrations as low as 0.07% (700 ppm) may cause:

a) an uncomfortable rotten egg smell.
b) unconsciousness and death.
c) an explosion.
d) burning of the eyes and throat.

1. the first line of defence against welding fumes and gases is:

a) a supplied air respirator.
b) source extraction equipment.
c) to complete all welding during the first half of your work shift.
d) to weld outside.

1. what device breaks the current flow while still at a low level to protect people from electrical shock?

a) heavy duty circuit breaker (hdcb)
b) ground fault circuit interrupter (gfci)
c) heavy duty electrode holder (hdeh)
d) transformer rectifier silicon diode (trsd)

1. a vessel that has contained a flammable substance can be made safe for welding by:

a) steaming thoroughly and welding while hot and still full of steam.
b) steaming well, then allowing the vessel to cool and dry out.
c) sealing all vents tightly to prevent atmospheric air from getting inside.
d) using a hot water flush, followed by cold water and a drying out period.

1. when working in confined spaces, it is recommended that cutting torches be ignited and extinguished:

a) outside the confined space.
b) inside the confined space.
c) near the confined space.
d) wherever it is most convenient.

1. before entering a vessel to make repairs, you should insist on testing the vessel for:

a) leaks in the vessel and piping system.
b) fumes and oxygen deficiency.
c) corrosion or erosion tolerances.
d) blockages in ventilation systems.

Explanation:

1. Cadmium - plated metals require safety procedures during welding. Referring to the Material Safety Data Sheet (MSDS) is crucial for safety.
2. Hydrogen sulphide at 700 ppm can cause unconsciousness and death due to its toxicity.
3. Source extraction equipment is the first - line to remove welding fumes and gases at the source.
4. A ground fault circuit interrupter (GFCI) breaks the current flow at a low level to protect from electrical shock.
5. Steaming well and then allowing the vessel to cool and dry out removes flammable substances and vapors, making it safe for welding.
6. Igniting and extinguishing cutting torches outside the confined space reduces the risk of fire and explosion inside.
7. Before entering a vessel for repairs, testing for fumes and oxygen deficiency is necessary to ensure a safe environment.

Answer:

1. B. consult MSDS for safety procedures to follow.
2. B. unconsciousness and death.
3. B. source extraction equipment.
4. B. ground fault circuit interrupter (GFCI)
5. B. steaming well, then allowing the vessel to cool and dry out.
6. A. outside the confined space.
7. B. fumes and oxygen deficiency.