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Steel girders are frequently used to form a structural base in bridge construction - Leaving Cert Engineering - Question (b) - 2021
Question (b)
Steel girders are frequently used to form a structural base in bridge construction. The girders are fabricated from long plates of steel that are continuously welded... show full transcript
Worked Solution & Example Answer:Steel girders are frequently used to form a structural base in bridge construction - Leaving Cert Engineering - Question (b) - 2021
Step 1
Describe, with the aid of a diagram(s), a suitable welding process to manufacture the girders for the bridge shown.
Answer
A suitable welding process for manufacturing steel girders is Submerged Arc Welding (SAW). This method involves the use of a bare wire electrode that is automatically fed from a spool. The process generates an electric arc to heat the metal, allowing for strong welds necessary for heavy structures like bridges.
Process Description:
- Setup: The welding machine includes a control unit, a hopper for the flux material, and the electrode positioning.
- Flux Feeder: The flux, which is in powder form, is fed from a hopper and covers the weld joint to prevent contamination and provides a protective coating as it melts.
- Welding Arc: An electric arc forms between the electrode and the workpiece, generating intense heat needed to melt the base materials and the electrode.
- Result: The molten metal fuses the steel together, and upon cooling, forms robust joints.
Diagram Reference:
Applications:
This process is widely used for large-scale projects involving straight-line welds, ideal for steel reinforcement beams and bridge construction.
Step 2
Outline three safety precautions to be observed when operating a welding unit.
Answer
- Wear a welding mask: To prevent 'arc-eye' and facial burns caused by the intense light generated during welding.
- Use heavy gloves: To protect hands from heat and potential burns during the welding process.
- Ventilation: Ensure a proper ventilation system is in place to eliminate toxic fumes produced during welding, safeguarding respiratory health.