Practical Workshop and Project Work
This domain tests bench skills, drawing interpretation and the ability to complete, test and document a small installation.
Core rules and concepts
- Read the drawing before touching a tool: plan, elevation and isometric; note the scale, pipe sizes, invert levels, fixture positions and valve locations. Convert scaled dimensions to real ones by multiplying by the scale factor.
- Marking out: datum line, chalk line, spirit level and plumb bob; check diagonals to prove squareness.
- Bench work: cut square, file and ream, thread with cutting oil, dry-assemble and check, then joint.
- A typical project: connect a wash basin with bottle trap, a bib cock and a WC with flush cistern to a floor trap, using correct gradients and clamps, then pressure test and record the result.
- Project report: aim, tools and material list, neat sketch, step-by-step procedure, test result, safety precautions followed, and any difficulty faced.
Worked example
Make a two-elbow offset in 20 mm GI joining two parallel lines 150 mm apart. Each 45° elbow shifts the line by 150 ÷ 2 = 75 mm, so the diagonal piece between them is 75 ÷ sin 45° ≈ 106 mm, less the thread engagement at both ends. Reasoning: sketch the offset, resolve the geometry with trigonometry, then deduct engagement to get the cut length before threading.
Traps that cost marks
- Cutting before checking the drawing scale.
- Assembling without a dry fit, so the last joint will not close.
- Forgetting the test result in the report.
- Leaving burrs, which damage the die and the seal.