Workshop Practice and Safety: Preparation, PPE and Fire Control
Core concepts to master
Workshop practice covers everything before and around the arc: joint preparation, fit-up, tacking, distortion control and inspection, plus the safety regime that makes the work legal and survivable. Know the standard joint types - butt, lap, tee, corner and edge - and the edge preparations (square, single-V, double-V, bevel, U) used as plate thickness rises. A single-V butt on 10 mm plate needs a root gap and a included angle typically 60–75 degrees so the root can be penetrated.
Distortion control is examined often. Understand the difference between angular distortion (from uneven shrinkage across the section) and longitudinal shrinkage. Countermeasures include balanced (back-step) welding, staggered sequence, pre-setting, clamping, and leaving the least critical weld last. For residual stress, stress-relieving heat treatment or peening is used.
Safety essentials
Personal protective equipment: welding helmet with correct shade (darker for higher current), leather gloves, apron, arm guards, safety boots and ear protection when chipping. Fume extraction or ventilation is mandatory; never weld in a confined space without gas monitoring and a standby person. Acetylene cylinders must be stored upright and never used above about 1 bar (15 psi) gauge; use a flashback arrestor on both torch and regulator. Never use oil or grease on oxygen fittings. Hot-work permits, a fire watch and suitable extinguishers (dry powder or CO2 for electrical fires) are standard.
Traps examiners set
Questions mix up shade numbers, gas pressures and the order of shutdown. Remember: close the acetylene torch valve first, then oxygen; open oxygen first when lighting. A common trap is confusing a fire watch's duration - it continues after hot work stops, not just during it.
Worked rule of thumb
Use a shade around 10–11 for typical 100–200 A arc welding; go darker for higher current or smaller arcs. Always treat a cylinder as full until proven otherwise, and cap it when moving.