Schedule 4 Processes to which s 73 (1) (o) applies
1 dry grinding of surfaces of metal, stone, concrete, or similar materials by means of a wheel or discs driven by mechanical power
2 cutting, dressing, or carving of stone, concrete or similar material by means of a portable tool driven by mechanical power
3 chipping, or scaling of painted or corroded metal surfaces or wire brushing of the surfaces by mechanical power
4 cutting out or cutting off of cold rivets or bolts from any structure or part of a structure
5 welding or cutting of metals by means of an electrical,
oxyacetylene or similar process