| 8151 |
Crushing-, grinding- and chemical-mixing-machinery operators |
| 8152 |
Chemical-heat-treating-plant operators |
| 8153 |
Chemical-filtering- and separating-equipment operators |
| 8154 |
Chemical-still and reactor operators (except petroleum and natural gas) |
| 8155 |
Petroleum- and natural-gas-refining-plant operators |
| 8159 |
Chemical-processing-plant operators not elsewhere classified |