การผลิตผลิตภัณฑ์วัสดุทนไฟ

This class includes:
- manufacture of refractory mortars, concretes etc.
- manufacture of refractory ceramic goods:
* heat-insulating ceramic goods of siliceous fossil meals
* refractory bricks, blocks and tiles etc.
* retorts, crucibles, muffles, nozzles