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, tubes, pipes etc.

This class also includes:
——manufacture of refractory articles containing magnesite, dolomite or chromite