Enamel coating applied to the surface of the apparatus, made from mild steel or cast iron.

Rice. 12.5. Elements of enamelled apparatus

Enamel coating, represents the mixture of sand, soda, potash, pigments and other elements, evenly applied on the pre-treated surface of the apparatus and then fired at temperatures 700-900 °C.

To obtain high quality enamel coating must comply with the following conditions:

- forms of apparatus should have smooth outlines; must not have sharp corners, edge and hollow;

- all parts of the apparatus before enamelling is carefully prepared: seams zashlifovyvayutsya, sharp corners and protrusions machined;

- the temperature must be strictly observed for uniform warmup, roasting and cooling of enamel coating;

- the nodes of the apparatus must be ravnostennymi, So ends the clutches and racks should be carried out after enamelling special linings, welded to the hull or bottom before enamelling (rice. 12.5,and and 12.5,b).

Choke executed with conical ends, butt welded to the edge of the hole otbortovannogo (rice. 12.5,in).

Enamel coating must have good adhesion (clutch) with the surface material, of the apparatus.