4. Materials used

The materials used in the construction of the flues defined below concern :

• external ducts ;

• interior ducts ;

• smoke flues.

Other materials are used for specific processes: casing, lining, etc.

The materials used for the flues are :

• standardized materials or traditional techniques;

• materials or processes subject to the Avis Techniques procedure (Specialized Group no. 11).

The following provisions define each type of material:

• FEATURES ;

• pipe composition ;

• stability requirements ;...