1.1 This standard establishes the requirements that must be met by steel twists intended to be used as active reinforcement in prestressed concrete. 1.2 Part 1 establishes the mechanical, technological and geometric characteristics, as well as the test methods that must be used in their determination. In part 2, the inspection and reception methods are established. 1.3 It is applicable to twines formed by two or three steel wires with a gray surface (not galvanized).