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    18—18 Corrosion-Resistant Retaining Rings for Nuclear Power Plant Generators

    Published: Jan 1986

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    Several years ago, the Pamiers Plant of the Compagnie Française de Forges et Fonderies (C3F) undertook a research program on the 18-18 corrosion-resistant grade for retaining rings.

    An extensive testing program conducted in association with Electricite de France led to a decision to equip the 900- and 1300-MW generators of French nuclear power plants with NMF 18 retaining rings (NMF 18 is the C3F trademark for the 18-18 material).

    To date, 20 rings have been manufactured in the following sizes: 1. Outer diameter: 1746 to 2040 mm (68.74 to 80.31 in.). 2. Thickness: 83 to 90 mm (3.27 to 3.74 in.). 3. Height: 700 to 775 mm (27.56 to 30.51 in.). 4. Weight: 2.5 to 3.5 metric tons.

    The guaranteed yield strength at midwall is 750, 850, or 900 MPa (109, 123, or 130 ksi), depending on the type of ring.

    After a review: (a) of the properties of the 18-18 grade and their comparison with the conventional 18-4 material and (b) of the principal results of the test program, we are describing the specifics of the manufacturing process and the facilities of these large rings.


    Nonmagnetic rings, austenitic manganese steels, corrosion-resistant grades, stress corrosion

    Author Information:

    Rambaud, JB
    Technical manager, Usinor, Paris,

    Cazenave, RH
    Chief metallurgist, Pamiers Plant, Compagnie Française de Forges et Fonderies, Pamiers,

    Committee/Subcommittee: A01.14

    DOI: 10.1520/STP17363S

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