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Priority claimed from US06/549,201external-prioritypatent/US4513823A/en
Application filed by Hydril CofiledCriticalHydril Co
Publication of NO852683LpublicationCriticalpatent/NO852683L/no
Publication of NO163073BpublicationCriticalpatent/NO163073B/no
Publication of NO163073CpublicationCriticalpatent/NO163073C/no