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Priority claimed from US06/562,448external-prioritypatent/US4624488A/en
Application filed by Hydril CofiledCriticalHydril Co
Publication of NO853209LpublicationCriticalpatent/NO853209L/no
Publication of NO164429BpublicationCriticalpatent/NO164429B/no
Publication of NO164429CpublicationCriticalpatent/NO164429C/no