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Priority claimed from US06/773,031external-prioritypatent/US4708513A/en
Application filed by Hydril CofiledCriticalHydril Co
Publication of NO871866D0publicationCriticalpatent/NO871866D0/no
Publication of NO871866LpublicationCriticalpatent/NO871866L/no
Publication of NO170902BpublicationCriticalpatent/NO170902B/no
Publication of NO170902CpublicationCriticalpatent/NO170902C/no