The present invention pertains to an improvement in buttress-threaded tubular connections. In particular, the connection is improved by controlling the tubular member thread pitch diameter tolerance to .+-.0.0015 inch, to provide a thread bearing contact pressure which is relatively constant over the...http://www.google.fr/patents/US5358289?utm_source=gb-gplus-shareBrevet US5358289 - Buttress-threaded tubular connection
