A pipe connector for offshore risers has conical thread forms. The connector has a pin with a nose, an external shoulder, and conical first and second pin threaded sections. The first and second pin threaded sections are axially separated by a pin intermediate section that is free of threads. The first...http://www.google.fr/patents/US6494499?utm_source=gb-gplus-shareBrevet US6494499 - Threaded connector for pipe
