China National Petroleum Corporation

Cnpc Tubular Goods Research Institute

Fangpo Li

Yonggang Liu

Xiaojun Li

Chun Feng

Qi Shi

A connection structure between an aluminum alloy drill pipe body and a steel joint of an aluminum alloy drill pipe includes a first joint at an end of the aluminum alloy pipe body and a steel second joint; wherein the first joint includes a first external threaded section and a second external threaded section provided from outside to inside thereof, and a major diameter of the first external threaded section is smaller than that of the second external threaded section; and wherein the second joint includes a first internal threaded section which is able to be fitted with the first external threaded section and a second internal threaded section which is able to be fitted with the second external threaded section, and a pitch diameter of the second external threaded section is larger than that of the second internal threaded section.

Connection structure between pipe body and steel joint of aluminum alloy drill pipe

A connection structure between a pipe body and a joint of an aluminum alloy drill pipe comprises a first joint portion located at an end of the aluminum alloy pipe body and a second joint portion, wherein the first joint portion comprises an external cone section, an external threaded section and a first seal end face sequentially provided from inside to outside thereof, and a taper of the external cone section is smaller than that of the external threaded section; wherein the second joint portion is cylindrical and comprises an internal cone section fitted with the external cone section, an internal threaded section fitted with the external threaded section, a second seal end face, an elevator shoulder face, and a concave arc transition section between the internal cone section and the internal threaded section.

Connection structure between pipe body and joint of aluminum alloy drill pipe

A connection structure between a pipe body and a joint of an aluminum alloy drill pipe is provided, and the connection structure comprises a first joint provided with an internal thread section, wherein an internal thread tooth bottom of the internal thread section is an inclined surface; and a second joint provided with an external thread section which is able to be fitted with the internal thread section and has threads of a complete tooth shape, a tooth height of the external thread section being larger than that of the internal thread section. The internal thread tooth bottom is designed as an inclined surface such that an external thread tooth crest is squeezed against the internal thread tooth bottom and plastically deformed along the inclined surface of the tooth bottom during an engagement, so that the engaged threads are self locked to effectively prevent the loosing of the engaged threads.

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Beijing, China

Fangpo Li