Patent ID: 7210710

Claim:
A double shoulder connection joint ( 4 ) for use in a drill stem, having a pin ( 10 ) with external threads ( 18 ) formed between a pin external shoulder ( 30 ) and a pin face ( 26 ), a box ( 12 ) with internal threads ( 20 ) formed between a box external shoulder ( 28 ) and a box internal shoulder ( 24 ), the box ( 12 ) having a counterbore section ( 14 ) between the internal threads ( 20 ) and the box external shoulder ( 28 ), the pin having a base section ( 16 ) between the external shoulder ( 30 ) and the external threads ( 18 ), and a nose section ( 22 ) between the external pin face ( 26 ) and the external threads ( 18 ), said internal threads ( 20 ) and said external threads ( 18 ) are arranged and designed for connection with each other so that said box ( 12 ) and said pin ( 10 ) are connected with a common center-line (C/L) and with a primary seal (PS) formed by said pin external shoulder ( 30 ) forced against said box external shoulder ( 28 ) and a secondary shoulder (SS) formed by said pin face ( 26 ) forced against said box internal shoulder ( 24 ), and wherein said connection joint is characterized by, said internal threads ( 20 ) and said external threads ( 18 ) having a thread taper (T th ) (C/L) which is greater than a thread taper (T th lower ) of 1.0 inch per foot, and which is less than an upper limit (T th upper ) of 1.2 inch per foot.