Patent ID: 11143337

Abstract:
A threaded connection for steel pipe with improved sealability against the internal and external pressures is provided. A threaded connection 1 includes a pin 10 and a box 20. The pin 10 includes a male thread 11, a nose 12, a pin shoulder surface 13, and a pin sealing surface 14. The box 20 includes a female thread 21, a box shoulder surface 23, and a box sealing surface 24. The box sealing surface 24 has a seal point SP on the taper surface 242 located at the midpoint thereof as determined along the direction of the pipe axis CL. The distance LSP between the tip of the nose 12 and the seal point SP as measured in the direction of pipe axis CL is 13 mm or larger. The shoulder angle α between the pin or box shoulder surface 13 or 23 and a plane VP perpendicular to the pipe axis CL is 2 to 13 degrees. The ratio TB/TP of the wall thickness TB of the box to the wall thickness TP of the pin 10 as measured at the seal point SP is 1.7 or higher.