To provide high galling resistance by forming a pin side seal face and a coupling side seal face into a conical face, and setting the seal taper angle defined as the angle between the bus and tube axis larger o the coupling side than on the pin side.
The seal taper angle αc on a coupling 2 side is set larger than the seal taper angle αp on a pin 1 side. When the coupling 2 is coupled with the pin 1 and fastened under the existence of a seal interference quantity 10, a displacement in the radial direction occurs to negate the seal interference quantity 10. Since αc>αp, a pin side seal section 4 having weak rigidity is shrunk in diameter, a coupling side seal section 5 having strong rigidity is slightly expanded in diameter, αp and αc are changed to the approaching side to each other, and a nearly ideal seal state is obtained that a pin side seal face 4S and a coupling side seal face 5S are closely stuck together in the desired range when fastening is completed. The occurrence of galling caused by offset contact can be suppressed.
UENO TAKEO
TOYOOKA TAKAAKI
Next Patent: EARTHQUAKE RESISTANT STRUCTURE FOR PIPE JOINT