Abstract: Threaded connections of casing pipes comprising male and female members with trapezoidal tapered threads arranged on outer and inner surfaces of end sections. Radial sealing surfaces and stop end surfaces contact forming an internal sealing zone. Threads on male and female members have a 1:16 taper ratio, a 23-25° stab flank angle, and a ?3 to ?5° load flank angle. During assembly, crests and stab flanks of thread profile form clearances. Radial sealing surfaces on male and female members are tapered and positioned at a 71-73° angle relative to the normal. Stop end surfaces on male and female members are positioned at a 14-16° angle relative to the normal. Stop end thickness of male member constitutes at least 50% of wall thickness. Tight sealing of connection is preserved under considerable combined loads, including high-torque exposure.

Abstract: A joint for pipes includes male and female portions, trapezoidal threads at taper sealing and bearing end surfaces, with slope angles between thread lead-in flanks and the thread axis normal line of 10-24° and between load flanks and the thread axis normal line of ?4° to +5°. The bearing end surfaces have a 10-20° slope angle from the thread axis normal line. There is 13-18° slope angle between the male portion sealing surface and thread axis normal line, and an 8-12° slope angle between the female portion sealing surface and thread axis normal line. The female portion thread run-out area and mating areas of the sealing and the bearing end surfaces have circumferential grooves. The female element sealing surface and circumferential groove surface and the male portion sealing surface and thread run-out surface are rounded.

Abstract: The invention belongs to the oil and gas-extraction industry. The joint contains male (1) and female (2) elements with trapezoidal threads (3) with 1:16 taper and contacting each other taper sealing (5) and bearing (6) end surfaces. The slope angle between the thread profile lead-in flank (7) and the thread axis normal line amounts to 10-24°, the slope angle between the load flank (8) and the thread axis normal line amounts to ?4 to +5°. The thread profile crests (9) and lead-in flanks make gaps (10, 11) in between, 0.05-0.15 mm wide, during joint make-up process. The thread profile on the area of mating of the load flank and the crest and on the area of mating of lead-in flank and the crest is produced rounded, with the different rounding radii for the male and female elements. The bearing end surfaces have a 10-20° slope angle with the thread axis normal line.