Buttress threaded coupling connections for casing pipes

 

Application

Coupling connection for casing pipes with a trapezoidal profile of the thread is intended for construction and operation of vertical wells in oil, gas, and gas-condensate fields.

 

Design description

The peculiar design feature of Buttress thread casing pipes is high resistance of the threaded connection to tensile loads. The Buttress thread profile has a shape of non-isosceles trapezoid with the pitch of 5.08 mm and taper of 1:16. The stab side receiving the load during stabbing and working in compression is at an angle of 10°, which ensures easy stabbing and reduces thread seizure. The load side of the profile receiving the tensile load has the angle of 3°, which reduces the risk of pipe thread coming out of contact with the coupling thread under significant tension and bending.

 

The tightness is ensured by thread-sealing lubricant pressure in design clearances of the connection thread profile. Upon consumer’s request, it is possible to manufacture the threaded connection with a fluoroplastic O-ring in the coupling.

Geometry of coupling

It is possible to manufacture couplings of two types: standard and special coupling with reduced outer diameter and increased external bevel. The design of the special coupling with reduced outer diameter improves passage of the casing string in points of high well deviation.

Make-up control

The machined make-up quality is controlled by the position of coupling face relative to the triangular sign on the pipe. The correctly assembled connection implies that the coupling face is at a distance of one turn from the base of the triangular sign.

Main features of Buttress thread connection

Pipe Coupling
Outer diameter D, mm Wall thickness S, mm Inner diameter d, mm Weight* of 1 m pipe, kg Outer diameter Dc, mm Min. coupling length Lc, mm Weight*, kg
1 2 3 4 5 6 7
114,30 5,69 102,92 15,63 127,00
123,82**		 225,42 4,55
6,35 101,60 16,91
7,37 99,56 19,44
8,56 97,18 22,32
127,00 6,43 114,15 19,12 141,30
136,52**		 231,78 5,85
7,52 111,96 22,16
9,19 108,61 26,70
11,10 104,80 30,73
12,14 102,72 34,39
12,70 101,60 35,86
139,70 6,98 125,73 22,85 153,67
149,22**		 234,95 6,36
7,72 124,26 25,13
9,17 121,36 29,52
10,54 118,62 33,57
146,10 7,00 132,10 24,00 166,0
156**		 237,0 9,70
7,70 130,70 26,20
8,50 129,10 28,80
9,50 127,10 32,00
10,70 124,70 35,70
168,28 7,32 153,64 29,06 187,71
177,80**		 244,48 11,01
8,94 150,40 35,13
10,59 147,10 41,18
12,06 144,16 46,46
177,80 8,05 161,70 33,70 194,46
187,32**		 254,00 10,54
9,19 159,40 38,21
10,36 157,10 42,78
11,51 154,80 47,20
12,65 152,50 51,52
13,72 150,40 55,52
193,68 8,33 177,00 38,08 215,90
206,38**		 263,52 15,82
9,52 174,60 43,24
10,92 171,80 49,22
12,70 168,3 56,68
14,27 165,10 63,14
15,11 163,40 66,54
219,08 8,94 201,20 46,33 244,48
231,78**		 269,88 20,86
10,16 198,76 52,35
11,43 196,22 58,53
12,70 193,68 64,64
14,15 190,78 71,51
244,48 7,92 228,60 46,20 269,88
257,18**		 269,88 23,16
8,94 226,60 51,93
10,03 224,40 57,99
11,05 222,40 63,61
11,99 220,50 68,75
13,84 216,80 78,72
15,11 214,25 85,47
273,05 8,89 255,30 57,91 298,45
285,75**		 269,88 25,74
10,16 252,70 65,87
11,43 250,20 73,75
12,57 247,90 80,75
13,84 245,40 88,47
15,11 242,80 96,12
298,45 9,53 279,39 69,94 323,85 269,88 28,03
11,05 276,35 80,36
12,42 273,61 89,29
339,72 9,65 320,40 78,55 365,12 269,88 31,77
10,92 317,90 88,55
12,19 315,30 98,46
13,06 313,60 105,21
* — estimated value
** — diameters of special couplings