JPH0112051Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a threaded joint for oil country tubular goods.

It is well known that steel pipes for oil wells such as casing pipes and tubing pipes used in oil or gas wells are connected in large numbers and inserted underground, but the joints must have sufficient strength and airtightness. Must have.

Fig. 1 shows an example of the joint structure of a conventional EL casing (Extreme Line Casing), in which a male thread side pipe end 1 and a female thread side pipe end 2 are screwed together at a threaded portion 3, and Thread side tube end 2
The distal end 4 of the male-thread side tube end 1 is abutted against the shoulder 5 of the male-thread side tube end 1, and the tip outer surface 6 of the male-thread side tube end 1 and the inner inner surface 7 of the female-thread side tube end 2 form a so-called metal touch. The structure is such that it is in contact with a sealed state.

However, in the case of such a structure, it is necessary to butt parts A in the figure, and taking into account dimensional errors, it is actually difficult to achieve a complete seal in part B, and the sealing performance inside the pipe is not necessarily sufficient. In addition, corrosion may progress from the clearance 10 due to muddy water flowing inside the pipe, or when inserting or pulling out a tubing pipe or drill pipe, the male thread side pipe end 8 may get caught, damaging the inner wall of the joint. It had various drawbacks, including the risk of

The present invention was proposed in order to improve such conventional drawbacks, and in particular, by interposing a packing material in the clearance 10, the sealing performance of the inner surface of the pipe is improved, and damage and corrosion of the inner wall of the joint are prevented. The present invention aims to provide a new threaded joint for oil country tubular goods that can prevent this.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. First, in FIG. 2, 20 is a male thread side tube end, and 30 is a female thread side tube end. The male thread side tube end 20 has a shoulder 21 formed on its outer surface, and the outer circumferential surface of the joint portion 22 is tapered in the distal direction, and a male thread 23 is formed in the intermediate portion thereof. The side end portion 24 is formed into a smooth surface shape, and the distal end portion 25 is formed into a slightly rounded surface shape. Further, the female thread side tube end 30 has a shoulder portion 31 formed on its inner surface, and the inner peripheral surface of the joint portion 32 is tapered in the distal direction in correspondence with the male thread side joint portion 22. A female thread 33 is formed in the middle part, and both ends 34 and 35 have smooth surfaces.

However, in the present invention, a packing material 40 is interposed between the shoulder portion 31 of the female threaded side tube end 30 and the distal end 26 of the male threaded side tube end 20, and therefore, as shown in FIG. The portion 31 is slightly inclined inward, and an R-shaped recess 36 is formed at the distal end of the smooth surface end 35, and a packing material 40 is attached to the recess 36. The packing material 40 may be made of rubber, fluorine resin, soft metal such as copper, etc., and the concave portion 36 may be fixed by baking, fixing with an adhesive, or the like.

In the case of the present invention, the inclination angle θ of the shoulder portion 31 is
is preferably 10° or less, preferably 5° to 10°.

According to the present invention as described above, when the female thread side tube end 30 is screwed into the male thread side tube end 20, the male thread 23 and the female thread 33 of both joint parts 22, 32 are screwed together, and the female thread side The distal end 37 of the tube end 30 and the shoulder 21 of the male thread side tube end 20 are butted together (A in the figure).
), and the end 25 of the male-thread side joint 22 and the inner smooth surface end 35 of the female-thread side joint 32 contact in a sealed state (section B in the figure), and the male-thread side joint 22 and the shoulder 31 of the female thread side tube end 30.
and are butted together with a packing material 40 interposed therebetween (section C in the figure).

As described above, according to the present invention, the packing material 40 is interposed between the tapered shoulder of the female thread side tube end and the concave portion in the vicinity thereof, and the distal end of the male thread side tube end, so that the metal touch Combined with the new parts B and A, the sealing performance is improved, and since there is no clearance like in the past, there are various advantages such as less corrosion and damage caused by inserting tubing pipes and drill pipes. That's what you get.

It goes without saying that the present invention is applicable not only to the above-mentioned casing pipe but also to tubing pipes and other oil country tubular goods. If the oil well pipe is made of alloy steel, the shoulder 21, end 37, end 24, end 34, male thread 23, female thread 33, end 25, end 35 can be baked with MoS. Screw galling can be prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional threaded joint for oil country tubular goods, FIG. 2 is a schematic diagram of a threaded joint for oil country tubular goods showing an embodiment of the present invention, and FIG. 3 is an enlarged view of the main part of FIG. 2. In the figure, 20 is the male thread side tube end, 21 is the shoulder part, 22 is the joint part, 23 is the male thread, 24 and 25 are the ends, 26
is the terminal end, 30 is the male thread side tube end, 31 is the shoulder part, 3
2 is a joint part, 33 is a female thread, 34 and 35 are end parts,
36 is a recessed portion, 37 is an end portion, and 40 is a packing material.

Claims (1)

[Scope of utility model registration request] A joint that connects pipe ends by screwing them together,
In addition, it is possible to butt the shoulder of the male thread side tube end and the distal end of the female thread side tube end, and at the time of this butt, there is a clearance between the shoulder of the female thread side tube end and the distal end of the male thread side tube end. In a threaded joint for oil country tubular goods that can press the outer surface of the tip of the male-threaded pipe end and the inner inner surface of the female-threaded pipe end, the shoulder part of the female-threaded pipe end tilts inward. and an R-shaped recess is formed on the inner surface of the tube end near the shoulder, and the taper and R-shaped recess are formed within the clearance between the shoulder and the distal end of the male thread side tube end. 1. A threaded joint for oil country tubular goods, characterized in that it is possible to butt the two by interposing a packing material attached in contact with the two.