CN1054422C

CN1054422C - High-airtight buttress thread casing-pipe connection structure

Info

Publication number: CN1054422C
Application number: CN96106583A
Authority: CN
Inventors: 侯毅
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-06-28
Filing date: 1996-06-28
Publication date: 2000-07-12
Anticipated expiration: 2016-06-28
Also published as: CN1169518A

Abstract

The present invention relates to a high airtight buttress thread casing-pipe connecting structure. Arc-shaped curved surfaces are formed on the wall thick end surfaces of both ends of a casing pipe, and the wall thick end surfaces of the connecting pipe ends of two casing pipes are mutually tightly pressed by an axial interference 'delta' after the two casing pipes are connected by a connecting hoop, so pipe walls generate elastic and plastic deformation to form a metal-to-metal connecting and sealing surface. The present invention is characterized in that the high airtight buttress thread casing-pipe connecting structure not only has the advantages of buttress thread connection, but also has the advantages of reliable sealing, simple structure of the connecting hoop, low cost, convenient operation of oilfield fastening, etc.; besides, the sealing performance of the fastening is easy to ensure. Furthermore, an interface position and an inner diameter of the pipe are consistent and smooth, so eddy current phenomenon is decreased, and the corrosion of the casing pipe caused by liquid reduced.

Description

High-airtight buttress thread casing-pipe connection structure

The present invention relates to a kind of buttress thread casing-pipe connection structure.

The used sleeve pipe of oil, natural gas extraction drilling well adopts buttress thread to connect, and can make full use of spiral shell tail screw thread (being so-called black skin buckle) and connects owing to have than being threaded of other patterns, does not weaken body; Screw thread is not easy slippage when being subjected to tension after sleeve pipe connects; The mechanical property and the body of its connection part are suitable; Casing threads can repeatedly be gone up, shackle, be difficult for to produce advantage such as thread gluing phenomenon and uses more and more widely.But it is big that BCSG connects rear thread thread form side clearance amount, and tightness is bad.For this reason, people have carried out various improvement to buttress thread casing-pipe connection structure, in the hope of improving the tightness of its connection.A kind of improvement structure commonly used in this all improvement is, add tapered annular sealing surface of system respectively in the both sides, adjacent central place of box cupling, centre at box cupling is shaped on an annular stop step between two conical seal (contact) faces simultaneously, corresponding pipe end outside at sleeve pipe two threaded end with box cupling adds makes the taper shoulder that adapts with box cupling tapered annular sealing surface, sleeve pipe is connected rear sleeve cone seal shoulder and box cupling with box cupling tapered annular sealing surface radial interference makes the joint sealing, and the stop ring-shaped step of box cupling is to sleeve pipe stop and prevent to connect loosening.Though having had obviously, the tightness that this improvement structure connects BCSG improves, the box cupling complex structure, and length is big, and weight increases, and the material base bite is big during processing and fabricating, and waste material raises the box cupling cost.

The purpose of this invention is to provide a kind of simple in structurely, make easily, cost is low, and sleeve pipe connects the reliable high-airtight buttress thread casing-pipe connection structure of back sealing.

The sleeve pipe two ends of high-airtight buttress thread casing-pipe connection structure are shaped on the trapezoidal partially outside thread of taper, the box cupling two ends are shaped on the taper buttress thread, sleeve pipe two ends tube wall end face is an arc-shaped curved surface, two sleeve pipes have axial connection interference " Δ " after being connected by box cupling, two sleeve pipe pipe ends are compressed mutually, tube wall axially produces elastoplasticity to be changed, and forms the sealing surface of metal to metal.

Further improving of high-airtight buttress thread casing-pipe connection structure be, it is wide that the every side in centre both sides of box cupling has at least the tooth of two teeth to be wider than orthodont tooth, and the wide difference of the wide and normal sound of baby talk of the wide sound of baby talk is connected rear thread thread form side clearance less than sleeve pipe and measures.

According to the difference of usage requirement and sleeve pipe caliber, wall thickness, grade of steel, the radius of curvature of sleeve pipe two end part arc tube wall end face can equate also can not wait, and the axial magnitude of interference " Δ " that casing threads connects is generally 0.1-2.0mm.

In the aboveground use of linking closely, the sleeve pipe oil field of high-airtight buttress thread casing-pipe connection structure tightens on the outer surface of end and tightens mark line for the ease of sleeve pipe, and being fastened on has the oil field to link closely on the box cupling outer surface on the sleeve pipe to tighten normal line.

The spiral shell tail of the made full use of screw thread that the existing buttress thread of high-airtight buttress thread casing-pipe connection structure connects is threaded and does not weaken the body wall thickness, join strength and body are quite, not thread gluing, screw thread is difficult for advantages such as slippage when being subjected to tension, and the sealing surface that is connected to form metal to metal by axial interference has good sealing simultaneously.Box cupling female thread portion tooth is wide to reduce the thread profile side clearance amount after the connection by increasing, thereby the sealing of connection is further improved, so its sealing is reliable.Secondly, the oil field is linked closely easy to operate, is easy to keep the sealing that links closely; Box cupling is simple in structure, and is easy to manufacture, and cost is low, helps exploiting drilling well and uses.

Accompanying drawing is one embodiment of the present of invention, and the present invention is not limited only to present embodiment, further specifies the present invention below in conjunction with embodiment.

Fig. 1 is the schematic representation of high-airtight buttress thread casing-pipe connection structure.

Fig. 2 is the A portion partial enlarged drawing of Fig. 1.

Fig. 3 is the pipe end wall structure schematic representation under the high-airtight buttress thread sleeve pipe free state.

As shown in the figure, the sleeve pipe of high-airtight buttress thread casing-pipe connection structure (1), sleeve pipe (2) two end part are shaped on the trapezoidal partially outside thread of taper, box cupling (3) two ends are shaped on the inclined to one side trapezoidal internal thread of taper, sleeve pipe two ends tube wall end face is made the circular arc of radius for " R ", and the radius of arc of sleeve pipe two terminal circle arc tube wall end face can equate also can be unequal.It is wide tooth that the contiguous box cupling centre of the inclined to one side trapezoidal internal thread of box cupling two end topers has 3-4 tooth, and the wide difference of the wide and normal sound of baby talk of the wide sound of baby talk is connected rear thread thread form side clearance amount less than sleeve pipe.After two sleeve pipes are connected by box cupling, axial connection magnitude of interference " Δ " is arranged, " Δ " is generally 0.1-2.0mm, and tube wall generation plastic deformation formation metal to metal compresses sturdy sealing surface thereby two sleeve pipes connect the end.The oil field of the sleeve pipe that dispatches from the factory tightens end to be had the oil field to link closely on the outer tube surface to tighten mark line (5), there is the oil field to link closely on the box cupling and tightens normal line (4), when linking closely should on be tightened to mark line and align with normal line, promptly reach the axial interference of setting, two pipe connected pipe walls produce elasto plastic deformation formation metal to metal and compress sturdy sealing surface.The width of line is a tolerance range, and (6), (7) are the tube wall end face under the sleeve pipe free state among Fig. 2, promptly as shown in Figure 3.

Claims

1, a kind of high-airtight buttress thread casing-pipe connection structure, the sleeve pipe two ends are shaped on the trapezoidal partially outside thread of taper, the box cupling two ends are shaped on the inclined to one side trapezoidal internal thread of taper, it is characterized in that said sleeve pipe two ends tube wall end face is an arc-shaped curved surface, two sleeve pipes have axial interference " Δ " after being connected by box cupling, two sleeve pipe pipe ends compress mutually, and tube wall axially produces elasto plastic deformation, form the sealing surface of metal to metal.

2, by the described high-airtight buttress thread casing-pipe connection structure of claim 1, it is wide that the inclined to one side trapezoidal internal thread that it is characterized in that said box cupling two ends has at least the tooth of two teeth to be wider than normal tooth in the every side in adjacent central place, and the wide difference of the wide and normal sound of baby talk of the wide sound of baby talk is connected rear thread thread form side clearance less than sleeve pipe and measures.

3, by the described high-airtight buttress thread casing-pipe connection structure of claim 1, it is characterized in that the radius of curvature of said sleeve pipe two end part arc tube wall end face can equate also can not wait, the axial interference " Δ " that casing threads connects is 0.1-0.2mm.

4, by the described high-airtight buttress thread casing-pipe connection structure of claim 1, it is characterized in that being fastened on and have the oil field to link closely on the outer surface of the box cupling on the sleeve pipe to tighten mark line, the oil field of sleeve pipe tightens on the end outer surface and tightens mark line.