GB2092092A

GB2092092A - Sealing cover for protecting threaded members

Info

Publication number: GB2092092A
Application number: GB8202532A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-01-30
Filing date: 1982-01-29
Publication date: 1982-08-11
Also published as: DE3201948A1; JPS57144397A; BR8200442A; SE8200463L; IT8149953A0; NL8200172A; DK39182A; FR2499030B2; BE891565R; NO820272L; FR2499030A2; IT1172175B

Abstract

A sealing cover for preventing ingress of fluid between water- engaging screw threads of an impact protection nipple (3) and e.g. the end (51) of a pipe (1), comprises a closure portion (4) for closing an end of the nipple (3) and a ring portion (30, 31) for sealingly engaging the outer surface of the pipe and connection to the closure portion (4). The ring portion is constructed as separate or articulated parts (30, 31) so that it can be assembled and secured around the pipe (1) without the need to remove the nipple (3) and closure portion (4) from the end of the pipe. <IMAGE>

Description

SPECIFICATION Apparatus for protecting borehole casing pipes Field of the Invention The invention relates to a sealing cover for preventing ingress of fluid between interengaging screw-threads of coaxially disposed inner and outer tubular members one of which is a pipe element which has a screw-threaded portion extending from one end and the other of which is a screw-threaded nipple which is in screwthreaded engagement with said screw-threaded end portion of the pipe element and has a first end which projects axially beyond said one end of the pipe element to protect the screw-thread on the end portion of the pipe element from damage by impact. In particular, although not exclusively, the invention is concerned with sealing covers for protecting the screw-threads formed on drilling rig casing pipes such as the casing pipes of oil drilling rigs.

Background Art Such pipes with screw-threaded frusto-conical ends are at present delivered from manufacturers with the following end protection: one of the ends is fitted with a first internally screw-threaded, frusto-conical metal nipple and the other end is fitted with a metal coupling socket which is internally screw-threaded at both ends, one end receiving the screw-thread at the other end of the pipe and the other end of the coupling socket receiving a second, externally screw-threaded metal nipple so that the screw-threads at the opposite ends of the pipe and at the other end of the coupling socket are-protected from damage by impact by the first nipple, by said one end of the coupling socket, and by the second nipple, respectively.

According to British Patent Specification No.

1 586 698, it is known to provide a sealing cover for preventing ingress of fluid between interengaging screw-threads of coaxially disposed inner and outer tubular members one of which is an externally screw-threaded integral end portion of a pipe or an internally screw-threaded end portion fitting around said pipe and the other of which is an internally or externally screw-threaded nipple which is in screw-threaded engagement with said screw-threaded end portion of the pipe and has a first end which projects axially beyond said end portion of the pipe to protect the screwthread on the end portion of the pipe from damage by impact, said sealing cover, when in use, making a sealing engagement with the outer surface of said outer tubular member, said sealing cover comprising a closure portion, for closing the screw-threaded nipple and having a sleeve portion capable of sealing engagement with the outer surface of the outer tubular member so that said closure portion encloses said end portion of the pipe, and a ring portion adapted to be detachably connected to said sleeve portion to form an extension of said closure portion which is capable of sealing engagement with the outer surface of the pipe.

Although this sealing cover works quite well, some difficulty is encountered when it is being mounted because of the requirement for sealing engagement between the ring portion and the outer surface of the pipe.

Disclosure of the Invention It is an object of the invention to provide a sealing cover in which the above-mentioned mounting difficulties are avoided and, in particular, a sealing cover which can be mounted on a pipe without the necessity of first removing an internally screw-threaded metal nipple or an internally screw-threaded socket.

The improvement forming the subject of the present invention concerns in actual fact the ease and convenience of installing the sealing cover.

Hitherto, the user of known sealing covers could adopt the following procedure: a) unscrew the metal nipple fitted by the factory to the end of the pipe, b) cover this nipple with the closure portion, if necessary preheating the latter, c) thread ring portion on the bare end of the pipe, d) rescrew in position the metal nipple covered by its closure portion, e) connect the closure portion and ring portion so as to achieve the complete protection.

This procedure can be improved on the basis of the following considerations: 1. The borehole casing pipes are supplied ex works already covered by their end metal nipples, 2. In general, it is recommended not to manipulate or handle the sealing covers once they have left the factory (which is the place best equipped to carry out the fitting operations), 3. For whatever reason, unscrewing the metal nipple and replacing it is time consuming and labour intensive, 4. Threading the ring portion onto the pipe requires that the pipe be manipulated, even if the end threading which it is desired to protect is exposed, 5. Mounting the closure portion on the nipple would not require tha nipple to be unscrewed since the ring portion with which it co-operates would be located on the pipe.

The problem to be solved is thus to avoid certain manipulations, whether at the factory or outside the factory, when fitting the sealing cover, and to join the closure portion and ring portion of the sealing cover without impairing the tightness characteristics, and the mprnvement should therefore not involve more complex casting or moulding work or an implementation cost which does not bear and relationship to the desired advantage.

The solution is achieved by forming the ring portion with two separable parts so that both of said parts are able to engage radially with the pipe being surrounded, and by forming both parts with fastening means enabling the ring portion to be reassembled.

According to one embodiment, the said ring portion comprises an axial articulation enabling it to be freely half-opened for engagement with the pipe being surrounded.

According to another embodiment, the said ring portion comprises two diametrically opposite semi-cylindrical parts which together surround the pipe, and fastening means enabling the two parts of the ring portion to be held together.

By these means, the problem of fitting the ring portion of the sealing cover, without having to unscrew the metal nipple or an internally screwthreaded socket, has been solved in a simple economic manner.

It goes without saying that the fastening means enabling the ring portion to be restored may exhibit widely varying forms of implementation, ranging from complementary profiles co-operating by "tangential" clamping or by sliding, to a clamp that locks appropriate terminal extensions of the split ring portion or of two halves of the ring portion.

Some of these embodiments are hereinafter described, by way of example, with reference to the accompanying drawings.

Brief Description of the Drawings Figure 1 is a perspective view of a borehole casing pipe with a metal nipple fitted with a sealing cover according to the invention (partially cut away) and a two-part ring portion, shown in the unassembled state and intended for tangential clamping; Figure 2 is a perspective view of a pipe similar to that of Figure 1 with a two-part ring portion, shown surrounding the pipe but not assembled, and intended for clamping by axial sliding; Figure 3 is a view of the embodiment shown in Figure 2, in which the two parts of the ring portion have been assembled by sliding one of them in the direction of the arrow F, though the assembled ring portion is still not engaged with the closure portion with which it co-operates;; Figure 4 is a sectional view along line IV-IVof Figure 3, showing an example of the coupling profile achieved by sliding; Figures 5 and 6 are views of the embodiment shown in Figures 2 and 3, the assembly of the ring portion and its engagement with the closure portion of the sealing cover taking place in a different manner to that illustrated in Figures 2 and 3; Figure 7 is a perspective view of a modified ring portion forming part of another embodiment of the invention the ring portion being slotted for assembly by "tangential" clamping; Figure 8 is a section along line Xll-Xll of Figure 7, showing the clamping profiles of the ring portion shown in Figure 7; Figure 9 is a perspective view of another slotted ring portion with clamping means of a dovetail clamp;; and Figure 10 is a section along line X-X of Figure 9, showing the clamping profiles of the ring portion shown in Figure 9.

Modes for Carrying Out the Invention Figure 1 shows a casing pipe 1 onto the threaded end 51 of which has been screwed a metal nipple 3, itself covered by a closure portion 4 of a sealing cover according to the invention. The closure portion 4 of a sealing cover has a tubular portion 6 which bears against the internal surfaces of the pipe 1 and the nipple 3 and a cylindrical sleeve portion 9 which terminates in an annularsection extension 1 5 provided on its external face with a serrated profile 1 6. The tubular portion 6 forms part of a dished end of the closure portion 4 enabling the pipe 1 to be handled with hooks; flat bottomed closure portions 4 completely engaging with the nipple 3 may also be provided.

A ring portion 13 of the sealing cover is made of two similar shells 30, 31, capable of being combined so as to enclose the pipe 1 by means of hooks 32 which can engage and be held in recesses 33. In this case, elastic joints may be interposed between the opposite faces 34, 35 and 34', 35'. Although Figure 1 shows a sealing cover for an internally screw-threaded nipple 3, it is clear that a sealing cover in accordance with the invention can be provided for an externally screwthreaded nipple engaging an internally screwthreaded end portion of the pipe which is not integral with the pipe, but is a connecting socket fitting around the pipe.

The ring portion 13 has a rim 19 from which three co-axial annular-section:lips extend of which only the outer lip 20 and inner lip 22 are shown in order to facilitate understanding of the drawing, the inner lip 22 being extended rearwardly to provide a slightly conical skirt projection 25. The outer lip 20 has a serrated profile 26 which is complementary to that to the annular-section extension 15 of the tubular portion 6 of the closure portion 4 for sealing engagement when the ring portion 13 engages the closure portion 4 and the extension 1 5 projects into the recess between the outer lip 20 and the central lip (not shown) extending from the rim 19.

Figures 2 to 6 illustrate the same type of ring portion 13 consisting of two shells 30, 31 intended for sliding assembly by engagement of tenons 36 (for example dovetails) in mortises 37 respectively provided on the opposite faces of the shells 30,31; these tenons 36 are dimensioned so as to abut the serrated profile 26 of the outer lip 20 of the ring portion 13. A joint may be inserted, as previously described, between the opposite faces of the shells 30, 31, and even if so desired at the bottom of the mortises 37.

Figure 3 shows the ring portion 13 in the assembled state, after the shells 30,31 have been moved from the position shown in Figure 2, Figure 4 illustrating a dovetail mode of assembly. When moved in the direction of the arrow F, the ring portion 13 can then engage with the closure portion 4 of the sealing cover, the serrated profiles 16 and 26 co-operating to hold the ring portion 13 in position against the closure portion 4.

Figures 5 and 6 illustrate a different mode of assembly of the sealing cover arrangement, wherein the shell 30 is first of all engaged with the extension 1 5 of the ring portion 13 and the shell 31 then simultaneously engaged with the shell 30 and extension 1 5 of the ring portion 13 by axial sliding.

The modified forms of the ring portion 13 shown in Figures 7 and 8 and in Figures 9 and 10 have longitudinally extending slots 43 and, adjacent the rim 19, fastening means for preventing the slots 43 from opening. The fastening means shown in Figures 7 and 8 comprise an extension in the form of a hook 44 and retention tooth 45, and the fastening means shown in Figures 9 and 10 comprise semi-dovetail tenons 46 and 47 capable of co-operating by axial sliding with a clamp 48.

The arrangements of hooks 44 and teeth 45 and of tenons 46 and 47 and clamps 48 enabling the ring portion 13 to be locked in both cases by clamping it around the pipe 1 to be protected. The ring portion 13 can then be moved towards the closure portion 4 covering the metal nipple 3 so as to achieve elastic coupling therewith. The clamp 48 is kept in position by a pin 49 which passes through holes in the clamp 48 and the tenons 46 and 47. It goes without saying that this clamp 48 could be locked irl positiorl in numerous ways, including glueing or the use of lugs which engage in the rim 19. The clamp 48 may, in addition, be made of any suitable material, and if necessary different to that from which the ring portion 13 and/or the closure portion 4 are made.

Figures 8 and 10 show how the closure of the ring portion 13 is effected in the two embodiments shown in Figures 7 and 9, it being understood that a joint (not shown) may be accommodated in the slot 43 before clamping so as to improve the tightness and fitting between the opposite faces of the ring portion 13.

It should be noted that the embodiments of Figures 7 and 9 may comprise an articulation diametrically opposite to the slot 43, allowing an unrestricted opening for surrounding the pipe 1 to be protected. This articulation may take various forms well known to those in the art, and will therefore not be described and have not been shown on the drawings.

Thus, as has been mentioned hereinbefore, the improvement constituting the subject of the present invention is basically concerned with the shape and structure of the ring portion 1 3 so as to enable the latter to be mounted on the pipe 1 without having to unscrew the metal nipple 3 on the threaded end of the pipe 1. The ring portion 1 3, irrespective of whether it is split, has or does not have an articulation, or is in two parts, may be closed according to numerous variations all of which are an integral part of the invention; the same applies as regards the materials of which the ancillary components, clamps, pins, etc., are made.

Claims

1. A sealing cover, for preventing ingress of fluid between inter-engaging screw-threads of coaxially disposed inner and outer tubular members one of which is an externally screw-threaded integral end portion (51) of a pipe (1) or an internally screw-threaded end portion fitting around said pipe (1) and the other of which is an internally or externally screw-threaded nipple (3) which is in screw-threaded engagement with said screw-threaded portion (51) of the pipe (1) and has a first end which projects axially beyond said end portion (51) of the pipe (1) to protect the screw-thread on the end portion (51) of the pipe (1) from damage by impact, said sealing cover, when in use, making a sealing engagement with the outer surface of said outer tubular member said sealing cover comprising a closure portion (4), for closing the screw-threaded nipple (3) and having a sleeve portion (9) capable of sealing engagement with the outer surface of the outer tubular member so that said closure portion (4) encloses said end portion (51) of the pipe (1), and a ring portion (13) adapted to be detachably connected to said sleeve portion (9) to form an extension of said closure (4) which is capable of sealing engagement with the outer surface of the pipe (1), characterised in that the ring portion (13) if formed with two separate parts (30 and 31) so that both of said parts (30 and 31) are able to engage radially with the pipe (1) being surrounded, and by forming both parts (30 and 31) with fastening means (32 and 33. 36 and 37, 44 and 45, or 46 to 49) enabling the ring portion (13) to be re-assembled.

2. A sealing cover, according to Claim 1, in which the ring portion (13) is split and the two parts of the ring portion (13) are adjacent parts of the split ring portion (13) which are separated by an axial slot (23).

3. A sealing cover, according to Claim 2, in which axially extending articulating means are disposed diametrically opposite the axial slot (23).

4. A sealing cover, according to Claim 1, in which the two parts (30 and 31) of the ring portion (13) are semi-cylindrical in form and capable of independent radial movement relative to the part (1) when separated from each other and from the closure portion (4).

5. A sealing cover, according to Claim 4, in which the fastening means (36 and 37) are of the complementary profile type, enabling clamping by axial sliding of the two parts of the ring portion (13).

6. A sealing cover, according to any one of Claims 1 to 4, in which the fastening means (46 to 49) comprise a clamp (48) adapted to engage with profiled extensions (46 and 47) on the two parts of the ring portion (13), and locking means (49) for holding the clamp (48) in place.

7. A sealing cover, according to any preceding claim, in which a resiliently compressible sealing joint is disposed between the two parts of the ring portion (13).

8. A sealing cover, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.