Stopper device for gas tubes

Abstract: A device for temporarily blocking medium-pressure gas pipes includes a cup-shaped body (12) for mounting on a sleeve (M) which is welded to the pipe (T) at right angles, and a rod (18) which is slidable sealingly relative to the cup-shaped body (12) and has an angled end with an annular seal (28) which can be expanded against the internal wall of the pipe (T).

Description: The present invention relates to a device for temporarily blocking gas pipes. In medium-pressure gas pipes there is often a need to operate on portions of the pipe without having to cut off the gas supply to the pipe. In low-pressure pipes, obturator balloons are introduced in the deflated configuration, under gas-tight conditions, through sleeves which are welded to the pipe at right angles. This solution is not reliable for medium and high-pressure pipes. US-A-4 202 377 discloses a device for temporarily blocking high or medium pressure gas pipes, having the features indicated in the pre-characterising portion of appended claim 1. The object of the present invention is to provide a blocking device which can cut off the gas supply to a portion of a medium-pressure pipe without the need to cut off the supply to the entire pipe. According to the invention, this object is achieved by virtue of the features stated in claim 1. By virtue of these characteristics, after two sleeves have been welded to the pipe at the ends of the portion in question and after the wall of the pipe has been drilled under gas-tight conditions by means of a suitable pipe-drilling machine, the cup-shaped bodies of the blocking devices, containing the angled obturating ends, are mounted on the sleeves with the interposition of flat valves with disc obturators. After the flat valves have been opened, each rod is then slid so that its angled obturating end is positioned in the pipe. The seal is then expanded radially by the operating means so as to lock the angled end of each rod within the pipe and form a perfect seal between the seal and the pipe so that work can be carried out safely on the isolated portion of the pipe without any danger of gas leaks. Preferably, the circular seal is annular and has an isosceles trapezoidal cross-section. Further advantages and characteristics of the device according to the invention will become clear from the detailed description which follows purely by way of non-limiting example, with reference to the appended drawings, in which: Figure 1 is a perspective view showing schematically a first embodiment of the device according to the invention, in use, Figure 2 is a longitudinal section of the device of Figure 1 mounted on the pipe, Figure 3 is a section taken on the line 111-111 of Figure 1, Figure 4 is an exploded, perspective view of the device of Figures 1-3, and Figure 5 is a variant of Figure 3 corresponding to a second embodiment of the invention. With reference to the drawings, a device, generally indicated 10, for temporarily blocking medium-pressure gas pipes T is used to cut off the supply of gas to an intermediate portion T₁ of pipe. The device 10 includes a cup-shaped body 12 with an end wall 12a having a central hole 14 in which a hollow rod 18, the function of which will be explained in the following description, is sealingly slidable and can be inclined with the interposition of an annular seal 16 of the O- ring type. The cup-shaped body 12 has a threaded mouth 12b which can be screwed onto a connector R of a gate valve V of the type with a disc obturator P. The mouth 12b of the cup-shaped body 12 may alternatively have a flange 2 for coupling to the valve V. The gate valve V in turn is mounted on a connecting sleeve M which is welded at right angles to the pipe T at S and in correspondence with which a through-hole F has been formed by a suitable pipe-drilling machine. The hollow rod 18 has a first end 18a to which a circular flange 20 with guide holes 20a is fixed in an angled position. The flange 20 has a conical front surface 22 facing a corresponding conical surface 24 of a compression disc 26 having guide pins 26a which are slidable in the guide holes 20a in the flange 20. A sealing ring 28 of elastomeric material with a trapezoidal cross-section is interposed between the flange 20 and the compression disc 26 and is adapted to be acted upon axially by the flange 20 and by the compression disc 26. The sealing ring 28 has an outside diameter substantially corresponding to the inside diameter of the pipe T. The rod 18 has a second end 18b with an external thread onto which is screwed a corresponding threaded sleeve 30 which can be operated manually by a hand wheel 32. The sleeve 30 has an internal annular shoulder 30a against which a traction bush 36 bears with the interposition of a thrust ball bearing 34, a first end 38a of a metal cable 38 being fixed to the bush 36 and its second end 38b being connected to the compression disc 26. A tubular locating element 40 slidable outside the rod 18 has two screws 42 for fixing it to the rod 18, as well as a control and locating rod 44, and an inclined end surface 46 which is intended to abut the outer surface 48 of the end wall 12a of the cup-shaped body 12. In order to prevent gas leaks, in addition to the sealing ring 16, there are O-ring-type sealing rings 43, 45 and 47 between the operating portion 32 and the threaded sleeve 30, between the threaded sleeve 30 and the rod 18, and between the cup-shaped body 12 and the gate valve V, respectively. The cup-shaped body 12 also has a valve 50 for letting off the gas trapped in the cup-shaped body 12 upon completion of the operation on the portion of pipe T₁. Figure 2 shows the mounting of the device 10 on the gate valve V which is in the closed configuration. At this stage, the end 18a of the rod 18 is housed completely within the cup-shaped body 12. After the body 12 has been mounted on the gate valve V, the gate obturator P is opened so that the rod 12 can slide and simultaneously rotate so as to be positioned as shown in Figure 3. The tubular element 40, which is fixed in a predetermined position on the rod 18 beforehand, enables the rod 18 to be positioned at an optimal inclination, preferably about 7° to the axis X-X of the cup-shaped body 12, and the flange 20 to be arranged perpendicular to the axis of the pipe T, by lining up the control rod 44 of the tubular element 40 with the pipe T (the control rod 44 should be within the plane in which the pipe T lies). The operator then deforms the sealing ring 28 by means of the hand wheel 32 so as to pull the cable 38 which passes around a transverse pin 52 at the end 18a of the rod 18 (Figure 3). For lubrication of the sliding pin, the side of the rod 18 has a grease hole 54 (Fig. 4) which can be closed, in the configuration of use, by a slidable sleeve 56 which is locked in position by the resilient ring 58. In order to remove the device 10, it suffices to carry out the steps indicated above in reverse. A closure plug (not shown) may be screwed, and perhaps subsequently welded, into an internal thread A in the sleeve M which is welded to the pipe T so that the gate valve V can then be removed. The sealing ring 28 may be resiliently deformed by a mechanical male-and-female screw system instead of by the cable 38. This control system is used in the embodiment shown in Figure 5. In this drawing, parts the same as those in Figure 3 are indicated by the same reference numerals. In the embodiment of Figure 5, the pressure disc 26 has an axial threaded shank 70 which is engaged in a female threaded member 71. The female threaded member 71 is mounted so as to be freely rotatable in the structure of the end portion 18a by means of a rolling bearing 72 and is integral with a bevel pinion 73 which meshes with a bevel pinion 74. The bevel pinion 74 is fixed to one end of a shaft 75 which is rotatable in the rod 18. The opposite end of the shaft 75 can be rotated by a lever 32a (shown in broken outline), preferably with the interposition of a ratchet mechanism of any known type (not shown in detail) so that the shaft 75 can be rotated continuously by successively pivoting the lever 32a to and fro. The tubular element 40 is not used and the correct angular positioning of the device is achieved solely with reference to a hand grip 44a. Moreover, the cup 18 has a valve 76 of known type for diverting the gas to a by-pass pipe. In order to urge the disc 26 against the sealing ring 28, it suffices to rotate the shaft 75 by means of the lever 32a in the manner described above. The shaft 75 transmits a corresponding rotation to the female threaded member 71 by means of the pair of bevel pinions 73, 74. The axial shank 70 is forced to move axially within the female threaded member 71 since the disc 26 is prevented from rotating by the friction between the contacting surfaces of the disc 26 and of the sealing ring 28. The disc 26 is thus compressed against the seal 28 so as to expand it radially against the internal surface of the pipe T.

Claims: A device for temporarily blocking gas pipes, including: a cup-shaped body (12) for mounting on a sleeve (M) which is welded to the pipe (T) at right angle in correspondence of a through-hole (F) provided in the pipe (T), a rod (18) which is slidably sealingly and centrally in a hole (14) in an end wall (12a) of the cup-shaped body (12) and has an angled obturating end (18a) including a flange (20, 26) arranged in a plane and associated with a circular seal (28) of elastomeric material which has an outside diameter substantially corresponding to the inside diameter of the pipe (T), the rod (18) being able to assume a first position, in which its angled end (18a) is housed in the cup-shaped body (12), and a second position, in which the rod (18) is arranged with its axis and the axis of the pipe (T) being in a common plane and its angled obturating end (18a) is inserted in the pipe (T) like a plug, and operating means (32, 30, 38, 20, 22) for expanding the seal (28) radially against the wall of the pipe (T) when the angled end (18a) of the rod (18) is in its second position, characterised in that the obturating end (18a) is fixed to the rod (18) so that the axis of the rod (18) forms a predetermined acute angle with respect to the plane of the flange (20, 26) of the obturating end (18a), and in that the cup-shaped body (12) is so shaped that, when the rod (18) is in its second position, the rod (18) abuts simultaneously at opposite locations with respect to its axis, in correspondence of the hole (14) in the end wall (12a) of the cup-shaped body (12) and against an edge of the through-hole (F) provided in the pipe (T), so that the axis of the rod (18) forms with the axis of the pipe (T) a substantially complemental angle with respect to said acute angle, whereby the flange (20, 26) of the obturating end (18a) positions by itself at right angle with respect to the axis of the pipe (T). A device according to Claim 1, characterised in that the operating means comprise: a pull cable (38) which is slidable within the rod (18) and has a first end (38b) fixed to a compression disc (26) which is in frontal contact with the seal (28) and a second end (38a) fixed to a traction bush (36), and a threaded sleeve (30) which is screwed onto the rod (18) and is adapted to move the traction bush (36), with the interposition of a thrust bearing (34), so as to squash the seal (28). A device according to any one of the preceding claims, characterised in that a tubular abutment member (40), which is slidable coaxially on the rod (18) and can be clamped in a predetermined position, has an end with an inclined flat frontal surface (46) so that it can abut the end wall (12a) of the cup-shaped body (12) in a configuration in which it is inclined to the axis (X-X) of the cup-shaped body (12), the predetermined inclination enabling the angled obturating end (18a) of the rod (18) to be positioned in an optimal position within the pipe (T). A device according to any one of the preceding claims, characterised in that the circular seal (28) is annular and has a trapezoidal cross-section. A device according to Claim 1, characterised in that the operating means comprise a male-and-female screw system (70, 71). A device according to Claim 5, characterised in that the male-and-female screw system includes a threaded axial shank (70) carried by a compression disc (26) which is in frontal contact with the seal (28) and a female threaded member (71) into which the shank (70) is screwed and which can be rotated by means of an operating lever (32a). A device according to claim 6, characterised in that the operating lever (32a) is connected to the female threaded member (71) by a transmission including a shaft (75) which is rotatable in the rod (18) and a pair of bevel pinions (73, 74) connecting the shaft (18) to the female threaded member (73). A device according to Claim 7, characterised in that the operating lever (32a) is connected to the shaft (75) with the interposition of a ratchet device.

Inventors: RAVETTI ROBERTO, RAVETTI, ROBERTO
Applicants: RAVETTI ROBERTO, RAVETTI, ROBERTO
Application year: 1991
Main classification: F16L55
IPC codes: F16L55