SAFETY SYSTEM FOR A CLAMPING TOOL

Description

TECHNICAL FIELD

[0001] The present invention relates to a safety system for a clamping tool suitable for clamping drill pipes and casings during drilling operations.

BACKGROUND ART

[0002] In the construction of oil or gas wells wrench assemblies are often used for making or breaking threaded joints between successive tubing elements (drill pipes) that make-up the continuous tubing string extending through a well bore into the underground deposits. US 2008/0202291 A1 discloses a known power tong. When making/breaking of pipe joints, extremely large forces (i.e. high torques) are involved, and accidental breakage of tools/components used during operation could seriously injure personnel and cause harm to expensive equipment.

DISCLOSURE OF THE INVENTION

[0003] It is an object of the present invention to solve or at least minimise the above mentioned problem.

[0004] This object is achieved essentially by means of a system as specified in appended claim 1. The object is also achieved by means of a safety arrangement according to the appended claims.

[0005] It is understood that the herein presented advantages relates to both said system and arrangement, even when referring only to "safety system".

[0006] Thanks to the system according to the invention there is achieved at least the advantage that in case of accidental breaking and/or cracking of the clamping tool body during operational use, said connecting element will keep any loose parts together, preventing them from getting ejected causing damage to surrounding persons and/or equipment. Thus said system contributes to improved safety during drilling operations.

[0007] Further advantageous embodiments of the system are specified in the dependent claims.

[0008] According to one embodiment said bore is a through bore extending through the body of the clamping tool. In this embodiment the elongated connecting element is extending through the bore and is coupled to the clamping tool body by means of withholding means. Said withholding means are arranged to couple the elongated connecting element to the clamping tool body at two different positions of the bore which are separated from each other, preferably with majority (at least 50%) of the clamping tool body in between them, so that the connecting element is withheld inside the bore. Preferably the withholding means are arranged to withhold the connecting means at two positions located at the respective two end portions of the bore. Preferably, the end portions of the connecting element are positioned close to the respective orifice of the through bore so that the connecting element is kept in place by the withholding means at each of its respective end portions. This leads to a particularly strong and reliable construction where the risk of breakage of the connecting element and/or the withholding means is minimised. Thus, in case the clamping tool would accidentally burst, e.g. during drilling operation, any loose parts of the tool are still kept together by the safety system/arrangement where the combination of withholding means and connecting element positioned in said bore provides a very strong safety connection.

[0009] Moreover, thanks to that the connecting element is shielded inside the bore it will not eject or get thrown away in the unlikely event of breakage/unfastening of the withholding means.

[0010] According to another embodiment, the through bore comprises two outer first portions (preferably one outer portion at each of its outer openings) having a first diameter and a middle second portion having a second diameter, where the first diameter is larger than the second diameter. Further, the withholding means has a body which comprises at least one cross-section which is larger than the diameter of the middle second portion of the bore. Preferably, said withholding means are positioned at each of the two outer first portions of the through bore in such a way that they are prevented from entering the middle second portion of the bore by means of positioning the cross-section which is larger than the diameter of the middle second portion of the bore in such a way that it stops the withholding means from entering the middle second portion of the bore.

[0011] According to yet another aspect the system according to the invention comprises a shock absorbing component arranged adjacent to the withholding means. Preferably the shock absorbing component is arranged at the outer first portions of the bore, located in between the middle second portion of the bore and the withholding means. Hereby there is provided a shock absorption in case any loose parts of the clamping tool would move/get ejected as a consequence of sudden bursting/breaking. Such absorption of kinetic energy is advantageous for damage reduction if the clamping tool would break, and thus provides a further safety function of the system. Said shock absorbing component also protects the connecting element reducing the risk that the connecting element and/or the coupling between the withholding means and the connecting element would break. Thus, in addition to the aspects previously presented, the object of increasing safety during making/breaking of joints between successive tubing elements can also be achieved by use of an energy absorbing arrangement comprising an elongated connecting element which at each end portion is coupled to a withholding means, and wherein a shock absorbing component is arranged adjacent to said withholding means at each end portion of the elongated connecting element. The shock absorbing component arranged together with the elongated element provides synergistic effects for improved security when used in a safety system for a gripping device: the elongated element provides a retaining function when coupled to the gripping device and the shock absorbing component in its turn reduces the risk that the couple between the elongated element and the gripping device break. Thus, when combined the shock absorbing component and the elongated element leads to increased safety and to minimized risk that pieces of a broken gripping device would get ejected in case of breakage of gripping equipment.

BRIEF DESCRIPTION OF THE FIGURES

[0012] The invention may be better understood by referring to the following figures. In the figures, like reference numerals designate corresponding parts throughout the different views.

Fig. 1 illustrates a perspective view of an example of an implementation of an automatically adjustable gripper device gripping a pipe section,

Fig. 2 illustrates a perspective view of a clamping tool according to one embodiment of the invention,

Fig. 3A illustrates a side view of the clamping tool seen in Fig. 2,

Fig. 3B is a cross-sectional view of the clamping tool of Fig. 3A taken along line IIIB-IIIB,

Fig. 3C is a detail view according to IIIC in Fig. 3B

Fig. 4 illustrates a side view of a connecting element according to one embodiment of the invention,

Fig. 5 illustrates a side view of a withholding means according to one embodiment of the invention,

Fig. 6A illustrates a perspective, partially transparent, view of a cracked clamping tool according to one embodiment of the invention,

Fig. 6B illustrates a frontal view of the clamping tool seen in Fig. 6A,

Fig. 7A illustrates a top view of the clamping tool seen in Fig. 6A, and

Fig. 7B is a cross-sectional view of the clamping tool of Fig. 7A, taken along line VIIB-VIIB.

DETAILED DESCRIPTION

[0013] The foregoing aspects and many of the advantages of this invention will become better understood by means of the following detailed description, when taken in conjunction with the accompanying figures. Further, the description, and the examples contained therein, are provided for the purpose of describing and illustrating certain embodiments of the invention only and are not intended to limit the scope of the invention in any way.

[0014] Referring firstly to Fig. 1 there is shown in a schematic way a portion of a wrenching equipment 1, herein also referred to as a "gripper" or "gripping device 1", intended for making or breaking threaded joints between successive tubing/pipe elements (e.g. drill pipes).

[0015] As shown in Fig. 1 the gripping device 1 is arranged with two articulated gripping arms 101 embracing a pipe section 11. The pipe 11 can be for example a drill pipe for a drill string or a borehole casing, and two grippers 1 can be used to grip two pipe sections 11 to connect or disconnect successive pipes at complementary threads in the pipes.

[0016] The gripper 1 according to the invention is suitable for use in conjunction with drilling in the ground or seabed for assembling and disassembling drill strings and borehole casings comprising a plurality of straight pipes connected end to end. However, it is to be understood that the arrangement according to the invention is not necessarily limited to equipment for oil/gas industry but that the safety arrangement according to the invention may be used for any gripping device intended for connecting and/or disconnecting pipe sections.

[0017] As seen in Fig. 1 each arm 101 of said gripper 1 is equipped with a clamping tool 2, herein also referred to as a "clamping jaw" or "holding device". Preferably the clamping tool 2 comprises a body in the form of a cast item with a single solid body preferably made of metal. Each clamping tool 2 holds at least one releasably attached pipe contacting element 3 which is arranged to be brought into direct contact with the pipe section 11 during gripping of the pipe section for connection/disconnection operation as previously described. A pipe contacting element 3 is herein also referred to as a die.

[0018] When the gripper 1 grips a pipe 11, the pipe contacting elements 3 are preferably in direct contact with the pipe 11.

[0019] The gripping arms 101 are connected with an articulated joint 102. Preferably the gripper 1 comprises a drive in the form of a hydraulic actuator (now shown). By means of the hydraulic actuator, the gripper 1 can rotate one of the gripping arms 101, in relation to the other gripping arm 101, about the articulated joint 102. Thereby, the gripper 1 is adapted to move the gripping arms 101 in relation to each other so as to grip a pipe P, whereby the dies 3 are in contact with the pipe, or so as to release to the pipe.

[0020] In Fig. 1 each clamping tool 2 holds two dies 3. This is seen more clearly for example in Fig. 2, which shows a perspective view of a clamping tool 2 provided with a pair of dies 3. Herein is also seen that the dies 3 have a surface presenting a curvature that is supposed to be identical to the curvature of the pipe 11 to be gripped. By switching between dies 3 having different dimensions/curvatures the gripper 1 is easily adapted to various sizes of pipe sections (pipes with different diameters) whereby connection/disconnection operations can be significantly improved. The curved surface of the dies 3 have, as can be seen in some of the following figures, small ridges to increase the friction or the grip between the dies and the pipe 11.

[0021] Using a die 3 having a dimension that does not match with the diameter of the pipe 11 to be gripped would lead to mechanical strain in the body of the clamping tool 2 holding the dies 3, and in the worse case scenario eventually lead to breakage of said clamping tool 2. Due to the large forces and high torques involved in wrenching the pipes 11, breakage of any components can be both very dangerous and risk damage other parts of the system, for instance in case loose parts would get ejected, hitting persons or materials, or if parts of the clamping tool 2 would break loose and fall into the well bore.

[0022] For this reason a safety system and a corresponding safety arrangement 9 is provided.

[0023] The safety system according to one embodiment of the invention will now be further described, referring mainly to Figs. 2, 3A, 3B and 3C. In Fig. 2 the clamping tool 2 is seen from a perspective view, positioned substantially horizontally presenting a frontal pipe gripping portion 104 provided with a slightly curved surface whereat there are arranged said two dies 3. The clamping tool body 2 comprises at least one bore 8 extending there through; in the appended figures the body of the clamping tool 2 comprises two horizontally extending through bores 8, 8'. As seen in e.g. the cross section of Fig. 3B an elongated connecting element 90, 90' extends through each bore 8, 8', and withholding means 92, 92' are coupled to the respective end portions 94, 94' of said connecting element 90, 90', in such a way that the connecting element 90 is withheld or secured inside the bore 8, 8'. Thus the withholding means 92 arranged at the end portions 94, 94' of the connecting element 90 couple the connecting element 90 to the clamping tool body 2 at two different positions of the bore 8, wherein said positions are separated from each other by a certain distance. In this context, the term "couple" used for describing the function of the withholding means 92, 92' means "to fasten in relation to", i.e. that the withholding means 92, 92' are arranged to fasten the connecting element 90 in relation to the clamping tool body 2 in such a way that the connecting element 90 cannot be removed from the tool body 2 unless either of the withholding means 92, 92' is removed. As seen in Fig. 3B the respective positions whereat the withholding means 92, 92' couple the connecting means 90, 90' to the clamping tool body 2 are separated from each other by a substantial portion of the clamping tool body 2, meaning that at least 50% of the clamping tool body 2 separates the coupling positions. A possible crack in the clamping tool body 2 will most likely develop in between said two coupling positions and thus in the event of breakage of the clamping tool body 2 any loose parts are still retained/held together by the connecting element.

[0024] In one embodiment said bore 8, 8' is a through bore having a first 83 and a second 84 opening and extending through the solid body of the clamping tool 2,as is illustrated in the cross section in Fig. 3B. The reference numbers for said first 83 and second 84 openings are shown only for the uppermost through bore 8, however the skilled person understands that also the lowermost bore 8' comprises corresponding first and second openings. At each of the first 83 and second 84 openings the bore 8 comprises two outer first portions 80 with a first diameter D. In between two outer portions 80 the bore 8 further comprises a middle second portion 82 with a second diameter d. The first diameter D is larger than the second diameter d and the outer portions 80 and the middle portion 82 of the bore 8 are connected by an flange 81 corresponding to the position of the bore whereat the diameter of the bore 8 is shifted. As a non-limiting example the first diameter D is between 10 - 20 mm, preferably between 13-17 mm, and the second diameter d is between 4 - 12 mm, preferably between 6 - 10 mm.

[0025] The elongated connecting element 90, 90' may for instance be a bar or a wire or any other suitable element which provides the required material strength and shape. In the figures, the connecting element 90, 90' is shown in the form of a solid bar having a circular cross section. The diameter of the bar is dimensioned to fit in the middle portion 82 of the bore. In one non-limiting example the bar 90, 90' has a diameter of 7 mm.

[0026] As a non-limiting example the solid bar 90, 90' can be made of a high strength steel, such as a high strength low-alloy structural steel. For instance the bar can be made of steel S355 (complying with European standard EN 10025) having a proof strength R_p0.2 of at least 520 N/mm2 and a tensile strength between 630 - 950 N/mm2.

[0027] Said withholding means 92, 92' are coupled to the respective end portions 94, 94' of the connecting element 90, 90'. The withholding means 92, 92' may for instance be a securing component such as a nut, as is illustrated in the figures. A securing component 92, 92' provides advantages related to assembly of the system in that the connecting element may firstly be inserted into the bore 8 whereafter the securing component is attached to the respective end portion of the connecting element e.g. by screwing thereby locking the connecting means into position. However the withholding means is not restricted to a nut component and many other types of components fulfilling the same function may be used, such as rivets, nail heads or any stopper or other securing element which can be coupled to the connecting element and lock/hold it in position inside the bore 8, 8'. The withholding means 92 has a body comprising at least one cross-section X (see Fig. 3C) which is larger than the diameter d of the middle second portion 82 of the bore 8. In one embodiment one withholding means 92 is fitted in each of the two outer first portions 80 meaning that the withholding means are dimensioned to fit in the bore portions 80 having the diameter D. Moreover, the withholding means 92 are arranged in such a way that their size prevents them from entering the middle portion 82 of the bore 8. In one example the withholding means in Fig. 3C is a nut with an outer diameter X. The diameter X is dimensioned so that the nut can be inserted into the first portion 80 of the bore 8 but is prevented from passing the flange 81 into the second portion 82 of the bore. Thus by coupling one nut 92 to each end portion 94 of the corresponding connecting element 90 the connecting element 90 is secured inside the through bore 8, and thereby the withholding means 92, 92' couple the connecting element to the clamping tool body 2. The withholding means 92 can be coupled to the connecting element 90 in various ways. For instance in the embodiment where the withholding means 92 is a nut and the connecting element is a bar, the nuts may be coupled to the end portions 94 of the bar by means of screwing, in which case the nut and the bar are preferably arranged with complementary inner and outer threads. However, the skilled person understands that other ways of coupling the withholding means 92 to the connecting element 90 are also conceivable, i.e. such as welding. The withholding means 92 are arranged to couple the connecting element 90 to the clamping tool body 2 at two different positions of the bore 8 which are separated from each other. In one example this means that one withholding means 92 is coupled to each end portion 94 of the connecting element 90 at said outer first portions 80 of the bore 8. In this example the two positions whereat the respective withholding means 92 couple the elongated connecting element 90 to the clamping tool body 2 are separated by a substantial portion of the body of the clamping tool 2, preferably a majority (>50%) of the body of the clamping tool 2.

[0028] One function of the nut 92 is to keep the connecting element 90 (i.e. the bar) in place inside the bore 8, but at the same time the bar 90 also holds the nut 92 in position meaning the nut 90 and the bar 90 cooperate in keeping the safety arrangement 9 in place.

[0029] Fig. 3A shows a side view of the clamping tool 2 with two horizontally extending connecting elements 90, 90' wherein each connecting element extends between bore openings 83, 84 at the respective vertical side portions of the tool body 2. The view in Fig. 3A shows one of the bore openings 84. Herein it is seen that said two through bores 8, 8' are arranged at different positions through the body 2 having different alignments, both at different vertical locations and different horizontal locations, meaning that the clamping tool 2 is arranged with an uppermost 8 and a lowermost 8' bore, as well as with a frontal 8' and a rear 8 bore. Like positioning of the bores 8, 8' may be advantageous for safeguarding that at least one of the connecting element 90, 90' will be able to retain broken loose parts of the clamping tool 2 in case of cracking of the tool body 2. However, it is evident that sometimes only one through bore 8 and safety arrangement may be sufficient.

[0030] The safety system according to one embodiment of the invention further comprises at least one shock absorbing component 91 preferably arranged at one of the outer first portions 80 of the bore 8 and adjacent to the withholding means 92. Preferably the safety system is arranged with one shock absorbing component 91 at each outer portion 80 of the bore 8, for instance in Fig. 3B it is seen that two shock absorbing components 91 are provided for each through bore 8: one at each outer portion 80 said through bore 8.

[0031] The position of the shock absorbing component 91 is shown in the enlarged cross section of Fig. 3C. In a preferred aspect of the invention the shock absorbing component 91 is designed as a casing embracing at least a part of the portion of the connecting element 90 (i.e. the bar) located at said outer first bore portion 80. Preferably the shock absorbing component 91 is dimensioned so that one end portion thereof abuts said flange 81 and another opposite end portion abuts the withholding means 92 leading to that the shock absorbing component 91 in one embodiment essentially fills the space which is defined by the outer first portion 80, the flange 81 and the side of the withholding means 92 which is facing the inside of the bore 8. In a preferred embodiment the withholding means 92 is arranged/dimensioned so that, when the withholding means 92 is coupled to the elongated connecting element 90 and placed inside the bore 8, a passage or opening 93 is created between the respective outer first portion 80 and the atmosphere outside the bore 8 at the outside of the clamping tool 2. Such a passage 93 may be achieved in that the withholding means in the form of a nut 92 is arranged with an indentation 93 or in that the diameter of the nut is made smaller than the diameter of the outer first bore portion 80 so that an annular opening is created between the outer circumference of the nut 92 and the inner walls of the respective outer first bore portion 80 when the nut is in position inside the bore 8. The function of the passage 93 will be described in more detail in connection to Figs. 6A - 6B.

[0032] The shock absorbing component 91 is arranged to at least partially absorb the energy generated upon burst of the tool 2. Such shock absorbing property may be achieved in many ways. For instance the shock absorbing component can be made of a shock absorbing material such as for instance plastic, rubber, silicone, metal, ethyl cellulose based material or clay based material able to absorb and/or dampen shock upon impact. Another way of achieving a shock absorbing property is to provide a component having a certain shape/design such as e.g. a compression spring made of metal.

[0033] In one embodiment the shock absorbing component is made of a deformable material. It is to be understood that "deformable" herein may refer to the property of altering the shape upon impact, either reversibly or non-reversibly. A reversibly deformable material may for instance be compressible and/or elastic. A non-reversibly deformable material may for instance be pliable and/or foldable.

[0034] As an example the shock absorbing element 91 is made of an elastic material such as rubber which is able to be compressed upon impact thereby absorbing shock caused by bursting and subsequently retake its original shape.

[0035] As another example the shock absorbing component 91 is a deformable component made of a flexible modeling compound which can be non-reversibly deformed upon impact.

[0036] As yet another example the shock absorbing component 91 is made of a ethyl cellulose based material, sometimes also comprising mineral oil. The shock absorbing component 91, e.g. a casing, may be drop-forged from said ethyl cellulose material into a desired shape with desired dimensions, thus being given the shape i.e. of a casing. The shock absorbing component 91 may also be die-cast from melted ethyl cellulose material into casings. Such material is non-reversibly deformable upon impact.

[0037] Fig. 4 shows a detailed view of an energy absorbing arrangement 9 according to one embodiment of the invention. The energy absorbing arrangement 9 is suitable for use in a safety system according to the invention. The energy absorbing arrangement 9 comprises an elongated connecting element 90 which at each end portion 94 is coupled to a withholding means 92, and further a shock absorbing component 91 is arranged adjacent to each of said withholding means 92 at said respective end portions 94 of the connecting element. Each of the respective shock absorbing components 91 is arranged at the side of the corresponding withholding means 92 which is facing the other opposite end portion of the connecting element 90. The embodiment shown in Fig. 4 comprises a connecting element in the form of a solid bar 90, two withholding means in the form of nuts 92 and adjacent each nut 92 is arranged shock absorbing components in the form of deformable casings 91.

[0038] The casings 91 (shock absorbing components 91) are arranged in such a way that they at least partially embraces said solid bar. The casings 91 are intended to function as energy absorbing elements in case of breakage of a clamping tool 2. Each end portion of the bar 90 is coupled to said withholding means 92, herein shown as a nut 92, which can be fastened to the bar 90 e.g. by means of screwing.

[0039] Fig. 5 shows a planar view of an example of a withholding means 92 in the form of a nut providing a securing function. The nut has a body which comprises at least one cross-section X (herein corresponding to the largest diameter of the essentially circular nut) which is larger than the diameter d of said second portion 82 of the bore 8. The nut comprises at least one indentation 93 which will later be described more thoroughly. In Fig. 5 the nut comprises two concave indentations 93 symmetrically arranged around the circumference of the nut 92. When the nut 92 is coupled to an end portion of the bar 90 and the bar is positioned inside the through bore 8 said indentation 93 creates an opening or a passage between the outer bore portion 80 and the outside of the tool 2.

[0040] The function of the safety system, as well as of the corresponding safety arrangement, will now be described in more detail, referring mainly to Figs. 6A-B and 7A-B respectively which schematically illustrates a broken clamping tool 2 which has a crack 200 splitting the tool 2 into two loose portions. Herein the crack 200 extends vertically through the clamping tool 2 resulting in that the body 2 is divided into a leftmost and a rightmost loose portion.

[0041] When a clamping tool 2 is subjected to mechanical stress, e.g. as a consequence of gripping a pipe 11 with a diameter that does not match the curvature of the dies 3 used for gripping, it may happen that the body of the tool 2 cracks apart. At the point when cracking/breaking occurs there is a risk that the tool 2 will burst apart suddenly and violently. Thanks to the safety system and safety arrangement retaining the resulting loose portions, a situation where parts of the clamping tool 2 are ejected into different directions and potentially would cause damage to surrounding individuals and/or equipment is prevented. The connecting element/s 90, 90' will function as a connector retaining the loose parts of the clamping tool 2. Furthermore, the shock absorbing component 91 will act as a shock/energy absorber during the burst and will efficiently dampen/absorb at least part of the kinetic energy generated during breakage. The presence of the shock absorbing components 91, 91' also leads to that the withholding elements 92, 92' and the connecting means 90, 90' are spared from at least a portion of the force generated during breakage of the tool 2 which further reduces the already very small risk that coupling between i.e. the nuts 92 and the bar 90 would also break.

[0042] The shock absorbing function of the shock absorbing element 91 is now to be further described. In one embodiment the shock absorbing component 91 is made of a casing in deformable material, for instance plastic based material. Bursting of a clamping tool 2 may lead to that loose parts will violently and suddenly split apart where said loose portions will move in high speed into different directions. This movement causes the shock absorbing component 91, which is positioned at the outer bore portion 80 adjacent to the nut 92, to be squeezed between said bore flange 81 and said nut 92. When this occurs the shock absorbing component 91 is deformed thus absorbing kinetic energy generated at the burst.

[0043] In one embodiment the withholding means 92 is arranged with a passage 93 connecting the outer bore portion 80 with the atmosphere outside of the clamping tool 2. The function of said passage 93 is now to be further described.

[0044] In the following example the shock absorbing component 91 is made of a deformable material. One example of a passage 93 is created by symmetrically arranged indentations 93 in the nut 92, seen in Fig. 5, but other ways of creating a passage are of course also conceivable. Presence of such a passage 93 allows for a portion of the deformable shock absorbing component 91 to exit the bore 8 during breakage of the clamping tool 2 which contributes to the cushioning effect. For example in Fig. 6B and Fig. 7B respectively there is illustrated a situation after breakage of the tool 2 where a portion of the shock absorbing component 91, 91' has exit the bore 8 due to squeezing during breakage.

[0045] At bursting of the clamping tool 2 the shock absorbing component 91 is squeezed between the flange 81 and the nut 92 resulting in that a portion thereof will pass through the passage 93 between the nut 92 and the corresponding inner wall of the outer first bore portion 80. In other words, the nut will stop a part of the material of the shock absorbing component 91 from exiting the bore, while the passage 93 will allow for a restricted portion to pass. Said passage 93 will hereby provide a choking effect and a shock absorbing effect is achieved which dampens the kinetic forces generated upon the burst.

[0046] As is previously described a passage 93 between the body of the withholding means 92 and the inner wall of the outer first bore portion 80 can be created in many ways, for instance as an annular passage between the outer circumference of a nut and the inner wall of said bore 8.

[0047] Altering the area of the passage 93 in relation to the area of the withholding means 92 will also alter the choking effect and also the shock absorption, i.e. the energy absorption. Also the mass or volume of the shock absorbing component 91 will affect the energy absorption which in its turn is dependent on the size/dimension of the outer first bore portion 80 whereat the shock absorbing component is arranged to be fitted. Thus, when adapting the system for being able to provide a certain dampening, the mass and volume of the shock absorbing component 91 is balanced against the area of the passage 93 and the (blocking) area of the withholding means 92.

[0048] Also the physical properties of the shock absorbing component 91 may affect the outline of the system. Increase viscosity of the material may require smaller passage and vice versa.

[0049] The "area of the passage" is to be interpreted as the difference between the cross area of the opening of the outer first bore portion 80 and the area of the withholding means 92 arranged to block the bore hole opening 84.

[0050] As one non-limiting example of dimensions the diameter of the bore hole opening 84 is 15 mm leading to a cross sectional area of around 177 mm2. The blocking area of the nut is around 122 mm2 and the total area of the passage 93 is thus around 55 mm2. The shock absorbing component 91 is made of an ethyl cellulose based material and has a essentially cylindrical shape with a diameter of 15 mm and a length of 20 mm resulting in a volume of around 3500 mm3.

[0051] The skilled person understands that the energy absorbing property of the shock absorbing component 91 can be achieved in different ways and that it can be made of various materials as well as having various shapes. For instance the shock absorbing component 91 may be an elastic casing made of rubber or silicone, or it may be a pliable, plastic based material which is injected into the bore 8 prior to/after fastening the nut 92 to the bar 90.

[0052] It is understood that the objects of the present invention set forth above, among those made apparent by the detailed description, shall be interpreted as illustrative and not in a limiting sense. Within the scope of the following claims the set-up of various alterations of the present invention may be possible.

[0053] For instance the connecting element can be a bar or a wire which is positioned inside the through bore 8.

Claims

1. A safety system for a gripping device comprising:

- a clamping tool, suitable for clamping drill pipes and casings (11) during drilling operations, having a body (2), wherein the axis of such drill pipes or casings, when clamped, define a vertical direction of the body (2) of the clamping tool,

- at least one through bore (8) extending in a horizontal direction through the body (2) of the clamping tool,

- at least one elongated connecting element (90) extending through the bore (8) between bore openings (83, 84) at the respective vertical side portions of the body (2), and

- withholding means (92) arranged to couple the connecting element (90) to the clamping tool body (2) at two different positions of the bore (8) separated from each other, wherein

- the connecting element is capable of keeping loose parts together in case of accidental breaking and/or cracking of the body (2) during operational use.

2. The safety system according to claim 1, wherein the body of the clamping tool (2) is a cast item with a single solid body preferably made of metal.

3. The safety system according to claim 2, wherein said bore is a through bore (8) comprising two outer first portions (80) and a middle second portion (82) located in between said two outer first portions (80), where said outer first portions (80) have a diameter (D) which is larger than the diameter (d) of the middle second portion (82), and further wherein the withholding means (92) has a body which comprises at least one cross-section (X) which is larger than the diameter (d) of the middle second portion (82) of the bore (8), where one withholding means (92) is positioned at each of the outer first portions (80) of the through bore (8) in such a way that they are prevented from entering the middle second portion (82) of the bore (8).

4. The safety system according to claim 3, wherein each of said withholding means (92) is dimensioned so that when it is positioned inside the outer first portion (80) a passage (93) is created between the outer first portion (80) of the bore (8) and the atmosphere outside the bore (8).

5. The safety system according to claim 3 or 4, wherein said withholding means is in the form of a securing component (92) arranged to be coupled to end portions (94) of the connecting element (90).

6. The safety system according to anyone of the previous claims, further comprising at least one shock absorbing component (91) arranged at an outer portion (80) of the bore (8) and adjacent to said withholding means (92).

7. The safety system according to claim 6, wherein said shock absorbing component (91) is made of a deformable/pliable material.

8. The safety system according to anyone of the previous claims, wherein said elongated connecting element (90) is a bar element made of steel material.

9. The safety system according to anyone of claims 1 - 7, wherein said elongated connecting element (90) is a wire element.

10. A gripper for gripping a pipe (P) comprising a safety system according to anyone of claims 1-9.

Ansprüche

1. Sicherheitssystem für eine Greifvorrichtung umfassend:

- ein Klemmwerkzeug, das geeignet ist, Bohrrohre und -schalungen (11) während Bohrarbeiten zu klemmen, und das einen Körper (2) aufweist, wobei die Achse solcher Bohrrohre oder -schalungen, wenn geklemmt, eine Vertikalrichtung des Körpers (2) des Klemmwerkzeugs definiert,

- mindestens eine Durchgangsbohrung (8), die sich in einer Horizontalrichtung durch den Körper (2) des Klemmwerkzeugs erstreckt,

- mindestens ein längliches Verbindungselement (90), das sich durch die Bohrung (8) zwischen Bohrungsöffnungen (83, 84) an den jeweiligen vertikalen Seitenabschnitten des Körpers (2) erstreckt, und

- Rückhaltemittel (92), die eingerichtet sind, das Verbindungselement (90) an zwei unterschiedlichen voneinander getrennten Positionen der Bohrung (8) an den Klemmwerkzeugkörper (2) zu koppeln, wobei

- das Verbindungselement imstande ist, lose Teile zusammenzuhalten, im Falle eines unbeabsichtigten Brechens und/oder Reißens des Körpers (2) während eines Arbeitseinsatzes.

2. Sicherheitssystem gemäß Anspruch 1, wobei der Körper des Klemmwerkzeugs (2) ein Gussgegenstand mit einem einzelnen festen Körper ist, vorzugsweise aus Metall gefertigt.

3. Sicherheitssystem gemäß Anspruch 2, wobei die Bohrung eine Durchgangsbohrung (8) ist umfassend zwei äußere erste Abschnitte (80) und einen mittleren zweiten Abschnitt (82), der sich zwischen den zwei äußeren ersten Abschnitten (80) befindet, wobei die äußeren ersten Abschnitte (80) einen Durchmesser (D) aufweisen, der größer ist als der Durchmesser (d) des mittleren zweiten Abschnitts (82), und wobei weiterhin das Rückhaltemittel (92) einen Körper aufweist, welcher mindestens einen Querschnitt (X) umfasst, welcher größer ist als der Durchmesser (d) des mittleren zweiten Abschnitts (82) der Bohrung (8), wobei ein Rückhaltemittel (92) an jedem der äußeren ersten Abschnitte (80) der Durchgangsbohrung (8) auf eine Weise positioniert ist, dass sie daran gehindert werden, in den mittleren zweiten Abschnitt (82) der Bohrung (8) einzudringen.

4. Sicherheitssystem gemäß Anspruch 3, wobei jedes der Rückhaltemittel (92) so dimensioniert ist, dass, wenn es innerhalb des äußern ersten Abschnitts (80) positioniert ist, ein Durchlass (93) zwischen dem äußeren ersten Abschnitt (80) der Bohrung (8) und der Atmosphäre außerhalb der Bohrung (8) erzeugt wird.

5. Sicherheitssystem gemäß Anspruch 3 oder 4, wobei das Rückhaltemittel in Form einer Sicherungskomponente (92) vorliegt, die eingerichtet ist, an Endabschnitte (94) des Verbindungselements (90) gekoppelt zu werden.

6. Sicherheitssystem gemäß einem der vorstehenden Ansprüche, weiterhin umfassend mindestens eine stoßabsorbierende Komponente (91), die an einem äußeren Abschnitt (80) der Bohrung (8) und benachbart dem Rückhaltmittel (92) eingerichtet ist.

7. Sicherheitssystem gemäß Anspruch 6, wobei die stoßabsorbierende Komponente (91) aus einem deformierbaren/biegbaren Material gefertigt ist.

8. Sicherheitssystem gemäß einem der vorstehenden Ansprüche, wobei das längliche Verbindungselement (90) ein aus Stahlmaterial gefertigtes Stabelement ist.

9. Sicherheitssystem gemäß einem der Ansprüche 1-7, wobei das längliche Verbindungselement (90) ein Drahtelement ist.

10. Greifer zum Greifen eines Rohrs (P) umfassend ein Sicherheitssystem gemäß einem der Ansprüche 1-9.

Revendications

1. Un système de sécurité pour un dispositif de préhension comprenant :

- un outil de serrage, adapté pour serrer des tiges de forage et des carters (11) pendant des opérations de forage, ayant un corps (2), l'axe de ces tiges ou carters, une fois serrés, définissant une direction verticale du corps (2) de l'outil de serrage,

- au moins un alésage traversant (8) s'étendant dans une direction horizontale à travers le corps (2) de l'outil de serrage,

- au moins un élément de liaison allongé (90) s'étendant à travers l'alésage (8) entre des ouvertures d'alésage (83, 84) au niveau des parties latérales verticales respectives du corps (2), et

- des moyens de retenue (92) agencés pour relier l'élément de liaison (90) au corps d'outil de serrage (2) à deux positions différentes de l'alésage (8) séparées l'une de l'autre,

- l'élément de liaison étant apte à maintenir ensemble des pièces séparées en cas de rupture et / ou de fissuration accidentelle du corps (2) pendant l'utilisation opérationnelle.

2. Le système de sécurité selon la revendication 1, dans lequel le corps de l'outil de serrage (2) est un élément moulé avec un seul corps solide de préférence en métal.

3. Le système de sécurité selon la revendication 2, dans lequel ledit alésage est un alésage traversant (8) comprenant deux premières parties externes (80) et une deuxième partie médiane (82) située entre lesdites deux premières parties externes (80), lesdites premières parties externes (80) ayant un diamètre (D) qui est plus grand que le diamètre (d) de la deuxième partie médiane (82), et, en outre, les moyens de retenue (92) ayant un corps qui comprend au moins une section transversale (X) qui est plus grande que le diamètre (d) de la deuxième partie médiane (82) de l'alésage (8), un moyen de retenue (92) étant positionné sur chacune des premières parties externes (80) de l'alésage traversant (8) de telle sorte qu'ils sont empêchés d'entrer dans la deuxième partie médiane (82) de l'alésage (8).

4. Le système de sécurité selon la revendication 3, dans lequel chacun desdits moyens de retenue (92) est dimensionné de sorte que, lorsqu'il est positionné à l'intérieur de la première partie extérieure (80), un passage (93) est créé entre la première partie extérieure (80) de l'alésage (8) et de l'atmosphère présente à l'extérieur de l'alésage (8).

5. Le système de sécurité selon la revendication 3 ou la revendication 4, dans lequel ledit moyen de retenue est sous la forme d'un composant de fixation (92) agencé pour être relié à des parties d'extrémité (94) de l'élément de connexion (90).

6. Le système de sécurité selon l'une quelconque des revendications précédentes, comprenant en outre au moins un composant (91) absorbant les chocs agencé au niveau d'une partie extérieure (80) de l'alésage (8) et adjacent auxdits moyens de retenue (92).

7. Le système de sécurité selon la revendication 6, dans lequel ledit composant (91) absorbant les chocs est constitué d'un matériau déformable / pliable.

8. Le système de sécurité selon l'une quelconque des revendications précédentes, dans lequel ledit élément de liaison allongé (90) est un élément en forme de barre en matériau d'acier.

9. Le système de sécurité selon l'une quelconque des revendications 1 à 7, dans lequel ledit élément de connexion allongé (90) est un élément en fil.

10. Un système de préhension pour saisir un tuyau (P) comprenant un système de sécurité selon l'une quelconque des revendications 1 à 9.

Drawing