The invention relates to a mounting device for a screw connection and a method for tightening a screw according to the preamble of the independent claim of the respective category.

Screw connections are very often used to connect two components together in a releasable manner. As an example, pumps for industrial purposes are mentioned here, in particular centrifugal pumps of the type used in the energy-producing industry, in the water industry or in the oil and gas industry. Such pumps usually comprise a casing, which is designed as a pressure-resistant casing and is composed of several components or casing parts. It is essential for the reliable operation and safe operation of the pump that the casing parts are connected to each other in such a secure and sealing manner that these connections can reliably withstand even the highest conveying pressures and conveying rates. In industrial applications, heads of 2000 m, or more, at flow rates of 800 m ³ /h, or more, may be required.

In order that the pressure-resistant casing of the pump and in particular the connections between the casing parts can withstand these enormous loads permanently and reliably, the housing parts are usually connected to each other via a large number of screw connections, wherein the screw connections - depending on the design of the pump - for example are arranged around the shaft of the pump, so that the longitudinal axes of the screw connections each extend in the direction of the shaft. In barrel casing pumps, for example, the barrel casing has a large number of threaded bolts being arranged around the pump shaft. After placing the cover on the barrel housing, the threaded bolts reach through the cover. Subsequently, threaded nuts are screwed onto the threaded bolts in order to connect the cover to the barrel housing in a pressure-resistant and sealing manner.

In ring section pumps, which usually comprise several pump stages, typically a plurality of stage casings is provided, which are arranged one behind the other in the direction of the pump shaft between an inlet suction casing and an outlet pressure casing. Then, a plurality of tension bolts or tie rods are provided as screw connections, which extend parallel to the pump shaft through the suction casing and through the pressure casing. One threaded nut is then screwed onto each tie rod on both sides, i.e. on the pressure casing and on the suction casing, whereby the pressure casing and the suction casing and the stage casings arranged between them are braced together so that pressure-resistant and tight screw connections are realized between the components.

It is clear that the screw connections are tightened according to a specified scheme, i.e. in particular in a specified sequence, and with specified torques.

To tighten each screw connection, it is necessary that this is as torsion-free as possible and as precise as possible with the predetermined torque. For this purpose, it is known that the threaded bolt, for example the threaded bolt of a screw or a tie rod, is pretensioned in order to fix the threaded bolt by screwing or tightening the threaded nut. This pre-tensioning of the threaded bolt should also be as torsion-free as possible and with a predeterminable pretension. The aim is that the desired torque with which the screw connection is to be tightened can be converted as reproducibly as possible into a corresponding pretension force for the screw connection. Meanwhile some mechanical tensioning devices are commercially available, which replace the conventional threaded nuts, for example hexagon nuts, and which enable the torsion-free pretensioning of a screw connection with a desired pretension force. Mechanical tensioning devices are known as well as hydraulic tensioning devices, in which the pretension for the bolt connection is generated with hydraulic forces.

One example is the tensioning system available under the trade names Hytorc or Hytorc Clamp, which replaces the conventional threaded nut in a screw

connection. Hytorc Clamp is a mechanical tensioning element which is mounted or dismounted with the aid of a hydraulic mounting device. Another example is the tensioning element marketed by the Nord-Lock Group under the trade name Superbolt, which is a purely mechanical tensioning device and replaces the conventional threaded nut in a screw connection. Superbolt is a tensioning element with multiple screws, which can be tightened or loosened mechanically or pneumatically with conventional tools. No hydraulic mounting tools are required for mounting or dismounting a Superbolt tensioning element. Another commercially available tensioning element is the expansion nut sold by devotee GmbH under the trade name CLAMP.

Even if such tensioning devices have proven themselves in practice, they also have disadvantages. The tensioning devices are significantly more expensive than conventional threaded nuts, so that replacing each threaded nut with such a tensioning device is a considerable cost factor. In addition, it is possible that specific material requirements may apply to the screw connections, for example in a pump, which may depend on the environment or operating conditions in which or under which the pump is operated (e.g. corrosive environment or environments requiring explosion protection). If the known tensioning devices are then not available made of materials which are certified or approved for such environments, at least additional and complex material tests or certifications are required. Starting from this state of the art, it is therefore an object of the invention to propose a possibly simple and cost-effective mounting device for a screw connection, which allows the screw connection to be pretensioned as precisely and torsion-free as possible. The mounting device should also be particularly suitable for larger screw connections which at least correspond to the M48 thread standard. It is further an object of the invention to propose an appropriate method for tightening a screw connection. The objects of the invention meeting this problem are characterized by the features of the independent claim of the respective category.

Thus, according to the invention, a mounting device for a screw connection is proposed, with a threaded bolt and and a polygonal threaded nut cooperating with the threaded bolt for fastening two components together, which mounting device comprises a rotating ring for rotating the threaded nut, a threadless sleeve for receiving the rotating ring and a tensioning device for a torsion-free pretension of the threaded bolt, wherein the rotating ring has a polygonal central opening for enclosing the threaded nut, which opening is designed in such a way that the threaded nut is rotatable by rotating the rotating ring, wherein the sleeve has a length in an axial direction, which is larger than a length of the rotating ring in the axial direction, wherein the sleeve has a first axial end face for placing on one of the components, a second axial end face on which a force can be exerted with the tensioning device, a continuous central recess for receiving the rotating ring and a shell surface connecting the end faces, which shell surface surrounds the central recess, wherein the central recess has a diameter in the region of the first axial end face, which diameter is larger than the outer diameter of the rotating ring in such a way that the rotating ring is rotatable about the axial direction relative to the sleeve, and wherein the shell surface of the sleeve has a longitudinal slot to allow a rotation of the rotating ring in the sleeve. The mounting device according to the invention allows a screw connection to be pretensioned torsion-free and with a high degree of pretensioning accuracy in a simple and cost-effective manner. The pretensioned screw connection can then be tightened and secured by simply rotating the threaded nut. After tightening the threaded nut, the entire mounting device, including the rotating ring, the sleeve and the tensioning device, can be loosened from the screw connection and used to tighten further screw connections. Thus, conventional threaded nuts can be used for the screw connection, without concessions to the torsion-free pretension or to the accuracy of the pretension are necessary. No special tensioning devices are required anymore, which are a permanent component of the screw connection. In principle, a single tensioning device is sufficient for torsion-free pretension of any or at least a very large number of screw connections. This means a

considerable reduction in costs, especially for devices such as pumps with a large number of screw connections, which have to be pretensioned torsion-free. All tensioning devices known per se for the torsion-free pretension of a screw connection are suitable as tensioning devices for the mounting device according to the invention, in particular also the tensioning devices mentioned above, which are commercially available under the trade names Hytorc Clamp or Superbolt or CLAMP expansion nut (from the company devote), or similar or equivalent tensioning devices. The tensioning device can be designed as a purely

mechanical tensioning device or as a hydraulically operated tensioning device.

The fact, that the tensioning device of the mounting device according to the invention is disconnected after the screw connection has been closed or tightened, has also the advantage that no certifications are necessary for the mounting device and in particular for the tensioning device with regard to the material. Even if the screw connections or the device with the screw connections, for example a pump, is operated in environments or under conditions which make special demands on the material, for example with regard to corrosion resistance or explosion protection, it is not necessary that the mounting device has the corresponding certifications or qualifications, because the mounting device itself is not a part of this device (pump), but is only used for tightening or loosening the screw connections and subsequently, i.e. in particular during the operation of the device (pump), is not a part of the screw connection, but is separated from it.

By means of the mounting device according to the invention, mechanical and/or hydraulic tensioning devices known per se can be used as mounting tools and are no longer a permanent part of the screw connection.

Of course, it is clear that the mounting device according to the invention is suitable both for tightening and loosening a screw connection.

The mounting device is preferably designed for the use of conventional threaded nuts. For this purpose, the rotating ring in particular is designed for cooperation with a hexagonal threaded nut.

The mounting device according to the invention is particularly suitable for large screw connections that require considerable forces to tighten the screw

connection. Therefore, it is preferred if the rotating ring is designed for the cooperation with a threaded nut which corresponds to thread standard M48 or larger. The mounting device can also be designed for significantly larger threaded nuts, for example for threaded nuts of size M95. Preferably, a plurality of bores are provided in the outer surface of the rotating ring, each of which is designed to for the cooperation with a tool for rotating the rotating ring. By this measure, it is particularly easy to rotate the rotating ring in the sleeve with a tool through the longitudinal slot in the sleeve. Furthermore, it is advantageous if the central recess has a diameter at the second axial end face, which is smaller than a maximum inner diameter of the central opening of the rotating ring. This measure makes it possible to realize a particularly large attachment surface for the tensioning device, with which a pretensioning force is generated on the sleeve.

It is preferred, if the central recess has a diameter in the region of the first axial end face, which is adapted to the rotating ring in such a way that the sleeve encloses the rotating ring with little clearance. The clearance is dimensioned in such a way that the rotating ring can still easily be rotated inside the sleeve.

Mounting device according to anyone of the preceding claims. Another

advantageous measure is that the shell surface of the sleeve has a plurality of longitudinal slots for rotating the rotating ring in the sleeve, each of which extending in the circumferential direction of the sleeve. This ensures a particularly good accessibility for rotating the rotating ring in the sleeve.

In a preferred embodiment, the tensioning device is designed as a mechanical tensioning device for a torsion-free pretension of the threaded bolt.

Furthermore, the invention proposes a method for tightening a screw connection with a threaded bolt and a polygonal threaded nut cooperating with the threaded bolt for fastening two components together, the method comprising the following steps:

- providing a mounting device, which is designed according to the invention,

- screwing the threaded nut onto the threaded bolt, - placing the rotating ring on the threaded nut, so that the threaded nut and the rotating ring engage,

- placing the threadless sleeve on one of the components, so that the first axial end face of the sleeve rests on the component,

- connecting the tensioning device to the threaded bolt in such a way that the tensioning device rests on the second axial end face of the sleeve, - pretensioning of the threaded bolt by means of the tensioning device,

- tightening the threaded nut by rotating the rotating ring,

- removing the tensioning device and the sleeve and the rotating ring.

Preferably, the thread bolt is pretensioned with a mechanical tensioning device or with a mechanical tensioning device, which is operated hydraulically. However, it is also possible to perform the pretensioning with a hydraulic tensioning device. The method according to the invention is particularly suitable for screw

connections in a pump. Therefore, it is a preferred embodiment if the two components that are fastened together are casing parts of a pump.

In particular, one of the components can be a barrel casing of a pump.

Furthermore, it is preferred if one of the components is a suction casing or a pressure casing of a ring section pump.

The method according to the invention is particularly suitable for such screw connections in which the threaded bolt has a thread diameter of at least 48 mm. Further advantageous measures and embodiments of the invention result from the dependent claims.

In the following, the invention is explained in more detail in terms of apparatus and in terms of process engineering with reference to embodiments and with reference to the drawing. In the drawing show:

Fig. 1 : a schematic view of a pump with screw connections for fastening two components together,

Fig. 2: an exploded view of an embodiment of a mounting device according to the invention, and

Fig. 3: a sectional view of the embodiment from Fig. 2 in a mounted

condition and placed on a screw connection.

Fig. 2 shows in an exploded view of an embodiment of a mounting device according to the invention, which is referred to as a whole with the reference sign 1 . For a better understanding, Fig. 3 still shows a sectional view of this mounting device 1 in a mounted condition and placed on a screw connection 10. The mounting device 1 is suitable for tightening or loosening the screw connection 10, which comprises a threaded bolt 1 1 and a polygonal threaded nut 12 cooperating with the threaded bolt 1 1 , and which is used to fasten two components together (see Fig 1 ). In a manner known per se, the threaded bolt 1 1 is provided with an external thread at least in the regions in which it is in operative connection with the threaded nut(s) 12, and the threaded nut 12 is provided with a corresponding internal thread, which is designed to cooperate with the external thread. The external thread and the internal thread, which are not shown in more detail in Fig. 2 and Fig. 3, are preferably standard threads which are designed according to one of the usual thread standards, for example as metric ISO threads. In the framework of this application, threaded nuts 12 or threaded bolts 1 1 , which are designed with threads according to one of the usual thread standards, for example with metric ISO threads, are referred to as "conventional". Furthermore, the term "threaded bolt" generally refers to components of a screw connection having an external thread, for example screws, bolts, threaded rods, rods or bolts which are only provided with an external thread over a part of their length.

In the following description of the embodiment of the mounting device according to the invention and the method according to the invention, it is referred to an application important for practice with an exemplary nature, namely that the screw connection 10 is part of a pump for industrial applications, more precisely that the screw connection 10 is used for fastening two components together, in particular two casing parts of a pump.

For a better understanding, Fig. 1 illustrates in a very schematic view an embodiment of a pump, which is referred to as a whole with the reference sign 100 and which is designed as a centrifugal pump. The pump 100 is designed as a multi-stage ring section pump, in particular as a high-pressure stage casing pump. Such pumps 100 are used, for example, in the energy generating industry as feed water pumps in industrial power plants. They can be designed for flow rates of up to 800 m ³ /h (or even more) and heads of 2000 m (or more) and they can generate water pressures of several hundred bar, for example 300 bar. It is clear that the casing of such a pump 100 must be designed as a pressure-resistant casing which can safely and reliably withstand these enormous loads.

As shown in Fig. 1 , the pump 100 comprises a suction casing 101 , at which an inlet 103 is provided for the fluid to be conveyed, e.g. water, and a pressure casing 102, at which an outlet 104 is provided for the fluid. A plurality of stage casings 106 being arranged one behind the other, is provided between the suction casing 101 and the pressure casing 102. Typically, one impeller (not shown) is provided in the suction casing 101 and in each of the stage casings 106 for conveying the fluid. All impellers are arranged on a common shaft 105, which is only indicated by a line in Fig. 1 , wherein each impeller is torque-proof connected to the shaft 105. The shaft 105 is driven for rotation by a drive unit, not shown, for example an electric motor, as indicated by the arrow D in Fig. 1 . All impellers are driven for rotation by the rotation of the shaft 105.

Thus the pressure-resistant casing of the pump 100 comprises the suction casing 101 , the pressure casing 102 and the stage housings 106 arranged between them. In order to connect the various housing parts 101 , 102, 106 in a pressure-resistant and sealing manner, a plurality of screw connections 10 is provided, each of which comprises a threaded bolt 1 1 , which is designed as a tension bolt. Only one of the threaded bolts 1 1 is shown in Fig. 1 . The threaded bolt 1 1 extends parallel to the shaft 105 and grips through both the pressure housing 101 and the suction housing 102. The threaded bolt 1 1 is fixed by a threaded nut 12 on the side of the suction casing 101 and the pressure casing 102 facing away from the stage housings 106. By tightening the threaded nuts 12, the threaded bolt 1 1 can be tensioned, whereby the suction casing 101 , the pressure casing 102 and the stage housings 106 arranged in between are braced together to form a pressure- resistant casing of the pump 100. As already mentioned, a plurality of such screw connections 10 is provided, each threaded bolt 1 1 extending parallel to the shaft 105, and the threaded bolts 1 1 being arranged around the shaft. It is clear that the invention is not limited to screw connections in a pump being designed in this way. The invention is particularly suitable for screw connections in pumps with different designs, for screw connections between pressure-resistant casing parts of other devices and for screw connections in general. The invention is also particularly suitable for screw connections in centrifugal pumps, which are designed as barrel casing pumps. In barrel casing pumps, the threaded bolts 1 1 are usually provided at one axial end of the barrel casing, the threaded bolts 1 1 each extending parallel to the pump shaft and being arranged around the shaft. A cover is then placed on these threaded bolts 1 1 in the end face of the barrel casing, which is then fastened to the barrel casing with threaded nuts 12 or braced with it.

For tightening such screw connections 10, especially in pumps 100, it is essential that the threaded bolts 1 1 are tensioned as torsion-free and with a force that can be adjusted as precisely as possible or that they are pretensioned as torsion-free and with a force that can be adjusted as precisely as possible before tightening the threaded nuts 12. As a rule, such torsion-free tensioning of the threaded boltsl 1 with an exact tensioning force can no longer be realized by simply tightening a conventional threaded nut 12, for example with a torque wrench. This applies in particular to larger threaded bolts 1 1 , for example those of thread standard M48 or larger.

The embodiment of the mounting device 1 according to the invention and an embodiment of the method according to the invention will now be explained in more detail with reference to Fig. 1 and Fig. 2. The screw connection 10 also shown in Fig. 2 and Fig.3 is, for example, one as explained in Fig. 1 . The threaded bolt 1 1 is provided at least at its end with an external thread, which is designed according to the metric ISO standard. The threaded bolt 1 1 is at least size M48, but can also be significantly thicker, for example M95. The longitudinal direction in which the threaded bolt 1 1 extends defines a direction called axial direction A.

The threaded nut 12 is designed as a conventional hexagon threaded nut and, of course, corresponds in size or internal thread to the same thread standard and thread size as the threaded bolt 1 1 , i.e. the threaded nut 12 is also at least size M48. Optionally, the screw connection 10 can also comprise a ring washer 13, which is arranged between the threaded nut 12 and the component on which the threaded nut 12 is supported, for example the suction casing 101 or the pressure casing 102.

The mounting device 1 comprises a rotating ring 2 for rotating the threaded nut 12, a threadless sleeve for receiving the rotating ring 2, so that the rotating ring is enclosed by the sleeve 3 and is arranged completely inside the sleeve 3, and a tensioning device 4 for a torsion-free pretension of the threaded bolt 1 1 .

The rotating ring 2 comprises a polygonal central opening 21 for enclosing the threaded nut 12, which opening 21 is designed in such a way that the threaded nut 12 is rotatable by rotating the rotating ring. Since the threaded nut 12 in the embodiment described here is designed as a hexagonal threaded nut 12, the central opening 21 in the rotating ring 2 is also designed as hexagonal. For this purpose, the inner diameter of the central opening 21 is dimensioned in such a way that the rotating ring 2 can be placed on the threaded nut 12, encloses said threaded nut 12 and the hexagonal outer contour of the threaded nut 12 enters into an operative connection with the hexagonal inner contour of the rotating ring 2 defining the central opening 21 , so that a torque can be exerted on the threaded nut 12 by means of the rotating ring 2. In the mounted state, the rotating ring 2 encloses the threaded nut 12 according to the principle of a ring spanner with an annular hexagonal profile.

Preferably, the length L2 of the rotating ring 2 in the axial direction A is smaller than the length LM of the threaded nut 12 in the axial direction A. The rotating ring 2 has an annular outer surface, which is designed as a smooth circular ring surface. A plurality of bores 22 is provided in the outer surface of the rotating ring 2, wherein the bores 22 are distributed over the circumference of the outer surface. A pin-shaped element of a tool can be inserted into these bores 22 in order to rotate the rotating ring 2 about the axial direction A.

The threadless sleeve 3 has a generally cylindrical shape and has a length L3 in the axial direction A larger than the length L2 of the rotating ring 2 in the axial direction A and larger than the length LM of the threaded nut 12 in the axial direction A.

With regard to the axial direction A, the sleeve 3 is limited by a first axial end face 31 and by a second axial end face 32, each of which is designed as circular surfaces. The first axial end face 31 is designed as contact surface, with which the sleeve 3 contacts one of the components which are fastened together by the screw connection 10. In the embodiment in Fig. 1 , the first axial end face 31 rests on the suction casing 101 or on the pressure casing 102 during mounting. A force is exerted on the second axial end face 32 while tightening the screw connection 10 with the tensioning device 4.

The sleeve 3 further has a continuous central recess 33 for receiving the rotating ring 2, which recess extends from the first axial end face 31 to the second axial end face 32. The central recess 33 has a diameter D1 being slightly larger than the outer diameter of the rotating ring 2 in the region of the first axial end face 31 , so that the rotating ring 2 can be inserted into the central recess 33 and can be rotated about the axial direction relative to the sleeve 3 when inserted. Preferably, the diameter D1 of the central recess 33 in the region of the first axial end face 31 is adapted to the rotating ring 2 in such a way that the sleeve 3 encloses the rotating ring 2 with little clearance. In the inserted condition, the rotating ring 2 should still rotate smoothly relative to the sleeve 3.

The region in which the central recess 33 has the diameter D1 , has an extension in the axial direction A which is larger than the length L2 of the rotating ring 2 in the axial direction A. The extension of this region in the axial direction is dimensioned in such a way that the rotating ring 2 and the optional washer ring 13 can be completely received by the recess 33 of the sleeve 3 with respect to the axial direction A and also a clearance 34 exists, so that the rotating ring 2 can also move in the axial direction A in the sleeve 3 and relative to the sleeve 3.

The region of the recess 33, which has the diameter D1 , is limited with respect to the axial direction A by an annular shoulder 35, which reduces the diameter of the recess 33 to a value being smaller than D1 . This value is dimensioned in such a way that, on the one hand, it is larger than the maximum outer diameter of the threaded nut 12 and, on the other hand, smaller than the outer diameter of the rotating ring 2. As a result, the shoulder 35 forms a stop, which limits the displacement of the rotating ring 2 in the axial direction A relative to the sleeve 3. At the second axial end face 32, the central recess 33 has a diameter D2 being smaller than the maximum inner diameter of the central opening 21 of the rotating ring 2. Preferably, the diameter D2 is dimensioned in such a way that, on the one hand, the threaded bolt 1 1 can still be passed through the second axial end face 32 without any problems, and that, on the other hand, the second axial end face 32 reaches as close as possible to the threaded bolt 1 1 , thus surrounding the threaded bolt 1 1 with the smallest possible diameter D 2.

The sleeve 3 further has an outer shell surface 36 connecting the first and the second axial end face 31 , 32, and which shell surface 36 surrounds the central recess 33. At least one longitudinal slot 37 is provided in the shell surface 36, which longitudinal slot 37 extends in the circumferential direction of the sleeve 3 and which allows the rotating ring 2 to rotate relative to the sleeve 3 when the rotating ring 2 is surrounded by the sleeve 3. The pin-shaped element of a tool can be engaged with one of the holes 22 through the longitudinal slot 37 in order to rotate the rotating ring 2 about the axial direction A. Preferably, a plurality of longitudinal slots 37 is provided in the shell surface 36 of the sleeve 3, each of which extending in the circumferential direction of the sleeve 3.

Optionally, a retaining ring 38 can be provided in the sleeve 3, which is designed as a Seeger ring, for example, and which prevents the rotating ring 2 from slipping out of the sleeve 3 through the first axial end face 31 . The retaining ring 38 is preferably inserted in a circumferential groove inside the sleeve 3, the

circumferential groove being arranged between the rotating ring 2 and the first axial end face 31 of the sleeve 3 with respect to the axial direction A. The inner diameter of the retaining ring 38 is dimensioned in such a way that, on the one hand, it is smaller than the outer diameter of the rotating ring 2 and, on the other hand, that the threaded nut 12 fits through the retaining ring 38.

Any known tensioning device 4 is suitable as tensioning device 4, with which a torsion-free pretensioning of the threaded bolt 1 1 is possible. The tensioning device 4 can, for example, be a purely mechanical tensioning device 4, or a mechanical tensioning device 4, which is operated hydraulically, or a hydraulic tensioning device 4. In particular, the tensioning devices described above, which are commercially available under the trade names Superbolt, Hytorc Clamp, CLAMP (company devotee), or tensioning devices that function according to the same or a similar principle, are suitable as tensioning devices 4 for the mounting device 1 according to the invention. Since such tensioning devices 4 are known per se, they need no further explanation here.

For tightening the screw connection 10 by means of the mounting device 1 , the procedure is preferably as follows: First, the threaded bolt 1 1 or the two components to be fastened together are placed, so that they are connected by the threaded bolt 1 1 . In the case of the embodiment shown in Fig. 1 , the threaded bolt 1 1 is therefore placed in such a way that it reaches through both the suction casing 101 and the pressure casing 102 and protrudes on both sides in the axial direction beyond the suction casing 101 and the pressure casing 102. In the case of a barrel casing pump, the cover is placed on the threaded bolts provided on the barrel casing, so that the cover is reached through by the threaded bolts 1 1 . To tighten the screw connection 10, the optionally provided ring washer 13 is first pushed over the threaded bolt 1 1 . The threaded nut 12 is screwed onto the threaded bolt 1 1 until the threaded nut 12 or the ring washer 13 abuts against the component, for example the suction casing 101 or the pressure casing 102. Now the sleeve 3 with the rotating ring 2 inside is placed on the threaded nut 12, so that the threaded nut 12 and the rotating ring 2, more precisely the central opening 21 of the rotating ring 2, interlock and the first axial end face 31 of the sleeve 3 abut against the corresponding component. The threaded bolt 1 1 is received by the central recess 33 and then protrudes beyond the second axial end face 32 of the sleeve 3. Now the tensioning device 4 is connected to the threaded bolt 1 1 in such a way that the tensioning device 4 rests on the second axial end face 32 of the sleeve 3 and that an operative connection is generated between the tensioning device 4 and the threaded bolt 1 1 . If the tensioning device 4 is designed as a Superbolt or a Hytorc Clamp or a CLAMP expansion nut from devotee, for example, the tensioning device 4 is screwed onto the threaded bolt 1 1 until the tensioning device 4 abuts against the second axial end face 32 of the sleeve 3.

The threaded bolt 1 1 is then pretensioned with a predeterminable pretensioning force by actuating the tensioning device 4, wherein the tensioning device 4 is supported on the second axial end face 32 of the sleeve 3 and the sleeve 3 is supported on the component with the first axial end face 31 . By pretensioning, the threaded nut 12 moves slightly away from the corresponding component. The pin- shaped element of a tool is now engaged with one of the bores 22 in the outer surface of the rotating ring 2 through the longitudinal slot 37, and by rotating the rotating ring 2 the threaded nut 12 is tightened until it or the ring washer 13 abuts against the corresponding component again. It is possible that the process of pretensioning the threaded bolt 1 1 by means of the tensioning device 4 and tightening the threaded nut 12 is carried out alternately several times. This means that first the threaded bold 1 1 is pretensioned, then the threaded nut 12 is tightened over the rotating ring 2, then the pretension of the threaded bolt 1 1 is increased and the threaded nut 12 is tightened again, etc. Of course, it is also possible that the predetermined pretension of the threaded bolt 1 1 is generated directly in only one step without torsion by means of the tensioning device 4 and then the threaded nut 12 is tightened. After the predetermined pretension of the threaded bolt 1 1 has been generated and the threaded nut 12 is tightened, the mounting device 1 , i.e. the tensioning device 4 and the sleeve 3 with the rotating ring 2 arranged therein, is removed from the screw connection 10 and is available for tightening the next screw connection 10.

The invention thus combines the advantages of torsion-free pretensioning with a precisely adjustable pretensioning force by means of a tensioning device 4 with the possibility of using conventional threaded nuts 12 for the screw connection 10. Thus, it is possible, for example, to deliver a pump 100 to the customer together with only one copy of a mounting device 1 according to the invention, and in principle only one tensioning device 4 is required to tighten (or loosen) all screw connections 10 on the pump housing. It is also particularly advantageous that the mounting device 1 with the tensioning device 4 does not remain permanently on the pump 100, but it is required only for the mounting (or dismounting), more precisely for tightening (or loosening) the screw connections 10, and then it is removed again. Since the mounting device 1 is therefore not a permanent component of pump 100, no qualification or certification is required for the materials of which the mounting device 1 is made.