Method for thread connection of flange connections

Abstract

In a method for the threaded connection of flanges (1, 2), a screw (5) extends through an opening therein, which screw is supported on the one hand with respect to the outside of one of the flanges and on the other hand with a nut (8) screwed onto a threaded section (5A) of the bolt body with respect to the outside of the other flange. In order to reliably close the gap (10) between the flanges (1, 2), it is proposed that an axial bolt clamping device is placed in such a way that the tensile force thereof acts on a threaded section (5A) of the bolt (5) protruding from the nut (8); the bolt (5) is longitudinally extended by increasing the tensile force, while continuously detecting the tensile force, continuously detecting and then rotating the nut (8), and continuously detecting the angle of rotation passed by the nut (8); for the detected rotation angle or rotation angle equivalent value, deriving a geometry characterizing the extension of the screw from the rotation angle (alpha) or rotation angle equivalent value in combination with the geometry of the threaded section (5A); constructing a function which associates the geometric size representing the extension of the bolt with the detected tension; performing a comparison operation of comparing a slope of the function with a slope of a predetermined reference curve; and generating result information according to a result of the comparison operation.

Description

Technical Field

[0001] This invention relates to a method for threading a flange connection structure, the flange connection structure comprising:

[0002] - A first flange having an outer side and a first flange face

[0003] - A second flange having an outer side and a second flange face opposite to the first flange face.

[0004] - The flange and the flange face have openings that are aligned with each other, through which the bolt body passes, the bolt being supported on the outside of the first flange on one hand and on the outside of the second flange on the other hand by a nut screwed onto the threaded section of the bolt body. Background Technology

[0005] A hydraulically operated bolt clamping device is known from EP3195991A1. This device is used to sequentially or in a predetermined order tighten multiple threaded fasteners arranged along a flange connection structure consisting of two flanges. Each threaded fastener includes: a bolt supported from below by a radially widened bolt head on the flange connection structure; and a nut screwed onto the threaded section of the bolt, supported from above on the flange connection structure. The fastener is retightened by axially rotating the bolt and then retightening or rotating the nut along the bolt thread after reaching maximum clamping force. The bolt clamping cylinder used additionally has a position sensor to receive its position signal until it reaches a position axially oriented relative to the axis of the threaded connection. This type of clamping cylinder is primarily used in the assembly of wind turbine equipment. For example, the static foundation frame of a wind turbine is composed of annular sections, each having annular flanges at its ends. At the annular flanges, tower sections are connected into a flange connection structure by means of bolts passing through them.

[0006] In the actual construction of wind turbine components, the flange faces (i.e., the pressing or contact surfaces) of the threaded flanges are not always precisely parallel to each other. Due to insufficient dimensional accuracy in the preceding production process, the annular flange faces often cannot be perfectly aligned, i.e., cannot be perfectly aligned without gaps. This insufficient dimensional accuracy, resulting in gaps, can occur either circumferentially along the annular flange or (though to a lesser extent) radially (i.e., inward or outward). These gaps may also have uneven gap heights and therefore uneven gap sizes. However, avoiding such gaps is crucial for the proper design of threaded connections. Because some areas of the flange remain open after the tightening process, the threaded connection is significantly overloaded in these areas. During wind turbine operation, vibrations in the tower act as additional thread forces on the various connections. Here, the threaded components or bolts located in the open areas receive a significantly higher share of the additional thread forces, potentially causing these components to fail or break before reaching their designed service life.

[0007] For safety reasons, the flange clearance must be closed, which can only be done by tightening the corresponding threaded connection. Also for safety reasons, companies performing this work are required to record the closure of the initial flange clearance, so that it can be traced later.

[0008] A method for connecting annular flanges is known from EP3663034A1, in which an initial, actual curve of the gap size is detected based on multiple individual gap size values ​​between two flanges. In this case, the individual gap size value is the vertical distance between the flange faces at a single measurement location. The detected gap between the annular flanges is closed by means of a clamping process. The flange faces are brought into complete axial contact by means of threaded fasteners during the clamping process, the positions of which are determined and therefore known from the structural side. Position values ​​are determined sequentially for each bolt position. The bolt clamping device, along with a gap detector mounted thereon, is moved from one threaded fastener to the next, and the corresponding gap size value is also measured for the position value at each location. This detection process is continued until the gap at all locations has been measured and detected.

[0009] EP3593939A1 also relates to a method for threading flange connections and for detecting gaps existing between flanges. This is performed using a gap measuring instrument having a motion device and, additionally, a camera facing the gap. The measurement is performed at the positions of the individual bolts. The motion device has a first motion element and a second motion element. These motion elements are constructed in the form of styluses and are supported for measurement purposes on the mutually opposing outer sides of the flanges to be threaded.

[0010] DE102018110482B4, particularly concerning the installation of wind power equipment, addresses the issue of flange compression and explains the importance of closing the remaining clearance between flanges. It describes how to first close the clearance between flanges when clamping a single bolt before applying the force needed to compress the flanges together. The method described in DE102018110482B4 utilizes continuously measured elongation values ​​related to actual bolt elongation, instrument compression occurring on the clamping device, and flange compression. This method is costly in practice because, for example, in addition to the typical elongation characteristics of the bolt, the instrument-specific compression characteristics of the bolt clamping device used must first be determined.

[0011] Furthermore, DE102018110482B4 describes a clamping cylinder for a bolt clamping device. First, a rotatable replacement bushing of the clamping cylinder is screwed onto the free end of the bolt protruding from the nut. For this purpose, the replacement bushing has a corresponding internal thread. The replacement bushing is housed within a hydraulic cylinder housing and surrounded by at least one piston. The piston, as part of a hydraulic piston-cylinder unit, is capable of axially actuating the replacement bushing, thereby extending the threaded bolt. After reaching maximum hydraulic pressure, the nut is then tightened again, i.e., rotated back. Operating parameters actually used during this process, as well as general data concerning thread conditions, can be detected and recorded.

[0012] Furthermore, it is known that threaded fasteners can be individually identified by scanning for unique identifiers present on each threaded fastener. These identifiers can also be recorded, for example, along with the applied tightening force and / or hydraulic tightening pressure. If the nut is re-rotated during longitudinal extension, for example, using a torque wrench, the actual tightening torque used at that time can also be stored as additional datasets. Summary of the Invention

[0013] The object of this invention is to provide a method for tightening threaded fasteners, taking into account that when threading flange connections, irregular gaps with uneven clearance heights often exist between the flanges to be connected. The actual closure of the initially existing gaps should be verifiable in a technically simple manner and traceable thereafter. Furthermore, it should be possible to record the specific details for each individual thread.

[0014] The objective is achieved by a method for threading flange connection structures having the features of claim 1. Preferred designs of the method are defined in the dependent claims.

[0015] The method uses an axially operating, preferably hydraulically actuated, bolt clamping device. This bolt clamping device is positioned such that the housing section surrounding the nut is supported on the outside of the corresponding flange, and furthermore, a tensile force can be applied by the bolt clamping device to the threaded section of the bolt protruding from the nut. The bolt is then gradually extended longitudinally by the bolt clamping device. This is preferably achieved by continuously increasing the tensile force applied by the bolt clamping device until a maximum tensile force is reached.

[0016] This is carried out during this longitudinal extension and until the maximum tensile force is reached:

[0017] - The tensile force can be continuously detected, for example, based on the combination of the separately acting hydraulic pressure and the piston surface of the hydraulic cylinder used in the bolt clamping device;

[0018] - The nut is continuously rotated by means of a torque applied to it, which can be done, for example, by a rotating sleeve coupled to the nut without relative rotation, the rotating sleeve being continuously driven by itself and more precisely by an electric motor and preferably by a constant torque, for example, 50 Nm;

[0019] - Continuous detection of the rotation angle or equivalent value of the rotation angle traversed by the nut during the re-rotation. This can be achieved, for example, by using a rotation angle sensor. This sensor can either directly detect the rotational movement of the nut or the rotating sleeve, or it can detect the equivalent value of the rotation angle, i.e., the movement in the preceding drive element that is mechanically coupled to the motion of the nut.

[0020] In another step, using the rotation angle or equivalent value of such a rotation angle, the geometry characterizing the bolt elongation is derived from the rotation angle or equivalent value in conjunction with the thread geometry of the threaded section. This thread geometry is preferably the pitch, i.e., the length of each thread turn.

[0021] Another step in the method involves constructing a function in which the geometry characterizing the bolt elongation is associated with the tensile force acting on the bolt.

[0022] From a graphical perspective, the function can be designed, for example, such that the horizontal axis represents the detected or calculated tension in the bolt, and the vertical axis represents the amount used for actual bolt extension, i.e., rotation angle, equivalent rotation angle, or equivalent length. The resulting rising line can have segments with linear slopes, nonlinear slopes, or zigzag slopes, depending on the specific threaded connection. The direction of this line and the function segments, as well as their slopes, allow for a clear determination of whether gaps exist in the bolted area of ​​the flange connection structure and whether initially existing gaps can be closed.

[0023] Therefore, based on the constructed function, a comparison operation is performed in the next step. In this comparison operation, the slope of the function is compared with the slope of a predetermined reference curve.

[0024] The reference curve and its derivation can be used, for example, with the results of previous tests or tests on the structure, using flanges, bolts and nuts implemented with the same structure and materials.

[0025] The method according to the invention is accomplished by generating a result report based on the results of the comparison operation. The result report includes information such as whether there are gaps in the flange connection structure within the area of ​​the tightened bolted connection, and whether any initially existing gaps can be closed.

[0026] The resulting report can be sent directly to the assembly personnel responsible for the tightening process, for example. This can occur, for example, by means of an optical display of the control and evaluation unit. The control and evaluation unit monitors the tightening process and preferably automatically coordinates its various steps.

[0027] The resulting report may also, or additionally, be part of a threaded connection record established by the control and evaluation unit for each tightening process. This threaded connection record detects and quantifies all operating parameters actually used for the threading process, as well as general data relating to the thread condition, including identifiers for recognizing the corresponding inserted bolts.

[0028] The basic concept in this invention is to work with fewer parameters, and in particular with parameters that are readily available or can be reliably detected or determined with relatively low technical costs, in order to obtain clear and effective results reports.

[0029] For example, instead of the purely calculated length value detected far above the bolt end according to DE102018110482B4, the rotation angle α, which is technically simple to detect, is used over the threaded nut. This rotation angle α is directly related to the bolt elongation via the thread geometry, or pitch. The advantage of evaluating the rotation angle α or its equivalent is that it eliminates parameters such as the effect of compression at the clamping tool used, compared to existing techniques. This is because, in the method according to the invention, the detected rotation angle α is at most significantly affected by flange compression and the elongation of the threaded connection.

[0030] Here, it is important to continuously detect the rotation angle α during the duration of hydraulic pressure buildup. This can be achieved, for example, by placing an electric drive, preferably using a structurally integrated rotation angle sensor, onto the gear transmission mechanism of the bolt clamping device that drives the nut to rotate the sleeve. The electric drive loads the nut with a predetermined constant torque, whereby the change in the bolt length is directly reflected in the detected rotation angle. The magnitude of the torque applied to the drive mechanism on the nut should be considered in terms of being sufficient to overcome the static friction of the nut without delay, while also not being excessive to avoid the risk of constant jamming.

[0031] In practice, the results of detecting the rotation angle α may be distorted due to the settling process at the beginning of the method. Therefore, it is proposed that the rotation angle or its equivalent value be detected immediately after calibration. The calibration is performed before the step of increasing the longitudinal extension. In the calibration, the bolt clamping device is operated with a calibration tension less than 20% of the maximum tension, and the nut is rotated at this time or immediately thereafter. The torque used in the calibration when rotating the nut is preferably also used with the same intensity and without interruption for subsequent continuous rotation of the nut. Attached Figure Description

[0032] The embodiments of the present invention illustrated with reference to the accompanying drawings are explained in detail below.

[0033] In the attached image:

[0034] Figure 1 The image shows flanges clamped together by means of threaded fasteners, each of which consists of threaded bolts with nuts.

[0035] Figure 2 A longitudinal sectional view of a hydraulically operated bolt clamping device is shown.

[0036] Figure 3 A perspective view of the bolt clamping device is shown, including an electrically driven mechanism mounted on its housing for re-rotating the nut.

[0037] Figure 4 The function curves are shown for two different thread conditions, which correlate the actual bolt elongation with the bolt tension that is simultaneously detected or calculated;

[0038] Figure 5 The function curve for the third type of thread is shown. Detailed Implementation

[0039] Figure 1 A small portion of a large flange connection structure consisting of two annular flanges 1 and 2 is shown. Numerous threaded fasteners are present around the periphery of the flange connection structure, preferably spaced at equal circumferential intervals. Such flange connection structures are used in wind power equipment. For example, the static foundation frame of such equipment is composed of annular sections, each with annular flanges at its ends. Tower sections are connected at the annular flanges to form a rigid flange connection structure by means of threaded fasteners distributed around the periphery and extending perpendicularly to the flange faces.

[0040] In practice, the flange faces 3 and 4 (i.e., the annular extrusion faces of flanges 1 and 2 to be threaded) used for mutual contact are not always constructed precisely parallel to each other, thus resulting in a gap 10. Due to insufficient dimensional accuracy in the preceding production process, the annular flange faces 3 and 4 often cannot be fully abutted, i.e., cannot be abutted without gaps. This insufficient dimensional accuracy leading to the gap 10 between flange faces 3 and 4 can occur either circumferentially along the flange or (though to a lesser extent) radially (i.e., inward or outward). The gap 10 may also have uneven gap height and therefore uneven gap size. To properly design the threaded connection, such gaps must be avoided or closed, and post-processing may be necessary. Because a portion of the relevant flange remains open after the threaded connection is completed, the threaded connection is significantly overloaded in this area. During wind power equipment operation, vibrations in the tower act as additional forces on the threads to each connection. Here, the threaded parts or bolts located in the open area receive a significantly higher share of the threaded additional force, causing these threaded parts to fail or break before reaching their designed service life.

[0041] Each of the threaded fasteners includes a bolt 5, which in this embodiment consists of a longitudinally extending bolt body and a radially widened bolt head, with the bolt head supporting it from below to the outer side 7 of the lower flange 2; and a nut 8 screwed onto the threaded section of the bolt 5, which supports it from above to the outer side 6 of the upper flange 1. Furthermore, in Figure 1 The gap 10 between flange faces 3 and 4, which should actually be in direct pressure contact, is shown. Washers may be additionally provided under the nut 8 and / or under the bolt head. Further washers may also be part of the threaded connection.

[0042] In order to tighten and, in particular, to retighten the threaded connection, the bolt 5 is axially extended by pulling on the threaded section 5A of the bolt that protrudes from the nut 8, and at this time the nut 8 is retightened or rotated.

[0043] to this end, Figure 2 The principle structure of the usable bolt clamping device 11 is shown. This bolt clamping device is a hydraulic clamping cylinder structure and is configured to extend or stretch the threaded connection by applying only axial tensile force. Here, longitudinal extension is achieved by axially pulling on the threaded section 5A of the threaded bolt 5 protruding from the nut 8, mainly the shank and part of the threaded section. The tensile force consumed at this time (which is equivalent to the corresponding hydraulic pressure) can be automatically stored in a recording module and thus used for subsequent inspection purposes. The tensile force is applied to the threaded bolt 5 by activating the hydraulic clamping cylinder, and the nut 8 is tightened by rotation. A replacement bushing 12, centrally located in the cylinder housing 17 of the bolt clamping device 11 and longitudinally movable, is provided with an internal thread 13. Before the clamping process, the replacement bushing 12 is screwed onto the threaded section 5A protruding from the nut 8 using the internal thread 13. For this purpose, the replacement bushing 12 may have a drive polygonal edge 14 on its other end.

[0044] During clamping, hydraulic pressure places the replacement bushing 12 under axial tension, thereby extending the threaded bolt 5. Here, the lower side of the nut 8 disengages, and the nut can rotate with relatively little resistance. This direct rotation is achieved by a rotating sleeve 16 supported in the support tube 18, which has a form-locking structure on its inner side, and in particular a hexagonal structure that form-locks around the nut 8. The rotating sleeve 16 is driven by an electric motor, and if necessary, via a transmission device with an intermediate connection.

[0045] and Figure 2 compared to, Figure 3 The housing of the electric motor 23 that drives the rotating sleeve 16 and the intermediate transmission device are also shown. These components are externally fixed to the housing of the bolt clamping device 11 as structural assemblies.

[0046] A rotation angle sensor 20 for detecting rotational motion is preferably also integrated into a structural assembly consisting of a rotating sleeve 16, an electric motor 23, and, if necessary, an intermediate connecting transmission device. The rotation angle sensor 20 is configured to continuously detect the rotation angle α traversed by the rotating sleeve 16 and thus the threaded nut, or alternatively, an equivalent value of the same rotation angle characterizing the force.

[0047] The hydraulic clamping mechanism is surrounded by a pressure-resistant cylinder housing 17. A downwardly rigid extension of this cylinder housing forms a support tube 18 surrounding the nut 8. This support tube can be integral with the cylinder housing 17. The support tube 18 is open on its lower side and supported on this lower side to the outer side 6 of the flange 1, to which the nut 8 is also supported. A hydraulic interface is provided on the exterior of the cylinder housing 17, and a hydraulic working chamber 21 (… Figure 2 It is connected to an external hydraulic supply device, such as a hydraulic pump, via this hydraulic interface.

[0048] A piston 25 is movably disposed within the cylinder housing 17 (towards the cylinder inner wall). By inputting hydraulic pressure into the hydraulic working chamber 21, the piston 25 is raised. The piston 25 annularly surrounds the replacement bushing 12. The piston has a stepped portion 27 on its inner wall, on which the replacement bushing 12 is supported. If a hydraulic pump inputs pressurized fluid into the working chamber 21, the piston 25 is raised and axially carries the replacement bushing 12, generating a pulling force on the bolt 5.

[0049] The purpose of the method described herein is to not only completely close the gap 10 between flanges 1 and 2 within the scope of the tightening process, but also to identify, indicate, and, if necessary, record this closure in a suitable manner.

[0050] Calibration is performed first. This is because, in practice, the expected results may be distorted due to the settling process at the beginning of the method. Therefore, the rotation angle α, or alternatively, its equivalent value, is checked immediately after the calibration. During this calibration, the hydraulic bolt clamping device 11 uses a force F less than the maximum tension subsequently applied. max 20% of the calibration tension F K Run and then turn nut 8 again. This minimizes settlement in the relevant pressing and clamping areas. Preferably, the torque (e.g., 50 Nm) used during the calibration when turning nut 8 again is applied with the same intensity and without interruption to the subsequent continuous turning of nut 8.

[0051] Following the calibration, the tension F generated by the hydraulic pressure is increased. Z With the help of bolt clamping device 11, the longitudinal extension of bolt 5 is gradually increased until the maximum tensile force F applicable to the specific thread condition is reached. max Until then. This maximum tensile force F max For example, it can be 1000kN to 1500kN. This applies during this longitudinal extension and until the maximum tensile force F is reached. max Until then:

[0052] - Continuous detection of tensile force F Z The nut 8 is rotated continuously by means of the torque applied to it;

[0053] - Continuous detection of the rotation angle α or equivalent value of the rotation angle traversed by the nut 8 during the re-rotation. This is performed using a rotation angle sensor 20. This rotation angle sensor directly detects the rotational movement of the nut 8 or the rotating sleeve 16, or detects the equivalent value of the rotation angle, i.e., the movement in the preceding drive element that is mechanically coupled to the motion of the nut 8.

[0054] In the next step, using the rotation angle α thus detected, the geometric dimension representing the achieved bolt elongation is derived from the rotation angle α and in combination with the thread geometry of bolt 5 at threaded section 5A. This thread geometry is specifically the pitch, i.e., the length of each thread turn.

[0055] according to Figure 4 and Figure 5 Another step of the method involves constructing a function F, in which the geometric magnitude of the bolt elongation is characterized by the increased tensile force F acting on bolt 5. Z The functions are related. The curves are described by rising lines. Here, the horizontal axis represents the increased tensile force F acting on bolt 5. Z The vertical axis represents the rotation angle α detected here as the amount of bolt elongation. Depending on the specific threaded connection condition, the function F has function segments with linear slopes, nonlinear slopes, or zigzag slopes. The specific direction of the function, and in particular the magnitude and arrangement of the slope, determine whether a gap 10 exists in the region of the tightened bolted connection of the flange connection structure and whether the initially existing gap 10 can be closed.

[0056] Figure 4 The function curves are shown for two different threaded connection conditions, where the flange and threaded parts, or bolts, are the same size:

[0057] - A line rising as linearly as possible with a small slope indicates that flanges 1 and 2 are in full-face contact from the initial stage, i.e., from the start of force loading, meaning there is no gap 10. The gradually increasing tensile force F... Z This results in compression of flanges 1 and 2. Here, the rotation angle α depicted on the vertical axis is kept relatively small as the amount of bolt elongation.

[0058] -exist Figure 4 The steeply sloping line shown indicates that in this other case, a gap 10 exists between the relevant flanges 1 and 2, but this gap cannot be closed over the entire duration of the force loading. The rotation angle α plotted on the ordinate is relatively large as the amount of bolt elongation, because a significant amount of deformation work must be provided to reduce the gap.

[0059] Figure 5The curve of function F is shown for other threaded connection conditions, but the flange and bolt dimensions are the same:

[0060] - Firstly, the slope of the line that rises as straight as possible with a relatively large slope indicates that there is an initial gap of 10 between the relevant flanges 1 and 2. Under tensile force F Z As the force increases further, the line bends or its slope decreases, and the line terminates as a function of smaller slope. Therefore, this depicts the case where the initially existing gap 10 is closed during the operation of gradually increasing force.

[0061] - After closure (represented by the bend in the function curve), the tension F Z The further increase in size leads to compression of flanges 1 and 2. Therefore, Figure 5 It also depicts the gap height, which decreases first and then becomes zero in the last third.

[0062] Based on the specifically constructed function F, a comparison operation is performed in the next step. In this comparison operation, the slope of function F and, in particular, the tension F are compared. Z The slope at the end of the increase is compared with the slope of the predetermined reference curve R. For the reference curve R ( Figure 5 ) and its derivation, for example, enabling the use of the results of previous tests or tests on structures when flanges, bolts and nuts are implemented with the same structure and materials.

[0063] Recommendation: The predetermined slope of the reference curve R in the comparison operation includes the tolerance range R. ＋ R － This means that a certain bandwidth is allowed.

[0064] Finally, a result report is generated based on the comparison operation results. The result report includes information such as whether a gap 10 exists in the area of ​​the tightened bolts in the flange connection structure and whether the initially existing gap 10 has been closed.

[0065] The evaluation of the results can lead to conclusions not only about the closure of the gap. If the slope of the function F (mainly in the last third) does not extend uniformly or decrease slowly, but instead increases or occupies zero, this may be a sign that plastic deformation is about to occur in the threaded connection.

[0066] The method also allows for the additional determination of the gap width 10 between flanges 1 and 2. To this end, the bend point in the slope of the function F is determined. Using the values ​​of the rotation angle and the thread geometry of the thread section 5A, the bend point is converted into a length change and / or gap length.

[0067] The clearance height can also be calculated, taking into account the stiffness of flanges 1 and 2, which are determined or already known.

[0068] Furthermore, it is possible to perform all or some steps in the determination, calculation, and evaluation process using self-learning methods and / or artificial intelligence methods. In this way, conclusions can be drawn, for example, regarding irregularities in the clamping process, defects in individual sections of the flange connection structure, or application errors by a particular operator.

[0069] List of reference numerals

[0070] 1 flange

[0071] 2 flanges

[0072] 3 flange faces

[0073] 4 flange faces

[0074] 5 bolts

[0075] 5A thread section

[0076] 6 outer side

[0077] 7 outer side

[0078] 8. Nuts, threaded nuts

[0079] 10 gaps

[0080] 11 Bolt clamping equipment

[0081] 12 Replace the bushing

[0082] 13 Internal Thread

[0083] 14-Drive Multi-Edge

[0084] 16 Rotating Sleeve

[0085] 17 cylinder housing

[0086] 18 support tubes

[0087] 20 Rotation Angle Sensor

[0088] 21 Hydraulic Working Chamber

[0089] 23 electric motors

[0090] 25 piston

[0091] 27 steps

[0092] α rotation angle

[0093] F function

[0094] F K Calibrate tension

[0095] F max Maximum tension

[0096] F Z pull

[0097] R reference curve

[0098] R ＋ Tolerance range

[0099] R － Tolerance range

Claims

1. A method for threading a flange connection structure, the flange connection structure comprising: - The first flange (1) has an outer side (6) and a first flange face (3). - A second flange (2) having an outer side (7) and a second flange face (4) opposite to the first flange face (3). - In the flanges (1, 2), the bolts (5) pass through the openings aligned with each other, the bolts (5) being supported on one side relative to the outside (7) of one of the flanges (2) and on the other side by a nut (8) screwed onto the threaded section (5A) of the bolt body relative to the outside (6) of the other flange (1). The method includes the following steps: - Place an axially operating, preferably hydraulically operated, bolt clamping device (11) onto the bolt (5), such that the housing section of the bolt clamping device (11) surrounding the nut (8) is supported on the outside (6) of the other flange (1) and the tension (F) applied by the bolt clamping device (11) is... Z The force (F) acts on the threaded section (5A) of the nut (8) protruding from the bolt (5), by increasing the tensile force (F) Z The bolt (5) is gradually extended longitudinally by means of the bolt clamping device (11) until the maximum tensile force (F) is reached. max Until the maximum tensile force (F) is reached during the longitudinal extension. max )until: - Continuously detect the tensile force (F) Z The nut (8) is rotated continuously by means of the torque applied to the nut (8); - Continuous detection utilizes the rotation angle (α) or equivalent value of the rotation angle traversed by the nut (8) during the re-rotation. For the detected rotation angle (α) or equivalent value of the rotation angle, the geometric size characterizing the bolt extension is derived from the rotation angle (α) or equivalent value of the rotation angle in combination with the thread geometry of the thread section (5A). - Construct a function (F) that will characterize the geometry of the bolt extension relative to the detected tensile force (F). Z Related to; - Perform a comparison operation that compares the slope of the function (F) with the slope of a predetermined reference curve (R); - Generate result information based on the result of the comparison operation.

2. The method according to claim 1, characterized in that, The resulting information is one of at least three possible results: the first result indicates that the flange faces (3, 4) achieve contact during the longitudinal extension of the bolt (5); the second result indicates that the flange faces (3, 4) do not achieve contact during the longitudinal extension of the bolt (5); and the third result indicates that the flange faces (3, 4) have gapless contact from the beginning during the longitudinal extension of the bolt (5).

3. The method according to claim 1 or 2, characterized in that, The rotation angle (α) or its equivalent value is detected only during calibration immediately before the increase in longitudinal extension, in which the calibration is performed at a value less than the maximum tensile force (F). max 20% of the calibration tension (F) K Operate the bolt clamping device (11) and at this time or then turn the nut (8).

4. The method according to claim 3, characterized in that, The torque used in the calibration when the nut (8) is rotated again is also used with the same intensity and without interruption for continuous rotation of the nut (8).

5. The method according to any one of the preceding claims, characterized in that, The slope of the reference curve (R) in the comparison operation includes a tolerance range (R). ＋ R － ).

6. The method according to claim 1, characterized in that, The method includes an additional determination of the gap width of the gap (10) between the flanges (1, 2), the additional determination having the following method steps: - Determine the inflection point in the slope curve of the function (F) based on the value of the rotation angle (α) or the equivalent value of the rotation angle and the thread geometry of the threaded section (5A); - Convert the inflection point into length change and / or gap length.

7. The method according to claim 1, characterized in that, The method includes an additional calculation of the clearance height of the gap (10), the calculation taking into account the determined or known stiffness of the flange (1, 2).

8. The method according to claim 1, characterized in that, Perform all or individual steps in the determination, calculation, and evaluation process using self-learning methods and / or artificial intelligence methods to draw conclusions, for example, about irregularities in the clamping process, defects in individual sections of the flange connection structure, or application errors at the hands of a particular operator.

9. The method according to any one of the preceding claims, characterized in that, In the comparison operation, the function (F) is mainly compared with the tensile force (F). Z The slope near the end is compared with the slope of the reference curve (R).

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