The object of the invention is a method for tightening a high-pressure pipe connection to a correct tightness, the high-pressure pipe connection including a connector body, a fastening means arranged on the pipe to be connected, and a connector nut, which nut is mounted behind the fastening means and can be threaded to the connector body in such a way that the fastening means, together with the pipe to be connected, will move towards the connector body, settling by its sealing face into sealing contact with the counter-sealing face of the connector body on the correct tightening level of the nut. A further object of the invention is a device for implementing the method.

The greatest challenge in successful hydraulics installation is to be able to install the pipelines in such a way that there are no leakages. Insufficient knowledge, skills or equipment, or a lack of appropriate installation equipment, may cause leakages in systems and thus even their breakdown. The reason why this happens is often the incorrect implementation of a cutting ring connection complying, for example, with the standard DIN 2353. The components of a DIN 2353 connection are a tube, a cutting ring, a nut and a connector body.

There has arisen a need for a tool which is a portable and reliable, as well as an easy to use final tightening wrench for hydraulic connectors, and which guarantees the correct tightness and thus tight connections. When using a cutting ring seal, the cutting ring seal must be pre-tightened to the correct position on the pipe. The final tightening is carried out on the basis of a degree value, which is manufacturer- specific.

[Every connector manufacturer has their own final tightening values depending on the connector construction, but most are tightened to so-called finger tightness and after that finally tightened by 90 degrees, whereupon the connection should be correctly made. Here lies a considerable risk of over-tightening the connection, especially with small and light-weight tubes, and thus of losing the alignment of the coning angles of the connection. There is, therefore, an obvious safety risk and, above all, it will only appear some time after the installation and pressure testing, when an unstable load or manual external vibration typical in hydraulics has been exerted on the system. Another, and humanly important reason, for developing the devices is physical strain, especially with the largest heavyweight connections, where the use of force is an essential part of the working method.

Tightening by current methods does not provide reliable documentation of the torque used for the tightening. In present connections are used various pipe and connector materials, often intermixed, small connections are over-tightened, large ones are tightened insufficiently. This results in delayed or interrupted processes, maintenance shutdowns, shorter life cycles due to over-tightening, replacement needs. At present, tightening requires a highly skilled mechanic.

The aim of the present invention is to provide a solution by means of which the problems of the prior art are avoided and a reliable and documented connection is accomplished. The user of the final tightening device according to the invention does not have to be highly trained.

To achieve this aim, the method according to the invention is characterised in that in the method is used a device which tightens the nut to a specific threshold value of the torque and once the threshold value has been reached, the device continues, either automatically or following a separate oommand by the user, the tightening by a predetermined degree value to the desired final tightness of the nut. The device according to the invention is in turn characterised in that the device comprises a tightening head with a sleeve part fitted to grip the connector nut in a form-locked manner, a torsion means for turning the sleeve part up to a specific threshold value of the torque and after that by a specific degree value to the correct final tightening value of the connector nut, the device comprising means for verifying the threshold value of the torque having been reached, and means for carrying out the final tight- ening by a determined degree value.

By means of the solution according to the invention, reliable implementation of connections is ensured, which results in savings both at the installation stage and dur- ing the life cycle through avoiding costs incurred by the leaking or breakdown of connections.

The invention is described in greater detail in the following, with reference to the accompanying drawings, wherein: shows a diagrammatic isometric exemplary view of an embodiment of a device usable in the method according to the invention, Figure 2 shows the device of Figure 1 , as seen from another direction, with the protective part of the tightening head removed,

Figure 3 shows the device of Figure 1 as seen from yet another direction, with the protective part of the tightening head removed, and

Figures 4-5 show different connector types to which the invention can be applied.

The method and device according to the invention are applicable for use in conjunction with various pre-tightened connections, such as connections provided with a cutting ring seal and cone connections. Figures 4 to 5 show diagrammatic views in principle of such known connection types. Figure 4 shows a connector type according to standard DI 2353, comprising a connector body 14, a connector nut 15 and a cutting ring seal 16 on the pipe 20 to be connected. The connector nut 15 is behind the cutting ring seal 16, as seen from the connected end of the pipe 20. The cutting ring seal forms a 24° angle with respect to the longitudinal direction of the pipe 20. Figure 5 shows a cone connection structure comprising a connector body 14, a connector nut 15, a conical collar part 18 at a 37° angle formed at the end of the pipe 20 to be connected, and a support part 17 which presses the collar part tightly against the connector body.

Figures 1 to 3 show diagrammatic views in principle of an embodiment of a device applicable for carrying out the method according to the invention. The device 1 comprises a body part 3 and a tightening head 2. The body part 3 comprises a display unit 5 and a control panel buttons 6 as well as a battery 4 acting as a power supply. The tightening head 2 is provided with a protective casing 7 which is omitted from Figures 2 and 3 to illustrate the details of the tightening head. The tightening head 2 comprises an auxiliary body 19 and, connected to it, a locking means 8 arranged at a lateral distance, by means of which the device can be locked to the connector body 14. In the auxiliary body 19 is provided a sleeve part 9 extending through the auxiliary body, corresponding to the connector nut 15, the sleeve part preferably being replaceable for the device to be used in connection with pipe connections of different sizes. In the sleeve part 9 is formed a longitudinal slot 21 by means of which the sleeve part can be passed onto the connector nut 15 and pipe 20. On the other side of the auxiliary body 19, over the sleeve part 9, is positioned a torsion means 10 which is operated by the power transmission means 12. The torsion means 10 has helical gearing, which turns the sleeve part 9 with counter- gearing, one or more tooth gaps at a time, and when turning back, the torsion means rises upwards and returns to the starting point. The torsion means 10 acts as a ratchet, whereby the sleeve part 9 is only able to rotate in one direction. The torque is generated by the power transmission means 12 which are reciprocated. With a small reciprocating movement is achieved even turning of the nut, whereby there is mostly only kinetic friction in the threading of the nut. The power transmission means may be mechanical, hydraulic, belt-driven or other power transmission means known as such, the power supply of which is a battery-operated electric motor or other suitable power supply, such as an electrically operated hydraulic pump. After the torsion means 10, a slide ring 11 is placed over the sleeve 9, the slide ring acting as a bearing means between the torsion means 10 and the spring 13 pressing it against the sleeve part 9. The device preferably includes the means required for wireless data transfer and/ or a separate memory card and/ or a fixed memory.

When using the device, an electrically correct connector size is first selected and the sleeve part is placed over the connector nut 15 and the device is then fixed to the connector body 14 with the accompanying locking key 8. This locking is necessary in order that the torque is not exerted on the pipeline, but that the torque is used for the work it is intended for, that is, for the final tightening of the connector, that is, a cutting ring connector, a flange connector or something in between, for example a cone connector. From the device's intelligence-controlled connector menu is selected, for example, a 22 mm connector complying with DIN 2353 from the file stored in the apparatus' memory. The apparatus is given a starting command with a button and the apparatus then rotates the connector nut until it reaches a specific threshold value which may be, for example, approximately 25 Nm, which is followed by final tightening to a value of, for example, approximately 150 Nm. The threshold value torque is experimental and statistical following testing. The user must accept the starting of the final tightening with a button, or alternatively, the device may continue automatically to the final tightening operation by a timer connection. After this, the apparatus rotates the connector nut by the set turn degree, for example, by 90 degrees. This can be monitored, for example, by means of a degree sensor which indicates the reaching of the desired degree and at the same time gives the control unit of the devioe a signal for finishing the tightening operation. After the operation, a ready light is lit on the display and the apparatus loosens the attachment either automati- cally or manually in such a way that it can be lifted off. The connection is thus finally tightened correctly and just as the connector manufacturer had intended. The reaching of the degree can also be monitored, for example, by calculating how many tooth gaps have been turned after reaching the threshold value, when it is known how many degrees one tooth gap equals. In the apparatus can be included an additional function with paint or a puncher, which indicates that the connection has already been tightened and thus preliminarily inspected before pressure testing.

Recording is preferably carried out through a wlan or other port in the apparatus on a computer with a monitoring program on all connectors of the object installed. This function guarantees the safety of the pipelines at the entire installation site since all connections are provided with markings of their appropriate and designed tightening. Of every previously unplanned site can also be taken out and recorded an output. The recording can also be done on a memory card connected to the apparatus. In the apparatus can also be entered advance information on all connections at the installation site, for example 12 x 22L connections and 20 x 12S connections. The apparatus then has the set values ready for operation and thus communication can be interactive with the monitoring or design program. By means of the device according to the invention can be implemented the measurement of the desired threshold value torque, and once this has been reached, the operation can be continued based on a degree value, that is, as a sum of two different measuring systems in such a way that the maximum torque is, however, not exceeded.

List of reference numerals

1 connector nut tightening device

2 tightening head

3 body part

4 battery

5 display unit

6 control panel buttons

7 protective casing of tightening head

8 locking key for locking to the connector body 9 sleeve part

10 torsion means

11 slide ring

12 power transmission means

13 spring

14 connector body

15 connector nut

16 cutting ring seal

17 support part

18 collar part

19 auxiliary body

20 pipe to be connected

21 longitudinal slot of sleeve part