EP0124340B1

EP0124340B1 - Apparatus for tensioning bolts and studs

Info

Publication number: EP0124340B1
Application number: EP19840302770
Authority: EP
Inventors: Roy Rushbrooke; Geoffrey Firth; Harry David Percival-Smith
Original assignee: Pilgrim Moorside Ltd
Current assignee: Pilgrim Moorside Ltd
Priority date: 1983-04-29
Filing date: 1984-04-25
Publication date: 1989-07-26
Also published as: EP0124340A2; GB8311702D0; DE3479100D1; EP0124340A3

Description

The present invention relates to a hydraulically operable device for applying tension to solid bolts and studs in bolted flange joints, such as for example in joints employed in off-shore structures.
Torque tightening of solid bolts or studs is time consuming and leads, frequently, to galling problems between mating surfaces. There is also a lack of predictability of the load in the torque- tightened bolt.
Hydraulically operable devices have been used to tension solid bolts or studs in flanged joints, for example in steam turbine casings. These comprise a device having a body portion which includes an annular piston surrounding the bolt or stud extending through the flange, and a puller member which is screwed onto a threaded extension of the bolt or stud. The annular piston is urged against the flange by hydraulic fluid under pressure in order to tension the bolt or stud and the nut on the bolt or stud is screwed down against the flange in order to maintain the tension when the hydraulic pressure is removed.
A stud manipulating device incorporating a hydraulically operable device of this type is disclosed in EP-A-0,009,973.
It has also been proposed in GB-A-1,467,234 to use a beam member in which spaced cylindrical pistons and cylinders are used in order to tension a bolt or stud. US-A-3,917,224 US-A-4,012,826 also relate to tensioning devices for screw- threaded fasteners.
Whilst all such tensioning devices involve the "pulling" of the bolt or stud in order to tension it, and do not involve "lifting", they are frequently known in the industry as jacks or jacking devices.
It has been found with such devices that the location of the puller member on the threaded stud is time consuming, and it is not possible to readily ascertain whether sufficient thread engagement has been achieved before the admission of the hydraulic fluid pressure.
A tensioning device is known in accordance with the prior art portion of Claim 1 from US Patent No. 4,020,720 in which the puller member has circumferentially spaced hook portions arranged to engage corresponding circumferentially spaced inclined projections on a washer integral with a nut on the bolt for tensioning the bolt. In addition, the hook portions are arranged to engage a member mounted on the nut to transmit rotation of the puller member to the nut for tightening the nut to maintain the tension.
Whilst this arrangement avoids the time consuming threaded engagement above-described and permits rotation of the nut only when the puller member and washer are engaged, it does not prevent the admission of hydraulic fluid if the puller member and washer are not properly engaged.
The present invention as defined in the Claims is intended to remedy this drawback. It solves the problem of how to ensure the required engagement between the puller member and the stud is obtained before the admission of the hydraulic fluid pressure by the provision of means for controlling the admission of hydraulic fluid pressure to the recess to tension the bolt or stud and a safety interlock device for controlling actuation of the means for controlling the admission of the hydraulic fluid pressure to the recess, the safety interlock device comprising a spring biassed keying member mounted in the puller member for axial movement relative thereto and having location means at one end for engagement with complementary location means on the head of the bolt or stud to permit actuation of the means for controlling the admission of hydraulic fluid pressure to the recess to tension the bolt or stud only when the respective connection means of the puller member and stud are engaged.
The main advantage of the invented apparatus is that the admission of hydraulic fluid before the puller member and stud are properly engaged is prevented by means of the interlock device which prevents actuation of the means controlling the admission of the hydraulic fluid until the proper engagement is obtained whereupon the interlock device is released to permit actuation of the means controlling the admission of the hydraulic fluid.
Preferably the keying member interlocks with an air valve which controls the supply of compressed air to an airdriven hydraulic pump such that the air valve can only be opened when the tensioning device is correctly located on the bolt or stud and the puller member is in engagement with the head of the bolt or stud.
The bayonet type connection may be of the conventional type in which radially extending lugs on the puller member are arranged to engage co-operating lugs on the head of the bolt or stud.
Preferably, however, the bayonet type connection is provided by a plurality of axially aligned sets of intermittent circumferential teeth on the puller member arranged to engage a corresponding plurality of axially aligned sets of intermittent circumferential teeth on the head of the bolt or stud. Such multiple axial connection will withstand heavy axial thrust.
The mating faces of the teeth may extend perpendicular to the axis of the puller member and of the bolt or stud with the other faces having a slope of about 45° to such axes. Alternatively both faces may be set at an angle, for example about 30°, to the horizontal. In this way the teeth mate with each other.
The keying member may, for example, have an elongated rectangular, square or cruciform projection which mates with a matching keyway or recess in the head of the bolt or stud. Alternatively, the keying member may be recessed to mate with a projection on the head of the bolt or stud.
The tensioning device may have a body portion consisting of a plurality of coaching components which together define the annular recess and form the abutment member. However, the body portion may be integral and shaped to define the annular recess between itself and the puller member. The puller member is provided with means for attachment to, or support by, the body portion at the end distant from the bolt or stud. Preferably a solid annular seal of a plastics material such as polyurethane is located at the bottom of the or each annular recess, and serves to prevent the leakage of hydraulic fluid. An annular tyre into which the hydraulic fluid is admitted to effect pressurisation may also be used but in general has insufficient strength for tensioning large bolts or studs.
Embodiments according to the invention will now be described by reference to the accompanying drawings in which:

FIGURE 1 is a view in section of an apparatus according to the present invention for tensioning a stud shown as a fastener for a flanged connection;
FIGURE 2 is a view of the stud used in Figure 1;
FIGURE 3 is a section of a first embodiment of the invention incorporating an air valve system;
FIGURE 4 is a section of a second embodiment of the invention;
FIGURE 5 is a cross-section on the line A-A of Figure 4; and
FIGURE 6 is a section of a third embodiment of the invention.
Figure 1 shows a flanged connection 1 provided with a stud 2 to be tensioned therethrough. The stud 2 is anchored at its lower end by a nut 3 or other suitable means. A further nut 4 is located adjacent the head end for transmitting the clamp load on the flanges.
Figure 2 shows in more detail the head 5 of the stud 2 which is of the bayonet type. The head 5 is shown with two lugs 6, although more may prove desirable. A transverse keyway 7 is located in the head 5.

A jacking device 10 for tensioning the stud 2 has a body portion 11 having an annular recess 12 with parallel axially directed side walls 13. An annular seal 14 is located in the recess 12 between the bottom thereof and an abutment member comprising a piston 15 slidably received in the recess 12. A passage 16 extends through the body portion 11 for the introduction of pressure liquid from the exterior into the recess 12.
The piston 15 is of sufficient length to abut the top face of the flanged connection 1 when located over the stud head 5 and its inner diameter is of such size as to allow free axial movement of the nut 4. A radial slot, not shown, through the wall of the annular piston 15 allows access to the nut 4 for turning it.
Mounted in the piston 15 is a puller member 17 attached to the body portion 11 by screw thread 19. The puller member 17 is shown with internal bayonet type connecting means 18 comprising two lugs 20 which engage with the lugs 6 on the stud head 5. The puller member 17 also incorporates a safety interlock device 21, shown in more detail in Figure 3.
The interlock device 21 shown in Figure 3 comprises a spring biassed keying member 21 in the form of a rod 22 slidably mounted in the puller member 17 and resiliently biassed towards the stud head 5.
The rod 22 has a projection 21 a at the lower end which engages, in use, with the keyway 7 in the stud head 5 only when the jacking device 10 is correctly positioned with the lugs 20 of the puller member 17 in engagement with the lugs 6 on the stud head 5.
At the upper end of the rod 22 is located an air valve 23 fitted with a flanged bush 24 to the upper end of which is attached an operating handle 27 for the air_'vatve 23.
The bush 24 .has a slot 25a which extends generally in the axial direction and a local circumferential slot 25b extending from the axial slot 25a.
The rod 22 has a cross key 26 located to slide in the axial slot 25a whereby, in use, the handle 27 can only be moved in the horizontal plane to operate the air valve 23 when the cross key 26 is aligned with and can slide in the circumferential slot 25b. This can only occur when the projection 21 a on the end of the rod 22 is correctly engaged in the keyway 7 on the stud head 5.
Also shown in Figure 3 are return springs 30 which act between the piston 15 and puller member 17 to restore the position of the jacking device 10 when the hydraulic operating pressure is released.
In operation, when the lugs 20 of the puller member 17 of the jacking device 10 are correctly engaged with the lugs 6 on the stud head 5, the projection 21a on the rod 22. of the keying member 21 mounted in the puller member 17 engages the keyway 7 in the stud head 5 allowing the handle 27 to be operated to open the air valve 23 and thereby start the air operated hydraulic pump (not shown).
Hydraulic fluid at high pressure is admitted to the recess 12 in the body portion 11 via passage 16. The seal 14 serves to prevent leakage of oil from the annular recess 12. The pressure urges the piston 15 against the top face of the flanged connection 1 and the load generated is reacted by the stud 2 through the engagement of the puller member 17 with the stud head 5 thereby stretching the stud 2 within its elastic limit.
With the stud 2 in the stretched state, the nut 4 is turned and nipped tight to maintain the tension by means of a tommy bar (not shown) inserted through the slot in the wall of the piston 15.
The operating handle 27 is then returned to its original position shutting of the air and automatically releasing the hydraulic pressure whereupon the jacking device 10 is restored to its original position under the action of the return springs 30 leaving the stud 2 in tension. The jacking device 10 may then be removed from the stud 2 ready for use on further studs.
Referring to Figures 4 and 5, a second embodiment of a jacking device 40 is shown having a body portion consisting of a piston 41a, 41b joined by a keep plate 42, and an inner ring 43 defining with the piston 41b two annular recesses 44,45 each having a respective annular seal 46,47 located at the bottom.
A nut 48 retains the body portion in place and is fastened by screw threads 49 to a puller member 50 and means for the supply of pressure fluid is provided as described for the first embodiment shown in Figure 3.
The puller member 50 has an internal bayonet type connecting means 51 which consists of a plurality of axially aligned sets of intermittent circumferential teeth 52 which mate with corresponding sets of teeth 53 on the head of a stud 54 to be tensioned. It will be seen that the mating faces of the teeth 52, 53 are perpendicular to the axis of the puller member 50 and of the stud 54 and that the other faces have a 45° slope relative to such axes. The engagement of the teeth 52, 53 is more clearly shown in Figure 5.
The puller member 50 also incorporates a safety interlock device 55 comprising a spring biassed keying member 55 having a square ended projection 56 at one end which engages with a matching square recess in the stud head. The other end of the keying member 55 operates an air valve (not shown) as described for the first embodiment shown in Figure 3.
This jacking device 40 operates in the same way as the jacking device 10 previously described with reference to Figures 1 to 3. The teeth 52 of the puller member 50 engage with the teeth 53 of the stud 54, and it is only when this engagement is correctly achieved that the projection 56 on the keying member 55 engages with the recess 57 in the stud head. This allows the air valve to be operated as in the first embodiment to admit hydraulic fluid at high pressure to the recesses 44, 45 thereby urging the piston 41a, 41b against the flanged connection. The reacting forces lead to stretching of the stud 54 and the nut (not shown) is tightened as described before to maintain the tension on release of the hydraulic pressure.
Referring now to Figure 6, there is shown a third embodiment of jacking device 60 having a body portion 61 with an integral piston and which defines two arinular recesses 62, 63 between itself and a puller member 64.
The puller member 64 is shown with a shoulder 65 which abuts he body portion 61 and dished disc return springs 66 are located above the shoulder 65 by retaining ring 67.
The puller member 64 mounts a safety interlock device as described for the second embodiment shown in Figures 4 and 5 and the engagement between the puller member 64, interlock device and stud to be tensioned is as described for the second embodiment.
In operation, hydraulic fluid is admitted to the recesses 62, 63 via inlet means 68 only after engagement of the projection on the keying member in the recess in the stud head as allowed when the correct engagement between the puller member 64 and the stud head is obtained.
The pressure in the recesses 62,63 urges the body portion 61, with its integral piston, against the top face of the flanged connection. The reaction through the puller member 64 stretches the stud and the nut (not shown) is tightened as described before to maintain the tension on release of the hydraulic pressure.
Jacking devices of the present invention are particularly useful for tensioning solid bolts and studs in flanged connections in offshore structures. Thus, they are particularly useful in oil-well riser pipe connections and in tension legs. Other applications include flanged connections in turbine generators and nuclear power plant.

Claims

1. Apparatus for tensioning a bolt or stud (2;54) for a flanged connection (1) comprises a jacking device (10;40;60) for operative engagement in use with a bolt or stud (2;54) extending through the flanged connection (1), the jacking device (10;40;60) having at least one annular recess (12;44,45;62,63) in which sealing means (14;46,47) is located, an abutment member (15;41a,41b;61) for surrounding the bolt or stud (2;54) and for abutting the adjacent surface of the flanged connection (1), a puller member (17;50;64) mounted in the abutment member (15;41a,41b;61) and having bayonet-type connection means (20;51) for engagement with complementary bayonet-type connection means (6;53) on the bolt or stud (2;54), and inlet means (16;68) for admitting hydraulic fluid pressure to the recess (12;44,45;62,63) to cause relative axial movement between the abutment member (15;41a,41b;61) and puller member (17;50;64) for tensioning the bolt or stud (2;54) characterised in that there is provided means (23) for controlling the admission of hydraulic fluid pressure to the recess (12;44,45;62,63) to tension the bolt or stud (2;54) and a safety interlock device (21;55) for controlling actuation of the means (23) for controlling the admission of hydraulic fluid pressure to the recess (12;44,45;62,63), the safety interlock device (21;55) comprising a spring biassed keying member (21;55) mounted in the puller member (17;50;64) for axial movement relative thereto and having location means (21a;56) at one end for engagement with complementary location means (7;57) on the head (5) of the bolt or stud (2;54) to permit actuation of the means (23) for controlling the admission of hydraulic fluid pressure to the recess (12;44,45;62,63) to tension the bolt or stud (2;54) only when the respective connection means (20,6;51,53) are engaged.

2. Apparatus according to Claim 1 characterised in that the means (23) for controlling the admission of hydraulic fluid to the recess (12;44,45;62;63) comprises an air valve (23) operable by a handle (27) connected to a bush (24) mounted on the keying member (21) and which can be turned by the handle (27) to operate the air valve (23) only when the respective connection means (20,6) are engaged.

3. Apparatus according to Claim 2 characterised in that the keying member (21) comprises a rod (22) extending through the bush (24) with the rod (22) having a cross key (26) engaging in an axial slot (25a) formed in the bush (24) and the cross key (26) being engageable in a lateral slot (25b) extending from the axial slot (25a) to permit turning of the bush (24) by the handle (27) only when the respective connection means (20,6) are engaged.

4. Apparatus according to any one of the preceding Claims characterised in that the respective connection means (20,6) comprise opposed radially inwardly directed lugs (20) on the puller member (17) arranged to engage radially outwardly extending lugs (6) on the head (5) of the bolt or stud (2).

5. Apparatus according to any one of Claims 1 to 3 characterised in that the respective connection means (51,53) comprise a plurality of axially aligned sets of intermittent circumferentially spaced teeth (52) on the puller member (50,64) arranged to engage a corresponding plurality of axially aligned sets of intermittent circumferentially spaced teeth (53) on the head of the bolt or stud (54).

6. Apparatus according to Claim 5 characterised in that one face of the teeth (52,53) extends substantially normal to the axis respectively of the puller member (50,64) or of the bolt or stud (54), and the other face of the teeth (52,53) extends inclined to such axes at 45°.

7. Apparatus according to any one of the preceding Claims characterised in that the respective location means (21a,7;56,57) comprise a projection (21a;56) on the end of the keying member (21;55) arranged to engage a complementary recess (7;57) in the head (5) of the bolt or stud (2,54).

8. Apparatus according to any one of the preceding Claims characterised in that the keying member (21 ;55) is resiliently biassed towards the head (5) of the bolt or stud (2;54) whereby the respective location means (21a,7;56,57) are engageable automatically when the respective connection means (20,6;51;53) are engaged.

9. Apparatus according to any one of the preceding Claims characterised in that return spring means (30;66) acts between the abutment member (15;41a,41b;61) and the puller member (17;50;64) to restore the position of the jacking device (10;40;60) following relief of the hydraulic fluid pressure admitted to the recess (12;44,45;62,63).

10. Apparatus according to any one of the preceding Claims characterised in that the recess (12) is formed in a body portion (11) and the abutment member (15) comprises a piston (15) slidably received in the recess (12).