GB2158761A - Bearing replacement apparatus - Google Patents

Abstract

A bearing replacement apparatus comprises a cage (6) carrying a hydraulic ram (10). The ram (10) can be releasably attached to a bearing (5) to draw it from a housing (3) to which the cage (6) is releasably secured. The apparatus and method of using the apparatus are particularly useful when replacing an in situ bearing underwater. The joint (2,3) carrying the in situ bearing is supported by temporary bearing segments while the in situ bearing is being replaced. Actuation of the apparatus is by means of hydraulic fluid and manually operable levers obviating the need for precise movements to be made by divers underwater. <IMAGE>

Description

SPECIFiCATION Bearing replacement apparatus This invention is concerned with replacement of bearings in underwater situations, in a reasonable time utilising apparatus that can be operated by divers who can exert very little force and have a limited ability to execute accurate movements.

Bearings that may be in need of replacement are provided in joints to be found at the foot of an articulated column extending from the water bed to the surface, the joint serving to connect the column to a base anchored to the water bed. One such bearing is disclosed in our British Patent Application No. 8317233.

It is important when replacing such bearings to leave the joints adequately supported, and, further to enable them to carry load and execute movement to reduce to a minimum disruption to operation of the column while the bearings are being replaced.

According to the present invention there is provided a bearing replacement apparatus, for use in replacing an in situ bearing disposed in a bearing housing, the apparatus comprising: a framework having first attachment means whereby the framework can be releasably attached to the housing; a piston and cylinder arrangement carried by the framework and having second attachmentmeans whereby the piston and cylinder arrangement may be releasably attached to the bearing; and means for actuating the piston and cylinder arrangement to withdraw the bearing attached thereto from the housing whereby the framework and the removed bearing can be moved clear of the housing and subsequently a replacement bearing attached to the piston and cylinder arrangement can be fitted in the housing.

Preferably, the apparatus further comprises: locking means associated with the piston and cylinder arrangement and capable of locking the piston with respect to the cylinder; and a rotatable plate, carried by the piston and cylinder arrangement, which plate carries the second attachment means and whose rotational movement enables the second attachment means to be located with respect to the bearing.

The actuating means may comprise hydraulic fluid, supplied, via supply lines, to the piston and cylinder arrangement. Further supply lines may be arranged to enable hydraulic fluid to be supplied respectively to an inner surface of the bearing housing and to the first and second attachment means.

The invention also provides a method of replacing an in situ bearing disposed in a housing, the method comprising: attaching a framework, carrying a piston and cylinder arrangement, to the housing; actuating the piston and cylinder arrangement first so as to cause the attachment means carried thereby to engage the in situ bearing and then so as to withdraw the in situ bearing from the housing; releasing the framework from the housing so that the bearing now carried thereby can be moved clear from the housing; replacing the bearing in the framework; reattaching the framework carrying the replacement bearing to the housing; actuating the piston and cylinder arrangement to cause the replacement bearing, attached to the attachment means, to move into the housing; releasing the replacement bearing from the piston and cylinder arrangement; and releasing the framework from the housing.

Preferably, the method further comprises, after actuating the piston and cylinder arrangement to cause the replacement bearing to move into the housing, actuating hydraulic fluid supply means to cause hydraulic fluid to be supplied to the bearing to operate a securing arrangement of the bearing to secure the bearing in the housing.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagram of a bearing replacement apparatus shown located at a bearing to be replaced; Figure 2 shows part of the apparatus of Figure 1 in more detail, with a bearing attached to a cage of the apparatus; Figure 3 shows the apparatus of Figure 2 but with the bearing placed in its working position; Figure 4 is an enlarged view of the bearing in the pos;tion shown in Figure 3; Figure 5 is a pictorial sketch illustrating the use of the bearing replacement apparatus; and Figure 6 is a more detailed view of part of the sketch of Figure 5.

The bearing replacement apparatus illustrated in the Figures is for replacing bearings of a joint at the foo.: o; an articulated column extending from the water bed to the surface in a deep water environment, the joint serving to connect the column to a base anchored to the water bed.

Referring first to Figure 1, the joint between the base 1 and a ballast tank 7 which is at the foot of the column 18 (Figures 5 and 6) includes opposed forks 2 and 3 extending respectively, upwardly from the base 1 and downwardly from the tank 7.

Between these forks 2, 3 there is supported, at a bearing housed in each of the forks, a cruciform 4.

The bearing replacement apparatus can be utilised to replace any one (or all four in turn) of these bearings.

Replacement of the bearing housed in the righthand fork 3 is illustrated in the Figures and in Figure 1 the joint is shown with the bearing removed and the cruiform supported by temporary bearing segments, such as those described in British Patent Application No. 8317233.

A cage 6, which has been lowered from the surface, is attached to the fork 3, and carries the replacement bearing (generally designated by reference numeral 5). The ballast tank 7 is provided with rails 8 along which the cage 6 can run by means of wheels 9. The fork 3 has connecting posts 3a used to locate the cage 6 with respect to the fork 3. The cage 6 comprises a rigid structure having a centrally mounted ram 10 in the form of a hydraulic cylinder capable of being locked in any position of its stroke. Typical characteristics of this ram 10 are: cylinder, outside diameter 533.4 mm, bore diameter 444.5 mm, rod diameter 203.2 mm, stroke 1346.2 mm, lock capacity 5.34 megaNewtons, operating pressure 34.5 megaPascalls, test pressure 51.7 megaPascalls.

Figure 2 shows part of the apparatus of Figure 1 in more detail, again with the bearing 5 carried by the cage 6. Figure 3 shows the bearing 5 in its normal working position in the fork 3 and supporting the cruciform 4. The operation of the bearing replacement apparatus will be described in more detail hereinafter with reference to Figures 2 and 3.

Figure 4 is a more detailed diagram showing the bearing in the position as shown in Figure 3. The bearing 5 is provided with locking dogs 51 and 52 having teeth which cooperate with teeth 53 on the fork 3 and teeth 54 on the cruciform 4 respectively.

Operation of the locking dogs 51 and 52 is controlled by respective wedge rings 55 and 56. Quick acting hydraulic couplings P4 and P1 enable hydrualic fluid to be supplied to control the operation of the wedge rings 55 and 56 respectively, while bolts B1 and B2 enable the wedge rings 56 and 55 respectively to be held in positions wherein the teeth of the locking dogs 51 and 52 engage the teeth 53 of the fork 3 and teeth 54 of the cruciform 4 respectively. Levers 57 and 58 control the operation of locking shims 59 and 60 respectively. Operation of hydraulic pistons 61 and 62 is controlled by hydraulic fluid supplied through quick acting hydraulic couplings P3 and P2 respectively. Reference numerals 63 and 64 designate manifolds, and reference numerals 65 and 66 designate cap screws.

Hydraulic fluid may be supplied to an outer, tapered surface 67 of the cruciform 4 by way of quick acting hydraulic couplings P5. Similarly; hydraulic fluid may be supplied to a tapered sleeve 68 between the inner surface of the fork 3 forming the bearing housing and the outer race of the bearing 5 by means of hydraulic couplings P6 and P7.

While it will be appreciated that the size of the bearing and cruciform may vary considerably, the following dimensions are given by way of example: nominal diameter of the bearing, a, = 1730 mm; outer diameter of the bearing, b, = 1694 mm; inner diameter of the fork 3, c, = 1799 mm; width of the shim 60, d, = 100 mm.

The ram 10 is fixed to the replacement bearing 5 by means of a four point guide post fixing 23 in the form of a revolving plate and having connectors 19 (Figure 3) arranged to cooperate with guide posts 11 on the bearing 5. The centre lines of both bearing and ram will coincide throughout a bearing replacement operation, by virtue of connectors 25 of the cage 6 being locked onto guide posts 3a on the fork 3. The cage 6 carries hydrualic distribution hoses, control valves and their associated interlocks to provide hydraulic fluid under pressure to couplings P1 to P12, couplings P1 to P7 being connectors to the bearing, couplings P8, P9 and PlO being connections to the ram 10, and couplings P11 and P12 being connections for connecting the cage 6 to the bearing 5 and fork 3 respectively.

Figures 5 and 6 illustrate auxiliary equipment associated with the bearing replacement apparatus.

A landing platform 12 is provided on the base 1, on to which landing platform 12 the cage 6 descends. Sheaves 13a and 13b enable tthe ascent and descent of the cage 6 to be effected by way of wires 14. These wires are wound on a constant tension which 15 at a surface vessel 17 and a winch 16 at the top of the column 18. The constant tension winch may be capable of carrying a safe working load of 25 tonnes and the winch 16 should be capable of a safe working load of 10 tonnes.

In addition to the winch 15, the surface service vessel 17 also carries other equipment for use with the system, in particular hydrualic hoses for supplying hydraulic fluid from the surface service vessel 17 to the cage 6 when on the sea bed. The fluid is supplied from two air driven hydraulic pumps capable of supplying hydraulic fluid (glycerinel water) at pressures of 7,000 psi (48.2 x 103 Nim2) and 15,000 psi (103.4 x103 Nim2). The pumps are mounted on a 30 gallon (1.36 x 105 cm3) reservoir complete with filters, filler, air breather, fluid level gauge, drain plugs, shut-off valves, air filteri lubricator, gauges and necessary pipework.

The air requirement is 100 cu. ft. per minute (4.7 x 104cm3/s) at 100 psi (6.89 x 105 Elm2. Two hoses for connection to couplings on the cage 6 are capable of 21,500 psi (1.48 x 105 N/m2) and have snap coupiings at each end.

One method of using the apparatus described above to replace an existing bearing will now be described. The service vessel 17 is brought alongside the column 18 (Figures 5) at whose base the bearing is situated. The rails 8, landing platform 12 and the existing bearing and its housing are cleaned by divers using water jet cleaning equipment, and the replacement bearing is also cleaned.

Similarly, the couplings P1 to P7 and P11 and P12 to which the hydraulic distribution hoses will be attached, and the guide posts 11 of the inner race of the in situ bearing 5 which accept the connectors 19, are cleaned of any marine growth which may hinder bearing removal. Further any elastomeric grease boxes are removed to uncover a front face of the bearing.

Temporary bearing segments are located behind the in situ bearing, that is, on the side remote from where the cage 6 is to be connected to the fork 3, these temporary segments being positioned, by hydraulic wrenches, to ensure that the centre line of the cruciform 4 and the fork 3 housing the bearing will remain coincident after the in situ bearing has been removed. Since it is only possible to attach the cage 6 to the fork 3, and the ram 10 to the in situ bearing 5, when the centre line of the cruci form 4 and the fork 3 are coincident the operation of positioning the bearing segments can be utilised, if necessary, to bring these centre lines into coincidence if such is not already the case (for example, because the cruciform centre line has shifted due to failure of the in situ bearing). The cage 6, without any bearing, is lowered as shown in Figure 5.The illustrated method enables the service vessel 17 to remain some distance from the articulating column 18 thus providing reasonable safety. The cage is suspended on the sheaves 13a.

These sheaves 13a and the cage 6 are in turn suspended from the wire 14 which runs from the constant tension winch 15. A wire is run from the winch 16 on the underside of the deck of the column 18 around the return sheave 13b bolted to the base 1 and back to the cage 6 and its associated sheaves 13a. With this arrangement, the cage 6 and associated sheaves 13a may be lowered diagonally from the service vessel 17 to a position vertically above the landing platform 12 provided on the base 1. During this lowering phase, the constant tension winch 15 is set to an allowable tension figure of approximately 15 tonnes and the winch 16 is used to pull the empty cage 6 to its position above the landing platform 12.At this point the platform winch 15 is stopped and the remainder of the cage lowering operation is done by a diver operating a tirfor 20 associated with the empty cage 6 and its sheaves 13a. This enables a gentle lowering of the cage 6 on to the landing platform 12 to be effected The wire of the constant tension winch 15 is then removed from the cage 6 and associated sheaves 13a. The wire from the winch 16 on the underside of the column deck is also removed from around the return sheave 13b and reattached to the cage 6 and its sheave arrangement 13a. A second tirfor 21 is now attached (using a sling) to the fork 3 directly inboard of the landing platform 12. This tirfor 21 with its attached wire 22 is used to pull the cage 6 onto the rails 8 beneath the column ballast tank 7.

As mentioned earlier, the operation of the bearing replacement system is being described herein with reference to one of the forks 3 extending downwardly from the tank 7. If instead bearing replacement were to be carried out at one of the forks 2 extending upwardly from the base 1, then the cage 6 would be lowered in an inverted position such that once on the landing platform 12 it may be pulled, using a similar tirfor, directly onto additional rails running across the base 1. In any event, the tirfor 20 associated with the cage sheaves 13a is used to lift (or lower) the cage 6 by an appropriate amount whilst at the same time the tirfor 21 providing horizontal pull is operated. Once the cage wheels 9 engage the rails onto the tank 7 or base 1 the wire to the winch 16 and the sheave arrangement 13a is disconnected from the cage 6.

The horizontal pull from the tirfor 21 is then continued until the cage 6 is located on the connecting posts 3a of the appropriate fork. Hydraulic fluid is applied to port P12 to open the connectors 25 receiving connecting points 3a.

Referring again, specifically, to the fork 3, the tirfor 21 continues to draw the cage 6 towards the fork 3, until the cage guide post connectors 25 engage the fork guide posts 3a, and pressure at port P12 is then released to close the connectors 25.

The cage 6 is thus firmly locked on to the fork 3 and the sequence necessary to remove the in situ bearing from its housing can commence. Divers attach hydraulic hoses to pressure connectors P1 to P7. Pressure connectors P8 to P12 are already connected to a hydraulic fluid source as part of the existing hydraulic connections of the cage assembly.

The ram 10 is now moved forward slowly by applying pressure at P10 gradually with pressure applied at P8 to hold the lock of the ram released.

Pressure P11 is also applied now to open the guide post connectors 19 ready for engaging the guide posts 11 on the inner race of the in situ bearing 5, the revolving plate 23 at the head of the ram 10 carrying the conectors 19 being adjusted by divers to locate the guide post connectors 19 centrally over the guide posts 11. Once the ram 10 is connected to the bearing, by releasing pressure P11, pressure P8 is removed to reengage the ram lock.

Bolts B1 and B2 (Figure 4) are loosened to enable the locking dogs 51, 52 on the inner and outer races of the bearing 5 to be withdrawn from the teeth in the cruciform 4 and the bearing housing 68 respectively.

Fluid is introduced at P6 and P7 to release the grip and friction of the bearing 5 in the housing 68.

Fluid is then introduced at P5 which causes the bearing to be urged outwards, it being prevented from doing so at this stage by the locked ram 10.

The ram lock is then released slowly by applying pressure at P8 so that the bearing extrudes out, towards the cage 6, due to the tapered surface 67 of the cruciform.

if the bearing fails to move out, the fluid introduced at parts P5 to P7 can be pulsated simultaneously to assist release of the bearing.

By applying pressures at P8 and P9, the cylinder 10 and bearing 5 are withdrawn until there is a distance of approximately 0.25 m between the bearing 5 and the end of the cruciform 4. The pressures at P8 and P9 respectively are then released, at which stage the bearing 5 becomes locked within the cage 6.

Pressure is then applied at P12 to allow the cage 6 to be removed from the fork 3, and the cage 6 and the removed bearing 5 to be returned to the service vessel 17 by the reverse of the process described with reference to Figures 5 and 6.

Once the bearing has been removed divers clean and inspect the surface 67, 68 on the cruciform 4 and the fork 3 to check for corrosion and marking.

These surfaces should be clean bright metal in the area of the bearing seats; if severe pitting or corrosion is detected then restorative action is taken, which may involve welding and grinding underwater.

When the surfaces 67, 68 are clean and prepared in readiness for a replacement bearing, the cage 6 carrying the replacement bearing is lowered to the seabed and positioned and latched on to the fork 3 as described hereinbefore, the replacement bearing having been provided on the service vessel 17 with hydraulic hoses attached to couplings P1, P2 and P5.

The replacement bearing 5 is driven forward on the cylinder 10 until its innermost spigot face 69 (Figure 2) meets the very end of the cruciform 4.

Hydraulic cylinders or piston rings 61, 62 are retracted at this point. Pressure at P8 is released to lock the ram 10 as described earlier.

Control valves are now operated by divers to carry out the following sequence of operations to fix the replacement bearing in its final position: a) pressure is introduced at P1 to engage the inner locking dogs 52; b) bolts B1 are locked to retain the piston ring 56 in a fixed position; c) high pressure is applied at P5 and low pressure at P2 to urge the replacement bearing forward until the locking shim 60 can be engaged by operating the lever 58; d) pressure at P2 is then released, pressure at P5 being maintained until pressure at P2 has reached zero and then being released - this creates an interference fit between the cruciform 4 and the inner race of the bearing 5, at the same time providing a preload between the locking dogs 52 on the cruciform 4 and the bearing 5 itself;; e) the divers remove the hoses from ports P1, P2 and P5 and attached them to ports P4, P3 and P6 to enable pressure to be applied at ports P3 and P6, until the shim 59 can be fully engaged by operating the lever 57, while P4 is vented; f) pressure at P3 is released once the shim 59 is engaged maintaining pressure at P6 until pressure at P3 has reached zero, pressure at P6 then being released-at this point the tapered sleeve 68 around the outer race of the bearing has an interference fit with the outer race of the bearing and the bearing housing; g) P4 is now pressurised to actuate the locking dogs 51 which provide a "back-up" retention of the bearing in its housing; h) bolts B2 are then tightened to prevent the locking ring 51 from running back; i) pressures are now released and the hoses detached from ports P1 to P7; and j) pressure at P11 is activated to release the ram 10 from the bearing 5, pressures at P8 and P9 are activated to release the ram 10 and withdraw it back into the cage 6 and pressure at P12 is then applied to release the cage 6 from the bearing housing 3 so that the cage 6 can be removed to the surface as described earlier.

The temporary bearing segments are removed by the divers using hydraulic tools, and finally the hydraulic ports P1 to P7 are capped, any rigging wires removed and if necessary, grease is injected into cavities left after the bearing insertion.

Finally, flexible elastomeric oil or grease boxes can be fitted over both sides of the fork 3 to cover the outside face of the new bearing and oil or grease is injected to displace all the seawater.

Claims (14)

1. A bearing replacement apparatus, for use in replacing an in situ bearing disposed in a bearing housing, the apparatus comprising: a framework having first attachment means whereby the framework can be releasably attached to the housing; a piston and cylinder arrangement carried by the framework and having second attachment means whereby the piston and cylinder arrangement may be releasably attached to the bearing; and means for actuating the piston and cylinder arrangement to withdraw the bearing attached thereto from the housing whereby the framework and the removed bearing can be moved clear of the housing and subsequently a replacement bearing attached to the piston and cylinder arrangement can be fitted in the housing.

2. An apparatus according to claim 1, further comprising: locking means associated with the piston and cylinder arrangement and capable of locking the piston with respect to the cylinder; and a rotatable plate carried by the piston and cylinder arrangement, which plate carries the second attachment means and whose rotational movement enables the second attachment means to be located with respect to the bearing.

3. an apparatus according to claim 1 or 2, wherein the actuating means is arranged for operation by hydraulic fluid supplied via first supply lines to the piston and cylinder arrangement.

4. an apparatus according to claim 1, 2 or 3, wherein second supply lines are arranged for supplying hydraulic fluid respectively to the first and second attachment means to operate said attachment means.

5. An apparatus according to any preceding claim, the bearing housing being defined by the inner surface of an outer member and the outer surface of an inner member, the apparatus further comprising: a securing arrangement provided with means for engaging respectively said inner and outer surfaces to secure the bearing in the housing; third hydraulic fluid supply lines by means of which hydraulic fluid may be supplied to the engaging means whereby, with the bearing fitted in the housing, the engaging means are actuated to secure the bearing within the housing, and, when the bearing is to be withdrawn from the housing, the engaging means are released.

6. An apparatus according to claim 5, further comprising fourth supply lines by means of which hydraulic fluid may be supplied respectively to said inner and outer surfaces of the bearing housing to aid movement of the bearing relative to the housing.

7. An apparatus as claimed in claim 6, further comprising means for supplying pulsed hydraulic fluid to the inner and outer surfaces to said said relative movement.

8. An apparatus according to claim 5, 6 or 7, further comprising a manually operable spacing means operable to space the bearing from the securing arrangement when the bearing is in the housing.

9. A bearing replacement apparatus substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 of the accompanying drawings.

10. Equipment for replacing an in situ bearing disposed in a bearing housing underwater comprising: a bearing replacement apparatus as claimed in any of claims 1 to 9; means for transferring the apparatus from and to a vessel on the surface of the water to and from respectively a base carrying the bearing housing; guide means for guiding the framework along the base to the housing; and hydraulic fluid supply means for supplying hydraulic fluid to the first, second, third and fourth supply lines.

11. Equipment for replacing a bearing underwater substantially as herein before described with reference to, and as shown in, the accompanying drawings.

12. A method of replacing an in situ bearing disposed in the housing, the method comprising: attaching a framework, carrying a piston and cylinder arrangement, to the housing; actuating the piston and cylinder arrangement first so as to cause the attachment means carried thereby to engage the in situ bearing and then so as to withdraw the in situ bearing from the housing; releasing the framework from the housing so that the bearing now carried thereby can be moved clear from the housing; replacing the bearing in the framework; reattaching the framework carrying the replacement bearing to the housing; actuating the piston and cylinder arrangement to cause the replacement bearing, attached to the attachment means, to move into the housing; releasing the replacement bearing from the piston and cylinder arrangement; and releasing the framework from the housing.

13. A method as claimed in claim 12, further comprising, after actuating the piston and cylinder arrangement to cause the replacement bearing to move in the housing, actuating hydraulic fluid supply means to cause hydraulic fluid to be supplied to the bearing to operate a securing arrangement of the bearing to secure the bearing in the housing.

14. A method of replacing an in situ bearing substantially as hereinbefore described with reference to the accompanying drawings.