Apparatus for use in installing a piece of equipment horizontally on a submerged unit and for removing it therefrom

A servicing apparatus for installing a piece of equipment horizontally on a submerged unit and for removing it therefrom, comprises a movable servicing module designed to engage on the upper part of the submerged unit, pivot thereabout and lock against it in a horizontal position, and a cradle supporting the piece of equipment. The cradle is carried, by means of connections allowing transverse adjustment, by sliding supports mounted in the servicing module, and movable longitudinally by means of jacks. Mutual engagement means are provided on the submerged unit and on the piece of equipment to ensure that the latter is positioned accurately on the unit.

The invention relates to an apparatus for use in servicing a submerged 
unit, for installing on it and removing from it a piece of equipment 
intended to be fastened horizontally against the unit by means of bolting. 
It is known that a piece of equipment can be brought vertically onto a 
submerged unit by means of guide lines, but this operation is made more 
difficult if the piece of equipment is to come up against the submerged 
unit sideways and be fastened to the unit in a precise relative position, 
particularly when the piece of equipment is heavy. Such a problem arises 
in particular where a submerged shut-off valve is concerned, when a 
removable lateral cap containing shut-off members and means for moving the 
shut-off members is to be attached to or removed from the valve. 
According to the present invention there is provided apparatus for 
installing a piece of equipment horizontally on a submerged unit and for 
removing it therefrom, comprising a receiving structure forming part of 
the submerged unit, a movable servicing module having a tubular frame 
defining a longitudinal direction and which is adapted to support the 
piece of equipment and to come up against the receiving structure with the 
frame in a substantially horizontal position, said longitudinal direction 
then being arranged substantially horizontally, complementary catching 
means on upper parts of the tubular frame and the receiving structure, for 
permitting the tubular frame, in an inclined position, to catch by means 
of its said upper part on the upper part of the receiving structure and to 
pivot relative to the structure to come up against the structure in said 
horizontal position, controllable interlocking means for locking the 
tubular frame to the receiving structure, longitudinal slideways provided 
on the tubular frame, slidable supports mounted on the slideways, a cradle 
provided with supporting means for supporting the piece of equipment and 
with bolt-screwing means for bolting the piece of equipment to the 
submerged unit, connection means between the cradle and each of the 
sliding supports for permitting transverse adjustment of their relative 
position, a longitudinal-travel jack for moving the cradle relative to the 
tubular frame and complementary mutual engagement means on the submerged 
unit and on the piece of equipment for centering the piece of equipment on 
the submerged unit by transverse adjustment of the relative position of 
the cradle and the sliding supports which is permitted for by said 
connection means. 
Each of these connections advantageously comprises two pistons, each 
attached to a rod which in the horizontal position of the tubular frame, 
is substantially vertical, the rod attached to one of the pistons being 
connected to one of the sliding supports by means of a joint having a 
longitudinal axis and the rod attached to the other of the pistons being 
connected to the cradle by means of a joint having a longitudinal axis, 
and a substantially vertical intermediate cylinder in which the two 
pistons each delimit a chamber, the volume of which tends to contract 
under the action of the weight of the cradle, a first of the chambers 
being subjected to a pressure slightly higher than, and the second to a 
pressure slightly lower than, the equilibrium pressure which would 
counterbalance the contracting action. 
Thus, the first chamber is a holding chamber which expands under the effect 
of the pressure prevailing in the chamber, but which can contract if a 
slight downwards force is exerted on the cradle, in order to allow the 
cradle to move downwards. The second chamber is a weight-compensating 
chamber which contracts under the effect of the weight of the cradle, but 
which can expand to allow the cradle to move upwards if a slight upwards 
force is exerted on the cradle. The two joints allow the cradle to execute 
a transverse relative movement in relation to the supports. 
Each of the bolt-screwing means comprises a hollow body for receiving a 
middle portion of a bolt with a nut fitted thereon and which is surrounded 
by rotation means for rotating the nut, a pull and rotation head arranged 
in a longitudinal extension of the hollow body, with means for relative 
longitudinal movement between the head and the hollow body, and which 
receives an end portion of the bolt and carries, at its longitudinal end, 
a drive member for rotating the bolt through a fraction of its 
circumference so as to act on the anchoring of its other end portion in 
the submerged unit, and lateral grasping means for grasping the bolt and 
allowing the means for relative longitudinal movement to exert a tension 
on the bolt before the rotation drive means is activated.

FIG. 1 shows a submerged stop valve 1 installed on an underwater pipeline 2 
for conveying hydrocarbons. This stop valve 1 comprises a body 3 which 
remains permanently secured to the pipeline 2 and the two lateral caps, 
such as the cap 4. If required, one of these caps can be separated from 
the body 3 to which it is bolted, in order to be raised to the surface to 
be repaired or exchanged. 
The cap 4 is removed and reinstalled by means of servicing apparatus 
comprising a module 5 which is lowered onto the sea bottom from a ship 6 
and which is raised to the surface by means of a crane 7, along guide 
lines 8, the module 5 being remotely-controlled from a booth 9 by means of 
an umbilical cable 10. 
The servicing module 5, which can be seen in FIG. 2, comprises a tubular 
frame 11 which is elongate in an approximately horizontal direction (as 
shown) and equipped, in its upper part, with catching means 12 for 
engaging a pivoting support or pivot pin 13 carried by a tubular receiving 
structure 14 forming part of the valve body 3. Two latches 15 are 
installed in the lower part of the tubular frame 11. The location of one 
of these latches can be seen in FIG. 2, and, as shown in FIG. 6, each 
comprises a hook 16 for engaging a tubular catching element 17 forming 
part of the receiving structure 14, the hook 16 being articulated on a 
pivot pin 18 and is brought into the catching position, or withdrawn from 
this position, by the action of a hydraulic jack 19. 
The module 5, during its decent towards the body 3, is supported by 
handling slings 20, the length of which can be adjusted by means of a 
hydraulic mechanism 21, in order to take into account variations in the 
weight and weight distribution of the module 5, depending on whether the 
module is loaded with a cap 4 or not. 
Mounted on the body 3 are two pins 22, 23 intended to engage corresponding 
recesses in the cap 4 to ensure exact centering of the cap 4 on the body 3 
when positioned against the body. 
The means for receiving the cap 4 in the servicing module 5, to allow 
transport of the cap, will be described with reference to FIGS. 2, 7 and 
8. The tubular frame 11 possesses two tubular slideways 24, 25, on which 
four supports, such as 26, slide. These sliding supports 26 are connected 
to a cradle 27 (FIG. 7) by means of suspension means 28. 
FIG. 8 shows one of the suspension means 28. As shown, a vertical 
cylindrical body 29, consisting of two parts joined to one another by 
means of bolts, forms an internal cylindrical space in which an upper 
piston 30, attached to a rod 31, and a lower piston 32, attached to a rod 
33, are slidable. The upper rod 31 is connected to one of the supports 26 
by means of a joint having a longitudinal axis 34 and the lower rod 33 is 
connected to the cradle 27 by means of a joint having a longitudinal axis 
35. Between the two pistons, the cylindrical body 29 carries a stop piece 
36. The pistons delimit the following spaced: between the body 29 and the 
upper piston 30, a holding chamber 37 subjected via an orifice 38 to an 
equilibrium pressure slightly higher than that which would be necessary to 
counter-balance the action of the weight of the cradle tending to contact 
the volume of the chamber 37; between the two pistons 30 and 32, an 
intermediate chamber 39 communicating via an orifice 40 with a 
pressure-equalizing bladder (not shown); between the lower piston 32 and 
the body 29, a weight-compensating chamber 41 subjected via an orifice 42 
to a pressure slightly lower than the equilibrium pressure which would be 
necessary to counter-balance the action of the weight of the cradle 
tending to contract this chamber 41. Since the weight of the cradle 27 in 
water is variable, depending on whether the cradle is carrying the cap 4 
or not, the pressures respectively slightly higher than and slightly lower 
than the equilibrium pressure are changed at the moment when the cap 4 is 
transferred from the cradle 27 to the body 3 of the valve or from the body 
3 to the cradle 27. 
Thus, the cradle 27 is in an exact longitudinal position relative to the 
sliding supports 26, whilst its transverse position can be adjusted 
without the need to exert substantial forces. The longitudinal position of 
the cradle 27 in relation to the tubular frame 11 is adjusted by means of 
two longitudinal-travel jacks 43, of which one can be seen in FIG. 2. 
The cap 4 is grasped by the cradle 27 by means of four supporting shafts, 
such as shafts 44, 45 (FIG. 2), fixed to the cradle, and four brackets 
fixed to the cap 4 and each for receiving one of the supporting shafts, 
whilst a controllable locking system (not shown) makes it possible to 
block these brackets longitudinally in engagement with the supporting 
shafts. 
The servicing module 5 also possesses screwing systems for screwing 
assembly bolts 46 (FIG. 2) joining the cap 4 to the body 3 of the valve. 
These screwing systems will be described in detail with reference to FIGS. 
9 and 10. There are four of them, and two of them referenced 47 and 48 can 
be seen in FIG. 7. These screwing systems can be mounted on the cradle 27 
by means of pivoting supports controlled by jacks, such as jack 49. The 
servicing module 5 has other elements, such as a hydraulic unit, a 
hydraulic distribution assembly, an electrical control assembly, grease 
injectors, nitrogen injectors and a manipulator for the hydraulic and 
electrical connectors of the cap 4, which are not shown in order to avoid 
complicating the drawing and the use of which will not be described 
because they do not form part of the invention. 
FIG. 2 shows the servicing module 5 at the moment when, during its lowering 
movement, inclined at approximately 15.degree. to the horizontal, it 
arrives at the receiving structure 14, and its upper part catches on the 
upper part of the receiving structure. 
The servicing module 5 then pivots about the pivot pin 13, to come up 
against the receiving structure 14 in a horizontal position and to lock 
against the latter by means of the latches 15. This is the position shown 
in FIG. 3. 
The longitudinal-travel jacks 43 are then actuated to bring the cap 4 up 
against the body 3. During this movement, the pins 22, 23, by engaging 
into the corresponding recesses in the cap 4, ensure centering of the cap 
4 on the body 3, the suspension means 28 making it possible, without much 
effort, for the cradle 27 to execute any required transverse movement 
relative to the tubular frame 11 which may be necessary. During this 
movement, the bolts 46 each enter, by means of an anchoring end, a 
receptacle provided for this purpose in the body 3. The position shown in 
FIG. 4 is thus obtained. The anchoring of the bolts 46 in the body 3, 
their tensioning and the tightening of the nuts locking them are then 
carried out, as will be later described with reference to FIGS. 9 and 10. 
The members holding the cap 4 in the module 5 can then be unlocked and the 
cradle 27 released by actuation of the longitudinal-travel jacks 43, the 
supporting shafts 44 and 45 being withdrawn from their receptacles in the 
brackets fixed to the cap 4. 
The module 5 is then empty and can be raised to the surface once more, 
after the latches 15 have been opened and the length of the slings 20 has 
been adjusted in order to give the module 5 an inclination of 
approximately 15.degree. again. FIG. 5 shows the body 3 with its new cap 
4, after the module 5 has been removed. 
The procedure to be adopted for removing a cap 4 from the body will be 
apparent from the foregoing, the successive operations of which are 
carried out in reverse order to that described above. 
One of the screwing systems, such as 47 and 48, will now be described in 
detail with reference to FIGS. 9 and 10. By screwing system is meant a 
system which serves both for screwing and for unscrewing. 
The system is supported in the cradle 27 by means of shock mounts 51. it 
possesses a main hollow body 52 directed longitudinally and surrounding 
part of one of the bolts 46. This hollow body has, internally, a first 
cylindrical portion of a diameter slightly greater than that of the bolt 
46, a conical portion and a second widened cylindrical portion allowing 
the clamping nut 53 for the bolt 46 to be introduced. The bolt terminates 
at its anchoring end in a head 54 to such a shape that, as a result of 
rotation of the bolt 46 by a quarter turn, this head 54 is retained in a 
receptacle 55 in the valve body 3, into which it was able to penetrate 
freely, before its rotation, during longitudinal movement of the cradle 27 
towards the body 3. This bolt 46 is shown in its entirety in FIG. 10, 
whereas the anchoring end of this bolt is not shown in FIG. 9. 
Mounted on the end of the main body 52 and in longitudinal extension of the 
main body, is a pull and rotation head 56 which is movable longitudinally 
relative to the main body 52 by sliding on three shafts, such as the shaft 
57, screwed in the main body 52. A restoring spring, here consisting of 
Belleville washers 58 held by means of a cap nut 59 screwed on each shaft 
57, tends to bias the pull and rotation head against the main body 52, 
whilst an annular jack, comprising an annular piston 60 and an annular 
chamber 61 formed in the main body 52 and supplied with fluid under 
pressure via a feed orifice 62, enable movement of the pull and rotation 
head 56 away from the main body 52. 
The pull and rotation head 56 comprises a housing 63, on which the annular 
piston 60 can act to move the pull and rotation head 56 away from the main 
body 52. The Belleville washers 58 likewise act on this housing 63, and it 
is this housing which slides on the shafts 57. The housing 63 contains two 
opposite jaws 64, 65 designed to grasp the bolt 46 between them by being 
moved towards one another in a direction perpendicular to the longitudinal 
axis of the bolt 46 by means of pistons 66, 67 mounted in cylinders 68, 69 
closed by means of plugs and supplied with a fluid under pressure. The 
jaws 64, 65 on the one hand, and the bolt 46 on the other hand, are 
equipped with a system of matching teeth and notches, allowing the jaws to 
engage with the bolt in such a way that a longitudinal movement of the 
housing 63 away from the main body 52 causes a pull on the bolt 46 
anchored in the body 3. 
Fastened to the longitudinal end of the housing 63 by means of a ring 70 is 
a lantern-shaped casing 71 of a drive member comprising a hydraulic rotary 
jack 72 designed to drive the free end 73 of the bolt 46 in a rotation of 
a quarter turn by means of a keyed sleeve 74 coupled with the free end 73 
of the bolt 46. A collar 75 mounted in the casing 71 serves as a stop for 
the bolt 46, the position of which is thus determined exactly in relation 
to the pull and rotation head. 
The main body 52 carries laterally, by means of a welded plate 76, a 
hydraulic motor 77 which drives a spur gear 78. The nut 53 is equipped 
with straight cut teeth on its outer surface. An intermediate gear 79 
meshing with the gear 78 is mounted so as to slide longitudinally on a 
shaft 80 carried by the main body 52. The intermediate gear 79 is biassed 
by a helical spring 81 towards an end plate 82 of shaft 80, and in this 
position it meshes with the straight cut teeth of the nut 53. 
In order to bolt a cap 4 to a body 3, the following procedure is adopted. 
When the head 54 of each bolt 46 has been introduced into its receptacle 
55 in the body 3 as a result of the movement of the cradle 27 towards the 
body 3, and with the bolt 46 held against a stop 50 and, at its other end 
73, against the stop collar 75 by means of the Belleville washers 58, the 
bolts 46 are rotated a quarter turn by means of the rotary jacks 72 in 
order to lock the bolt heads 54 in their receptacles 55. The pairs of jaws 
64, 65 are then clamped on each bolt 46 by means of the pistons 66, 67, 
and a hydraulic pressure is conveyed into the chambers 61 in order to 
tension the bolts 46 to a certain prestress value. The nuts 53 are 
subsequently screwed, until they come in contact with the cap 4, by means 
of the hydraulic motors 77. The pressure in the chambers 61 can then be 
relieved and the pairs of jaws 64, 65 moved apart, in order to separate 
the screwing systems from the bolts 46, at the same time as the cradle 27 
is released from the cap 4. By performing these operations in reverse, it 
is possible to unscrew the bolts 46 when a cap 4 is to be removed from the 
body 3. 
There is thus provided servicing apparatus which facilitates handling and 
lateral positioning of a piece of equipment on a submerged unit.