Apparatus for inspecting, cleaning and/or performing other tasks in connection with a welded joint

An apparatus is disclosed for inspecting, cleaning and/or performing other tasks in connection with a welded joint between intersecting tubular members of an offshore platform a substantial distance beneath the water surface. The apparatus includes a support body adapted to be moved onto and removed from one of the tubular members, and a carrier rotatable about the body, when clasped about the one tubular member, and having the task performing devices thereon for traversing the joint as the carrier is so rotated.

This invention relates generally to apparatus for use in inspecting, 
cleaning and/or performing other tasks in connection with a welded joint. 
More particularly, it relates to improved apparatus of this type in which 
the welded joint connects intersecting tubular members of an offshore 
platform which are located a substantial depth beneath the water surface. 
It is common practice to perform tasks in and around subsurface portions of 
offshore platforms by means of vehicles which are remotely operated from 
the surface level. These vehicles, which are known in the trade as ROV's, 
have thrusters or other suitable means for propelling them through the 
water in response to the supply thereto of a source of power located on 
the top of platform or a vessel near the platform. Thus, a package 
comprising one or more task performing devices is delivered by the ROV to 
the desired site where each device is then positioned relative to the ROV 
to perform its intended task by means of a manipulator which, like the 
vehicle itself, is operated from a remote power source. Power is delivered 
to the vehicle, and thus to the task performing devices and their 
manipulators, and signals are transmitted between the vehicle and a 
control station on the platform or vessel, through an umbilical connecting 
the vehicle and station. The vehicle may be lowered to and raised from the 
level at which it is to operate by means of a cage which may be lowered 
from and then raised back to the surface level and to which the ROV is 
connected by means of a tether which permits the ROV to maneuver at such 
level. 
An ROV whose task performing package includes devices for inspecting and/or 
cleaning a welded joint is so large that it is difficult to maneuver in 
and around the restricted area of the framework of the platform in which 
the joint is located, especially when it requires a large and cumbersome 
umbilical for performing other tasks as well as propelling the ROV itself 
into and out of desired positions. Hence, the ROV often must be 
repositioned many times in order to enable the task performing package to 
traverse the joint in order to perform the desired tasks thereon, since 
once the ROV is positioned, the maneuverability of its task performing 
devices is limited to that of their manipulators. Also, in order that it 
may be fixedly positioned at or near the work site for this purpose, the 
vehicle has been provided with suction cups adapted to be attached to an 
adjacent area of the framework of the platform, ordinarily the 
intersecting tubular member whose peripheral and edge is welded to the 
other member. This proves difficult because of the need for first removing 
marine growth from the member or other piece to which the cup is attached. 
Attempts have been made to improve upon apparatus of this type by providing 
individualized task performing packages adapted to be interchangeably 
attached to a basic ROV. Although this reduces the size of the overall 
vehicle, it nevertheless is subject to other shortcomings above noted. 
Also, it may require recovery and redeployment of the ROV to exchange one 
such package for another. In any event, the delivery and other functions 
of the ROV are necessarily shut down until the joint has been inspected 
and/or cleaned. 
Co-pending patent application, Ser. No. 726,798, entitled "Method and 
Apparatus for Inspecting, Cleaning and/or Performing Other Tasks in 
Connection With A Welded Joint", filed Apr. 24, 1985, by Michael L. 
Gernhardt, and assigned to the assignee of the present application, 
relates to apparatus in which the task performing package may be 
maneuvered in and around the restricted areas in which the joint may be 
located, which does not require repositioning of the ROV or other delivery 
package for the purpose of enabling the work performing package to 
traverse the welded joint in inspecting, cleaning or performing other 
tasks at the job site, and in which the task performing package may be 
positioned for traversing the joint with a minimum of time and effort. 
More particularly, the illustrated embodiment of the prior apparatus 
includes a support body which is adapted for connection to a delivery 
package so that it may be moved onto and clamped about the tubular member 
whose peripheral end edge is welded to the other member, and a carrier 
having means for inspecting, cleaning and/or performing other tasks in 
connection with the joint and so mounted on the body for rotating about 
it, when the body is so clamped, whereby such means is caused to traverse 
the joint independently of the delivery package. More particularly, the 
apparatus has means which is remotely operable, in response to the supply 
thereto of power from a remote source, for selectively clamping the 
support body about or unclamping the body from the tubular member, 
rotating the carrier about the support body, and activating the task 
performing means as it traverses the joint during rotation of the carrier. 
Since the apparatus is clamped to the tubular member, the tubular member 
need not be cleaned or otherwise prepared. Furthermore, due its relatively 
small size and thus its ability to be maneuvered in and around the work 
site, the apparatus may include a task performing package for performing a 
large number of tasks in connection with the joint. Preferably, the ROV or 
other delivery package may be removed from the apparatus when the support 
body has been clamped about the tubular member, and prior to traversing 
the joint, whereby the ROV may be deployed for other tasks. 
The power for operating the components of the apparatus may be received 
through an umbilical connecting it to the ROV to which power is in turn 
supplied through an umbilical connecting with a power source on a vessel 
at water level. This same power source may also be used to operate 
manipulators connecting the task performing means with the carrier, and, 
when the means for cleaning the joint is a jet nozzle, for supplying the 
jetting fluid thereto from a remote source. Alternatively, power may be 
supplied to the components independently of the ROV, such as directly from 
a source on the cage or at the water surface. 
In the prior apparatus, each of a main portion of the body which is clamped 
to the tubular member and the carrier mounted on it have throats in their 
sides to permit them to be moved onto or removed from the tubular member 
when the carrier is moved to a position in which its throat is generally 
aligned with that of the main body portion. The carrier is rotated about 
the body by means of a partial ring gear extending about its outer 
circumference generally from one side to the other of its throat, and 
pinion gears mounted on the main body portion to drivingly engage the 
teeth of the ring gear. 
In an underwater environment, debris may accumulate between the teeth of a 
conventional ring gear, and meshing of the pinion gear with the teeth 
merely mashes the debris more firmly into the valleys between them. As a 
result, unless the debris is removed, the gears may jam and the carrier 
rendered incapable of rotation. Also, the pinion gears are rotated by 
remotely operable actuators including a hydraulic motor or the like, and 
if the power source is lost, because of severing of a hydraulic line 
leading to the motor or otherwise, the carrier may be locked in a rotative 
position on the body which prevents its removal from the tubular member. 
An object of this invention is to provide apparatus of this type in which 
the means for rotating the carrier is less liable to become jammed, and, 
more particularly, in which the carrier is rotated by means of such 
construction that there is little tendency for debris to accumulate 
between its teeth, and which is self cleaning in the sense that debris 
which might form is automatically removed therefrom during rotation of the 
carrier. 
Another object is to provide apparatus of this type in which the carrier 
may be rotated to a position in which the apparatus may be removed from 
the tubular member even though the actuator is rendered inoperable, 
whether by power failure or otherwise, to return the carrier to a position 
in which its throat is aligned with that of the main body portion, and 
more particularly in which the pinion gears may be moved out of driving 
engagement with the carrier by means which may be manipulated by a diver 
who may then manually rotate the carrier. 
These and other objects are accomplished, in accordance with the 
illustrated embodiment of this invention, by apparatus which is similar to 
that disclosed in the prior co-pending application in that it includes a 
support body including a main portion having a throat in one side and 
means connected to the main portion for movement between outer positions 
to one side of the throat to permit the main portion to be moved onto or 
removed from the one member whose peripherial end edge is welded to 
another member, and inner positions tightly engaged with the one member 
for clamping the body thereabout. Also, a carrier is mounted on the 
support body for rotation thereabout and has a throat in one side thereof 
which, when the carrier is in a first rotative position, is generally 
aligned with the body throat to permit the carrier to be moved with the 
body onto or removed from the one tubular member. As in the prior 
apparatus, the carrier has means thereon for inspecting and/or cleaning 
the joint as the carrier is rotated into other positions about the body, 
and a means is provided for supplying power from a remote source for 
moving the clamping means between inner and outer positions, rotating the 
carrier about the body, and activating the means for inspecting, cleaning 
and/or performing other tasks in connection with the joint. 
In accordance with the novel aspects of the present invention, the means 
for rotating the carrier comprises pins which are mounted on the carrier 
in circumferentially spaced relation to form a partial ring of teeth 
concentrically of the axis of rotation of the carrier and extending 
generally from one side to the other of the throat in the carrier. More 
particularly, pinion gears are mounted on the main body portion with their 
teeth arranged to successively move into and out of the open spaces 
between the pins in order to rotate the carrier upon rotation of the 
pinion gears. Due to the open spaces between the teeth, there is little or 
no tendency for debris to accumulate between them, as might occur in the 
case of a ring gear of conventional construction. Furthermore, debris 
which might accumulate within the open spaces will be removed as the teeth 
on the pinion gear move successively into and out of the spaces between 
the pins on the carrier. 
In the illustrated embodiment of the invention, the means for rotating each 
gear comprises a frame mounted on the body, a shaft rotatably mounted on 
the frame and on which the pinion gear is mounted, a second gear on the 
shaft, and a double acting, hydraulically operated actuator having a rod 
with a worm thereon engaging the second gear for rotating it and thus the 
shaft and pinion gear in response to reciprocation of the rod. Also, the 
main body portion has an outer circumferential groove arranged 
concentrically of the axis of rotation of the carrier and extending 
between opposite sides of the throat in the main body portion, and the 
carrier has an inner circumferential flange guidably slidable in the 
groove. More particularly, the pins on the carrier are disposed generally 
radially opposite and outwardly from the flange, and the pinion gears on 
the body are disposed radially intermediate the pins and flange, to 
provide a very compact arrangement having working parts which are disposed 
inwardly of the outer dimensions of the apparatus and thus protected from 
damage. 
More particularly, the pinion gears on the main body are mounted for moving 
between positions drivingly engaged with and disengaged from the partial 
ring of teeth, and a manually manipulatable means is provided for moving 
the pinion gears between such positions so that they may be moved out of 
driving engagement with the teeth to permit the carrier to be rotated 
independently of the actuators for rotating the pinion gears. Thus, in the 
event the actuator is jammed or otherwise malfunctions with the carrier in 
a position which locks the apparatus on the tubular member, a diver may 
move the gears to positions in which he may then manually rotate the 
carrier into a position in which its throat is generally aligned with that 
of the body to permit removal of the apparatus from the tubular member. 
In the illustrated embodiment of the invention, the aforementioned frame is 
pivotally mounted on the main body portion between positions in which the 
pinion gear thereon is drivingly engaged with or disengaged from the teeth 
of the ring. Each of the main body portion and frame have cam slots 
therein to receive a follower rod having an arm thereon which may be 
manually manipulated to move the follower laterally within the slots, and 
the slots are so contoured as to swing the frame between said positions as 
the rod is so manipulated, whereby the arm may be moved by the diver to 
manipulate the rod and thus move the pinion gear to the desired positions.

The portion of the underwater platform shown in FIG. 1 includes a 
substantially upright leg L which is anchored at the underwater surface 
for extension upwardly to the water level, and horizontally and diagonally 
extending tubular members TM connecting with the leg L to form part of a 
rigid framework. More particularly, the peripherial end edges of the 
tubular members are welded to the leg by means of annular welds W, which, 
as can be seen from FIG. 1, are in areas which are restricted due to the 
relatively small angle formed between the members. The apparatus 
constructed in accordance with the present invention, and indicated in its 
entirety by reference character 20, is shown to be so mounted on the 
horizontal tubular member as to enable it to perform certain tasks on the 
welded joint between it and the leg L. 
This apparatus comprises a main body portion 21 which, as best shown in 
FIGS. 4, 5 and 6, has a throat 22 in one side to permit it to be moved 
onto or removed from the horizontal tubular member, and arms 23 which are 
hingedly connected to the main body portion generally opposite the throat 
22 for swinging between positions to one side of the throat, as shown in 
phantom in FIG. 4, as the body is moved onto or removed from the tubular 
member, and positions tightly engaged with the tubular member so as to 
clamp the body portion thereon, as shown in solid lines in FIGS. 4, 5 and 
6. As best shown in FIG. 11, the upper ends of the arms on one side of the 
body are connected to an inner sleeve 23A and the upper ends of the arms 
on the other side are connected to an outer sleeve 23B rotatable about and 
extending from opposite ends of the inner sleeve. The inner sleeve is 
rotatably mounted on the main body portion and the rods of actuators 23C 
mounted on the main body are connected by crank arms 23D to the inner and 
outer sleeves in order to rotate the cranks and thus swing the clamping 
arms between clamping and unclamping positions in response to extension 
and contraction of the actuators. 
As previously described, the apparatus also includes a carrier 24 mounted 
on each end of the body for rotation about the main body portion, and, as 
shown in FIG. 1, task performing devices are mounted on the carrier by 
means of manipulator arms 25 supported on the carrier at one end for 
extension and retraction toward and away from the apparatus, and thus for 
moving the devices on their ends into and out of positions for traversing 
the welded joint upon rotation of the carrier. As shown, each such carrier 
also has a throat 26 in one side thereof which, when generally aligned 
with the throat in the main body portion of the apparatus, permits the 
apparatus to be moved onto or removed from the tubular member. As more 
fully described in the prior co-pending application, the devices on the 
ends of the manipulator arms may comprise, for example, a TV camera or a 
nozzle adapted to deliver a fluid jet to the welded joint, and the 
manipulator arms are of conventional construction including hingedly 
connected joints adapted to be extended and contracted by suitable 
hydraulically operated means on the carrier. 
The apparatus is adapted to be delivered to and lowered onto the tubular 
member, and then removed therefrom, by means of an ROV which, as well 
known in the art, and as described in the prior co-pending application, is 
provided with thrusters or other means for enabling it to be maneuvered 
within the water to and from desired positions relative to the platform. 
Thus, the ROV is connectable to the apparatus to permit the apparatus to 
be moved into and removed from mounted position on the tubular member, 
and, when the apparatus has been clamped to the tubular member, may be 
released from the apparatus for deployment at another location, leaving 
the apparatus for the purposes to be described. 
As also previously described, the ROV has means which is hydraulically 
operated not only to permit it to be so maneuvered, but also to permit it 
to transmit power from a suitable source to the operating means on the 
apparatus, including the above described clamping arms and manipulators as 
well as other parts to be operated, as will be described to follow. 
Alternatively, and again as described in the prior application, the 
apparatus may instead be delivered to and removed from the tubular member 
by a package other than the ROV, as for example by one or more divers, 
especially when the welded joint is at a depth which permits divers to 
maneuver for longer periods of time than is possible at greater depths. 
Also, power for operating the various components of the apparatus may be 
supplied to a control station on the apparatus from a source other than 
that which is supplied to and used to operate the ROV. 
As shown, the main portion 21 of the body is made up of a series of 
longitudinally spaced apart plates which are of inverted U-shape and 
connected to one another by lateral bracing, each of the plates having a 
throat in one side aligned with the throats in the others. These plates 
include an inner pair 27 which are spaced apart to receive the crank arms 
and actuators therebetween, as best shown in FIG. 2, and are connected to 
one another as well as to outer spaced apart plates 29 and 30 at each end 
of the main body portion by lateral braces 28 which extend longitudinally 
along the sides and upper portion of the main body portion. 
As best shown in FIG. 12, each outer plate 29 includes a first "U" shaped 
plate portion 31 to which the ends of the lateral braces 28 are connected, 
and a second, "U" shaped plate portion 32 having a flange 33 on its outer 
side which extends through the upper end of the throat in the plate 
portion 31. When assembled, the plate portions 31 and 32 are bolted or 
otherwise connected together and a ring 34 (see FIG. 9) is welded to the 
outer circumference of the outer end of the flange of the plate portion 32 
so as to form a circumferential groove G between it and the outer side of 
the plate portion 32 which extends circumferentially from one side to the 
other of the throat formed in the plate 29. Each plate 30 is connected to 
the lateral braces to dispose it in a position spaced from the inner side 
of the plate 29 for purposes to be described to follow. 
The carrier 24 at each end of the apparatus comprises an inverted U-shaped 
frame 35 which has an outwardly extending flange along the top and sides 
thereof, and a lower extension 36 which, when the carrier is mounted on 
the main body, as will be described, permits the entire apparatus to be 
supported on a flat surface with the main body and the clamping arms 
raised above the surface. Another inverted U-shaped member 37 of the 
carrier has a radially outwardly extending flange 38 and a longitudinally 
inwardly extending flange 39 which extends through the upper end of the 
throat in the frame 35. The lower side of the flange 39 fits closely 
within and is rotatably slidably mounted in the groove 35 in the plate 29 
of the main body portion to permit each carrier to be rotated about the 
axis of the tubular member when mounted thereon. More particularly, the 
flange which is slidable within the groove extends throughout 
substantially the same arcuate extent as the throats in the plates of the 
main body, so that with the carrier in the upright position, the throats 
which are formed in the carriers are generally aligned with one another 
and those of the main body portion to permit the apparatus to be moved 
onto or removed from the tubular member as a unit. 
Each carrier also includes a partial ring 41 which is connected to the 
frame 35 on its inner side by means of bolts 42 and spaced therefrom by 
means of sleeves 43 about the bolts. The ring and the row of bolts are 
arranged concentrically of the axis of the rotation of the carrier and 
extend in equally spaced relation from one side to the other of a throat 
in the side of the ring aligned with the throats in the frame 35 and "U" 
shaped member 37. The bolts thus provide a partial ring of spaced-apart 
pins on teeth radially outwardly of the flange 39 and thus in position to 
be drivingly engaged by pinion gears mounted on the body, as will be 
described to follow. 
A series of frames 50 are disposed between and pivotably connected to the 
pairs of spaced plates 29 and 30 of the main body portions by means of a 
pin 51 extending between them. A hydraulically operable actuator 52 is 
mounted on the frame 50 to dispose the rod 53 thereof in position to be 
extended and retracted with respect to the length of the frame. Brackets 
54 are mounted on the frame near the end of the rod to support a shaft 55 
for extension laterally therefrom, and a gear 56 is mounted on the shaft 
intermediate the brackets in position to be engaged by worm 57 mounted on 
the rod 53, whereby extension of the rod rotates the shaft in one 
direction and retraction thereof rotates the shaft in the opposite 
direction. 
The shaft 55 extends beyond the plate portion 31 and has a pinion gear 58 
on its outer end whose teeth are positioned to drivingly engage between 
the equally spaced apart teeth formed by the pins 42. Thus, rotation of 
the shaft through extension of contraction of the actuator rod 53 will 
cause the pinion gear to drivingly engage the teeth on the carrier to move 
the carrier in a desired direction with respect to the main body portion. 
In this way, of course, the various devices mounted on the outer ends of 
the manipulator arms are able to traverse the welded joint. Due to the 
arcuate extent of the partial ring of teeth, as well as the location of 
the pinion gears opposite the opening of the throat of the main body 
portion, the carrier is driven by at least two of the gears as it 
traverses the joint. 
As previously described, the open spaces between the teeth reduce to a 
minimum the likelihood of accumulation of debris. Furthermore, any debris 
which does accumulate between adjacent pins will be removed as that 
portion of the carrier traverses one or more of the pinion gears. 
A plate 60 depends from the end of each frame adjacent the outer end of the 
actuator 52 for disposal opposite a plate 61 welded in position between 
the plates 29 and 30 of the main body portion. The plates 60 and 61 are 
provided with cam slots 60A and 61A, respectively, therethrough to receive 
the follower rod 62 of a manually manipulatable arm 63 which extends 
through the main body and the carrier to dispose its outer end adjacent 
the end of the apparatus, and thus easily accessible to a diver. 
During normal operation, the follower 62 rests within a detent groove 63A 
in the slot 61A so as to support the end of the frame and thus maintain 
the pinion gear mounted thereon drivingly engaged with the pins forming 
the partial ring of teeth on the carrier. However, the slot 60A is 
inclined, as shown in FIGS. 9 and 10, so that when the arm 63 is pulled 
outwardly, the follower will engage the upper surface of the slot 60A in 
plate 60 of the frame 50 so as to raise the end of the frame and cause it 
to swing about the pin 57. This in turn will move the pinion gear out of 
driving engagement with the partial ring of teeth on the carrier, and 
enable the carrier to be rotated manually about the main body portion. 
Thus, if power for the actuator should be lost, or the actuator otherwise 
rendered inoperable to return the carrier to a position in which its 
throat is aligned with the throat in the main body portion, pulling of the 
arm 63 in the manner described will disengage the pinion gear to permit 
the carrier to be manually rotated to a position in which its throat is 
aligned with the throat of the main body portion. 
From the foregoing it will be seen that this invention is one well adapted 
to attain all of the ends of objects hereinabove set forth, together with 
other advantages which are obvious and which are inherent to the apparatus 
and method. 
It will be understood that certain features and subcombinations are of 
utility and may be employed without reference to other features and 
subcombinations. This is contemplated by and is within the scope of the 
claims. 
As many possible embodiments may be made of the invention without departing 
from the scope thereof, it is to be understood that all matter herein set 
forth or shown in the accompanying drawings is to be interpreted as 
illustrative and not in a limiting sense.