Access equipment

Apparatus enabling access to the interior surfaces bounding a large spaced comprises a pole adapted to extend vertically through the height of the space with its lower end located at the base of the space, at least one boom structure connected with said pole, a working platform connected to the end of said boom structure remote from said pole and the height of said boom structure is adjustable relative to said pole.

This invention concerns apparatus enabling an operator or operators to have 
access to the interior surfaces bounding large spaces, particularly though 
by no means exclusively, the cargo storage spaces of ships and especially 
the sections of the cargo tanks of very large crude carriers, for 
inspection, cleaning, shot-blasting, painting and general repair purposes. 
Very large crude carriers are constructed in the form of a series of 
rectangular sections, each such section forming a tank or part of a tank. 
Typical dimensions for such a section in a half-million ton tanker are as 
follows: 
Length (longitudinally of the ship)--5 meters 
Depth--36 meters 
Width (transversely of the ship)--21 meters 
The walls between adjacent sections may be flat and plane or plane with 
vertical or horizontal ribs at various spacings and may sometimes be 
provided with large interconnecting holes. 
Access to the interior surfaces of these sections (that is the vertical 
walls and underside of the deck or deck head) present a particularly 
difficult problem in that the hull of the ship is designed as a continuous 
closed box, so that the only access to the sections is through small holes 
varying from circular holes of 0.3 meters diameter to oval holes of 1.5 
meters by 1.0 meters in the deck. In general, there is no more than one 
such hole per section, usually located on the longitudinal centre line of 
the section, but positioned anywhere along the length of the centre line. 
In some cases there is no access hole in the deck and access to a 
particular section must be through a hole in a vertical wall between the 
section and an adjacent section. 
The apparatus of the invention is intended for use separately with each 
section, and an access hole in the deck of each section is assumed. 
Obviously, where this is not the case holes must be cut in the deck to 
give access to each section, and such holes must be provided with suitable 
covers then forming part of the permanent structure of the ship. 
According to the present invention, apparatus enabling access to the 
interior surfaces bounding a large space comprises a pole adapted to 
extend vertically through the height of the space with its lower end 
located at the base of the space, at least one boom connected with said 
pole, a working platform connected to the end of said boom remote from 
said pole and means for adjusting the height of said boom relative to said 
pole. 
According to a preferred feature of the invention, said boom can be 
adjusted so as to move said working platform towards or away from said 
pole. 
Preferably, said boom is pivotally connected to a carriage which is 
vertically slidable along said pole and means is provided for adjusting 
the angle of inclination of said boom relative to said pole and the height 
of said carriage on said pole. 
As we have seen, the depth of the cargo sections can be quite substantial 
and the pole must thus be of considerable length. For it to be rigid its 
cross-sectional area must be substantial. Increase in cross-sectional 
area, however, tends to be self-defeating in that the weight of the pole 
and hence degrees of compression therein is increased, thus facilitating 
flexing of the pole. 
Thus, according to a further preferred feature of the invention, means is 
provided to ensure that the pole is in a state of tension when the 
apparatus is in use. 
Preferably, means is located on the base of the section which restrain the 
lower end of the pole from lateral movement whilst not supporting same 
against downward movement, the pole being secured at its upper end, all 
whereby the pole is in a state of tension by virtue of its own weight. 
The invention will be further apparent from the following description with 
reference to the several figures of the accompanying drawings which show, 
by way of example only, two forms of apparatus embodying the invention.

Referring now to the drawings, it will be seen that the apparatus embodying 
the invention essentially comprises a pole 10 whose construction will be 
described in greater detail hereinafter. The pole 10 extends vertically 
through a section of cargo tank, and has its lower end located in a 
special fitting 11 which is positioned on the base of the section. The 
fitting 11 may be secured by means of clamps or the like, but may be 
provided as a part of the permanent structure of the ship, being welded or 
otherwise secured in position. 
The pole 10 is assembled in the section in a manner to be described 
hereinafter, but has its upper end held by a special fitting 12 positioned 
on the topside of the deck over a hole H in the deck giving access to the 
section and through which components of the pole are passed to permit its 
assembly within the section. 
The fitting 11 restrains the lower end of the pole from lateral 
displacement and rotational movement but does not support same against 
downward movement. In this way the pole 10 is maintained in a state of 
tension by virtue of its own weight, thus increasing its rigidity and 
reducing its tendency to flex when subjected to lateral loads. 
Two carriages 13 are provided and located one on each of opposite sides of 
the pole 10. Each carriage 13 carries a plurality of flanged rollers 14 
which engage with corners of the pole 10 and thus prevent movement of the 
carriage away from the pole in two directions. Each carriage 13 is 
restrained from movement away from the pole 10 in the remaining direction 
by a shoe member 15 which is partially located within the confines of the 
pole 10 and as clearly shown in FIG. 6. Each carriage 13 is able to be 
moved up and down along the length of the pole 10 by means of a cable 16 
secured to same and passing out through the hole H in the deck to a 
suitable winch 17 mounted on a derrick 18 which has been erected above the 
hole H. It will be understood that two winches 17 are provided, one for 
each carriage 13. 
A boom generally indicated at 19 extends outwardly from each carriage 13. 
Each boom comprises upper and lower arms 20 and 21 whose inner ends are 
anchored to plates 22 and 23 respectively. The plates 22 and 23 are 
pivotally connected to the carriage 13 at vertically spaced axes each 
parallel with the longitudinal axis of the ship. Likewise, the outer ends 
of the arms 20 and 21 are anchored to plates 24 and 25. The outer end of 
each boom 19 carries a working platform or cage generally indicated at 26, 
and which essentially includes a section 27. The plates 24 and 25 are 
pivotally connected to the section 27 at vertically spaced axes, each 
parallel with the longitudinal axis of the ship. It will be understood 
that the arms 20 and 21 together with the carriage 13 and section 27 form 
a parallelogram linkage such that the working platform or cage 26 will 
always maintain a horizontal position in space regardless of the angle of 
inclination of the boom 19. The boom is arranged to hinge through a 
vertical arc of approximately 150.degree. whereby the cage 26 can be moved 
between positions closely adjacent the pole 10, either above or below the 
location of the carriage 13. Each of the arms 20 and 21 is telescopically 
extendible and can be locked at a required length by manual means 28 best 
seen in FIG. 2. Equally the inner and outer ends of each of the arms 20 
and 21 may be anchored to their associated plates at adjustable angles to 
enable the cage 26 to be located centrally longitudinally of the section 
regardless of the position of the pole 10 and hence hole H longitudinally 
of the section. 
As best seen from FIG. 2, the working platform or cage 26 is provided with 
three further sections which are detachable from the central section 27. 
In this way, the shape and size of the cage 26 may be varied readily to 
accommodate varying lengths of tank section and to clear any corners in a 
tank section. 
On the derrick are a total of four winches. Two 17 are provided to enable 
the carriages 13 to be raised and lowered as previously described, and a 
further two indicated at 29 are provided to adjust the elevation of each 
of the cages 26 relative to its associated carriage 13 by means of wires 
30 extending from the winches 29 to the outer ends of the booms 19. 
In use, the carriages, boom parts and cages are taken into the tank section 
to which access is required and assembled ready for connecting to the pole 
10 when the latter is erected and in position. It follows that the 
carriages, booms and cages must all be capable of being stripped down to 
components which can be passed through such holes as are available to give 
access to the section. 
When the apparatus is fully assembled access may be had to all positions on 
the walls and roof of the tank section, the two cages servicing opposite 
halves of the section, as clearly seen from FIGS. 3 and 4. Preferably 
arrangements are provided whereby the movements of the carriages and booms 
can be controlled from the cages, a pendant type electrical push-button 
control being particularly suitable for this purpose. 
Turning now to FIGS. 5 to 7 inclusive, it will be seen that the pole 10 is 
conveniently comprised by a plurality of sections 50 arranged vertically 
one above the other. Each section 50 is comprised by two opposed halves 
51. Each such half 51 consists of a channel member 52 and a lacing strip 
53 secured on the inside thereof. Each lacing strip defines a plurality of 
land portions 54 located outwardly of the edge of the flanges of the 
channel member 52. The two halves 51 of each section 50 are jointed by 
bolting together the oppositely disposed of these land portions 54. 
The vertically adjacent channel members 52 of adjacent sections 50 are 
joined together by hinge members 55 and fish-plates 56. 
If the pole 10 has an overall cross-sectional area greater than the 
cross-sectional area of the hole H in the deck, the halves 51 of each 
section 50 of the pole 10 must be lowered separately through the hole, 
using the winches on the derrick as a crane, and bolted together to form 
the pole from the inside of the cargo section. By virtue of the hinges 55 
each half 51 can be secured to the half immediately therebeneath before 
being lowered through the hole H. 
Referring now to FIG. 8, it will be seen that in this embodiment of the 
invention the arms 20 and 21 cannot be pivoted about a vertical axis 
relative to the carriage 13 or cage 26. In this arrangement the arms 20 
and 21 support a transversely extending beam 100 on which the cage may be 
mounted at different lateral positions, as an alternative means of 
adjusting the position of the cage laterally in a direction transverse to 
the direction in which the arms 20 and 21 extend. 
Normally the arms 20 and 21 will be provided with shock-absorbing means and 
the carriage 13 with automatically operable brake means as a precaution 
against breakage of a cable 30 or cable 16 respectively. 
It will be appreciated that it is not intended to limit the invention to 
the above example only, many variations, such as might readily occur to 
one skilled in the art, being possible without departing from the scope 
thereof, as defined by the appended claims. 
Thus, for example, the angle of inclination of the boom relative to the 
pole may be adjusted by means of an hydraulic cylinder extending between 
the carriage and linkage on the boom or by other actuating means. 
It is an essential feature of the invention that the working platform or 
cage can be moved towards and away from the pole. This is conveniently 
achieved by means of a pivoting boom as described hereinbefore. As an 
alternative the boom which connects the working platform or cage with the 
pole may be of telescopic construction or again constructed in the fashion 
of "lazy tongs." 
Again, for example, the working platform or cage need not be comprised by a 
plurality of sections and may be comprised by a single section only. 
Yet again, for example, the halves 51 of the sections 50 of the pole 10 may 
be joined together by fish-plates alone rather than hinges 55 as well as 
fish-plates. 
Still again, for example, the pole need not be formed from two laterally 
adjacent halves but may have a cross-section comprised by one piece. Such 
a simplified pole would be particularly suitable where its height does not 
need to be too great.