| JP05132288 | SHIPPING LASHING FOR CRANE AND LASHING CABLE |
| WO/2004/054872 | SELF-PROPELLING BARGE |
| WO/1999/051487 | A REMOTE-CONTROL DEVICE TO RELEASE LOCKS ON STACKS |
FREDBORG, Andreas, Jo, Falk (P.O. Box 683, Stord, N-5404, NO)
| A support structure for supporting loads placed essentially in a ship's deck area, the ship being provided with traverse stiffening structures, characterised in that when placed on board the ship the support structure has a longitudinal extent in the ship's longitudinal direction, a width extent in the ship's width direction and a height extent in the ship's height direction and that the support structure has a first connecting area for transmitting forces from the load to the support structure and a second connecting area for transmitting forces from the support structure to transverse stiffening structures arranged in the ship. A support structure according to claim 1, characterised in that the ship's transverse stiffening structures are composed of transverse bulkheads. A support structure according to claim 1, characterised in that a cross section of the support structure with orientation perpendicular to the support structure's longitudinal direction has a substantially square shape. A support structure according to claim 1 or 2, characterised in that it is composed of a lattice structure, truss structure or plate structure. A support structure according to one of the preceding patent claims, characterised in that the first connecting area is comprised of a number of receiving elements which are mounted to the support structure, each receiving element being arranged for support of at least a part of the load. A support structure according to one of the preceding patent claims, characterised in that a pipe rack constitutes at least a part of the support structure. A system comprising a support structure according to one of the preceding patent claims, characterised in that the support structure is placed on board the ship positioned in such a manner that the load in the ship's deck area is supported. A system according to claim 6, characterised in that a pipe rack constitutes at least a part of the load supported by the support structure. 9. A system according to one of the claims 6 or 7, characterised in that processing equipment modules constitute at least a part of the load. 10. A system according to one of the preceding patent claims 6-8, characterised in that the second connecting area is composed of arrangements for supporting the support structure mounted in the ship's transverse stiffening structure. 1 1. A system according to one of the preceding patent claims 6-9, characterised in that the support structure is designed in a continuous, discontinuous or partially continuous manner between two and two of the ship's transverse stiffening structures. 12. A system according to one of the preceding patent claims 6-10, characterised in that the support structure's neutral axis is positioned essentially in the ship's deck area. 13. A system according to one of the preceding patent claims 6-1 1, characterised in that at least a part of the load is composed of units where each unit has a mass which is between 1/400 and 1/20 of the ship's displacement. |
The invention relates to a support structure which supports equipment placed essentially in the ship's deck area. The support structure according to the invention can be used on ships without longitudinal internal bulkheads or inside a double hull. There may be different reasons for a ship being designed without longitudinal internal bulkheads. An example of ship without longitudinal internal bulkheads is a type of ship where the tanks for storing LNG are of a size which helps to increase the tank volume relative to the ship's displacement. The tanks can be dimensioned so as to extend over the whole width of the ship. By employing tanks with a large tank volume, the number of systems can be reduced.
A problem on ships without longitudinal internal bulkheads of the type described above is that the ship does not have sufficient strength to support equipment of a certain mass and stiffness in the deck area. An example of this type of equipment that may be mentioned here is process modules.
A processing plant is typically composed of different modules, each of which is intended for different tasks related to the process in question. The modules are advantageously placed in two rows along each side of the ship, so that the piping between the modules can be placed in a central pipe rack. According to the prior art the modules are normally supported by module supports. The module supports are mounted on reinforced points in the ship's deck. These reinforced points are in the form of internal bulkheads, in addition to transverse frames. The transverse frames alone can support a limited load, but are normally inadequate as a foundation for module supports bearing heavy process modules.
This prior art technique of supporting such process modules is adapted for ships which either have a longitudinal centre bulkhead, or other kinds of longitudinal internal bulkheads. The module supports are placed on transverse bulkheads or over longitudinal bulkheads in such a manner that the forces from the module support are transmitted to the greatest possible extent directly to the bulkhead below.
Other solutions consist in the use of a large number of points of support. The reac- tion forces in each point are then reduced, since the forces are distributed over several points. This requires the modules to have a low degree of stiffness, thereby preventing the module stiffness from producing constraining forces when the ship is deformed, for example in the event of sagging/hogging. Such solutions therefore require light modules, or modules which are constructed with only one level and are therefore pliant. If the reaction forces become sufficiently low, the transverse frames can thereby be employed as a support for module supports. These known solutions cannot be used on ships without internal longitudinal bulkheads, for example in the storage of heavy processing equipment, if the modules are too heavy and stiff to be supported on transverse frames alone.
It is an object of the present invention to provide sufficient support for equipment which has to be placed in the deck area and which will be suitable for use on ships which have no internal longitudinal bulkheads and/or where the modules are heavy and stiff. This is achieved by the support structure as indicated in the independent patent claim. Further embodiments of the invention are indicated in the dependent patent claims.
The support structure has a longitudinal extent, a width extent and a height extent which together form a three-dimensional body. When the support structure is placed on board the ship for supporting loads located essentially in a ship's deck area, the support structure is positioned with the longitudinal extent in the ship's longitudinal direction, the width extent in the ship's width direction and a height extent in the ship's height direction. The support structure may be composed of a longitudinal structural portion, a width structural portion and a height structural portion.
The load which has to be supported may be placed at the ship's deck level or at a distance above or below the deck level. The support structure is provided with a first connecting area for transmitting forces from the load to the support structure and a second connecting area for transmitting forces from the support structure to transverse stiffening structures provided in the ship.
The longitudinal support structure extends between the transverse stiffening structures provided in the ship. The transverse stiffening structures may be in the form of bulkheads or frames. They are usually provided as bulkheads. If the transverse stiff- ening structures are provided as frames, they will have a stronger structure than the ship's normal transverse frames. The frame structure may often be composed of modified bulkheads, i.e. bulkheads which are partially open.
A cross section of the support structure with orientation perpendicular to the support structure's longitudinal direction may be substantially square in shape, and the support structure may be in the form of a torsion box. The support structure's cross section may have different shapes, such as rectangular, circular or oval.
The support structure may be produced in different ways as an open structure or as a closed structure, for example in the form of a lattice structure, truss structure, plate structure or another type of structure in which the forces can be transmitted to the load via the first connecting area and on to the second connecting area of the ship's transverse stiffening structures. In an embodiment where a pipe rack is to be employed on board the ship, the pipe rack may be designed in such a manner that it forms the support structure, or the pipe rack may be designed so that it forms a part of the support structure.
The first connecting area may be provided in different ways, but in an embodiment it will comprise a receiving portion for supporting the load. Depending on how the support structure is designed, the receiving portion for transmitting the forces from the load may be designed in such a manner that the transmission either takes place as a point transmission or a more continuous transmission to the support structure. In an embodiment the first connecting area may comprise a number of receiving elements which are mounted or attached to the support structure. Each receiving element is arranged to support at least a part of the load and may be designed for receiving a transfer structure such as a support or module foot which bears the load and helps to transfer the load to each of the support structure's support elements as point load transfer. The receiving elements may be mounted along the support structure's longitudinal lateral edge.
When the support structure is placed on board the ship, positioned in such a manner that the load in the ship's deck area is supported, the support structure forms a part of a system together with the ship. In an embodiment the support structure's neutral axis may be positioned essentially in the ship's deck area.
In an embodiment of the invention the pipe rack forms at least a part of the load, which is supported by the support structure and the pipe rack, may be placed on top of the support structure. Furthermore, processing equipment modules may constitute at least a part of the load, possibly together with the pipe rack. The support structure is adapted to support other types of load or equipment than processing equipment modules and pipe racks. In an embodiment of the invention at least a part of the load is composed of units where each unit has a mass which is between 1/400 and 1/20 of the ship's displacement.
The ship's transverse stiffening structure may be designed with, for example recesses for support of the support structure. In an embodiment of the invention this arrangement may constitute the second connecting area, where a person skilled in the art will appreciate that other types of arrangements may also be employed for arranging the transmission of forces from the support structure to the ship's transverse stiffening structure.
The support structure may be designed in a continuous, discontinuous or partially continuous manner between two and two of the ship's transverse stiffening struc- tures. By a continuous support structure is meant that the height of the support structure in the transition between two transverse stiffening structures corresponds to the height of the support structure, thereby giving the support structure continuity in the longitudinal direction. In another embodiment, the height in the transition between one part of the support structure and the next may form a part of the support system's height extent between two of the ship's transverse stiffening structures, in which case the support structure is partially continuous. If the height extent in the transition between two parts of the support structure is zero between two of the ship's transverse stiffening structures, the support structure is discontinuous and 5 appears to be divided into two parts or more if the support structure is discontinuous at several points. The support structure may therefore extend continuously over all the ship's transverse stiffening structures or may be continuous, discontinuous or partially continuous between two and two of the ship's transverse stiffening structures, since each part of the support structure will extend over at least two transit) verse stiffening structures.
A continuously designed support structure is exposed to a greater portion of the ship's global stresses than a discontinuous support structure which behaves more independently of the ship's global deformation (hogging/sagging). Continuity in the support structure gives higher capacity of the actual support structure, but also re-
15 suits in stresses from the ship's deformations being transmitted to a greater extent to the longitudinal support structure. The ship's global bending stresses are highest near longitudinal bulkheads, particularly along the ship's side. The invention exploits this fact by placing the longitudinal support structure away from this area, for example at the centre of the ship, such that global bending stresses are not transmit- 0 ted to such a great extent to the support structure. This transmission can also be further reduced by making the longitudinal support structure discontinuous.
An example of an embodiment of the invention will now be explained with reference to the figures, in which;
Fig. 1 is a perspective view of the support structure mounted on the ship.
5 Fig. 2 is a cross sectional view of the support structure on board a ship stressed by a load from modular units.
Fig. 3 illustrates the support structure supporting a load from modular units, viewed in a longitudinal section of the ship.
The figures illustrate the support structure 1 arranged substantially centrally in a 0 ship 10 in such a manner that the support structure's 1 longitudinal axis is positioned coincident with the ship's longitudinal direction. The support structure's 1 cross section is essentially centred about the ship's longitudinal central axis.
The support structure 1 is composed of an elongated body with a longitudinal extent which coincides with the ship's longitudinal direction L. The cross section of the 5 elongated body extends in the ship's width direction B and the ship's height direction H. In the figures the support structure 1 is depicted as a three-dimensional box- shaped body composed of plate structures, an upper and lower plate structure la, lb extending in the ship's length L and width direction B and side plate structures lc, Id extending in the ship's length L and height direction H. In addition, the box- shaped support structure 1 may be equipped with internal plate structures le extending in a similar manner to the upper and lower plate structures la, lb in a position between the upper and lower plate structures la, lb. The support structure 1 also has internal plate structures If oriented perpendicular to the side and the upper/lower plate structures.
These plate structures If may be dimensioned so as to cover the whole or parts of the support structure's cross section.
As a person skilled in the art will understand, the support structure 1 may be designed with different cross sections than the square example illustrated in the figures, such as for example circular or oval. The support structure 1 may also be provided with additional plate structures oriented for stiffening if necessary. The support structure may be composed of structures other than plates within the scope of the invention. For example, a lattice structure or truss structure may be employed.
The support structure 1 is arranged to support loads from equipment such as the illustrated modular units 4, for example processing equipment modules, located in the ship's deck area. Forces from the load are transmitted in a first connecting area to the support structure 1. As illustrated in the embodiment in the figures, this first connecting area is comprised of receiving elements 2 which are provided protruding from the support structure 1 and arranged for receiving a load-transferring structure such as the illustrated support or the foot 6. In this embodiment external receiving elements 7 are also provided along the ship's lateral edges for receiving the foot points 5 of the modular unit which are oriented in this position when the load is placed on the ship. The receiving elements 2 are illustrated here protruding from the support structure's lateral surfaces lc, Id. The forces from the modular units 4 are then transmitted to the support structure 1 in dedicated point areas. The point areas may be in different positions from the illustrated protruding receiving elements 2, for example the load transfer may take place against the top of the support structure, illustrated here at upper plate structure 1 a. It is of course also possible to use another type of load transfer than point transfer, for example a continuous load transfer along the support structure's surfaces.
The support structure 1 has a second connecting area for transmitting force to the ship's transverse stiffening structure, illustrated here as transverse bulkhead 3. The support structure 1 may be connected to the ship's transverse stiffening structure by the transverse stiffening structures being designed to be suitable for supporting receipt of a portion of the support structure. In an embodiment this may be arranged as illustrated in the figures where the transverse bulkhead 3 has a recess for receiving and securing a lower portion of the support structure 1. The support structure may be located in different positions in the ship and in an embodiment may be positioned in such a manner that its neutral axis is located approximately at the ship's deck level.
In an embodiment a pipe rack 8 may form a part of the load that has to be supported by the support structure 1. Forces from the pipe rack 8 are then transmitted through the pipe rack's 8 contact points with the support structure's 1 top surface. In another embodiment the pipe rack 8 may constitute the actual support structure. In yet another embodiment the pipe rack may be integrated as a part of the support structure.
The support structure has a longitudinal extent which forms a part of the ship's length. In an embodiment the support structure may have a longitudinal extent where it extends from one transverse support structure, transverse bulkhead or frame to another. The support structure may of course also have an unbroken longitudinal extent, with the result that it extends over several transverse support structures as a continuous support structure. An example of a continuous support structure is illustrated between the transverse bulkheads 3a, 3b in figure 3. Several support structure parts in succession which are completely or partly separated from one another may also be used, thereby achieving a discontinuity or partial continuity in the arrangement. An example of a support structure which has partial continuity is illustrated between the double transverse bulkheads 3c and 3d.