US2817212A - Method for erecting and dismantling support structure - Google Patents

Description

Dec. 24, 1957 H. F. STUBBS 2,317,212

METHOD FOR ERECTING AND DISMANTLING SUPPORT STRUCTURE Filed Oct. 25, 1954 3 Sheets-Sheet l Hen/"y f. Jzubbs INVENTOR.

ATTORNEYJ H. F. STUBBS Dec. 24, 1957 METHOD FOR ERECTING AND DISMANTLING SUPPORT STRUCTURE Filed Oct. 25, 1954 3 Sheets-Sheet 2 INYENTOR. B 5 v /1 I 7' IATTORNEVJ Jfubbs Henry F Dec. 24, 1957 H. F. STUBBS 2,817,212

METHOD FOR ERECTING AND DISMANTLING SUPPORT STRUCTURE Filed Oct. 25, 1954 3 Sheets-Sheet 3 Henry Jzubba INVENTOR.

A TTORNE Y6 2,817,212 Patented Dec. 24, 1957 ice METHOD FOR ERECTING AND DISMANTLING SUPPORT STRUCTURE Application October 25, 1954, Serial No. 464,532

4 Claims. (Cl. 61-465) This invention relates to a method and apparatus for transferring a platform or like structure from a floating support on which it may be transported to a desired fixed location to fixed supports projecting from a body of water at such desired fixed location.

The transportation or a prefabricated structure such as a platform of the character employed in the drilling of wells from a land base to a desired location over a body of water by placing it on a floating structure such as a barge and transporting it to the desired location is one which has been both proposed and practiced in the past. However, when the proposed fixed location is one which is on open water which is subject to substantial wave action great difliculty has been experienced in accomplishing the transfer from the floating support to fixed supports such as pilings or caissons because of the tendency of the floating support to slap and pound against the structure as it is lifted slowly from the floating support onto the fixed supports. Various means have been devised for preventing destruction or damage to the floating barge structure or to the platform or the like because of such wave action but none has heretofore proven entirely satisfactory. It is an object of this invention to provide a method of and apparatus for elfecting the transfer of such structures from floating barge supports to fixed supports or vice versa with the elimination of substantially all of the slapping or pounding resulting from wave action in the course of such transfer.

Another object of this invention is to provide such an apparatus which will yield to the force of excessive wave action to permit some movement between the floating barge structure and the platform or the like during the course of the transfer but which will resist such movement with a force great enough to prevent damaging contact between the parts due to such wave action.

Another object of this invention is to provide such an apparatus into which safety factors are built such as will prevent the excessive stressing of the apparatus due to wave action yet which will provide at all times for a maximum of resistance to wave action and thus to the maximum of resistance to the destructive effect of wave action.

Further objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein it is set forth by way of illustration and example one embodiment of this invention.

In the drawings:

Fig. 1 shows a side view of a barge structure on which is supported a platform which is about to be transferred from the barge structure to the fixed supports illustrated by means of the method and apparatus of this invention.

Fig. 2 is a similar view showing the next step in carrying out the method of this invention.

Fig. 3 is a top plan view of the structure illustrated in Figs. 1 and 2.

Fig. 4 is a fragmentary view illustrating the hydraulic jack structure forming a part of the apparatus of this inventlon.

Fig. 5 is a fragmentary structure in top plan view taken on the line 5-5 of Fig. 4 illustrating the connection between the hydraulic jack structure of Fig. 4 and the tension support members forming another part of the apparatus of this invention.

Fig. 6 is a fragmentary elevational view of a guide and contact member adapted to be placed on a portion of the platform to engage with the tension member which forms a part of this invention.

Fig. 7 is a diagrammatic view of the hydraulic system whereby the hydraulic jack structure illustrated in Figs. 1 to 4, inclusive, may be operated.

Referring now more in detail to the drawings, there is illustrated in Fig. 1 in side elevation the position of the various apparatus including the barge structure and platform in the position which it occupies just before the beginning of the operation of shifting the platform from the barge structure to the fixed supports.

The barge structure is illustrated at 1 and by reference to Fig. 3, which is a plan view of the same structure, it will be seen that in this instance there are employed two barges 1 and 2. On these barge structures is mounted the platform 3 which has structural beams 4, 5 and 6 forming a part thereof and extending transversely so that their respective ends overlie the barges 1 and 2. Underneath the central structural beam 6 is an additional portion 7 extending downwardly therefrom for a purpose presently to be described.

The end portions of the structural beams 4, 5 and 6, the latter through the downward extension 7, are adapted to rest respectively upon block supports 8, 9 and 10 upon the upper decks or surfaces .of barges 1 and 2. During the transportation of the platform on these barges from the base to the intended location of the platform these structural beam members 4, 5 and 6 are preferably secured to the barge by any suitable securing means.

Upon the platform 3 there may be carried any desired apparatus to be used on the platform after it is located in its fixed position, an example of such being the derrick structure 11.

In the particular apparatus illustrated it is intended that the fixed supports 12 in the form of caissons will be supported in upright position from the platform during the operation of transporting to the desired location. When located in the position desired these supports 12 will be lowered into engagement with the earth and caused to firmly imbed themselves in the earth in any suitable fashion until they provide a substantially fixed support projecting above the surface of the body of water upon which the barge structure floats.

The platform 3 also preferably carries suitable means 13 for engaging the supports 12 to hold the platform against downward movement with respect to the supports 12 and either incorporated in the same structure or in a different structure there is further provided a means whereby the platform may be raised or lowered with respect to the respective supports 12.

As shown in Fig. 3, each of the barges is provided with suitable anchor cables 14 so that it may be accurately and fairly fixedly positioned in the desired location where the platform is to be erected.

In accordance with this invention, each of the barges is provided with a pair of support structures 15 and 16 adjacent its opposite ends, these preferably being fabricated from suitable metal shapes and of suflicient strength to bear the loads hereinafter described. Near the top of each of these support structures is a roller or pulley 17 and 18, respectively, and one or more tension members 19 are passed over these pulleys 17 and 18 and permitted to extend between the support structures and 16 to provide a sort of sling or catenary. The cables 19 may be of a type woven so as to be somewhat flat instead of round in order to rovide a greater bearing surface on the pulleys 17 and 18 and against the load to be supported, although round cables may be employed if desired so long as they provide adequate load bearing surface.

At their opposite ends each of the cables 19 is connected to a piston rod 20 which forms part of a hydraulic jack. This piston rod 20 in each case carries on its opposite end a piston 21 which is located within a cylinder 22. The cylinders 22 are each anchored by means of pivot ins '23 in engagement with fixed brackets 24 on the barge.

Thus, it will be seen that an actuation of the hydraulic jacks just described in a direction to pull the piston rods 20 into the cylinders 22 will result in increasing the tension on the tension members 19 and as shown in Figs. 1 and 2 this will cause an upward force to be exerted on the platform tending to separate the platform and the barge.

The end of each cylinder 22 through which the rod 20 extends is provided with a cylinder head 25 held in place by means of studs 26 having nuts 27 and 28 on their opposite ends. It will be appreciated that any suitable means for securing the cylinder head 25 in place may be employed, the particular means forming no part of this invention.

A suitable seal is likewise provided between the cylinder head 25 and the end of the cylinder 22 such as the seal ring 29, and a stuffing box having packing 30 is formed in the cylinder head around the piston rod 20, the same adapted to be tightened into sealing engagement by means of a gland 31.

Each cylinder is provided with an inlet connection 32 and an outlet connection 33 for the purpose presently to be set forth.

The connection between the piston rods 20 and the respective cables 19 is illustrated more in detail in Figs. 4 and 5. In these figures it will be seen that the end of the piston rod is bifurcated at 34 and provided with a pivot pin 35 which passes through the bifurcated ends of the rod 20 and through clamping plates 36 and 37 which are provided with holes registering with each other and with the holes in the bifurcated ends 34 for the purpose of receiving the pin 35.

Each of the cable ends is formed with a loop 38 which passes around a rod 39 and the end of the cable is then doubled back upon itself and held in such position by simple means such as the bolts 40. The clamping . plates 36 and 37 are then clamped against the looped portion of the cables closely adjacent the part which passes around the pin 39 and tightened against each other with the looped portion of the cable between them by means of bolts or the like 41. Thus, it will be seen that a secure yet flexible connection is made between the ends of the cables 19 and the pistonrods 20, respectively.

Referring to Figs. 1, 2 and 6, it will be seen that the cables 19 pass underneath the fabricated beams 4, 5 and 6 so as to exert force upwardly against such beams and against the platform structure as a Whole when tension is placed on the cables. In order to prevent the sharp edges of the beams 4 and 5 from breaking or cutting the cables, the edges of these fabricated beams, where the cables engage the same at their outer corners, are provided with rounded guards 42 so that the cables will encounter the rounded guards and not be forced to take a sharp bend.

Referring now to Fig. 7, there is illustrated the diagram for the hydraulic fluid system for the hydraulic jacks formed by the piston rods 20, the pistons 21 and the cylinders 22. While only one jack is illustrated in Fig. 7, it will be appreciated that preferably the jacks on the opposite ends of a single cable system will be connected in parallel so that they will act simultaneously and under identical pressures.

Referring more in detail to Fig. 7, it will be seen that the system includes a pressure vessel 43 which is actually an accumulator in whichhydraulic fluid under pressure is stored to keep the vessel partly full so that it may receive additional hydraulic fluid under certain circumstances and feed out hydraulic fluid under other circumstances. This vessel is preferably provided with a safety or relief valve 44 at its upper end which limits the maximum pressure to which the vessel may be subjected without relief, and a drain cock 45 at the lower end.

The pressure vessel 43 is charged with hydraulic fluid from an open reservoir 46 by means of pum 47 which pumps fluid to the pressure vessel 43 through a liquid level control 48. Preferably this line also has a shut-off valve 49 therein for use when desired. The liquid level controller 48 will be set so as to open and permit the entry of hydraulic fluid into the vessel 43 whenever the level in this vessel falls below a predetermined minimum.

A second liquid level controller 50 is provided in a line 51 leading from a somewhat higher point on the pressure vessel 43 to the open fluid reservoir 46, so as to release fluid from the pressure vessel 43 into the reservoir 46 whenever the liquid level in the vessel 43 tends to exceed a predetermined maximum height. Preferably this line 51 also has a shut-oil? valve 52 incorporated therein for use when desired.

A suitable source of compressed air at a pressure in excess of that which is the minimum required for the actuation of the jacks is indicated at 53 and this source of compressed air is connected through a pressure regulator 54 and a one-way or check valve 55 to the upper end of the vessel 43 whereby the upper end of the vessel 43 may be pressured with a supply of compressed air to such pressure as may be desired. This pressure is maintained by means of the regulator 54. Preferably this line likewise will .have incorporated therein a shut-off valve or cook 56.

Through a branch line from its outlet the pump 47 is adapted also to supply fluid through a check valve 57 to the inlet fitting 32 of the cylinder 22. Thus, this pump can be employed to actuate the jack in a direction to place tension on the cables 19 without use of the pressure vessel 43, but it will be appreciated that the rate of application of such pressure fluid to the cylinder by means of the pump 47 directly will be less than that which may be had by use of the pressure vessel 43 in the manner now to be described.

In the use of the pressure vessel 43 for the purpose just mentioned, it is provided with a connection in the form of a pipe 58 of much larger diameter than that leading from the pump 47 to the cylinder 22 so that fluid may flow very rapidly from the lower end of the pressure vessel 43 through the pipe 58 and the check valve 59 to the inlet fitting 32 of the cylinder 22. This line 58 preferably has a shut-off valve 60 incorporated therein.

It will be seen that in order to provide a pump 47 of sufiicient capacity to take up quickly any slack in the cables 19, would require a quite expensive installation. However, by providing the pressure vessel 43 having pressure sufllcient to force fluid into the cylinder 22 and take up such slack and by providing a large flow line 58 for this purpose, any slack in the cable 19 will be very quickly taken up without necessity for an expensive pump installation of large capacity.

In order to provide for relief of pressure fluid from the cylinder 22 in the event that the stress on the cable 19 becomes excessive at any time, there is connected to the outlet fitting 33 of the cylinder 22 a line 61 in which is incorporated a relief valve 62 preset for the desired pressure at which such relief may be had. Incorporated also in this line there is preferably a restriction in the form of an orifice member 63 so that even when the relief valve 62 opens under excessive pressure the rate of flow from the cylinder 22 will be restricted and hence the rate of slacking off on the cable 19 will likewise be held down.

In order to provide against the possibility of the force against the cable by virtue of wave action or the like becoming higher at a faster rate than can be accommodated through the orifice 63, there is provided a third line 64 which is likewise connected to the outlet 33 of the cylinder 22 and which has incorporated in it a relief valve 65 which would be set at some higher value than that for the relief valve 62. The line 64 has no restriction in it, however, and when the relief valve 65 opens very rapid flow will be permitted from the cylinder 22 through the line 64 to the pressure vessel 43.

In order to provide for releasing the hydraulic fluid from the space above the piston 21 so as to permit the entire force to be relieved from the cable 19, there is provided a return line 66 from the intake fitting 32 of the cylinder 22 leading back to the atmospheric reservoir 46. Incorporated in this line is a manually controlled valve 67 which will be closed at all times except when pressure fluid is to be released from the interior of the cylinder as just described.

In order to provide for the draining of any hydraulic fluid which may accumulate in the lower end of the cylinder 22 and to provide for assisting in the movement of ,the piston 21 upwardly within the cylinder 22 when tension on the cable 19 is to be released, there is provided a three-way valve 68 adapted to be operated manually and connected by means of a line 69 to the lowermost point of the cylinder 22. This three-way valve is so connected that in one position it will provide communication between the line 69 leading to the lower end of the cylinder 22 and the line 66 leading to the open atmospheric reservoir 46. When in this position fluid will be drained from the cylinder 22 into the reservoir 46. In another of its positions the valve 68 is adapted to provide communication between the line 69 leading to the lower end of the cylinder 22 and a compressed air line 70 communicating with the source of compressed air 53 heretofore mentioned. This compressed air line 70 preferably has incorporated therein a manually controlled cutofi' valve 71. When the manually controlled cutoff valve 71 is open and the valve 68 is so positioned as to provide communication between the line 70 and the line 69, air under pressure will be forced into the lower end of the cylinder 22 thereby forcing the piston 21 upwardly and assisting in the back flow of liquid through the line 66 to the reservoir 46 so as to release all tension on the cable 19.

In operation, the equipment illustrated in Fig. 1 will be towed to the position where the platform 3 is to be positioned for use, and the supports are lowered into engagement with the earth below the water and caused to engage the earth in such manner as to provide adequate support for the platform 3. The barges 1 and 2 will then have water admitted to them so as to somewhat decrease their buoyancy and hence the tendency of the wave action to cause the barges to bob up and down. The holding devices 13 are then set so that upon further lowering of the barges 1 the platform 3 will be supported on the supports 12. The barges will then be flooded until they have a buoyancy only slightly more than enough to support the barges themselves in the water. At a minimum this flooding should be sufficient so that the reduced buoyancy of the barges will approach the weight of the platform. As the weight of the platform tends to become equalized the truss or beam ends of the beams 4, 5, 6 and 7 will be dis connected from the barges and pressure will be applied to the tension cylinders 22 so as to place tension upon the cables 19, thus having the eflect of applying a force tending to force the barges and the platform apart. This force will naturally have the tendency to separate the barges from the platform, lifting the platform from the blocking 8, 9 and 10 which can then be removed. Tension will be maintained, however, on the cables 19 so that the wave action on the barges will be prevented from moving the barges upwardly to the extent that they would hammer against the platform. In the event the wave action should become so great as in the case of a wave with a high crest, that the tension on the cable 19 increases to a dangerous point, the hydraulic fluid will be released from these cylinders at a restricted rate through the relief valves 62 and the orifice fittings 63. In the event this rate of release is insufficient to keep the pressure within the cylinders 22 and the tension on the cable 19 within reasonable limits, the relief valve 55 will open and permit a much more rapid release of the hydraulic fluid from the cylinders 22. In either event, however, the back pressure will remain on the hydraulic fluid within the cylinders 22 and they will thus continue to apply a great force tending to separate the barges and platform or rather to keep them separated.

If it be assumed that a high wave crest has acted in the manner just described and has caused the pistons within the cylinders 22 to move upwardly towards the upper ends of these cylinders a considerable distance, then when the crest of such Wave passes the barge will tend to drop rapidly away from the platform. In order to take up the slack on the cables and prevent the barge from becoming freed from the platform prematurely, the pressure reservoir 43 then comes into action and feeds hydraulic fluid very rapidly through the line 58 and check valve 59 into the upper end of the cylinders.

When it becomes desirable to release the tension on the cables 19, this is accomplished by opening the valve 67 and permitting the fluid Within the upper end of the cylinders to flow back through the line 66 to the reservoir 46.

However, after the barge has had its buoyancy reduced in the manner and to the degree above mentioned, in order to avoid the possibility that it might be thrown upwardly against the platform by wave action before it could be removed from beneath the platform, the platform is preferably elevated by the elevating means engaged with the supports 12 as hereinbefore described. This elevation of the barge will take place while the tautness of the cables 19 is maintained to provide the shock absorber ac tion above described. When the platform has attained a height such that it stands above the upper surface of the barge by a distance greater than the prevailing wave action, the pressure within the cylinders 22 may be relieved thereby relieving the tension on the cables 19 and permitting the barges to float free of the platform. They may then be warped out from under the truss ends 4, 5 and 6 and disconnected from the platform completely.

Transfer of the platform from the fixed supports 12 to the barges for relocation elsewhere is accomplished by a reverse of the operation just described.

It will be seen from the foregoing that a method and apparatus have been provided which are fully capable of accomplishing all of the objects and advantages sought by this invention.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the appa ratus.

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.

The invention having been described what is claimed is:

1. The method of transferring a platform in the presence of wave action from blocks on a barge structure floating on a body of water to fixed supports projecting above the surface of said body of water, which method comprises securing the platform to said supports against taining said yieldable force until said platform is a distance above said barge structure greater than the prevailing wave height, discontinuing said yieldable force, and removing said barge structure.

2. The method of transferring a platform in the presence of wave action from blocks on a barge structure floating on a body of water to fixed supports projecting above the surface of said body of water, which comprises securing the platform to said supports against downward movement with respect thereto, exerting a predetermined yieldable force less than the weight of the platform between said platform and barge structure tending to separate them, reducing the buoyancy of the barge structure to a value just above the weight of the barge to cause said blocks to separate from said platform under the influence of said yieldable force, removing the blocks, raising the platform by exerting a force between said platform and said fixed supports while maintaining said yieldable force until said platform is a distance above said barge structure greater than the prevailing wave height, discontinuing said yieldable force, and removing said barge structure.

3. The method of transferring a platform in the presence of Wave action from blocks on a barge structure floating on a body of water to fixed supports projecting above the surface of said body of water, which method comprises securing the platform to said supports against downward movement with respect thereto, exerting a predetermined yieldable force less than the weight of the platform between said platform and said barge structure tending to separate them, reducing the buoyancy of the barge structure by a minimum of substantially the weight of the platform to cause said blocks to separate from said platform under the influence of said yieldable force, removing the blocks, resisting up to a predetermined maximum force the tendency of said barge structure to move upwardly under wave action towards said platform before permitting such movement, raising the platform by exerting force between said platform and said fixed supports while maintaining said yieldable force until said platform is a distance above said barge structure greater than the prevailing wave height, discontinuing said yieldable force, and removing said barge structure.

4. The method of transferring a platform in the presence of wave action from blocks on a barge structure floating on a body of water to fixed supports projecting above the surface of said body of water, which method comprises securing the platform to said supports against downward movement with respect thereto, exerting a predetermined yieldable force less than the weight of the platform between said platform and said barge structure tending to separate them, reducing the buoyancy of the barge structure by a minimum of substantially the weight of the platform to cause said blocks to separate from said platform under the influence of said yieldable force, removing the blocks, resisting up to a predetermined first maximum force the tendency of said barge structure to move upwardly under Wave action towards said platform before permitting such movement and resisting up to a predetermined greater maximum force the tendency of said barge structure to move upwardly under Wave action towards said platform at greater than a predetermined rate, raising the platform by exerting force between said platform and said fixed supports While maintaining said yieldable force until said platform is a distance above said barge structure greater than the prevailing wave height, discontinuing said yieldable force, and removing said barge structure.

References Cited in the file of this patent UNITED STATES PATENTS 2,334,992 Crake Nov. 23, 1943 2,352,370 Carruthers June 27, 1944 2,581,098 Guenzel Jan. 1, 1952 2,598,329 Vilson May 27, 1952 2,603,068 Wilson July 15, 1952 2,657,540 Templeton Nov. 3, 1953 2,677,238 Greer May 4, 1954 2,692,660 Good et a1 Oct. 26, 1954 2,771,747 Rechtin Nov. 27, 1956

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