US3851482A

US3851482A - Sectionalized leg for drilling platform and method of assembling same

Info

Publication number: US3851482A
Application number: US00363987A
Authority: US
Inventors: R Letourneau; C Hall
Original assignee: IHC Holland Letourneau Marine Corp
Current assignee: IHC Holland Letourneau Marine Corp
Priority date: 1973-05-25
Filing date: 1973-05-25
Publication date: 1974-12-03
Anticipated expiration: 1991-12-03

Abstract

A leg or spud structure for a jack-up-type offshore drilling platform has longitudinally separable sections of triangular or other polygonal cross-section, including longitudinal corner chords one or more carrying driving means. Joint structures separably secure together the pairs of abutting chords with the mating rack sections accurately aligned and timed.

Description

llnitecl States Patent [19 1 LeTourneau et a1.

I Assignee:

SECTIONALIZED LEG FOR DRILLING I PLATFORM AND METHOD OF ASSEMBLING SAME Inventors: Richard L. LeTourneau; Chester G.

Hall, both of Longview, Tex.

IHC Holland-Le Tourneau Marine Corporation, Kilgore, Tex.

Filed: May 25, 1973 Appl. No.: 363,987

US. Cl 61/465, 52/123, 52/637, 403/368 Int. Cl E0219 17/00 Field of Search 61/465; 52/123, 637, 638, 52/726; 403/368, 369, 370, 371; 182/178 References Cited UNITED STATES PATENTS 6/1959 Powell et a1. 403/370 1 Dec. 3, 1974 2,908,142 10/1959 Suderow 61/465 2,924,077 2/1960 LeTourneau 61/465 3,628,336 12/1971 Moore et a1. 61/465 Primary Examiner.lacob Shapiro Attorney, Agent, or FirmBertram H. Mann; Frank B. Pugsley [57] ABSTRACT A leg or spud structure for a jack-up-type offshore drilling platform has longitudinally separable sections of triangular or other polygonal cross-section, including longitudinal corner chords one or more carrying driving means. Joint structures separably secure together the pairs of abutting chords with the mating rack sections accurately aligned and timed.

11 Claims, 14 Drawing Figures SHEU IN 5 PAIENTEL DEE 3l974 SECTIONALIZED LEG FOR DRILLING PLATFORM AND METHOD OF ASSEMBLING SAME RELATED APPLICATION A jack-up and drilling platform generally embodying the present leg joint structure as well as other features is disclosed in copending application Ser. No. 297,225 filed Oct. 13, 1972, in the name of Richard L. LeTourneau.

BACKGROUND OF THE INVENTION a serious stability problem. The above-mentioned copending application discloses novel means for longitudinally sectioning the legs, for safely stowing dismantled leg sections upon the platform with minimum space requirement, and for reassemblying the legs at the drilling site. Of especial importance in such a concept are the joint means facilitating dismantling and reassembly of the legs, which maintain theleg sections firmly assembled during jack-up and drilling operations with the leg-manipulating racks carried by adjoining sections accurately aligned and with their teeth in uniform spaced and timed relationship, and which may pass freely through the leg wells without interference from the leg guides therein. Such longitudinally separable legs have not achieved substantial use in offshore drilling both because there has been no practical joint structures and no feasible way to handle and store the dismantled sections.

SUMMARY OF THE INVENTION In accordance with this invention, a leg assembly consists of truss-type sections of triangular or other polygonal cross-sectional shape have longitudinal structural chords at their corners, one or more having outwardly facing rack means, complementary chord and rack sections in the assembly being accurately aligned and with the rack teeth properly positioned for meshing BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings which illustrate the invention,

FIG. I is a side. view and partial section illustrating portions of a drilling platform and a spud or leg movably carried thereby. I FIG. 2 is an enlarged detail side view showing joined portions of the leg structure.

FIG. 3 is an elevation of joint mounting base plate I parts of FIG. 2, taken at to FIG. 2.

FIG. 4 is an end view of the structure in FIG. 2.

FIG. 5 is a still further enlarged elevation of the upper joint part.

FIG. 6 is an end view and section taken substantially on line 6-6 of FIG. 7. A

FIG. 7 is a view similar to FIG. 5 but showing the lower male joint portion.

FIG. 8 is an end view and section taken substantially on line 8-8 of FIG. 5.

FIG. 9 shows the joint structure of FIG. 2 viewed from the inside thereof.

FIG. 10 is a view of the assembled joint taken substantially on the vertical center line of the joint and also showing a pin applying and removing ram arrangement.

FIG. 11 is an end view of the pin and collet taken from the left side of FIG. 10, with cover 98 removed.

FIG. 12 is an enlarged horizontal section taken on line 1212 of FIG. 1.

FIG. 13 is a view of a portion of FIG. 10 taken from the right-hand side thereof.

FIG. 14 is an enlarged, schematic section of the assembled joint parts after removal of the assembling ra device.

DETAILED DESCRIPTION OF EXE'MPLARY EMBODIMENT FIG. 1 illustrates at A an edge portion of a drilling platform or hull having a leg well B through which extends'the lowermost section C of a truss-type leg or spud with separable leg sections C and D. Upper leg section D is joined to lower section C by joints, generally designated E and E A plurality of such legs or spuds are provided, as three or more, and each is equipped with elevating and lowering mechanisms, as at F and G, whereby the legs may be elevated to the marine transport position, with the enlarged bases I-I thereof received in recesses I in the bottom of the hull or platform. At the drilling site, mechanisms F and G lower the legs for planting on the bottom and thereafter for elevating the platform to the desired drilling height above the surface of the water. It will be obvious that these legs must be sufficiently massive and rugged to withstand immense compressive, bending, and twisting forces when supporting a heavy drilling platform and,

possibly, a long string of pipe or casing, above the water surface.

The spud legs preferably are triangular in crosssection each with three hollow structural chords of rectangular section, one at each corner (FIGS. 4, 6,

and 8).

Leg guides

10, 10a, 11, and 11a are positioned and 8) and 18-21 (FIG. 6) with adequate internal brac-' ing, not shown except for the diagonal base plates, as 22 and 23 at the joints, which areseparately shown in FIG. 3. Projecting outwardly at right angles to the base plates and diagonally of the chord sections are

rack sections

24 and 25, which are continuous in the assembly. Upper guides for the chords are provided at 10,

10a (FIG. 12) and at the bottoms of the leg wells, as at 11 and 11a in FIG. 1.

Projecting oppositely to lower rack section 25 (FIGS. 6 and 7) from'diagonal base plate 23 is a tongue forming web 30 of generally frusto-triangular configuration, except for its top edge (FIG. 7) which has a semicircular bulge or bay 31. A pair of

annular pads

32 and 33 are welded to web 30 coaxially with bulge 31, and the

central openings

34 and 35 therein are continued through web 30, as at 36 (FIG. 6). The

chord sides

20 and 21 are cut away as at 77 (FIGS. 2 and 7) to accommodate bracing members, as will be explained.

The complementary joint structure at the abutting end of upper chord section 12 (FIG. is, in general, similar to the structure of FIG. 7, except that a pair of ear-like webs or

lugs

37 and 38, forming a slot, project laterally from diagonal base plate 22, being welded thereto, and have semicircular bays or bulges, as 39, at their lower edges (FIG. 7). Annular reinforcing

pads

40, 41, 42, and 43 are welded to these webs or lugs concentrically on bays or bulges 39, and their

central openings

44, 45, 46, and 47 are continued through

webs

37 and 38, as at 48 and 49. The chord side walls 16 and 17 are cut away, as at 50, to accommodate reinforcing members, as will be described.

Diagonal base plates

22 and 23, in the ultimate assembly, have slight clearance between their adjacent ends and are provided, respectively, with interfitting longitudinal tongue and recess elements 51 and 52 (FIG. 3). These tongue and recess elements, in effect, form transversely disposed positioning shoulders disposed diagonally of the chord. A reinforcing flange 53 (FIG. 7) extends along the inclined inner edge of male joint web 30, while a transverse bracing plate 54 (FIG. 5) traverses the inner edges of female or slot

joint member webs

37 and 38.

In addition to the

structural corner chords

12, 13, etc., each leg truss is reinforced by sets of horizontal side members 57 and 58 (FIG. 4) merging at 60 degrees, other such sets of horizontal members being indicated in part at 59, 60, and 61 in FIG. 2. Short members as 62 and 63 (FIG. 9) join the merging horizontal side members somewhat inwardly of the corner chords, the intersections being reinforced by

gussets

64, 65, 66, and 67. Angled

braces

68 and 68a and their

opposite counterparts

69 and 69a extend from the intersections of these short members with

side members

57, 58 and 60, 60a to the intersections of female member flange 54 and fin 5.6 and male member flange 53 and fin 55. Angled members 70 and 70a extend from short member 62 to the intersection of female

joint member webs

37 and 38 and base plate 22, chord side wall 16 being cut away at 77 to accommodate these bracing members. Opposite bracing members 71 and 71a similarly extend from short member 63 to the intersections of male member base plate 23. All of the webs, plates, fins, and other members of the joint structure as well as the entire leg truss, of course, are strongly welded together.

FIG. shows the fully assembled joint, with the complementary joint members firmly secured together by locking cone or pin means including a circumferentially split or sectioned, internally tapered collet 72 held assembled by retainer rings 82, and a massive tapered pin or cone 73. The pin is driven home so as to eliminate all play or looseness in the joint by means of a hydraulic ram motor including a cylinder 74 having suitable hydraulic pressure connections, as at 74a, and control valving (not shown) and enclosing a piston and piston rod 75. In use of the tool, rod 75 is pinned at 76 to an eye at the adjacent end of a bolt 78 extending axially through tapered pin 73. Ram-

motor

74, 75 has lateral arms 74b (FIGS. 10 and 13) seated in recesses 79 in the side walls of a cradle 80 which is detachably secured to the exposed face of the corresponding female joint member by means of lugs on the joint received in clevises 96 on the cradle and locked by pins 97 (FIG. 13). A pinion lever 84 and rack 85 engaging the collet are provided for starting the pin means while the pin means is finally driven home by the ram motor bearing against the tapered'pin 73, as will be' e xplained. After the ram motor and cradle are removed (FIG. 14), a protective cap 98 is applied over the small end of the pin and a locking plate 99 and a cotter key 100 cooperate with castellated nut 81 to prevent inadvertent loosening of the pin. The cradle will be removed after use. When the cradle is removed, the large end of the pin may be covered by the key plate or hood 101 (FIG. 14) having lateral ears, corresponding to ears 96 in FIG. 13, for securement to joint lugs 95. The cover has internal ears 102 for securement to perforated lug 76 on bolt 78 to further resist turning and loosening of the bolt.

OPERATION The procedure for connecting the leg sections is as follows: With an upper leg section supported above a lower section the joint tongue and slot are interfitted and substantially aligned. Cradle 80, bearing the ram motor and a pin and collet assembly in retracted position, is pinned to the exposed face of female joint ear pad 43 (FIGS. 10 and 13) with the free end of the pin and collet assembly started in the hole therein and rack 85 engaging the collet end face. The rack is driven leftwardly by rotation of handle lever 84 to cause full seating of the greased collet and pin assembly in the aligned holes, the collet, of course, being collapsed to permit this, since the holes probably will be slightly out of register. The ram motor is then operated to drive the pin fully home causing the collet to expand to fit tightly in the joint holes enforcing exact registry thereof to insure an accurate, timed relationship of the chord and rack sections. The ram motor is now disconnected from bolt eye 76a, the cradle is unpinned from joint ear pad 43, and the cradle and ram are moved to another joint or to storage. Finally, covers 98 and 101 are secured over the ends of the pin as protectors and grease retainers.

Interfitting tongue and

recess

51 and 52 in

joint base plates

22 and 23 firmly maintain proper centering of the joint parts diagonally of the abutting chord sections, while the aggregate of all assembled joint elements otherwise maintain the leg sections properly aligned as well as strongly joined.

It is contemplated that the joint parts will be properly positioned during construction. To achieve this, with the legs aligned, the joint parts will be temporarily welded together, as by use of the web extension 86 in FIG. 2. Preferably, the adjacent ends of

base plates

22 and 23 will be slightly spaced apart by shims. The holes through the joint ears will then be drilled in alignment and the racks will be welded to the aligned chords in their accurately timed positions. Thus, accurate positioning of the leg sections and racks is assured whenever the complementary joint ears are pinned together,

as in FIG. 10. Usually there will be slight disalignment of the joint holes when the leg sections are brought together, but the collapsed condition of the split collet will permit its full insertion for later tightening by full seating of the tapered pin in the joint holes.

To separate the leg sections, the protective covers will be removed and the cradle with the ram motor will be pinned to the joint and piston rod 75 pinned to bolt eye 76a. The ram motor is energized reversely to withdraw pin 73 and the collapsed collet.

In an exemplary embodiment in which the overall length of legs was 43l feet plus, the joint members were correspondingly massive. For instance, the diagonal

base plate elements

22 and 23 each was 8 /2 feet long and approximately 35 inches wide, and the male and female joint members each was 6 feet long and the registering apertures in the joint members were approximately 16 inches in diameter. Consequently, the massive joint structure disclosed is well-adapted to securely interconnect separable leg sections and may be manipulated, particularly with the use of hydraulic ram or motor means, as disclosed, for assembling and disas-v sembling the leg sections. An important advantage of the joint structure shown is that it avoids the necessity of lifting the upper joint section and the entire platform, during disassembly of the leg sections. Rather, disassembly involves simple removal of a pin and sideward movement of the unpinned upper section. In assembly the upper leg section is lifted to the proper elevation, then shifted horizontally to bring the pin holes into substantial alignment.

The invention may be modified in various respects as will occur to those skilled in the art; for instance, certain features may be utilized with different types of legs and drive mechanisms. Exclusive use of all modifications as come within the scope of the appended claims is contemplated.

We claim: A

l. A leg structure for a jack-up-type drilling platform comprising a plurality of aligned, longitudinally and laterally separable sections, lifting and lowering means on abutting leg sections, and separable joint means on said abutting sections capable of securing said abutting sections in alignment with said lifting and lowering means in accurately timed relationship.

2. A leg structure as described in claim 1 in which said lifting and lowering means comprises a rack section on each leg section.

3.A leg structure as described in claim 2 including a plurality of pairs of longitudinal chords, said joint means being adapted to secure each of said pairs in aligned end-toend relationship.

4. A leg structure as described in claim l in which said joint means comprises overlapping apertured parts respectively on adjacent ends of said leg sections and pin means securing said overlapping parts together and in accurate alignment.

5. A leg structure as described in claim 2 further including interengaging transversely facing shoulder means on each of said leg sections for accurately positioning and aligning the respective rack pairs.

6. A leg assembly for a jack-up-type drilling platform comprising a truss having longitudinally separable sections each with a plurality of longitudinal chords with a rack sections projecting therefrom, complementary chords of adjoined sections having abutting parts each with a base plate at 90 degrees to the corresponding rack section, apertured webs projecting laterally from said plate and oppositely of said rack section, the webs of abutting complementary chords having registering apertures, and pin means inserted in the registering web apertures to secure together corresponding pairs of chords with corresponding pairs of rack sections accurately aligned and timed.

7. A leg structure as described in claim 6 in which said base plates are disposed end-to-end in the assembly and further include interfitting tongue and groove elements for insuring alignment of the corresponding rack sections transversely of the rack teeth, said pin means maintaining alignment and timing of the connected pairs of rack sections longitudinally of the rack teeth.

8. A leg structure as described in claim 6 in which the pin means for each set of apertured webs comprises a radially expansible, internally tapered collet fitting within the registering leg apertures and a tapered pin received in said collet for rigidly securing together the pairs of chords and racks.

9. A leg structure of the type used in jack-up drilling barges comprising longitudinally separable sections, joint means connecting said sections including overlapping tongue and slot members with aligned apertures, a pin for joining said members, a removable support projecting from an exposed face of one of said sections adjacent said members, a ram motor on said support, and means for connecting said motor to said pin to enforce insertion of said pin in said apertures and alignment of the leg sections for bringing the same into accurate alignment in assembly and for withdrawal of said pin from said apertures in disassembly.

10. Leg structure as described in claim 9 further including a split collet encompassing said pin, the engaging surfaces of said pin and collet being tapered, the exterior of said collet, when collapsed about said pin, being of less diameter than the interior of said aligned apertures to permit insertion of the pin and collet ase. energizing said power means to drive the pin home.

Claims

1. A leg structure for a jack-up-type drilling platform comprising a plurality of aligned, longitudinally and laterally separable sections, lifting and lowering means on abutting leg sections, and separable joint means on said abutting sections capable of securing said abutting sections in alignment with said lifting and lowering means in accurately timed relationship.

3. A leg structure as described in claim 2 including a plurality of pairs of longitudinal chords, said joint means being adapted to secure each of said pairs in aligned end-to-end relationship.

4. A leg structure as described in claim 1 in which said joint means comprises overlapping apertured parts respectively on adjacent ends of said leg sections and pin means securing said overlapping parts together and in accurate alignment.

10. Leg structure as described in claim 9 further including a split collet encompassing said pin, the engaging surfaces of said pin and collet being tapered, the exterior of said collet, when collapsed about said pin, being of less diameter than the interior of said aligned apertures to permit insertion of the pin and collet assembly in said apertures, even though slightly disaligned, for bringing the same into alignment.

11. The method of assembling the separable sections of a spud leg having pin and slot joint parts with apertures and with a connecting pin which comprises a. placing the leg sections substantially in their aligned, assembled relationship; b. mounting a cradle adjacent said joint parts; c. mounting power means on said cradle; d. sUpporting said pin on said cradle between said power means and said apertures; and e. energizing said power means to drive the pin home.