US3805834A

US3805834A - Double counterbalanced marine loading arm

Info

Publication number: US3805834A
Authority: US
Inventors: P Bily
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1970-11-16
Filing date: 1970-11-16
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23
Also published as: NL7109074A; FR2113851A1; JPS559360B1; FR2113851B1; GB1362059A

Abstract

A double counterbalanced fluid transferring apparatus of the marine loading arm type, including a vertical riser section, an intermediate arm section extending from a pivotal mounting at the riser section, an inboard arm section pivotally connected to the intermediate arm section, an outboard arm section pivotally connected to the inboard arm section, a supporting boom pivotally mounted at the riser section and extending beneath the inboard arm section to a pivotal connection to the outboard arm section, a primary counterbalancing assembly for counterbalancing the arm and boom about a horizontal axis through the riser, and a secondary counterbalancing assembly for counterbalancing the outboard arm section when out of a vertical position and providing counterweight assistance to the primary counterbalancing assembly. A power system for maneuvering the arm about horizontal and vertical axes also is disclosed.

Description

United States Patent .9. Bily DOUBLE COUNTERBALANCED MARINE LOADING ARM [75] Inventor: Peter J. Bily, Sunset Beach, Calif.

[73] Assignee: FMC Corporation, San Jose, Calif.

[22] Filed: Nov. 16, 1970 [21] Appl. No.: 89,917

[451 Apr.-23, 1974 Primary Examiner-Robert G. Nilson Attorney, Agent, or Firm--W. W. Ritt, Jr.; C. E. Tripp 5 7 ABSTRACT A double counterbalanced fluid transferring apparatus of the marine loading arm type, including a vertical riser section, an intermediate arm section extending from a pivotal mounting at the riser section, an inboard arm section pivotally connected to the intermediate arm section, an outboard arm section pivotally connected to the inboard arm section, a supporting boom pivotally mounted at the riser section and extending beneath the inboard arm section to a pivotal connection to theoutboard arm section, a primary counterbalancing assembly for counterbalancing the arm and boom about a horizontal axis through the riser, and a secondary counterbalancing assembly for counterbalancing the outboard arm section when out of a vertical position and providing counterweight as-,

sistance to the primary counterbalancing assembly. A

power system for maneuvering the arm about horizontal and vertical axes also is disclosed.

13 Claims, 7 Drawing Figures DOUBLE COUNTERBALANCED MARINE LOADING ARM BACKGROUND OF THE INVENTION The field of art to which the present invention pertains includes marine loading arms for transferring fluid between a wharf and a vessel floating alongside, such as a cargo of petroleum or petroleum products into or from a marine tanker. In a more specific sense, the present invention involves that field of art disclosing double counterbalanced marine loading arms provided with a power system for maneuvering the arm about horizontal and vertical axes.

The advent of transporting petroleum and other fluid cargoes in marine supertankers of 250,000 dead-weight tons or more has created a demand for greatly increased speed and efficiency in loading and unloading these huge vessels in order to keep their profitdepleting wharf-side time to a minimum. Marine loading arms, generally comprising a plurality of rigid tubular conduits pivotally interconnected by pipe swivel joints and mounted on an upright riser conduit on a wharf or pier, have been found most'suitable for this purpose. but reaching the manifolds on these vessels and transferring the maximum volume of fluid in the shortest possible time period sometimes requires loading arms having a reach of up to 100 feet and fluid conduits of 24 inches in diameter. Loading arms of these dimensions are huge in size, ranging upwards of 100,000 pounds in weight including the required counterbalances and hydraulic power systems, and arms of such great weights require unusually sturdy foundations for their support. All this adds'up to increased costs, and a commensurate increase in demand for ways to cut these costs without sacrifice in operational efficiency.

Of the several types of marine loading arms available at this time, the double counterbalanced style has been found to be most desirable when large capacities and reach are required. This style of arm is easier to counterbalance accurately, and it can be constructed in various configurations to meet many requirements. However, the weight of the counterbalancing mechanisms consitiutes a very significant portion of the total weight of the entire arm structure, and every pound tied up in counterweights is non-functional as far as transferring the fluid is concerned. In the present day double counterbalanced arms both the primary and secondary counterweights are mounted for pivotal movement about a common horizontal axis at the riser, thereby requiring a substantially pound-for-pound ratio of counterweight to loading arm to achieve total counterbalance.

Another undesirable feature of many conventional doublecounterbalanced loading arms is; the rather elaborate mechanisms utilized to transfer the moment exerted by the outboard arm section about its pivotal axis back to the secondary counterbalancing system. Not only are these mechanisms a significant cost item, they also add appreciably to the overall weight of the apparatus.

SUMMARY OF THE INVENTION The present invention solves the foregoing problems associated with double counterbalanced marine loading arms by mounting the secondary counterbalancing system on the primary counterweights supporting structure at a point significantly behind the arms horizontal pivot axis at the riser, providing an intermediate conduit or arm section pivotally interconnected between the riser and the inboard arm section, and pivotally mounting a supporting boom structure on the riser so that this boom extends parallel to, but beneath, the inboard arm section to its pivotal juncture with the outboard arm section. This establishes a parallelogram I structure wherein the inboard arm section and the boom comprise the longer parallel sides, and the intermediate arm section and that portion of the outboard I axis at the riser. The secondary counterweights and their supports are directly linked to the inboard arm section through a strut element to form a second parallelogram structure with the intermediate arm section and the secondary counterweight supports comprising one pair of opposite sides, and thes'trut element and the portion of the primary counterweight supports between the armshorizontal pivot axis at the riser and the secondary counterweight supports pivot axis on the primary counterweight supports comprising the second pair of opposite parallel sides. The inboard arm a section, the intermediate arm section, and the parallelogram portion of the outboard arm section assist the secondary counterweights in counterbalancing the outboard arm section about its pivot axis on the inboard arm section when the outboard arm section is in a position other than vertical, and the secondary counterbalancing assembly assists the primary counterbalancing assembly in counterbalancing the entire loading arm about the horizontal pivot axis at the riser. The invention further involves three power assemblies to maneuver the arm, one to raise and lower thesupport boom, one to slew or pivot the arm about a vertical axis through the riser, and one to pivot the secondary counterweights about their mounting axis on the primary counterweight supports, and thus pivot the outboardarm section about the axis through itspivotal connection tothe inboard arm section..

- Accordingly, it is an object of this invention to provide a new type of double counterbalanced fluid'load ing apparatus that overcomes the aforementioned problems associated with conventional apparatus of this general category. t

Another object of the present invention is to provide a new secondary counterbalancing arrangement for fluid loading apparatus.

Another object of the'present invention is to provide a new style of linkage arrangement for interconnecting the secondary counterbalancing assembly of a fluid loading arm to the outboard arm section.

Still another object of the present invention is to pro-' A further object of the present invention is to utilize BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in perspective, from the front and to the right of center, of a marine loading arm embodying the principles of the present invention, showing the arm in a partially extended position.

FIG. 2 is a view in side elevation of the loading arm of FIG. 1, showing the inboard arm section and the supporting boom in a horizontal position and the outboard arm section substantially extended.

FIG. 3 is a plan view of the loading arm in the FIG. 2 position.

FIG. 4 is a fragmentary view in rear elevation of the upper portion of the riser, the inner end portion of the inboard arm section, and the intermediate arm section that interconnects the riser and the inboard arm section, with the inboard arm section in a vertical position and the outboard arm section extending downwardly and outwardly at approximately a 45 angle from the vertical.

FIG. 5 is a fragmentary view in side elevation of the arm in the FIG. 4 position.

FIG. 6 is a fragmentary view in side elevation of the inner portion of tha arms outboard arm section, showing its juncture with the inboard arm section and the boom.

FIG. 7 is a fragmentary view in end elevation taken along the line 7-7 of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Broadly considered, and as illustrated best in FIGS. 1, 2 and 3 a marine loading arm constructed in accordance with this invention comprises an upright support riser 22, an intermediate arm section 24 extending from the riser and connected to a fluid riser therein for pivotal movement about a generally horizontal axis A, an inboard arm section 26 connected through a pipe swivel joint 28 to the intermediate arm section 24 for rotation with respect thereto about a generally horizontal axis B, an outboard arm section 30 connected through a pipe swivel joint 32-to the inboard arm section 26 for rotation with respect thereto about a generally horizontal axis C, a fluid conduit support boom 34 pivotally mounted on the support riser 22 for rotation about an axis A and also pivotally connected by trunnion bearings 36 to the outboard arm section 30 so that it and the arm section 30 can pivot with respect to each other about a generally horizontal axis D, primary and

secondary counterbalancing assemblies

38, 40, respectively, for counterbalancing the arm sections and the boom about the axis A, and a hydraulic power system 42 for maneuvering the arm vertically as well as slewing or pivoting it horizontally about a generally vertical axis E.

The support riser 22 normally is mounted in a vertical attitude on a wharf 44, and a pipe line 46 leads into the riser from a reservoir or other system (not shown) for storing or providing the petroleum or other fluid to be conducted through the arm. As shown best in FIG. 4, the riser 22 comprises a lower non-rotatable section 48 and an upper, rotatable T-shaped section 50, the two sections fastened together by a swivel bearing 52 that facilitates rotation of the upper section 48 about the vertical axis E. Within the support riser 22 is a fluid riser 54 comprising a lower, non-rotatable section 56 that is connected in fluid communication to the pipeline 46, and an upper, elbow-shaped section 58 that is connected through a pipe swivel joint 60 to the lower section 56. The swivel bearing 52 and the swivel joint 60 are coaxial on the axis E, so that the upper support riser section 50 and the upper fluid riser section 58 can I rotate in unison about this axis. A pipe swivel joint 62 interconnects the upper fluid riser section 58 and the intermediate arm section 24, this swivel joint 62 being coaxial on the horizontal axis A with a pair of

trunnion bearings

64, 66 that pivotally mount the boom 34 on the support risers upper section 50, thereby enabling the boom 34 to pivot in unison with the intermediate arm section 24 about the axis A. Thus the intermediate, inboard and outboard arm sections and the boom all can pivot about both axes A and'E, and the loading arm is fully maneuverable in a horizontal as well as vertical direction.

A coupling assembly 68 is mounted on the outer end of the outboard arm section 30 for connecting the arm to a marine tanker manifold. The coupling assembly 68 can be of any suitable type including the conventional style illustrated in the drawings, which comprises a first elbow 70 connected by a first pipe swivel joint 72 to a terminal elbow 74 on the' outer end of the arm section 30, a second elbow 76 connected to the first elbow 70 by a second pipe swivel joint 78, and a terminal flange section 80 connected to the second elbow 76 by a third pipe swivel joint 82. Hence the coupling assembly 68 facilitates universal movement between the tanker and the loading arm when it is coupled to the tankers manifold.

The primary counterbalancing assembly 38, which functions to partially counterbalance the loading arm about the axis A, comprises a'pair of

counterweights

84, 86 mounted individually on beam-like supports 88,

90 that extend rearwardly from the boom 34 to which they are fixed. As seen best in FIGS. 3 and 4, the-

supports

88, 90 are spaced apart sufficiently so that they straddle and pass by the support riser 22 and the various elements attached thereto as the arm is elevated into a vertical, upright position, thereby facilitating stowing the arm in a minimal space and providing maximum clearance'to' a tanker at the wharf. The total weight of the counterweights '84, 86 is divided evenly between them, so that the load on the

trunnion bearings

64, 66 essentially is equal. If desired, provision can be made for adjusting the position of the

counterweights

84, 86 on their

support

88, 90 relative to the axis A,.thereby allowing the arm to be very accurately balanced on this axis. For example, hydraulic cylinders as described. in my earlier US. Pat. No. 3,455,333, issued July 15, 1969 and entitled Counterbalance Systern for a Marine Loading Arm, can be employed for this purpose. h

The secondary counterbalancing assembly 40 similarly comprises a pair of

counterweights

92, 94 individually mounted on a pair of beam-

like supports

96, 98. However, the inner ends of these supports 96, 98 are pivotally mounted on the primary counterweight supports 88, 90, respectively, behind the trunnion bearings axis A, so that they pivot about a substantially horizontal axis F and their weight and that of the

secondary counterweights

92, 94 is additive to the

primary counterweights

84, 86. Mounting the secondary counterweights in this manner significantly reduces the deadweight required of

counterweights

84, 86 to counterblance the arm about the axis A, and thereby provides for a material savings in terms of original cost, maintenance and operating expense, items of considerable import with huge structures of this type. The secondary counterbalancing assembly is linked to the inboard arm section 26 to a cross-member 100 secured to the

supports

96, 98, and a strut 102 pivotally connected to the cross-member 100 and welded or otherwise fixed to the rear portion of the arm section 26. If desired, these

secondary counterweights

92, 94 also can be adjustably secured to their

supports

96, 98, and provision made for hydraulically or otherwise carrying out their adjustment, for instance as explained above in conjunction with the

primary counterweights

84, 86.

As illustrated in F IG. 2, the longitudinal dimensions of the inboard arm section 26 and the boom 34 are such that the distance between axes B and C is the same as that between axes A and D. In corresponding manner, the intermediate arm section 24 and the inner portion 30a of the outboard arm section 30 are dimensioned so that the distance between axes C and D is equal to that between axes A and B. Thus, the inboard arm section 26, the boom 34, the intermediate arm section 24 and the outboard arm sections inner portion 30a form, collectively, a parallelogram structure. Likewise, the points at which the secondary counterweight supports 96 98 are secured to the primary counterweight supports 88, 90 and the cross-member 100 are positioned so that the

supports

96, 98 are parallel to the intermediate arm section 24 and the

supports

88, 90 are parallel to the strut 102, these elements thereby forming another parallelogram structure. Therefore, regardless of the position of the outboard arm section 30, i.e., vertical, horizontal, or anywhere in between, the intermediate arm section 24 and the secondary counterweight supports 96, 98 will be parallel to it, and alsoparallel to each other.

Because of the above described unique mounting of the inboard and

outboard arm section

26, 30 and the secondary counterbalancing assembly 40, a portion of the moment exerted by the outboard arm section 30 and the coupling assembly 68 about the axis A, when this arm section is not in a vertical position, is offset by a counter-moment exerted jointly by the outboard arm sections inner portion 30a, the inboard arm section 26, and the intermediate arm section 24 about the axis A. Therefore, the secondary counterbalancing assembly 40, the cross-member 100, and the strut 102 need only be adequate to counter the remaining portion of that moment, thereby facilitating a reduction in size of these elements as compared to a conventional doublecounterbalanced loafing arm wherein the secondary counterbalancing mechanism is supported directly on or decrease in the counter-moment about the axis A equivalent to the increase or decrease in moment about that axis as the outboard arm section 30 moves away from or towards a vertical position, respectively. The result, therefore, is that the outboard arm section 30 is counterbalanced about the axis A in all positions in which it might be placed, and this by a counterbalancing assembly of substantially less size, and hence smaller cost, than heretofore required using the conventional double-counterbalancing systems.

The pivotal mounting of the arms supporting boom 34 on the support riser 22 independently of the pivotal connection of the intermediate arm section 24 to the fluid risers upper section 58 facilitates independent pivotal movement of the boom and the intermediate arm section about the axis A. Therefore, if the boom is precluded from pivoting about this axis, pivoting the intermediate arm section will cause the outboard arm section 30 to pivot aboutthe axis D an equal amount andv in the same direction. On the other hand, if the boom 34 and the intermediate arm section 24 are pivoted in unison about the axis A, the outboard arm section 30 does not pivot about the axis D, but remains in the same angular relation to the boom 34. Hence, by selective pivotal movement of the boom 34 and the intermediate arm section 24 about the axis A, and of course by pivoting or slewing the entire loading arm about the vertical axis E, the coupling assembly 68 can be easily and precisely maneuvered into any position within the arms reach for connection to a nearby tankers manifold.

The current demands of the petroleum industry frequently necessitate the use of the largest loading arms available, i.e., those of the longest reach and that can transfer the most fluid in a given time between the tanker and the shore or other facility to which the loading arm is connected. Loading arms with a reach of 100 feet or more, and with fluid conduits of 24 inches in diameter can be constructed according to this inventionto satisfy these demands. However, an apparatus of this size can weigh over 100,000 pounds, necessitating the employment of a power system to maneuver it efficiently, and the system 42, as illustrated in FIGS. 1-5, has been found highly satisfactory for this purpose. This system comprises an assembly 104 for pivot-v ing the boom 34 about the axis A, an assembly 106 for slewing or pivoting the entire loading arm about the verticalaxis E, and an assembly 108 for pivotingthe secondary counterbalancing assembly 40 about the axis F.

The power assembly 104 comprises two pairs of hydraulic clyinder's 110,112, 114, 116, a pair of

sheaves

118, 120 fixed to the boom 34 on opposite sides of the T-shaped rotatable section 50 of the support riser'22,

and a cable 122 extending from each of the

cylinders piston rods

110a, 112a, 114a, 1160 to and around the corresponding sheave. Thus, by retracting the piston rods 110a, 114:: into their cylinders and simultaneously extending the .rods 112a, 116a from their cylinders, the boom can be pivoted about the axis A in a counterclockwise direction as reviewed in FIG. 2,-i.e., can be lowered. Correspondingly extending the

rods

110a, 114a and retracting the rods 112a, 116a will pivot'the boom clockwise, i.e., raisev it. The cylinders are mounted on a bracket ,l24'that is fixed to the support risers rotatable section 50, so that as the loading arm is slewed or pivoted about the vertical axis E the bracket and cylinders pivot with it.

The power assembly 106 comprises a pair of

hydraulic cylinders

126, 128 also mounted on the bracket 124, a guide rim 132 circumscribing and fixed to the support risers lower non-rotatable section 48, a pair of guide for handling fluids at sub-zero or cryogenic temperatures. Whereas when used in such cold service loading I arms of other designs require expensive stainless and pulleys 134, 136 rotatably mounted on the bracket 124 so that the plane through the cable groove in the guide rim 132 is substantially tangent to the pulleys rims, and a cable 138 running from the,

cylinders piston rods

126a, 128a over the

pulleys

134, 136 and around and secured to the guide rim 132. Hence, by retracting the piston rod 126a into its cylinder and simultaneously extending the piston rod 128a from its cylinder the loading arm will slew or pivot counterclockwise about the axis E as viewed in FIG. 3, and by extending the rod 126a and retracting the rod 128a the arm can be slewed in a clockwise direction.

The power assembly 108 comprises a pair of

hydraulic cylinders

140, 142 pivotally mounted on opposite sides of the arms support boom 34, with their

piston rods

140a, 142a pivotally connected to the secondary counterweight supports 96, 98, respectively. Accordingly, extending or retracting the piston rods will cause the counterweight supports to pivot clockwise or counter-clockwise about the axis F as viewed in FIG. 2, causing like pivotal movement of the outboard arm section 30 about the axis D, and causing relative pivotal movement between the inboard and

outboard arm sections

26, 30 about the axis C, between the intermediate and

inboard arm sections

24, 26 about the axis B, and

between the upper fluid riser section 58 and the inter-,

mediate arm section 24 about the axis A.

It can therefore be seen that the above described counterbalancing and power arrangements facilitate maneuvering the unique fluid loading apparatus of this invention into any desired position within its reach capabilities, without anyrestriction whatsoever, while at the same time providing for stowage of the apparatus in an upright position requiring minimal space, thus enabling the apparatus to be mounted unusually close to the wharfs edge without danger of presenting an obstruction to vessels moored alongside.

As will be readily apparent to those skilled in this art, a suitable chain and sprocket assembly, or a gear system, can be substituted for the various cable and sheave assemblies described above and illustrated in the drawings, so long as the equivalent motive power is supplied to the pivotal-elements of the apparatus.

Among the several unusual features of this invention is the outstanding ease by which the various swivel joints and bearings can be reached for periodic maintenance. For example, when it is desired to service the fiuid'risers swivel

joints

60 and 62, a manholecover 150 in the topof the support risers upper section 50 is removed, providing direct access to the elbow shaped upper fluid riser section 58, which can then be disconnected from the fluid conduit system at these swivel joints and removed, exposing the joints for repacking, etc. Another feature is that the fluid conduit system comprising the riser 54, the intermediate arm section 24, the inboard arm section26, and the outboard arm section 30 is a complete assembly in itself, independent of the boom 34 and supportriser 22, and therefore can be readily isolated from these supporting structures by insulation to make the apparatus suitable close proximity to the cold zone, a loading arm according to the present invention allows free use of lower cost steels for the support structures.

Yet another important feature of this invention is the ready adaptation of the apparatus to some form of standardization. Since the fluid conducting arm sections and riser must support only their own weight plus the contained fluid, these elements are not subject to structural changes. Thus a pipe given size can be used for all of the fluid conducting elements with a change in length as the only consideration for fitting into the supporting structure.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

What is claimed is:

l. A fluid transferring apparatus of the doublecounterbalanced marine loading arm type, including:

1. an intermediate fluid conduit arm section mounted upon an upstanding riser for pivotal movement about a first generally horizontal axis;

2. an inboard fluid conduit arm section connected to the intermediate fluid conduit arm section for pivotal movement about a second generally horizontal axis;

3. an outboard fluid conduit arm section connected I at its inner end to the inboard fluid conduit arm section for'pivotal movement about a third generally horizontal axis;

4. an arm-supporting boom mounted for pivotal movement about the first axis and extending generally parallel to the inboard fluid conduit arm section to a pivotal connection with the outboard fluid conduit arm section intermediate the third axis and the outboard fluid conduit arm sections outer end, said pivotal connection establishing a fourth generally horizontal pivot axis; and

5. means for counterbalancing the intermediate, in-

' board and outboard fluid conduit arm sections and the boom about the first -axis=in all operating positions.

2. The apparatus of claim 1 wherein the counterbalancing means comprises a primary counterbalancing assembly for counterbalancing the apparatus about the first axis when the outboard arm section is in a substan- I tially vertical position, and a secondary counterbalancing assembly for counterbalancing'the outboard arm section about the fourth axis when the outboard arm section is in a position other than vertical.-

3. The apparatus of claim '2 wherein the secondary counterbalancing assembly provides assistance'to the primary counterbalancing assembly in counterbalancing the apparatus about the first axis when the outboard arm section is in a vertical as well as a non-vertical position.

4. The apparatus of claim 2 including first power means for pivoting the apparatus about the first axis, second power means for slewing the apparatus about a vertical axis through the riser, means interconnecting the secondary counterbalancing assembly and the outboardarm section, and third power means to change the attitude of the secondary counterbalancing assembly and the outboard arm section.

5. The apparatus of claim 4 wherein the first, second and third power means comprise hydraulic cylinders.

6. The apparatus of claim 1 wherein the inboard arm section and the boom define two opposite sides of a parallelogram, and the intermediate arm section between the third and fourth axes define the other two opposite sides of the parallelogram.

7. The apparatus of claim 1 wherein at least a portion 9. The apparatus of claim 1 including a support riser circumscribing but spaced from the upstanding riser, wherein the boom is mounted on the support riser for pivotal movement about the first axis, and wherein the upstanding riser and the intermediate, inboard and outboard arm sections comprise a separate fluid conducting system independent of thesupport riser and the boom.

10. A fluid transferring apparatus of the double counterbalanced marine loading arm type, including:

1. an intermediate arm section mounted upon an upstanding riser for pivotal movement about a first generally horizontal axis;

2. an inboard arm section connected to the intermediate arm section for pivotal movement about a second generally horizontal axis;

3. an outboard arm section connected at its inner end to the inboard arm section for pivotal movement about a third generally horizontal axis;

4. an arm-supporting boom mounted for pivotal movement about the first axis and extending generally parallel to the inboard arm section to a pivotal connection with the outboard arm section interme- 10' diate the third axis and the outboard arm sections outer end, said pivotal connection establishing a fourth generally horizontal pivot axis; and

5. means for counterbalancing the intermediate, in-

board and outboard arm sections and the boom about the first axis in all operating positions, said counterbalancing means comprising a primary counterbalancing assembly including primary counterweight means mounted on primary support means fixed to the boom and extending generally rearwardly from the first axis for counterbalancing the apparatus about the first axis when the outboard arm section is in a substantially vertical position, and a secondary counterbalancing assembly including secondary counterweight means mounted on a secondary support means that is mounted behind the first axis for pivotal movement about a fifth generally horizontal axis.

11. The apparatus of claim 10 wherein the primary counterweight means comprises a pair of substantially equal counterweights, the primary support means comprises a pair of generally beam-like support elements extending parallel and rearwardly from the boom on opposite sides of the riser, and each support element has one counterweight mounted thereon, said support elements and counterweights being spaced sufficiently to facilitate positioning the boom in an upstanding vertical attitude without interference from the riser.

12. The apparatus of claim 10 wherein the secondary counterweight means comprises a pair of substantially equal counterweights, the secondary support means comprises a pair of beam-like support elements pivotally mounted on the primary support means and each supporting one of the counterweights, and wherein the apparatus includes rigid means interconnecting the secondary counterweight means and the inboard arm section.

13. The apparatus of claim 12 wherein the primary support means, the secondary beam-like support elements, the rigid means, and the intermediate arm section together define a parallelogram.

PATENT NO.

DATED INVENTOR(S) I 'UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION April 23, 1974 PETER J. BILY It is certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 4, line Column 5, line Column 5 line Column 5, line [SEAL] A nest:

RUTH C. MASON r-irtvslr'ng Officer Signed and Sealedthis twenty-third D ay Of September 1975 C. MARSHALL DANN (mnmim'nner nj'larenls and Trademarks

Claims

1. A fluid transferring apparatus of the doublecounterbalanced marine loading arm type, including: 1. an intermediate fluid conduit arm section mounted upon an upstanding riser for pivotal movement about a first generally horizontal axis; 2. an inboard fluid conduit arm section connected to the intermediate fluid conduit arm section for pivotal movement about a second generally horizontal axis; 3. an outboard fluid conduit arm section connected at its inner end to the inboard fluid conduit arm section for pivotal movement about a third generally horizontal axis; 4. an arm-supporting boom mounted for pivotal movement about the first axis and extending generally parallel to the inboard fluid conduit arm section to a pivotal connection with the outboard fluid conduit arm section intermediate the third axis and the outboard fluid conduit arm section''s outer end, said pivotal connection establishing a fourth generally horizontal pivot axis; and 5. means for counterbalancing the intermediate, inboard and outboard fluid conduit arm sections and the boom about the first axis in all operating positions.

2. The apparatus of claim 1 wherein the counterbalancing means comprises a primary counterbalancing assembly for counterbalancing the apparatus about the first axis when the outboard arm section is in a substantially vertical position, and a secondary counterbalancing assembly for counterbalancing the outboard arm section about the fourth axis when the outboard arm section is in a position other than vertical.

3. The apparatus of claim 2 wherein the secondary counterbalancing assembly provides assistance to the primary counterbalancing assembly in counterbalancing the apparatus about the first axis when the outboard arm section is in a vertical as well as a non-vertical position.

3. an outboard fluid conduit arm section connected at its inner end to the inboard fluid conduit arm section for pivotal movement about a third generally horizontal axis;

4. an arm-supporting boom mounted for pivotal movement about the first axis and extending generally parallel to the inboard arm section to a pivotal connection with the outboard arm section intermediate the third axis and the outboard arm section''s outer end, said pivotal connection establishing a fourth generally horizontal pivot axis; and

4. The apparatus of claim 2 including first power means for pivoting the apparatus about the first axis, second power means for slewing the apparatus about a vertical axis through the riser, means interconnecting the secondary counterbalancing assembly and the outboard arm section, and third power means to change the attitude of the secondary counterbalancing assembly and the outboard arm section.

4. an arm-supporting boom mounted for pivotal movement about the first axis and extending generally parallel to the inboard fluid conduit arm section to a pivotal connection with the outboard fluid conduit arm section intermediate the third axis and the outboard fluid conduit arm section''s outer end, said pivotal connection establishing a fourth generally horizontal pivot axis; and

5. means for counterbalancing the intermediate, inboard and outboard fluid conduit arm sections and the boom about the first axis in all operating positions.

5. means for counterbalancing the intermediate, inboard and outboard arm sections and the boom about the first axis in all operating positions, said counterbalancing means comprising a primary counterbalancing assembly including primary counterweight means mounted on primary support means fixed to the boom and extending generally rearwardly from the first axis for counterbalancing the apparatus about the first axis when the outboard arm section is in a substantially vertical position, and a secondary counterbalancing assembly including secondary counterweight means mounted on a secondary support means that is mounted behind the first axis for pivotal movement about a fifth generally horizontal axis.

7. The apparatus of claim 1 wherein at least a portion of the weight of the intermediate arm section functions to assist the counterbalancing means in counterbalancing the outboard arm section when in a non-vertical position.

8. The apparatus of claim 1 including pipe swivel joint means interconnecting the riser, the intermediate arm section, the inboard arm section, and the outboard arm section, and means for obtaining access to the interior of the pipe swivel joints without completely dismantling the apparatus.

9. The apparatus of claim 1 including a support riser circumscribing but spaced from the upstanding riser, wherein the boom is mounted on the support riser for pivotal movement about the first axis, and wherein the upstanding riser and the intermediate, inboard and outboard arm sections comprise a separate fluid conducting system independent of the support riser and the boom.