SAME

SPECIFICATION

RELATED APPLICATIONS

[0001] This disclosure is a patent cooperation treaty (PCT) application that claims the priority to pending U.S. Patent Application Serial No. 15/249,001 filed on August 26, 2016, which is a continuation of U.S. Patent Application Serial No. 15/053,856 filed on February 26, 2016, the entirety of which are incorporated herein by this reference.

FIELD

[0002] Embodiments within the scope of this disclosure relate, generally, to apparatuses, systems, and methods for fitting tubulars or pipes as spreader bars onto a shackle or lifting sling. This is accomplished through the use of an "end cap" fitting, which keeps the tubular in a compressive state and allows the tubular to be quickly and easily attached and disconnected from the lifting system without material alteration.

BACKGROUND

[0003] The use of spreader bar systems for lifting tubulars is well-known in the art.

Examples of such spreader bar systems include, e.g., US Patent No. 4,397,493 to Khachaturian, et al., and US Patent No. 5,603,544 to Bishop, et al. The advantage of these systems is that they allow the force of a single-point lifting system, such as a shackle or hook, to be divided into multiple lifting points, thus avoiding the material stress and safety concerns associated with lifting a heavy load by a single point. [0004] In order to adapt the shackle and spreader bar systems for various dimensions and weights, it is common to utilize an "end cap" system (also known as a compression cap system) for attaching spreader bars to the shackle. In this system, the spreader bar is fitted between two "end caps," which contain multiple orifices for connecting to both the lifting mechanism above and the load below. This allows for quick swapping of various sizes and weights of spreader bar as necessitated by the lift.

[0005] However, there are still several drawbacks to the state of the art in spreader bar lifting. Assembly of the end cap requires precise alignment of the end cap with the spreader bar, and often requires a tubular spreader bar to be physically altered (e.g., through spot welds or attachment holes) which can weaken the spreader bar' s tolerance for metallurgical stresses.

[0006] Additionally, the process of determining the correct end cap fitting for use with a given load and span of weight to be lifted can often be time-consuming and prone to error when calculated by workers in the field. This can lead to an increased stress on the equipment and the risk of lift failure.

[0007] A need therefore exists for an end cap system in which both the method of selecting a properly rated and sized end cap and the physical method of fixing the end cap to a selected spreader bar are simplified to allow field personnel to more quickly and reliably rig-up lifting systems. Embodiments disclosed in the present invention meet these needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the detailed description of various, example embodiments within the scope of the present disclosure, reference is made to the accompanying drawings, in which:

[0009] FIG. 1 depicts the overall layout of an embodiment of the end cap system in the context of connections to a single-point lift and a load to be lifted.

[00010] FIG. 2 depicts an embodiment of the end cap described in the present invention in perspective view.

[00011] FIG. 3 depicts an embodiment of the end cap described in the present invention in an exploded view.

[00012] FIG. 4A depicts an embodiment of the end cap described in the present invention in an outward-facing longitudinal view.

[00013] FIG. 4B depicts an embodiment of the end cap described in the present invention in a plan (overhead) view.

[00014] FIG. 4C depicts an embodiment of the end cap described in the present invention in a side view.

[00015] FIG. 4D depicts an embodiment of the end cap described in the present invention in an inward-facing longitudinal view.

[00016] FIG. 4E depicts an embodiment of the end cap described in the present invention in perspective view. [00017] FIG. 5 depicts the overall layout of an embodiment of the end cap system in the context of connections to a multi-point lift and a load to be lifted.

[00018] FIG. 6 depicts an embodiment of the end cap described in the present invention in perspective view.

[00019] FIG. 7 depicts an embodiment of the end cap described in the present invention in an exploded view.

[00020] FIG. 8A depicts an embodiment of the end cap described in the present invention in a plan (overhead) view.

[00021] FIG. 8B depicts an embodiment of the end cap described in the present invention in a outward-facing longitudinal view.

[00022] FIG. 8C depicts an embodiment of the end cap described in the present invention in a side view.

[00023] FIG. 8D depicts an embodiment of the end cap described in the present invention in an inward-facing longitudinal view.

[00024] FIG. 9A depicts a series of equations used to derive pre-calculated tolerances for the end cap described in the present invention.

[00025] FIG. 9B depicts a series of equations used to derive pre-calculated tolerances for the end cap described in the present invention.

[00026] One or more embodiments are described below with reference to the above-listed

Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS [00027] Before describing selected, example embodiments of the present disclosure in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein. The disclosure and description herein is illustrative and explanatory of one or more example embodiments and variations thereof, and it will be appreciated by those skilled in the art that various changes in the design, organization, order of operation, means of operation, equipment structures and location, methodology, and use of mechanical equivalents may be made without departing from the spirit of the invention.

[00028] As well, it should be understood the drawings are intended to illustrate and disclose presently example embodiments to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products, and may include simplified conceptual views as desired for easier and quicker understanding or explanation. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention.

[00029] Moreover, it will be understood that various directions such as "upper," "lower,"

"bottom," "top," "left," "right," and so forth are made only with respect to explanation in conjunction with the drawings, and that the components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the concept(s) herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting. [00030] Referring now to FIG. 1, a lifting assembly 1 utilizing an embodiment of two end caps 10, 11 is illustrated. Lifting assembly 1 comprises spreader bar 2, lift point 4, and four shackles 6, 7, 8, 9. Shackles 6, 8 are connected by slings 12, 14 to lift point 4, while shackles 7, 9 are connected by slings 12, 14 to a weight to be lifted (not shown). Optimally, the relationship between the slings 12, 14 and the spreader bar 2 are defined by a minimum angle (also known as a fleet angle), shown as a, so as to keep the compressive force exerted on the spreader bar 2 within a maximum tolerance.

[00031] Referring now to FIG. 2, the embodiment of the end cap 10 illustrated in FIG. 1 is shown in greater detail. End cap 10 comprises a load lug 20 extending longitudinally from a load plate 30. Load lug 20 in turn comprises two apertures 22, 24, which accommodate the shackles 6, 7 (not shown, illustrated in FIG. 1). To reinforce the strength of the material, apertures 22, 24 are reinforced through pairs of cheek plates 23A, 23B, and 25A, 25B, respectively (B plates not visible).

[00032] Load plate 30 faces a first end of spreader bar 2, which is compressed against load plate 30 and extends through a pipe retainer, also known as receptacle, 40, which extends from load plate 30 in the opposite longitudinal direction from load lug, also known as lifting lug, 20. In this embodiment, pipe retainer 40 is a hollow cylinder through which spreader bar 2 can be fitted. Pipe retainer 40 also comprises two apertures 42, 44 (not visible) through which two retaining bolts, also known as pinch bolts, 43, 45 (45 not visible) extend to compress against spreader bar 2. Retaining bolts 43, 45, allow the use of intact pipe for spreader bar 2, rather than pipe which has had holes torched through it, thereby compromising the material stress properties thereof. [00033] Extending downward from pipe retainer 40 and normally to load plate 30 is leg plate 46, which terminates at foot plate 50. Leg plate 46 and foot plate 50 allow the end cap 10 to be easily mounted to spreader bar 2 in parallel with another end cap 11 (see FIG. 1).

[00034] Additionally, end cap 10 comprises two alignment references. Alignment aperture 35 is located through load plate 30 and serves to align two end caps (e.g., end caps 10 and 11 as depicted in FIG. 1) when in use. Angle reference 37, meanwhile, is located on load lug 20 and serves as a visual safety reference to keep the angle of the shackles 6, 8 and slings 13, 15 (depicted in FIG. 1) at a minimum effective angle.

[00035] In the present embodiment, angle reference 37 is depicted as a second aperture, however, it may be appreciated that other embodiments may include a simple surface reference (e.g. , a reflector), a round steel bar (as shown in FIG. 4E), or additionally or alternatively, a protruding physical stop. Any feature which serves to visually or physically mark the minimum effective angle (depicted as □ in FIG. 1) between slings 13, 15 and spreader bar 2 may be utilized without departing from the scope of this invention. In an example embodiment, the minimum effective angle is a 45 degree angle, which is specifically referenced in the associated chart for this specific system but may differ in other embodiments.

[00036] Referring now to FIG. 3, the embodiment of the end cap 10 illustrated in FIGS.

1-2 is shown in an exploded view. Retaining bolt 45, aperture 42, and cheek plates 23B, 25B are visible in this view. Additionally, braces 32, 34 are also illustrated, which brace load plate 30 against load lug 20.

[00037] FIG. 4A-4E show embodiments of the end cap 10 illustrated in FIGS. 1-3. Specifically, the end cap 10 is shown in an overhead view (FIG. 4A), left side view (FIG. 4B), side-on view (FIG. 4C), and right side view (FIG. 4D). FIG. 4E shows an additional or alternative embodiment with Significantly, the side views in FIG. 4B and 4D illustrate how alignment aperture 35, which is located on load plate 30, may ensure that two end caps are properly aligned when mounted onto a spreader bar, as one end cap 10 will be in the position illustrated by FIG. 4B and the other in the position illustrated by FIG. 4D. Aperture 35 can also be used for a connection or "tag" line used with an adjoining rope or line to allow the spreader bar system to be guided from a safe distance from the load that is being lifted. The end caps 10 disclosed within the scope of the disclosure include embodiments include end caps 10 that vary in size and shape from the end cap 10 of FIG. 3. For example, FIG. 4E shows an embodiment of the end cap 10 that has a lifting lug 20 that is longer and thus extends the apertures 22, 24 further from the brace load plate 30. This longer lifting lug 20 may enable a greater variance in the types of fasteners that may be connected to the apertures 22, 24. For example, a larger range of rigging applications such as braided slings, thimble eye slings, synthetic slings, or other larger-diameter fasteners may be used with the lifting lug 20 shown in FIG. 4E. The lifting lug 20 may also include a round bar 37a as an angle reference. The round bar 37a may be placed at a location to indicate a minimum for the angle a, such that if the round bar 37a is not visible from the side of the end cap 10, then the fleet angle is too small for the designed lifting assembly 1. The round bar 37a may be constructed of a wide variety of materials including steel or other metals, ceramics, polymers, or others. The round bar 37a may be welded, glued, or otherwise attached to a top side of the lifting lug 20. [00038] While all of the embodiments thus shown are directed to two-point lifts, it can be appreciated that the principles of the invention can also apply to more elaborate lifting systems. FIG. 5 illustrates a perspective view of another embodiment of the invention: an end cap system directed to four-point lifts rather than two-point lifts.

[00039] Continuing with FIG. 5, the depicted embodiment comprises a plurality of end caps HOa-d, connected by a plurality of spreader bars 112a-d, wherein each end cap 1 lOa-d is connected by an upper sling 114a-d (114c not visible) connecting to a common lift point 105, and a lower sling 116a-d (116c not visible) connected to a load to be lifted (not visible).

[00040] Turning now to FIG. 6 and FIG. 7, these drawings depict a perspective view and exploded view, respectively, of an embodiment of the four-point end cap 110. End cap 110 comprises mounting plate 120, and similar to the embodiment shown in FIG. 1-4, additionally comprises load plates 130a 130b, pipe retainers 140a, 140b, and feet plate 150a, 150b (150a not visible in FIG. 6). Pipe retainers 140a, 140b enclose spreader bars 112a, 112b, respectively. Pipe retainers 140a, 140b are supported in place by load plates 130a, 130b, as well as support braces 132a, 132b inside braces 134a-b (134b not visible in FIG. 6), outside braces 136a-b (136a not visible in FIG. 6), and mounts 138a, 138b. In addition to compression forces, pipe is fixed in place through retaining pinch bolts 143a, 143b and 145a, 145b (145a not visible in FIG. 6).

[00041] In this embodiment, upper and lower shackles 106 and 108 are connected to mounting plate 120 via two different means. Upper shackle 106 is connected to swivel ring 126, which is connected to mounting plate 120 via a ring bushing 128 seated in an aperture 127. Lower shackle 108 is connected to lifting lug 121, a structure that partially duplicates the structure depicted in the embodiment of FIGS. 1-4, with an aperture 122 through which shackle 108 can be attached and reinforced by cheek plates 123 a, 123b.

[00042] Additionally, as with the embodiment depicted in FIGS. 1-4, this embodiment comprises two horizontal foot plates 150a, 150b, which, in turn, are connected to mounting plate 120 via two vertical leg plates 146a, 146b.

[00043] Turning now to FIGS. 8A-8D, the embodiment shown in FIGS. 5-7 is depicted in overhead, front, side, and rear views, similar to those of FIG. 4A-4D for the previous embodiment. (Note that FIG. 8B and 8C can be distinguished by the position of lower shackle 108 with respect to the face-on foot plate 150a or 150b.)

[00044] Turning now to FIGS. 9A and 9B, a method of calculation is disclosed whereby the design parameters of various embodiments of the present invention can be pre-calculated from the load and span required in a lifting job. In this method, the load is purely compressive, i.e., the horizontal resultant is aligned with the pipe centerline. The exemplar calculations shown are for a load of 30 tons having a span of 20 ft to be lifted using a spreader bar of cylindrical pipe, made of standard ASTM A53B carbon steel.

[00045] The material parameters used in the calculation are as follows: Minimum yield

(F _y , 35 ksi), density (p, .284 lbf/in3), modulus of elasticity (E, 29,000 ksi), outside diameter (OD, 6.625 in), wall thickness (t _w , schedule 40). Additionally, the spreaders in this calculation are presumed to be 9.75 inches in length, making the unbraced insert length (L _sprd ) 220.5 in (span minus two spreaders). [00046] From the above material parameters, several secondary parameters can be deduced, such as inside diameter (ID), area of section (A _sect ), MOI (I _p ), section modulus (S _p ), radius of gyration (r), and linear weight ( D _p ), using the formulas at the top of FIG. 9A. Additionally, a design parameter (N _d ) is given in ASME BTH- 1 2005, which for the purposes of the exemplar calculation is 3.0 (Category B).

[00047] Box 1, two compression load factors are calculated: a slenderness ratio, and a column slenderness ratio separating elastic and inelastic buckling, using the formulas given in Box 1. Depending on which of the two results is greater, the allowable column stress can be calculated using the formulas in Box 2A and Box 2B, while the actual column stress can be calculated using the formula in Box 3.

[00048] Meanwhile, the allowable and actual bending load stresses can be calculated using the formulas in Box 4. Then, the allowable and actual combined (Euler) stresses can be calculated utilizing the formulas in Box 5.

[00049] Finally, a two-part unity check is performed utilizing the values derived in Box 3,

Box 4, and Box 5, and plugging them into the equations of Box 6.

[00050] While the exemplar calculations are given for a load of 30 tons having a span of

20 ft, it should be appreciated that these calculations may be performed in advance for any number of specific weights and spans. In addition, other parameters such as diameter, thickness, and weight of the end caps may also vary while still remaining within the scope of the present disclosure. In a method embodiment, the maximum tolerance for a given weights and span is pre- calculated and placed in a chart having weights and spans corresponding to different scales of end cap (e.g., diameter, thickness), for field workers to quickly and reliably select an embodiment of the present invention having dimensions which tolerate the lift stresses of a given task. While various embodiments usable within the scope of the present disclosure have been described with emphasis, it should be understood that within the scope of the appended claims, the present invention may be practiced other than as specifically described herein.