WO2016178583A1

WO2016178583A1 - Breakable coupling between lifting equipment and load

Info

Publication number: WO2016178583A1
Application number: PCT/NO2016/050080
Authority: WO
Inventors: Knut STEINHOVDEN; Loyd Arve Nornes
Original assignee: Steinhovden Knut
Priority date: 2015-05-06
Filing date: 2016-05-03
Publication date: 2016-11-10
Also published as: GB201720011D0; GB2554615B; GB2554615A8; GB2554615A; NO341119B1; NO20150558A1

Abstract

A breakable coupling in a load coupling (1) which fits complementarily in a coupling holder (2), the load coupling (1) comprising a locking-dog casing (13), which is connected to a load attachment (12), and being formed with locking dogs (132) which are movable between a non-locking position and a locking position, and a locking-dog blocking element (15) being movable between a blocking position, in which the locking dogs (132) are prevented from being moved out of their locking positions, and a non-blocking position, and the load attachment (12) being locked to the locking-dog casing (13) by means of a shear pin (14) having a weakened middle portion (144) and being dis- placeable between a normal position, in which it forms a connection between the load attachment (12) and the locking-dog casing (13) by first and second end portions (141, 142), and a release position, in which the first end portion (141 ) has been pulled away from the load attachment (12) and into the locking-dog casing (13) and the weakened middle portion (144) is arranged in an interface between the load attachment (12) and the locking-dog casing (13).

Description

BREAKABLE COUPLING BETWEEN LIFTING EQUIPMENT AND LOAD

A breakable coupling in a load coupling which fits complementarily in a coupling holder is described, the load coupling comprising a locking-dog casing, which is connected to a load attachment, and being formed with at least one locking dog which is radially movable between a pushed- in or swung-in, non-locking position and a pushed-out or swung-out, locking position, the locking dog fitting complementarily in the coupling holder, and the load coupling being provided with a locking-dog blocking element which is movable between a blocking position, in which the locking-dog blocking element prevents the locking dog from being moved out of its locking position, and a non- blocking position in which the locking dog is free to be moved away from its locking position, and the load attachment, which is axially movable relative to the locking-dog casing, being locked to the locking-dog casing by means of a shear pin.

Many operations include the use of elongated bodies, for example in the form of chains or wires, for lifting or as guides. When such operations take place under water, couplings are often used between the elongated body and the element to which said body is connected, for example a load or a foundation, the coupling being lockable or releasable in a simple way. During some of these operations, it is important that a load coupling which is connected to the elongated body will release in all situations without the vital components involved being overloaded. At the same time, it is vital that all the components belonging to the load coupling, which may be connected to a coupling holder fixed to the element to which the elongated body is attached, will go with the released load coupling so that the coupling holder is immediately ready, so that that a new load coupling may be connected to it.

Examples of such couplings are disclosed in DE 4240090, WO 01/87761 , WO 01/79107, DE 0328196 and GB 2466983 and in the applicant's own patent NO 31 1816.

In such couplings, for extra safety, a mechanism is arranged which can be broken if the ordinary coupling mechanism does not work when there is a need to release the elongated body from its connected element. Typically, such a safety coupling is formed as a shear pin of such dimensioning that it will break when a certain tensile force is applied to the elongated element which is far greater than what is required in order to lift the element or keep the elongated element tensioned if said elongated element is used as a guide for other elements, for example an element that is to be landed on a foundation on the seabed. The applicant's own patent NO 334870 discloses an overload-releasable load coupling which fits complementarily in a coupling holder, the load coupling including a locking-dog casing, which is connected to a load attachment, and being formed with at least one locking dog which is radially movable between a pushed-in or swung-in passive position and a pushed-out o swung-out active position, the locking dog fitting complementarily in the coupling holder, and the load coupling being provided with a blocking body which is movable between a blocking position, in which the blocking body prevents the locking dog from being moved out of its locking position, and a free position, in which the locking dog is free to be moved away from its locking position. The load coupling is characterized by the load attachment, which is axially movable relative to the locking-dog casing, being locked to the locking-dog casing by means of a shear pin.

It may be a drawback that the elongated element or a connected load, foundation, winch et cetera will have to be subjected to the increased load that is required in order to make the safety coupling in the form of a shear bolt, shear pin et cetera release.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.

The object is achieved through the features, which are specified in the description below and in the claims that follow.

For an overload-releasable load coupling of the kind disclosed in NO 334870, an improved shear pin has been provided. The load coupling fits complementarily in a coupling holder, and the load coupling includes a locking-dog casing which is connected to a load attachment, and the load coupling is formed with at least one locking dog which is radially movable between a pushed-in or swung-in passive position and a pushed-out or swung-out active position, the locking dog fitting complementarily in the coupling holder. The load coupling is provided with a locking-dog blocking element which is movable between a blocking position, in which the locking-dog blocking element prevents the at least one locking dog from being moved out of its locking position, and a free position, in which the at least one locking dog is free to be moved away from its locking position. The locking-dog blocking element includes an elongated stem extending into an axial centre bore of the locking-dog casing.

The locking-dog casing, which is axially dispiaceable in the load attachment, is locked to the load attachment by means of a shear pin. The shear pin, which is arranged substantially perpendicularly to the centre axis of the load coupling, is provided with a weakened middle portion, and the shear pin is movable in its own axial direction between a normal position, in which it forms a connection between the load attachment and the locking-dog casing by both its end portions, and at least to a release position, in which a first end portion of the shear pin has been pulled away from the load attachment and into the locking-dog casing and the weakened middle portion is arranged in the interface between the load attachment and the locking-dog casing. In a second end portion, the shear pin may be connected to an actuator, which preferably has a work range, which is restricted in such a way that the shear pin can be moved between its normal position and said release position. The actuator may be formed as a screw arranged in a lateral cut-out in the load attachment, where a tool may be inserted. A threaded portion, which is comple- mentary to the threads of the screw extends through an inner portion of the cut-out and may appropriately have an extent limited outwards in the radial direction of the load attachment so that when the screw has been completely unscrewed from the threaded portion, the shear pin has reached its release position.

The shear pin and the actuator may be provided with means for easy axial connection to the actua- tor, for example in the form of a bayonet coupling.

The weakening in the middle portion may be provided in various ways. The middle portion may have a smaller diameter than the end portions, in a preferred embodiment, the shear pin is formed with two end sections, which are interconnected by means of a middle section. The middle section forming the weakened middle portion of ihe shear pin may be formed as a pin extending into bores in the opposite end faces of the end sections. The middle section may be formed from a material with oiher properties ihan the end sections of the shear pin, for example a maierial with lower breaking strength et cetera.

The first end portion of the shear pin may be provided with a projecting abutment portion, which projects from the load attachment in the normal position of the shear pin, A locking element, which is movable in the axial direction of the load coupling encloses a portion of the load attachment and may be moved into abutment against a peg projecting from the shear pin. A cut-out in the locking element is arranged to receive the abutment portion of the shear pin to hold the locking element. A connecting element in the form of a bolt extends diametrically through the locking element and through diametrically opposite, oblong slots directed axially in the load at- tachment and through corresponding slots in the locking-dog casing. The connecting element extends through a bore in the stem of the locking-dog blocking element and forms an axially fixed connection between the locking-dog blocking element and the locking element. The locking-dog blocking element may thereby be displaced and fixed by means of the locking element and the engagement of the locking element with the projecting abutment portion of the shear pin. The invention is defined by the independent claim. The dependent claims define advantageous embodiments of the invention.

The invention relates more specifically to a breakable coupling in a load coupling which fits complementarity in a coupling holder, the load coupling comprising a locking-dog casing, which is connected to a load attachment, and being formed with at least one locking dog which is radially mov- able between a pushed-in or swung-in, non-locking position and a pushed-out or swung-out, locking position, the locking clog fitting complementarily in the coupling holder, and the load coupling being provided with a locking-dog blocking element which is movable between a blocking position, in which the locking-dog blocking element prevents the locking dog from being moved out of its locking position, and a non-blocking position, in which the locking dog is free to be moved away from its locking position, and the load attachment, which is axially displaceable relative to the locking-dog casing, being locked to the locking-dog casing by means of a shear pin, characterized by the shear pin comprising a weakened middle portion, and the shear pin being movable between a normal position, in which it forms a connection between the load attachment and the locking-dog casing by first and second end portions, and a release position, in which the first end portion has been pulled away from the load attachment and into the locking-dog casing and the weakened middle portion is arranged in an interface between the load attachment and the locking-dog casing.

The weakened middle portion of the shear pin may be formed as a reduction in area of the cross section of the shear pin.

The weakened middle portion of the shear pin may be formed as a middle section that forms a connection between two end sections, the middle section standing less shear force than the material of the end sections.

The weakened middle portion of the shear pin may be formed as a middle section that forms a connection between two end sections, the middle section exhibiting a smaller cross section than the end sections.

The weakened middle portion of the shear pin may be formed as a middle section that forms a connection between two end sections, the middle section being provided in a material different from the material forming the end sections.

The weakened middle portion of the shear pin may be provided as a cylinder-shaped middle section, which is fixed in complementary, opposite end bores formed in two end sections.

The shear pin may be connected to an actuator, which is arranged to subject the shear pin to an axial displacement.

The actuator may be provided with means restricting the axial displacement of the shear pin so that the displacement stops when the weakened middle portion has been moved into the interface between the load attachment and the locking-dog casing.

The shear pin may be connected to a screw which is in engagement with a surrounding threaded portion until the weakened middle portion of the shear pin has been moved into the interface between the load attachment and the locking-dog casing.

Alternatively, the shear pin may be connected to a screw which is in engagement with a surround- ing threaded portion, and in which an end stop is arranged to rest against the screw when the weakened middle portion of the shear pin has been moved into the interface between the load attachment and the locking-dog casing.

On fracture of the coupling between the load attachment and the locking-dog casing, a first portion of the shear pin may be shut up in the locking-dog casing and a second portion of the shear pin may be shut up in an actuator housing.

The first end portion of the shear pin may be provided with an abutment portion which, on the displacement of the shear pin out of the load attachment and towards a locking element encircling a portion of the load attachment and being connected to the locking-dog blocking element, fixes the locking-dog blocking element in its blocking or non-blocking position.

In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which:

Figure 1 shows, in perspective, a load coupling according to the invention, which is connected to a coupling holder;

Figure 2 shows an axial section of the load coupling and the coupling holder, in which a locking-dog blocking element is locked in a pulled-up position to provide free movement of the locking dogs of the load coupling;

Figure 3 shows an axial section of the load coupling connected to the coupling holder, the locking-dog blocking element having been moved to a position in which the locking dogs are blocked in a pushed-out gripping position;

Figure 4a shows an axial section of the shear pin, the load coupling and the coupling holder in a detail view, in which a shear pin has been pulled to its release position before it has been shorn; and

Figure 4b shows an axial section of the load coupling and the coupling holder, in which a shear pin has been pulled to its release position and been shorn so that the load coupling has been released from the coupling holder.

In the drawings, the reference numeral 1 indicates a load coupling, which is releasably connectable to a coupling holder 2 which is typically permanently or temporarily connected to an object not shown, which is to be lifted, an anchoring point not shown, for a wire guide or the like. The load coupling 1 includes a load attachment 12 partly accommodating a locking-dog casing 13. The locking-dog casing 13 is axially displaceable in the load attachment 12, but is connected, in the normal state, to the load attachment 12 by means of a shear pin 14. A locking-dog blocking element 15 (see figures 2-4) is arranged in an axially displaceable manner in the locking-dog casing 13 by means of a locking element 17.

The load attachment 12 is provided with lifting eye 121 for the connection of a wire or the like extending from a remote winch by means of a shackle or the like.

Reference is now made to figure 2 in particular. The locking-dog casing 13, which is substantially tubular, is arranged in a central recess in the load attachment 12, said recess having its mouth in the lower end of the load attachment 12, remote from the lifting eye 121 . The locking-dog casing 13 projects with its lower portion from the load attachment 12, the locking-dog casing 13 being provided with a number of radial locking-dog cut-outs 131 which are distributed around a centre axis 1 1 shared by the load coupling 1 , the load attachment 12, the locking-dog casing 13 and the locking- dog blocking element 15. In each locking-dog cut-out 131 , a locking dog 132 is arranged, which is pivotable around a pivot axle 133 between a swung-in, inactive position and a swung-out, locking position.

The terms upper and lower refer to the normal working position of the load coupling 1 .

At its middle portion, the locking-dog casing 13 is formed with two diametrically opposite first through slots 134 oblong in the axial direction. A first shear-pin bore 135 extends diametrically through the locking-dog casing 13 at the upper end portion of the locking-dog casing 13.

The load attachment 12 encircles the locking-dog casing 13 in an axially movable manner. The load attachment 12 is also provided with two diametrically opposite, second through slots 122 oblong in the axial direction, corresponding to the slots 134 in the locking-dog casing 13. A second shear-pin bore 123 extends diametrically through the load attachment 12 and corresponds to the first shear-pin bore 135 in the locking-dog casing 13. In one of the end portions of the second shear-pin bore 123, a linear actuator 145, also called a shear-pin actuator, is arranged.

The locking-dog blocking element 15 is arranged centrically and axially displaceably in the locking- dog casing 13. The locking-dog blocking element 15 is provided with a stem 151 extending through parts of a centre bore 136 in the locking-dog casing 13. A diametrical bore 152 extends through an upper portion of the stem 151 . A connecting element 171 , here in the form of a bolt, extends through the bore 152, the slots 134 of the locking-dog casing 13 and the slots 122 of the load attachment and out to the external, axially displaceable locking element 17 which is sleeve-shaped here and encircles a portion of the locking-dog casing 13, possibly also a portion of the load at- tachment 12.

The shear pin 14 is in the shear-pin bores 135, 123. A first end portion 141 is formed of a first end section 141 ' and is provided with a peg-shaped, projecting abutment portion 1412. The first end section 141 ' is fixedly connected to a second end section 142' by means of a middle section 144', shown here as a pin arranged in end bores 1421 of the end sections 141 ', 142'. The middle section 144' forms a weakened middle portion 144 of the shear pin 14. The second end portion 142 of the shear pin 14 is provided with means 142 for connecting the shear pin 14 to the shear-pin actuator 145, shown here as a bayonet coupling.

The shear-pin actuator 145 is shown as a screw 1451 arranged in engagement with a threaded portion 1453 internally in a tubular actuator housing 1452. The shear-pin actuator 145 is formed in such a way that the axial displacement of the shear pin 14 from a normal position, in which the shear pin 14 is arranged in both portions of the shear-pin bore 123 of the load attachment 12, stops automatically when the shear pin 14 reaches its release position, in which the weakened middle portion 144 of the shear pin 14 is in the interface between the load attachment 12 and the locking- dog casing 13. In the embodiment shown, this is achieved by the threaded portion 1453 having an axial extent which is such that when the screw 1451 has been unscrewed from the threaded portion 1453, possibly hits an end stop 1454, the middle portion 144 of the shear pin 14 is positioned in the interface between the load attachment 12 and the locking-dog casing 13.

When the locking element 17 is in its upper position, in which the abutment portion 1412 is in en- gagement with a cut-out 172 in the locking element 17, see figure 2, the locking-dog blocking element 15 has been pulled up and allows the locking dogs 132 to pivot freely. In this state, the load coupling 1 can be connected to the coupling holder 2 by the lower portion of the load coupling 1 being inserted into the coupling holder 2. The locking element 17 is then moved downwards, so that the locking-dog blocking element 15 is brought into abutment against the lower portion of the locking dogs 132. The locking dogs 132 engage with annular grooves 21 in the coupling holder 2, and the shear pin 14 is displaced in such a way that the projecting abutment portion 1412 rests against the locking element 17 and prevents the locking element 17 from being moved upwards, see figure 3.

The load coupling 1 is released from the coupling holder 2 by the shear pin 14 first being pulled slightly into the load attachment 12 by means of the shear-pin actuator 145, so that the locking-dog blocking element 15 may then be pulled upwards and the locking dogs 132 may freely pivot inwards and disengage from the grooves 21 in the coupling holder 2. If this disengaging process fails for some reason and use must be made of the backup solution that the shear-pin connection between the load attachment 12 and the locking-dog casing 13 represents, the following is done: Reference is now made to figure 4a. In a situation in which the releasing of the locking dogs 132 does not work on the ordinary withdrawal of the locking-dog blocking element 15, the shear-pin actuator 145 is activated; in the embodiment shown, by a tool (not shown) being inserted into the end portion of the screw 1451 and the screw 1451 being unscrewed as far as it can be moved, so that the shear-pin 14 reaches its release position. This procedure is typically performed with the help of a diver or an unmanned, remotely operated vehicle (ROV). When the shear pin 14 has reached its release position, it is only the weakened middle portion 144 that is holding the load attachment 12 and the locking-dog casing 13 together in a normal position, and this connection is broken by a moderate tensile load from the connected lifting equipment not shown. The locking- dog casing 13 and the locking-dog blocking element 15 are moved axially in the load attachment 12 until the bolt 171 through the stem 151 of the locking-dog blocking element 15 hits the lower edge of the elongated slots 122 of the load attachment 12. The locking-dog casing 13 continues its axial movement until the bolt 17 hits the upper edge of the elongated slots 134 of the locking-dog casing 13. The relative motion between the locking-dog casing 13 and the locking-dog blocking element 15 results in the locking-dog blocking element 15 being pulled away from the locking dogs 132 so that these may be swung in, and the load coupling 1 is released from the coupling holder 2.

This "emergency" release is carried out without the components of the load coupling 1 being left behind at the coupling holder 2, as the locking-dog casing 13 stays connected to the load attachment 12. The load coupling 1 in this state is shown in figure 4b.

The middle section 144' may exhibit a wide variety of forms as long as the middle portion 144 of the shear pin 14 has the properties that are the most important object of the invention, namely providing a shear pin 14 with a weakened middle portion 144 which, on the axial displacement of the shear pin 14, is moved into the interface between the load attachment 12 and the locking-dog casing 13.

The use of the verb "to comprise" and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article "a" or "an" before an element does not exclude the presence of several such elements.

The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.

Claims

C l a i m s

1 . A breakable coupling in a load coupling (1) which fits complementarily in a coupling holder (2), the load coupling (1) comprising a locking-dog casing (13), which is connected to a load attachment (12), and being formed with at least one locking dog (132) which is radially movable between a pushed-in or swung-in, non-locking position and a pushed-out or swung-out, locking position, the locking-dog (132) fitting complementarily into the coupling holder (2), and the load coupling (1) being provided with a locking-dog blocking element (15) which is movable between a blocking position, in which the locking-dog blocking element (15) prevents the locking-dog (132) from being moved out of its locking position, and a non-blocking position in which the locking dog (132) is free to be moved away from its locking position, and the load attachment (12), which is axially movable relative to the locking-dog casing (13), being locked to the locking-dog casing (13) by means of a shear pin (14), c h a r a c t e r i z e d i n that

the shear pin (14) includes a weakened middle portion (144);

the shear pin (14) is displaceable between a normal position, in which it forms a connection between the load attachment (12) and the locking-dog casing (13) by first and second end portions (141 , 142), and a release position, in which the first end portion (141) has been pulled away from the load attachment (12) and into the locking-dog casing (13) and the weakened middle portion (144) is arranged in an interface between the load attachment (12) and the locking-dog casing (13).

2. The breakable coupling in accordance with claim 1 , wherein the weakened middle portion (144) of the shear pin (14) is formed as a reduction in area of the cross section of the shear pin (14).

3. The breakable coupling in accordance with claim 1 , wherein the weakened middle portion (144) of the shear pin (14) is formed as a middle section (144') forming a connection between two end sections (141 ', 142'), the middle section (144') standing less shear force than the material in the end sections (141 ', 142').

4. The breakable coupling in accordance with claim 1 , wherein the weakened middle portion (144) of the shear pin (14) is formed as a middle section (144') forming a connection between two end sections (141 ', 142'), the middle section (144') exhibiting a smaller cross section than the end sections (141 ', 142').

5. The breakable coupling in accordance with claim 1 , wherein the weakened middle portion (144) of the shear pin (14) is formed as a middle section (144') forming a connection between two end sections (141 ', 142'), the middle section (144') being provided in a material different from the material forming the end sections (141 ', 142').

6. The breakable coupling in accordance with claim 1 , wherein the weakened middle portion (144) of the shear pin (14) is formed as a cylinder-shaped middle section (144') which is fixed in complementary, opposite end bores (1421) formed in two end sections (141 ', 142').

7. The breakable coupling in accordance with claim 1 , wherein the shear pin (14) is connected to an actuator (145) which is arranged to subject the shear pin (14) to an axial displacement.

8. The breakable coupling in accordance with claim 7, wherein the actuator (145) is provided with means (1451 , 1453, 1454) restricting the axial displacement of the shear pin (14), so that the displacement stops when the weakened middle portion (144) has been moved into the interface between the load attachment (12) and the locking-dog casing (13).

9. The breakable coupling in accordance with claim 8, wherein the shear pin (14) is connected to a screw (1451) which is in engagement with a surrounding threaded portion (1453) until the weakened middle portion (144) of the shear pin (14) has been moved into the interface between the load attachment (12) and the locking-dog casing (13).

10. The breakable coupling in accordance with claim 8, wherein the shear pin (14) is connected to a screw (1451) which is in engagement with a surrounding threaded portion (1453), and wherein an end stop (1454) is arranged to abut against the screw (1451) when the weakened middle portion (144) of the shear pin (14) has been moved into the interface between the load attachment (12) and the locking-dog casing (13).

1 1 . The breakable coupling in accordance with claim 1 , wherein, on fracture of the coupling between the load attachment (12) and the locking-dog casing (13), a first portion of the shear pin (14) is shut up in the locking-dog casing (13) and a second portion of the shear pin (14) is shut up in an actuator housing (1452).

12. The breakable coupling in accordance with claim 1 , wherein the first end portion (141) of the shear pin (14) is provided with an abutment portion (1412) which, on the displacement of the shear pin (14) out of the load attachment and towards a locking element (17) encircling a portion of the load attachment (12) and being connected to the locking-dog blocking element (15), fixes the locking-dog blocking element (15) in its blocking or non-blocking position.