GB2524969A

GB2524969A - Pipeline breakaway coupling assembly

Info

Publication number: GB2524969A
Application number: GB1406226.9A
Authority: GB
Inventors: Ian Pillay; Robert Quantrill
Original assignee: SHAND ENGINEERING Ltd
Current assignee: SHAND ENGINEERING Ltd
Priority date: 2014-04-07
Filing date: 2014-04-07
Publication date: 2015-10-14
Also published as: GB201406226D0

Abstract

A pipeline breakaway coupling assembly comprises first and second sub assemblies 2, 4. The first sub assembly 2 is adapted for connection to a first section of pipeline. The second sub assembly 4 is adapted for connection to a second section of pipeline. Each sub-assembly 2, 4 has an inner wall 22, 62 defining a bore 24, 64. A fastening mechanism such as break bolts 6a, 6b, 6c holds the two sub assemblies 2, 4 together. The fastening mechanism 6a, 6b, 6c is adapted to fail when a predetermined tensile load is applied to the first and second sub assemblies 2, 4. A valve arrangement 44, 78 is associated with each sub assembly 2, 4. Each valve arrangement 44, 78 is positioned in the bore 24, 64 of the corresponding sub assembly 2, 4 and comprises a valve member 46, 80 and a valve seat 54, 59. Each valve arrangement is 44, 78 is switchable between an open state, and a closed state when the fastening mechanism 6a, 6b, 6c fails and the sub assemblies 2, 4 are broken apart allowing pins 122, 124 to disengage from arms 102, 104. Each valve arrangement is adapted such that, when the first and second sub assemblies 2, 4 are held together and each valve arrangement 44, 78 is in the open state, each valve member 46, 80 is positioned away from the peak flow region of that bore. A threaded tool 154 may be used to hold the valve in an open configuration for assembly, and subsequently removed in use. The hole 164 left behind being closed by a plug 168b.

Description

Pipeline Breakaway Coupling Assembly

Field of the Invention

The invention relates to pipeline breakaway coupling assemblies.

Background to the Invention

Flowable materials, such as liquids, gases and certain forms of solids, such as powders or granules, may be stored in tanks and may be transferred from a first tank to a second tank using a pipeline. At least one of the tanks in-volved in a transfer may be mobile; for example, it may be on a lorry or a ship.

Slack in the pipeline will permit some relative movement between the two tanks without the pipeline being subjected to a tensile load. In the event of excessive movement, say, for instance, because one of the tanks is on a ship that breaks away from its mooring, the pipeline may be stretched to the extent that it is placed under a tensile load sufficient to cause the pipeline to rupture, which may lead to flowable material leaking out. Depending on what the flowable ma-terial is, there may be financial, safety, environmental and other consequences from a leak.

To protect against rupture, a pipeline may be provided with a breakaway coupling assembly which typically comprises two sub-assemblies held together by a mechanism that is designed to fail at a predetermined tensile load, which is less than a pipeline rupture load. One of the sub-assemblies is connected to a first section of pipeline from the first tank, and the other sub-assembly is con-nected to a second section of pipeline to the second tank. Each sub assembly has an associated valve arrangement comprising a valve member and a valve seat. When the sub-assemblies are held together, each valve arrangement is retained in an open state with the corresponding valve member in a position in which it is disengaged from its valve seat. In this state, flowable material is able to flow from the first section of pipeline, through a bore in the first assembly, through a bore in the second assembly and into the second section of pipeline.

When the pipeline is stretched to the extent that the assembly is subject to the predetermined tensile load, the two sub-assemblies break apart, thereby avoid- ing a rupture. As the sub-assemblies break apart, each valve arrangement au-tomatically switches to a closed state with each valve member in a position in which it is in engagement with its corresponding valve seat, so as to seal off the bore in the corresponding sub-assembly and prevent the flowable material from leaking out of the associated pipeline.

The flow rate of a flowable material through a pipe with a generally cylin-drical bore varies across the diameter of the bore. The peak flow region is in the centre region of the bore, that is, around about the central cylindrical axis of the bore, and flow rate decreases with radial distance away from the centre region.

In known breakaway couplings, such as the one disclosed in (iS 20009/0008935, with the valve arrangements of both sub-assemblies in their open states, both valve members are in positions such that they are in or partly in the peak flow region of the corresponding sub-assembly. This is undesirable because of the impact on flow through the pipeline.

Summary of the Invention

According to a first aspect, there is provided a pipeline breakaway cou- pling assembly comprising first and second sub-assemblies, the first sub as-sembly being adapted for connection to a first section of pipeline, the second sub assembly being adapted for connection to a second section of pipeline, each sub-assembly having an inner wall defining a bore in the corresponding sub-assembly, a fastening mechanism for holding the two sub-assemblies to-gether, the fastening mechanism being adapted to fail when a predetermined tensile load is applied to the first and second sub-assemblies, a valve arrange- ment associated with each sub-assembly, each valve arrangement being posi-tioned in the bore of the corresponding sub-assembly and comprising a valve member, a valve seat and an urging device, wherein each valve arrangement is switchable between an open state with the corresponding valve member in a position in which it is not in engagement with the corresponding valve seat and flowable material is able to flow through the corresponding bore, and a closed state in which the corresponding valve member is in a position in which it is in engagement with the corresponding valve seat and flowable material is pre- vented from leaking from the corresponding bore, wherein each valve arrange-ment is urged by the urging device to switch from an open state to a closed state when the fastening mechanism fails and the sub-assemblies are broken apart, and wherein each valve arrangement is adapted such that, when the first and second sub-assemblies are held together and each valve arrangement is in the open state, each valve member is positioned away from the peak flow re-gion of the corresponding bore. The open state position of the valve members of the invention means that they have less impact on flow through the pipeline than the valve members of prior art breakaway coupling assemblies.

In one example assembly, each valve arrangement further comprises an arm having two ends and a bracket, wherein one end of each arm is pivotably attached to the corresponding bracket and the corresponding valve member is attached at the other end of each arm, each arm being pivotable about the bracket so as to move the corresponding valve member from the open state po-sition to the closed state position, and the urging device comprises at least one coil spring In the one example assembly, each valve member is attached to its corresponding arm by an attachment arrangement comprising a resilient com- ponent that enables each valve member to flex with respect to the correspond-ing arm. For instance, if each valve member is attached to the corresponding arm by a bolt, a rubber bush or spring around the shaft of the bolt may act as the resilient component. In addition, flexing is aided by the interfacing surfaces of each valve arm and the corresponding valve member being cambered. By flexing with respect to the corresponding valve arm, each valve member is ef- fectively free floating, which assists each valve member in aligning itself in en-gagement with the corresponding valve seat. In the one example assembly, each sub-assembly further comprises an end pate having an opening and an edge around the opening serves as the valve seat, and each valve member is generally disc-shaped, wherein, in the closed state position, the valve member fills the opening in the corresponding end plate.

Each sub-assembly may be provided with a tool for holding the corre- sponding valve arrangement in the open state before and while the sub-assembly is fitted to the other sub-assembly and while the two sub-assemblies are fastened together. In the one example assembly, each valve arm comprises a tapped hole, each tool has a threaded shank and each sub-assembly has an aperture through which the shank of the corresponding tool is inserted, thereby enabling the shank to be screwed into the hole in the corresponding valve arm.

Once the sub-assemblies are fastened together, the tool is removed. Also in the one example assembly, each sub-assembly is provided with a bung for sealing the corresponding hole after the corresponding tool is removed.

Each sub-assembly may have a retaining mechanism for retaining the corresponding valve arrangement in the open state. The retaining mechanism may be actuated by fitting the first and second sub-assemblies together. The mechanism may be de-actuated by the first and second sub-assemblies break- ing apart. Also in the one example assembly, the retaining mechanism compris-es a retaining pin which is movable between an unlocking position and a locking position and an urging device which urges the resilient pin to the unlocking posi- tion, wherein the retaining pin is positioned such that, when the two sub-assemblies are fastened together, the retaining pin engages a retaining pin in the other sub-assembly, which causes the retaining pin to move into the locking position, against the urging of the resilient component.

The fastening mechanism may comprise at least one break bolt. Holes for the bolts may be arranged in each sub-assembly so that there are a number of ways of fastening the two sub-assemblies together. For instance, there may be three bolts and three equiangularly spaced holes. Alternatively, holes for the bolts may so arranged that there is only one way of fastening the two sub-assemblies together According to a second aspect, there is provided a sub-assembly for an assembly according to the first aspect.

According to a third aspect, there is provided a method of making a pipe-line comprising coupling a first section of pipeline to a second section of pipeline using an assembly according to the first aspect.

According to a fourth aspect, there is provided a method of transferring a flowable material from a first tank to a second tank comprising using a pipeline including an assembly according to the first aspect.

Brief Description of the Drawings

Figure 1 is an isometric view of a pipeline breakaway coupling assembly according to the invention; Figure 2 is an isometric view of the female sub-assembly of the assembly shown in figure 1, looking from the mating end; Figure 3 is an isometric view of the female sub-assembly of figure 2, ex-cept that the valve member is shown in engagement with the valve seat, looking from the pipeline connection end and partially cut away; Figure 4 is an isometric view of the male sub-assembly of the assembly shown in figure 1, looking from the mating end; Figure 5 is a longitudinal sectional view of the assembly shown in figure 1; and Figure 6 is a longitudinal sectional view of the assembly shown in figure 1, shown shortly after the male and female sub-assemblies have broken apart.

Detailed Description of the Illustrated Embodiment

With reference to figure 1, a pipeline breakaway coupling assembly indi- cated generally at 1 has a first, female sub-assembly 2 and a second, male sub-assembly 4. The first and second sub-assemblies 2, 4 are fastened together by a fastening mechanism in the form of three equiangularly spaced break bolts 6a, 6b, 6c (only two of which are shown in figure 1). Each sub-assembly 2, 4 has a mating end 8,10 which is adapted to fit together in mating relationship with the mating end 10, 8 of the other sub-assembly 2,4, and an opposite, pipe- line end 12, 14. The first sub-assembly pipeline end 12 is adapted to be con-nected to a first section of pipeline (not shown) from a first tank (not shown) and the second sub-assembly pipeline end 14 is adapted to be connected to a sec-ond section of pipeline (not shown) to a second tank (not shown).

With reference to figures 2, 3 and 5, at its mating end 8, the first, female sub assembly 2 has an increased outer diameter portion 16 that is fluted to one side and flat to the other. The flat side provides an annular abutment surface 18. Three equiangularly spaced holes 20a, 20b, 20c for the break bolts 6a, 6b, 6c (only one shown in figure 5)extend through the increased outer diameter por-tion 16 of the female sub-assembly 2 from one side to the other. The female sub-assembly 2 has an inner wall 22 that defines a generally cylindrical bore 24 which, for a portion 26 extending from the pipeline end 12 of the female sub-assembly 2, generally has the same, first diameter. At the mating end 8 of the female sub-assembly 2, a portion 28 of the bore 24 has an increased, second diameter. The step-change in the bore 24 from the first diameter to the second diameter provides an annular attachment surface 30. A circular end plate 32, of the same diameter as the second diameter portion 28 and having a circular, off-centre opening 34, is bolted to the attachment surface 30. An 0-ring seal 36 is provided in a recess 38 between the end plate 32 and the attachment surface (see figure 5). The inner wall 22 of the increased diameter portion 28 of the bore 24 includes a recess 40 in which an 0-ring seal 42 is located.

The female sub-assembly 2 has an associated valve arrangement 44 comprising a valve member 46, a valve arm 48, a mounting bracket 50 and two urging devices in the form of coil springs 52a, 52b (see figure 3). A valve seat is provided by an inside edge 54 of the end plate 32, around the opening 34.

With further reference to figure 4, towards its mating end 10, the second, male sub assembly 4 has an increased outer diameter portion 53 that is fluted to one side and flat to the other. The flat side provides an annular, increased diameter abutment surface 58. Three equiangularly spaced holes 60a, 60b, 60c for the break bolts 6a, 6b, 6c (only two visible in figure 4) extend through the in- creased outer diameter portion 53 from one side to the other. The male sub-assembly 4 has an inner wall 62 that defines a cylindrical bore 64 which has generally the same diameter over its entire length. The mating end 10 of the male sub-assembly 4 has a protruding portion 66 that extends beyond the abutment surface 58 and has an end 72. A circular end plate 68, having an off centre, circular opening 70, is bolted to the end 72 of the protruding portion 66.

An 0-ring seal 74 is provided in a recess 75 between the end plate 68 and the protruding portion 66 (see figure 5).

As with the female sub-assembly 2, the male sub-assembly 4 has an as-sociated valve arrangement 78 comprising a valve member 80, a valve arm 82, a mounting bracket 84 and two urging devices in the form of coil springs 86a, 86b (only one of which is visible in figure 4). A valve seat is provided by an in-side edge 58 of the end plate 68, around the opening 70.

With particular reference to figure 5, with the two sub-assemblies 2, 4 fit- ted together in a mating relationship, the protruding portion 66 of the male sub- assembly 4 extends into the end portion 28 of the bore 24 of the female sub-assembly 2 such that the end plates 32, 68 and the abutment surfaces 18, 58 of both sub-assemblies 2, 4 are in engagement. The two sub-assemblies 2, 4 are oriented such that the bolt holes 20a, 20b, 20c, 60a, 60b, 60c in each sub as-sembly 2, 4 and the openings 34, 70 in the two end plates 32, 68, which are identical, are aligned. The 0-ring seal 42 in the inner wall 22 in the end portion 28 of the wall 22 of the female sub-assembly 2 seals against the protruding por-tion 66 of the male sub-assembly 4.

The mounting bracket 50, 84 of each valve arrangement 44, 78 compris- es an elongate member 89, 91 which is attached at one end 94, 95 to the bore-facing side of the corresponding end plate 32, 68, closely adjacent to the inner wall 22, 62 of the corresponding sub-assembly 2, 4. Each bracket member 89, 91 has a raised part 96, 97 that supports a transverse axle 98, 100. Each valve arm 48, 82 has a generally elongate body part 102, 104 and a support part 106, 109. Each valve arm body part 102, 104 has a free end pivotably mounted on the corresponding axle 98, 100 and the corresponding valve member 46, 80 is attached by a bolt 114, 116 to the corresponding support part 106, 109. A resili-ent component in the form of a rubber bush 117, 119 is provided around the shaft of each bolt 114, 116, between the bolt head and the corresponding sup-port part 106, 109. Each bush 117, 119 enables each valve member 46, 80 to flex with respect to the corresponding valve arm 48, 82. The interfacing surfac-es of each valve arm 48, 82 and the corresponding valve member 46, 80 are cambered to aid flexing.

The coil springs 52a, 52b, 86a, 86b wrapped around each bracket axle 98, 100 are adapted to urge the corresponding valve arm 48, 82 towards the corresponding end plate 32, 68.

Each valve arrangement 44, 78 is shown in figure 5 in the open state with each valve member 46, 80 in a position in which it is not in engagement with the corresponding valve seat 54, 58. The female sub-assembly 2 is shown with a tool 154 still in situ, which is used for holding the valve arrangement 44 in the open state, against the urging force of the coil springs 52a, 52b, before and while the sub-assemblies 2, 4 are fitted together and then while they are fas-tened together.

The tool 154, which is similar in shape to a screw driver, has a shank 156, having a tip 160, and a handle 158. The tip 160 of the shank is threaded. A tapped hole 162 is provided in the back of the valve arm 48. Before the sub-assemblies 2, 4 are fitted together, the valve arrangement 44 is man-handled into the open state. A counter-sunk aperture 164 in the sub-assembly 2 is aligned with the hole 162 in the valve arm 48 in the open state of the valve ar-rangement 44. The tool 154 is inserted through the aperture 164 and the shank 156 is screwed into the hole 162 until the handle 158 is up against the sub-assembly 2. The valve arrangement 44 is then held in the open state and the sub-assembly 2 can be fitted to the sub-assembly 4. Once that has been done and the two sub-assemblies 2, 4 have been fastened together, as shown in fig-ure 5, the tool 154 is ready to be unscrewed and removed.

In figure 5, sub-assembly 4 is shown after its tool (not shown), which is identical to the one used for sub-assembly 2, has been removed and an aper-ture 166 in the sub-assembly 4 has been sealed with a bung 168b. An identical bung 168a (see figure 6) is used to seal the aperture 164 in the sub-assembly 2.

In the open states of the valve arrangements 44, 78, flowable material (not shown) is able to flow through the first section of pipeline from the first tank, through the bore 24 in the female sub-assembly 2, through the opening 34 in the female sub-assembly end plate 32, through the opening 70 in the male sub-assembly end plate 68, through the bore 64 in the male sub-assembly 4 and through the second section of pipeline to the second tank. As is well known, the peak flow rate of the flowable material as it flows through the two sub- assemblies 2, 4 will be in the centre regions of the bores 24, 64 of the two sub-assemblies 2, 4, that is, around about the central cylindrical axes of the bores 24, 64. In the open state of each valve arrangement 44, 78, each valve arm 48, 82 is pivoted to a position closely adjacent the inner wall 22, 62 of the corre-sponding sub-assembly 2, 4. As a consequence, each valve member 46, 80 is positioned away from the centre region of the bore 24, 64 of the corresponding sub-assembly 2, 4. In other words, in their open state of the valve arrangements 44, 78, each valve member 46, 80 is positioned away from the peak flow region of the flowable material through the corresponding bore 24, 64.

Each valve member 46, 80 is retained in the open state position by an associated retaining mechanism 118, 120 comprising a retaining pin 122,124 which is slidably movable in a channel 126, 128 extending the full length of the corresponding bracket member body part 90, 92, and an urging device in the form of a coil spring 130, 132 in the channel 126, 128, wrapped around the cor-responding pin 122, 124. Each pin 122, 124 is movable between an unlocked position, in which it extends out of a hole 134, 136 in the corresponding end plate 32, 68, which is aligned with the channel 126, 128 at the end plate-end of the bracket member body part 90, and a locking position, in which it extends out of the channel 126, 128 at the opposite, free end of the bracket member body part 90, 92. Each spring 130, 132 in each channel 122, 124 acts on a collar 138, 140 around the corresponding pin 122, 124 so as to urge that pin 122, 124 towards the unlocking position.

Each retaining mechanism 118, 120 is actuated by fitting the first and second sub-assemblies 2, 4 together. The retaining pins 122, 124 in each sub-assembly 2, 4 are in opposed positions in each sub-assembly 2, 4. When the first and second sub-assemblies 2, 4 are brought together, the retaining pins 122, 124 engage one another and force one another against their respective springs 130,132, from their respective unlocking positions, into their respective locking positions. Each valve arm 48, 82 is provided with a recess 142, 144 in the corresponding support part 106, 108, which, when that valve arm 48, 82 is positioned closely adjacent the inner wall 22, 62 of the corresponding sub-assembly 2, 4, is aligned with the channel 126, 128 in the bracket member body part 90, 92. When the first and second sub-assemblies 2, 4 are fitted together, each retaining pin 122, 124 extends out of the channel 126, 128 at the free end of the body part 90, 92 of the corresponding bracket member 50, 84 and into the corresponding recess 142, 144 so as to retain the corresponding valve arm 48, 82 closely adjacent the inner wall 22, 62 of the corresponding sub-assembly. With the retaining pins 122, 124 in their locked positions, the tools 154 holding the valve arrangements in their open states can be removed.

Each valve arrangement 44, 78 is shown in figure 6 in the closed state with each valve member 46, 80 in a position in which it is in engagement with the corresponding valve seat 54, 88. In this state, flowable material is not able to flow from the bore 24, out through the opening 34 in the female sub-assembly end plate 32, or out of the bore 64 through the opening 70 in the male sub-assembly end plate 68. In the event that the sections of pipeline attached to each of the sub-assemblies 2, 4 are stretched, the coupling assembly 1 will be subject to a tensile load. The break bolts 6a, 6b, Sc are selected so that they will fail when the coupling assembly 1 is subjected to a predetermined tensile load, which is less than the load required to rupture the pipeline. When the break bolts 6a, 6b, 6c fail and the male and female sub-assemblies 2, 4 break apart, each retaining mechanism 118, 120 is de-actuated; the retaining pins 122, 124 in each sub-assembly 2, 4 no longer engage each other and there is no force opposing the urging forces applied by their respective springs 130, 132. As a result, each pin 122, 124 is urged into the unlocking position in which it extends through the hole 134, 136 in the corresponding end plate 32, 68 and it slides out of the recess 142, 144 in the valve arm support part 106, 108. Consequently, each valve arm 48, 82 is no longer retained closely adjacent the inner wall 22, 62 of the corresponding sub-assembly 2, 4 and is free to move. The coil springs 52a, 52b, 86a, 86b are adapted to urge the corresponding valve arm 48, 82 to-wards the corresponding end plate 32, 68. Each valve arm 48, 82 continues to move towards its corresponding end plate 32, 68 until the corresponding valve member 48, 82 is in a position in which it is in engagement with the correspond- ing valve seat 54, 88 (as shown in figure 6). Each valve member 46, 80 is gen-erally disc-shaped and, in the closed state of each valve arrangement 44, 78, each valve member 48, 82 fills the opening 34, 70 in the corresponding end plate 32, 68. Each valve member 46, 80 is effectively "free floating" because each valve member 46, 80 is able to flex with respect to the corresponding valve arm 48, 82, which enables each valve member 46, 80 to self-centre once it has positioned itself on a single point on the valve seat 54, 88. When each valve member 46, 80 is centred, each bolt 114, 116 is aligned with the centre of the corresponding opening 34, 70. Each valve seat 54, 88 is chamfered. An 0-ring seal 146, 148 is provided in a recess 150, 152 around each valve seat 54, 88. Each valve member 46, 80 has a chamfered periphery which compliments the chamfer of the corresponding valve seat 54, 88.

Claims

CLAIMS1. A pipeline breakaway coupling assembly comprising first and sec-ond sub-assemblies, the first sub assembly being adapted for connection to a first section of pipeline, the second sub assembly being adapted for connection to a second section of pipeline, each sub-assembly having an inner wall defin-ing a bore, a fastening mechanism for holding the two sub-assemblies together, the fastening mechanism being adapted to fail when a predetermined tensile load is applied to the first and second sub-assemblies, a valve arrangement as-sociated with each sub-assembly, each valve arrangement being positioned in the bore of the corresponding sub-assembly and comprising a valve member, a valve seat and an urging device, wherein each valve arrangement is switchable between an open state with the corresponding valve member in a position in which it is not in engagement with the corresponding valve seat and flowable material is able to flow through the corresponding bore, and a closed state in which the corresponding valve member is in a position in which it is in engage-ment with the corresponding valve seat and flowable material is prevented from leaking from the corresponding bore, wherein each valve arrangement is urged by the urging device to switch from an open state to a closed state when the mechanism fails and the sub-assemblies are broken apart, and wherein each valve arrangement is adapted such that, when the first and second sub-assemblies are held together and each valve arrangement is in the open state, each valve member is positioned away from the peak flow region of that bore.
2. The assembly according to claim 1 wherein each valve arrange-ment further comprises an arm having two ends and a bracket, wherein one end of each arm is pivotably attached to the corresponding bracket and the corre- sponding valve member is attached at the other end of each arm, each arm be-ing pivotable about the bracket so as to move the corresponding valve member from the open state position to the closed state position, and the urging device comprises at least one coil spring.
3. The assembly according to claim 2 wherein each valve member is attached to its corresponding arm by an attachment arrangement comprising a resilient component that enables each valve member to flex with respect to the corresponding arm.
4. The assembly according to claim 3 wherein the attachment ar-rangement comprises a bolt having a shaft and a rubber bush or spring around the shaft act as the resilient component.
5. The assembly according to claim 3 or claim 4 wherein the interfac- ing surfaces of each valve arm and the corresponding valve member are cam-bered.
6. The assembly according to claim 2 wherein each sub-assembly comprises and end plate having an opening and an edge around the opening serves as the valve seat, and each valve member is generally disc-shaped, wherein, in the closed state position, the valve member fills the opening in the corresponding end plate.
7. The assembly according to any of claims 1 to 6 wherein each sub assembly is provided with a tool for holding the corresponding valve arrange-ment in the open state before and while the sub-assembly is fitted to the other sub-assembly and while the two sub-assemblies are fastened together.
8. The assembly according to claim 7 wherein, each valve arm com-prises a tapped hole, each tool has a threaded shank and each sub-assembly has an aperture through which the shank of the corresponding tool is inserted, thereby enabling the shank to be screwed into the hole in the corresponding valve arm.
9. The assembly according to claim 8 wherein each sub-assembly is provided with a bung for sealing the corresponding hole after the corresponding tool is removed.
10. The assembly according to any preceding claim wherein each sub assembly has a retaining mechanism for retaining the corresponding valve member in the open position.
11. The assembly according to claim 10 wherein the retaining mecha-nism is actuated by fitting the first and second sub-assemblies together.
12. The assembly according to claim 11 wherein the retaining mecha-nism is de-actuated by the first and second sub-assemblies breaking apart.
13 The assembly according to claim 10 wherein the retaining mecha-nism comprises a retaining pin which is movable between an unlocking position and a locking position and a resilient component which urges the resilient pin to the unlocking position, wherein the retaining pin is positioned such that, when the two sub-assemblies are fastened together, the retaining pin engages a re-taining pin in the other sub-assembly, which causes the retaining pin to move into the locking position, against the urging of the resilient component.
14. The assembly according to any preceding claim wherein the fas-tening mechanism comprises at least one break bolt.
15. A sub-assembly for an assembly according to any preceding claim.
16. A method of making a pipeline comprising coupling a first section of pipeline to a second section of pipeline using an assembly according to any of claims ito 14.
17. A method of transferring a flowable material from a first tank to a second tank comprising using a pipeline including an assembly according to any of claims ito 14.