NO340806B1 - Weak link-preserving cover - Google Patents

Description

WEAK LINK-PRESERVING COVER

The present invention relates to a weak link-preserving cover for at least partly covering a weak link.

A weak link is a connector for cables, wires, tubing, and hoses or similar, that acts as a deliberate point of weakness. The weak link is designed to break if it is exposed to a certain level of tension. Its purpose is to provide a controlled point of breakage if equipment is exposed to tension above a certain threshold, to avoid more hazardous and/or costly ruptures.

Mann Tek's safety break-away coupling is a typical example and much used type of weak link for the offshore oil industry. The safety break-away coupling is typically installed into hose assemblies, and comprises two halves, each with a closing valve. Furthermore, the safety break-away coupling comprises three bolts. When the coupling is exposed to too high levels of tension, the bolts will break off, the two halves will separate, and the valves will shut rapidly. This way, the safety break-away coupling prevents spilling during and after breakage.

The weak links, comprising bolts, that are used in the offshore oil industry are exposed to rough conditions that takes its toll on the equipment. Due to this, the bolts have to be replaced frequently. It is known that in some cases, when the original bolts need to be replaced, the original bolts are replaced by stronger replacement bolts. The replacement bolts affect the weak link and make the weak links stronger than they were designed to be, thus altering their threshold for breakage. This may lead to a weak link becoming a strong link, a link that no longer functions as the point of weakness and point of breakage.

If a weak link loses its function as a weak link, it will be as if there was no weak link present. There will be a risk of a rupture in e.g. a hose, if hoses are what the weak link binds together. A rupture in a hose may lead to spilling of vast amounts of fluids that may be hazardous for personnel and/or for environment. It is thus obviously of great importance to preserve the functionality of the weak link.

Another hazard is that the bolts of the weak links may, when broken, constitute falling objects. As the weak links are often used on assemblies that may move, e.g. as a result of high winds, and often used high above a ground level, the impact zone of the bolts as falling objects may be big and hard to define. The size of the impact zone increases the risk involved.

Falling objects is a major safety concern in the petroleum industry, and any risk reducing measure that relates to this concern will likely be highly appreciated. The weak link-preserving cover will reduce the frequency of which bolts will break, and thus constitute an important safety measure in this regard.

The intention behind the weak link-preserving cover is to ensure that the weak link retains its threshold for breakage throughout its lifetime. By providing a cover for the weak link and its bolts that prolongs the lifetime of the bolts, the frequency of which bolts break or bolts needs to be replaced will be reduced. This should reduce the temptation to 'cheat' by replacing the original bolts by stronger replacement bolts, and reduce the risk of broken bolts as falling objects.

It is known from prior art to equip weak links with a protective cover. Mann Tek's safety break-away couplings comprises a protective cover made from a hard plastic material, in two pieces. One piece of the cover sits on each of the two halves of a break-away coupling. When the two halves of a break-away coupling are mounted together, the two pieces of the protective cover will be arranged together.

The protective cover known from the Mann Tek break-away couplings is not particularly well suited for the purpose of retaining the weak link's threshold for breakage throughout its lifetime. It is known that the protective cover on the Mann Tek safety break-away couplings tends to break from heavy impacts, that it isn't particularly well suited for an offshore environment, and that it does little to protect the bolts.

Prior art document CN102635338 (A) describes a safety protection device for a bailing device in a flexible bar of an intelligent intermittent bailing type oil pumping unit.

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

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

The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect, the invention relates to a weak link-preserving cover for at least partly covering a weak link, wherein the weak link-preserving cover is made from an elastomer material with a hardness of between 15 shore A and 35 shore A.

Preferably, the hardness may be in the range 18-30 shore A. Even more preferably, the hardness may be in the range 18-25 shore A.

The hardness of the elastomer material is of great importance to the weak link-preserving cover. If the hardness is too high or too low, its capacity to absorb shocks will be reduced. It is also of vital importance that the weak link-preserving cover does not significantly alter the threshold for breakage of the weak link, which a hard rubber material would do. Furthermore, it is preferable that the weak link-preserving cover can be pulled onto a weak link by hand, which would be very difficult if the hardness of the material was too high.

The weak link-preserving cover may typically be shaped to fit tightly around a weak link, and it may typically be arranged with an opening in a top end and a bottom end through which equipment may extend. Equipment, in this context, may be parts of the weak link, or it may be whateverthe weak link binds together, such as tubing, hoses, wires or cables.

Furthermore, the weak link-preserving cover may be arranged with at least one opening for removing, inserting and/or inspecting a bolt. Bolts are mainly what hold weak links together, and it is therefore of importance, for maintaining the correct threshold for breakage, that the bolts can be inspected easily and regularly, and that they can be replaced when required, without håving to remove the cover.

The weak link-preserving cover may be consisting of a single piece of elastomer material. Håving the weak link-preserving cover in one piece may be beneficial as it may make it easier to apply the weak link-preserving cover onto a weak link, and as it may improve the ability of the weak link-preserving cover to remain in position on the weak link.

The weak link-preserving cover may be made from silicone. Silicone has preferable attributes, as it is very well suited for rough weather conditions, it has great elasticity, and it has the ability to absorb shocks without breaking or håving its form altered. Elasticity is beneficial for making it easy to pull the weak link-preserving cover onto a weak link by hand, and for not significantly altering the threshold of breakage for a weak link equipped with a weak link-preserving cover.

The weak link-preserving cover may comprise one or more reinforced zones. The purpose of a reinforced zone is to increase the ability of the weak link-preserving cover to absorb shocks in certain areas. A reinforced zone may typically be arranged to protect a vulnerable part of a weak link, such as a bolt, and/or to protect a part of a weak link more likely to experience shocks. A reinforced zone may be a zone where the layer of elastomer material is thicker than it is on average for the weak link-preserving cover, it may be a zone reinforced with a different material, and/or it may be a zone reinforced by a different elastomer hardness.

Furthermore, the weak link-preserving cover may comprise one or more zones with lower hardness or a thinner than average layer of elastomer material, to increase the flexibility of the weak link-preserving cover, to make it easier to apply the weak link-preserving cover to a weak link.

In a second aspect, the invention relates to a weak link comprising the weak link-preserving cover.

In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein: Fig. 1 illustrates the weak link-preserving cover, seen in a side view; Fig. 2 illustrates a weak link comprising the weak link-preserving cover, seen from above;

and

Fig. 3 illustrates a weak link comprising the weak link-preserving cover, seen in a side view. Figure 1 shows the weak link-preserving cover 1, seen in a side view. The figure shows a top end 11 and a bottom end 12, and an opening 15 through the side for inspecting, installing or removing a bolt. Figure 2 illustrates a weak link 2 comprising the weak link-preserving cover 1 in the embodiment shown in illustration 1, seen from above. The illustration shows a top end 11 of the weak link-preserving cover 1, three openings 15a, 15b, 15c through the side of the weak link-preserving cover, and it shows bolt holes 25a, 25b, 25c that are visible through the openings 15a, 15b, 15c. Figure 3 illustrates the same as figure 2, but in this figure the weak link 2 comprising a weak link-preserving cover 1 is seen in a side view. This figure shows how the weak link 2 extends through an opening in a top end 11 of the weak link-preserving cover 1 and through an opening in a bottom end 12 of the weak link-preserving cover 1. Furthermore, it shows two openings 15a, 15b through the side of the weak link-preserving cover 1.

The inside of the weak link-preserving cover 1 is not shown in the illustrations, but has advantageous features. It is molded to fit to the exterior of the weak link 2, which is beneficial as a good fit makes it easier to apply the weak link-preserving cover 1 to the weak link 2, and it makes the weak link-preserving cover 1 sit better on the weak link 2 once it has been applied. Furthermore, the weak link-preserving cover 1 is arranged with a thicker layer of silicone around the openings 15a, 15b, 15c through its sides, and a thicker layer of silicone where the weak link-preserving cover's outer diameter is at its greatest. The thicker layer around the openings 15a, 15b, 15c is beneficial as it will aid in preserving bolts, while the thicker layer where the outer diameter of the weak link-preserving cover 1 is at its greatest is beneficial as this is where most of the shocks will take place and thus where the shocks will have to be absorbed.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such ele-

ments.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims (6)

1. A weak link-preserving cover (1) for at least partly covering a weak link (2),characterised in that: the weak link-preserving cover (1) is made from an elastomer material with a hardness of between 15 shore A and 35 shore A.

2. A weak link-preserving cover (1) according to claim 1, wherein the weak link-preserving cover (1) is arranged with at least one opening (15a, 15b, 15c) for removing, inserting and/or inspecting a bolt.

3. A weak link-preserving cover (1) according to claim 1 or 2, wherein the weak link-preserving cover (1) is consisting of a single piece of elastomer material.

4. A weak link-preserving cover (1) according to any one of the previous claims, wherein the weak link-preserving cover (1) is made from silicone.

5. A weak link-preserving cover (1) according to any one of the previous claims, comprising one or more reinforced zones.

6. A weak link (2) comprising the weak link-preserving cover (1) according to any one of the previous claims.