The present invention relates to a stocking to safeguard a suspended, oblong and heavy object, such as a hose, line, pipe or the like, that is used in connection with production of petroleum, from severely coming apart on breakage. The invention also concerns a method and also an application of the same.

Lately, incidents with hoses that are suspended above drilling floors have occurred, such as for example "rotary hose/Kelly hose" in "top drive" on a drilling floor, have fallen down after they have "ruptured". Today, there are no satisfactory safeguarding systems that can prevent this. Therefore, there is a need for a solution that can prevent falling objects, that can hold separated hose parts, which can not hook, together and provides the possibility for a visual control, which is simple to fit and use and that does not affect working procedures.

The method that is mainly used on a rig today to safeguard hoses is a simple two-piece clamp that is fastened around the hose and further to a permanent anchorage point by a chain. The method has severe limitations and has led to injury to personnel and damage to equipment: What happens when a hose breaks apart is that the two-piece clamp loses its grip on the hose and the hose becomes free and falls down.

The present invention is a product that is developed to safeguard, in particular, suspended hoses in connection with petroleum production on a rig. In drilling operations after oil/gas, flexible hoses are used with the purpose that the drill stem can be moved vertically. The main hose for drilling fluid (Kelly Hose) is about 30 meters long and with an inner diameter of 10 cm and high working pressure. Primarily, it is this hose that can lead to the most dangerous situations when breakage occurs. Such breakages are severe so that the hose breaks off completely and will be able to fall down and swing round with blowouts of mud so that personnel can be injured. Other hoses contain hydraulic fluid and, in some cases, compressed air.

For transfer of fluids and dry materials between oil platforms and supply vessels, hoses of varying dimensions are used. The most common is that the hoses hang from the platform and down to the supply ship. Here, the same situation is relevant: Breakages in the hose will be able to cause injury to personnel that are on the supply vessel and the present invention will also be suitable for this purpose.

What is special with the present invention is that the product holds the hose fast after a breakage has happened. The hose will thereby neither fall down nor spray fluid round in all directions in an uncontrolled manner. This satisfies the requirements users seek.

The object of the present invention is to prevent hose parts, lines, pipes, etc. from coming apart after a breakage. A safeguard against unwanted falling objects (UFO) is also achieved. The stocking according to the invention can be fitted by company personnel, the stocking can replace existing solutions, such as a "clamp", it has an extremely low weight, it allows visual control and cleaning and has a documented stress strength.

Minimum activating area for the stocking according to the invention is preferably five meters when it is used for safeguarding of a such "rotary hose" or "Kelly hose". In other connections the minimum activating area can vary, but it is preferred that the stocking envelops at least the main part of the object that shall be safeguarded. Detailed studies of incidents that have occurred offshore indicate that probable breakage of a hose will occur in the transition between hose connection and the hose itself, and the stocldng can thereby be arranged around that part of the hose where experience indicates breakages will happen.

Briefly, an embodiment of the present invention functions in the following way: Two special straps, each with four fibre straps, are preferably fastened to two certified anchorage points above the hose. All the eight fibre straps are then braided down the hose and fastened to the hose by a roundsling or a shrink stocking. If breakages occur in, for example, the hose, the stocking will tighten around the two hose parts so that these move only minimally away from each other, and thereby also prevents that one or more of the hose parts from falling to the deck. Such a hose can weigh several tonnes and thereby constitutes a considerable risk for personnel if it should fall down.

At a possible breakage of the hose, the rope will be tightened as "Chinese fingers" and prevent the hose parts from coming apart. The fibre straps that are used can be, for example, DEXTON™ 12 PLUS ₅ diameter 8 mm and a breaking strength of 8.1 tonnes. A stocking according to the invention can thereby be comprised of a total of eight 8 mm fibre straps.

The above mentioned object is achieved with a stocking according to the characteristic in the independent claim I ₅ in that the stocking essentially envelops the main part of the

suspended part of the object, and that the stocking comprises a number of fibre straps that are braided around the object after the "Chinese finger" principle.

Preferred alternative embodiments of the stocking are characterised by the dependent claims 2-6, in that the stocking can comprise two special straps each with four fibre straps, where each of the special straps is set up to be fastened to two anchorage points above the object. The eight fibre straps are then braided down the object and fastened to the object by a roundsling or a shrink stocking.

The fibre straps can be manufactured from a thermoplastic, in particular, polyethylene with extremely high molecular weight (UHMWPE) such as DEXTON™ 12 PLUS, diameter 8 mm and a breaking strength of 8.1 tonnes.

The above mentioned objects are also achieved by a method as defined in the characteristic of the independent claim 7, by braiding a stocking comprising at least one special strap with a number of fibre straps about, at least, parts of the object after the "Chinese finger" principle.

Alternatively, the production of the stocking can be carried out in the following steps: to fasten at least two special straps to associated anchorage points above the object, to distribute the respective fibre straps with equal distance around said object, and to braid the stocking by placing one fibre strap from each special strap over each other, where each fibre strap is fitted over/under each other every other time, to continue crossing fibre straps over/under until the fibre straps begin to run out, and to fasten the fibre strap ends around the object.

Furthermore, the fibre strap ends can be fastened to the object using a roundsling or a shrink stocking. The fibre straps cross each other, in the main, preferably perpendicularly so that a reasonably equal mesh size is obtained.

The invention also relates to use of a stocking as defined in the independent claim 11, and associated dependent claims 12-14.

The invention shall now be described further with the help of the enclosed figures, in which:

Figure 1 shows parts of a stocking according to the invention, arranged around a hose. Figure 2 shows a special strap that makes up a part of the stocking according to the invention before fitting.

Figure 3 shows a complete stocking according to the invention arranged around a hose.

Braiding after the "Chinese finger" principle is known from other connections, both as a toy and in connection with equipment for pulling up hoses, pipes and the like. In the last mentioned case, only a short end is fastened around the end of the hose that shall be pulled up.

Figure 2 shows a special strap that is used to braid a stocking 16 according to the invention. It is preferred that two special straps 10,20 are used for this purpose, but, in some cases, fewer or more than two such special straps can also be used. Such special straps comprise a number of fibre straps or ropes 12, preferably four fibre straps 12 as shown in the figures.

The construction and function of the stocking 16 according to the present invention are such that a number of fibre straps 12 or ropes are placed around a hose 14 or the like in a simple braiding pattern over a defined length. The end of the fibre straps 12 is fastened to a suspension point near the hose suspension. The end that terminates on the hose can be fastened to the hose with the help of a roundsling or a strap 18. This prevents the end from sliding and prevents the stocking 16 from letting go of the hose 14 when the breakage happens. When a breakage happens, the part that tries to fall will be caught and held in place by the fibre straps 12 becoming stretched and squeezing over each other because of the braiding pattern and against the hose 14, because of the constriction made by the extension-distance of the hose breakage. Technically, it is thus the friction between the fibre straps and the straps against the hose that leads to the holding force in the longitudinal direction of the hose.

The braiding pattern of the fibre straps 12 is initially special and must be carried out correctly in a correct order if the gripping effect against the hose shall function. Preferably, eight parts from two special straps 10,20 are used. The special straps encompass their own lifting ear 22,24. The lifting ears 22,24 are fastened temporarily at the same height as a clamp anchorage point of the hose, so that the fibre straps 12 hang freely down over the hose 14 onto which they are to be fitted. Every other fibre strap is threaded over the first and under the second. It is very important to start correctly, i.e. one must start with two fibre straps 12 that have come straight from the respective lifting ears 22,24 to obtain a criss-cross. This is of decisive importance for the

distribution of tension strength of all eight fibre straps. One must continue in the same pattern throughout the whole process, if not, the strength of the stocking 16 can be considerably diminished, and the desired tension/tightening strength will be considerably reduced. It is particularly important that the hose 14 hangs freely so that the fitting operator shall be able to move around the hose. The stocking 16 according to the invention can be braided around one or both ends of the hose, or alternatively around the whole hose. The method is the same for all the variations.

The stocking 16 according to the invention is preferably manufactured from a special type of fibre that is resistant to drilling fluids, oil, salt water, and UV radiation. In addition, the material must be very strong and have little elasticity. For example, thermoplastic fibres can be used, particularly preferred are thermoplastics of UHMWPE: Ultra high molecular weight polyethylene (polyethylene with extremely high molecular weight), but fibre straps of other material that provides corresponding or similar characteristics can also be used.

The stocking 16 according to the invention can be produced in three steps: The hose that is to be fastened is considered by specialists and user data are collected. Based on relevant information the stocking is constructed (designed) and the production follows thereafter.

The production takes place in two steps: Production of all component parts, such as suspension rope, "finger" rope and "roundsling" rope. Adjusting to and production (braiding) directly onto the hose they then belong to. The end of the "finger" is fastened by roundsling to the hose.

The stocking according to the invention is therefore an individual, tailor-made product where the last part of the production preferably takes place on the hose itself for different applications.

Tests have been carried out to examine the load limit of the chosen materials. The tests were carried out by placing a hose horizontally on the floor. The one end of the hose was fastened to a permanent point and the other end of the hose was fastened to a load cell that in turn was fastened to a pulling point. The fibre straps 12 were thereafter braided around the hose as previously described. At the one end, the straps are fastened to the fastening point above the hose, at the other end 18 they are fastened with a roundsling or a shrink stocking to the hose 14.