Field of the invention

The present invention relates to a fire safety valve system to be installed in a hydraulic pipeline, which provides hydraulic liquid to a sub sea safety valve installed at or near a wellhead of an oil or gas well, said fire safety valve system comprising at least a pressure relief facility and a blocking facility, said pressure relief facility comprising a fusible plug, where said fusible plug is a temperature sensitive device comprising means that, when released at a certain temperature level, will relieve the pressure of the hydraulic pipeline to the ambient pressure, where said blocking facility comprises mechanical blocking means that when activated blocks the hydraulic pipeline, where said fire safety valve system further comprises a standardized connection flange for connection to said hydraulic pipeline. Background of the invention

In the off shore industry it is well known that safety in many aspects is very important. When extracting oil or gas from e.g. a subsea well it is very important that the pipeline connection to said well, and that all equipment installed at or in connection with said pipeline is operating as intended. If a leakage or any other kind of failure occurs of if there is an outbreak of fire, safety systems will be engaged in order to either stop the leakage or in any other manner minimize the damage and in order to perform a repair or exchange of the damaged components.

On wells it is common to have a so called Sub Sea Safety Valve (SSSV) installed in the well underneath the seabed. This valve is a spring loaded and normally closed valve, meaning that if the valve is not activated it will be closed. During normal operation this valve is kept open by means of a hydraulic pilot pressure to its valve actuator. In case of emergency the hydraulic pilot pressure must be relieved in order to let the valve close and secure against oil and gas streaming from the well.

On the hydraulic pilot pressure line it is thus common to have a so called fire safety valve (FSV) comprising so called fusible plugs i.e. a temperature sensitive device that in case of fire shall melt and relieve the hydraulic pilot pressure thus letting the SSSV go into fail safe position and thus closing the well.

In some situations the fail safe position at the FSV is a closed valve and in another situation it is a pressure relief position where the pressure in the pilot pressure pipeline in question is relieved to the ambient pressure. The last mentioned situation is mainly used for valves at pipelines that are used to control valves or other types of equipment via a hydraulic pressure further down in an oil or gas well such as a SSSV.

In order to overcome some very specific demands and in some cases just in order to meet traditions such equipment will have to comprise standardized interfaces e.g. a special type of flange such as a Grayloc, an ANSI or a DN flange or any other type of flange that is approved according to specific standards. To ensure the operation of the safety SSSV it is very important to avoid dirt in the actuator. This is avoided by incorporating a filter device in the pilot line. In order to change the filter during operation it is crucial to have manual operated valves in the pilot line that can be closed during filter change. Filter device, manual valves and fusible device all together is commonly named "fire safety valve kit" or "FSV kit".

It is very common to arrange the various parts of a fire safety valve system at e.g. a Grayloc flange using fittings such as pipes, nipples and other very common plumbing and piping equipment. When installing the various components and the fittings at the standardized flange using threaded connections it is impossible to install all the com- ponents aligned without having to tighten and then to loosen some of the connections again. This kind of challenge is well known in any part of the plumbing and piping industry. In many cases this does not cause problems but any leakage in equipment such as for offshore or onshore oil or gas wells is not acceptable and must be avoided.

A fire safety valve kit for an oil or gas well as described above can very easily become quite long and heavy due to being assembled using fittings between the valve components, and thus there will be quite an unattractive load - a torque, (a bending moment) - on the fittings and on the connection flange at the wellhead. Thus there is room for improvement of such systems as described above and there is a call for development of a new and improved fire safety valve system, which is simple, effective and easy to install and to operate.

Object of the invention

It is an object of the invention to provide a fire and safety valve system for a wellhead that is simple, effective and easy to install and to operate.

Another object of the invention is to provide a fire and safety valve system that has a minimum of interfaces for components and thus a reduced risk of leakage.

Yet another object of the invention is to increase safety for workers when performing maintenance work on the fire safety valve system or the hydraulic pipeline in which the fire safety valve system is installed.

Description of the invention

As mentioned above, the invention relates to a fire safety valve system for installation in connection with a hydraulic pipeline, which provides hydraulic pilot pressure to a sub sea safety valve installed at or near a wellhead of an oil or gas well, said fire safety valve system comprising at least a pressure relief facility and a blocking facility, said pressure relief facility comprising a fusible plug, where said fusible plug is a tempera- ture sensitive device comprising means that, when released at a certain temperature level, will relieve the pressure of the hydraulic pipeline to the ambient pressure, where said blocking facility comprises mechanical blocking means that when activated blocks the hydraulic pipeline, where said fire safety valve system further comprises a standardized connection flange for connection to said hydraulic pipeline.

The new and inventive step of said fire safety valve system is that it comprises one standardized flange, e.g. a Grayloc, an ANSI or a DN flange, and that said fusible plug, said mechanical blocking means of said blocking facility and said standardized flange are arranged in or at one single block, said one single block comprising two interfaces, the first interface being the standardized flange and the second interface being another suitable type of interface e.g. a threaded bore in said block. A fire and safety valve (FSV) system as mentioned above has several advantages compared to the known solutions. One very important and radical difference is that the fire and safety valve system is an integrated unit comprising said flange, said fusible plug and said mechanical blocking means and of course also an interface for connec- tion to a hydraulic pressure line. As all the components are arranged in or at one block there is no need for a number of extra nipples between individual components and there is thus a highly reduced risk of having leaks. It is however a fact that the fusible plug and the blocking means are fastened to a central valve block comprising the flange and the second mentioned interface, but compared to the solutions known until know, there is no need to adjust the position of the various parts in relation to each other in order to have them arranged in an aligned manner. Exactly the need to arrange the different components, as used so far, in an aligned manner, provides a higher risk of leaks as the components typically is joined by threaded nipples and thus it is sometimes preferred to tighten a bit more than needed just to align the components. Over tightening may cause the threads or the component or the nipple to break. In other situations it is needed to loosen a threaded connection a bit in order to align the components and this also increases the risk of having unwanted potential leaks.

Having a single block comprising one interface for a flange and another interface for a hydraulic pilot pressure pipeline there is no components to align and thus there is no risk for leaks. The fusible plug and the mechanical blocking means are installed in suitable bores in said single block and there is no need to align these components further. On the contrary it is very easy to tighten these parts to the single block using tools to obtain a certain torque in the respective connection. By being able to tighten the connections as needed and not only in order to have a proper looking FSV system a more secure and robust solution is obtained. The reduced number of leaks of hydraulic oil has positive impact on the environment. In addition, the fire safety valve according to the present invention is easy and flexible to install meaning only limited tools are required and results in a positive impact on the ergonomic position for the installation and maintenance crew installing and/or performing maintenance work. In an embodiment of a safety valve system according to the invention said safety valve system can comprise two or more fusible plugs. By having more than one fusible plug an extra safety factor is built into the system. A safety valve system according to the invention may comprise that said fire safety valve system comprises two or more sets of mechanical blocking means, which increases the safety when the mechanical blocking means are activated during maintenance work at or near the safety valve or the hydraulic pipe line system. In addition, when the two or more mechanical blocking means are operated independently from each other an even further increased safety is obtained, because the risk of any leaks of hydraulic liquid, which is usually an oil, is reduced when maintenance work is performed at the fire safety valve system or at the hydraulic pipeline in which the FS V system is mounted.

Said mechanical blocking means can be manual blocking means or blocking means operated via a pilot pressure line or alternatively via a fusible plug.

In an advantageously embodiment of the invention a fire safety valve system may comprise that at least one fusible plug is arranged between said standardized flange and said one or more sets of mechanical blocking means. This will be the most common type of arrangement and it will be able to substitute any of the already installed FSV systems without introducing any problems. In another embodiment of a fire safety valve system according to the invention at least one set of mechanical blocking means is arranged between said standardized flange and said one or more fusible plugs. For an example such a solution allows for a service check or replacement of the fusible plug without having to do any further dismantling of parts or components.

In yet an advantageously embodiment of a fire safety valve system according to the invention said fire safety valve system comprises a valve body, where said valve body at a first interface comprises a standardized flange and a passage extending from said first interface to a second interface, where said second interface comprises coupling means for coupling to further components e.g. a hydraulic pressure line, where said valve body further comprises a first radial bore, where said first radial bore is connected to said passage and comprises a third interface and a fusible plug installed at said third interface, where said valve body further comprises a second radial bore, where said second radial bore is connected to said passage and comprises a fourth interface and mechanical blocking means installed at said fourth interface.

Said passage extending from said first interface to a second interface can be either a direct or an indirect passage as said passage can comprise one or more bores that is connected inside said valve body and thus constitutes said passage. Further said radial bores can be arranged perpendicular or not to said passage as long as said radial bores are in contact with said passage. An example of such a valve block will be given be- low in the detailed description and in the figures.

Preferably said valve body further comprises one or more additional radial bores connected to said passage and one or more additional mechanical blocking means installed at interfaces at said one or more additional radial bores. For example the one or more additional radial bores may intersect with the second radial bore or said passage for installation of a second mechanical blocking means. Installing two (or more, if necessary) mechanical blocking means in the FSV valve body ensures that the flow in hydraulic pipeline can be shut off locally during maintenance work, even if one of the mechanical blocking means are defective, contrary to some prior art FSV systems which do not provide any integrated mechanical blocking means for shutting off the hydraulic pressure line locally, e.g. manually, during maintenance work.

In one embodiment of a fire safety valve system according to the invention said mechanical blocking means comprises a manually operated handle. This is a simple way of performing a block of the passage in the FSV system but in another embodiment of a fire safety valve system according to the invention, said mechanical blocking means comprises operating means for semi or fully automatically operation of said mechanical blocking means. Alternatively a FSV system can comprise both types of mechani- cal blocking means in order to have a redundant system that can be operated in an automatic manner or in a manual manner.

The embodiments of a FSV system as described above is simple, effective and easy to install and to operate and further and very important there is a minimum of interfaces for components and thus a highly reduced risk of leakage and succeeding failure.

Description of the drawing

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 shows a three dimensional drawing of a fire safety valve.

Fig. 2 shows a fire safety valve in a two dimensional view.

Fig. 3 shows a cross section of a fire safety valve as seen in fig. 2.

Fig. 4 shows a fire safety valve in another two dimensional view.

Fig. 5 shows a cross section of a fire safety valve as seen in fig. 4.

Fig. 6 shows a diagram of a fire safety valve in an operating situation coupled to a hydraulic system at a wellhead.

Fig. 7 shows a diagram of a fire safety valve in a pressure relieved situation coupled to a hydraulic system at a wellhead.

Fig. 8 shows a three dimensional drawing of an alternative embodiment of the fire safety valve.

Fig. 9 shows a cross section of a fire safety valve as seen in fig. 8, the cross section is provided through the first mechanical blocking means. Fig. 10 shows a cross section of a fire safety valve as seen in fig. 8, the cross section is provided through the second mechanical blocking means.

In the following text, the figures will be described one by one, and the different parts and positions seen in the figures will be numbered with the same numbers in the different figures. Not all parts and positions indicated in a specific figure will necessarily be discussed together with that figure.

Detailed description of an embodiment according to the invention

Fig. 1 shows a three dimensional drawing of a fire safety valve 1 comprising a valve body 2 having a first interface 3, here seen as a so called Greyloc flange, but said flange could be any type of standardized flange. At the end of the valve body 2 facing the opposite direction of the first interface 3 the second interface 4 is situated. On the side of the valve body 2 a fusible plug 5 and mechanical blocking means 6 are ar- ranged. As it appears from fig. 1 the FSV kit 1 is very compact and robust and all the parts are arranged in rigid and solid connection with the valve body 2. In fig. 2 a firc safety valve 1 is seen in a two dimensional view from a first angle. Here the internal passage 7 between the first interface 3 and the second interface 4 is seen as well as the first radial bore 8 and the third interface 9 for the fusible plug 5. The third interface 9 comprises threads 10 for engaging with corresponding threads on the fusi- ble plug S. Further the handle 11 of the mechanical blocking means 6 is seen above said mechanical blocking means 6.

Fig. 3 shows a cross section of a fire safety valve 1 as seen in fig. 2. Fig. 4 shows a fire safety valve 1 in another two dimensional view from a second angle. Also here the internal passage 7 between the first interface 3 and the second interface 4 is seen as well as the second radial bore 12 and the fourth interface 13 for the mechanical blocking means 6. In fig. 5 a cross section of a fire safety valve 1 as seen in fig. 4 is seen. Extending from the fourth interface 13 a small bore 14 is seen. Said small bore 13 is a functional "telltale" opening that if leaking reveals a broken sealing, e.g. a broken O-ring, in the mechanical blocking means 6. The second radial bore 12 is a rather complex bore. At the fourth interface 13 there is arranged threads 15 for engaging with corresponding threads at the mechanical blocking means 6 and further the second radial bore 12 comprises several different shapes that correspond to the mentioned mechanical blocking means 6 and thus constitutes a seating for a not seen valve element of said mechanical blocking means 6. Fig. 6 shows a diagram of a fire safety valve 1 in an operating situation coupled to a hydraulic pipeline 16 at a wellhead 17, said wellhead 17 symbolized by two corresponding flanges where one is the first interface 3. The second interface 4 is between the first box 18 and the second box 19, both seen with dotted lines. The first box 18 comprises hydraulic means for establishing pressure via the fire safety valve 1 seen partly in the second box 19 - partly because the fusible plug 5 is depicted above said second box 19. Inside the second box 19 the mechanical blocking means 6 is depicted as a valve. It can be understood from this figure that the fusible plug 5 is not released as the pipeline/the second radial bore 12 is blocked. Fig. 7 shows a diagram of a fire safety valve 1 in a pressure relieved situation coupled to a hydraulic pipeline 16 at a wellhead 17. The only difference compared to the diagram in fig. 6 is that the fusible plug S is released due to high temperature and thus the second radial bore 12 and also the hydraulic pipeline 16 is pressure relieved.

Figs. 8-10 show an alternative embodiment of the FSV valve system , in which two mechanical blocking means 6', 6" are installed in the valve body in the fourth interface 13 in the second radial bore 12 and a fifth interface 21 in a third radial bore 20. The two mechanical blocking means provide a dual shut-off facility at the passage 7,7',7" through the valve body as discussed further below. Features which are identical to the embodiment shown in figs. 1-7 will not be discussed again in detail. Fig. 8 shows locking plates 22 at the mechanical blocking means, which are not shown in fig. 1 but may also be used in the valve shown in fig. 1. The second radial bore 12 is connected to inlet at the first interface 3 via the passage 7 and the first internal passage T, see fig. 9. The fusible plug 5 is installed in the first radial bore 8, which intersects with the first internal passage 7\ see figs. 9-10. The second radial bore 12 intersects with the third radial bore 20, and the third radial bore 20 is connected with the second interface 4, i.e. the outlet of the valve body, via a sec- ond internal passage 7", see in particular fig. 10. Thus the first mechanical blocking means 6' mounted in the second radial bore 12 shut off the flow of hydraulic liquid means between the first internal passage T and the third radial bore 20, while the second mechanical blocking means 6" will shut off the flow of hydraulic liquid between the second radial bore 12 and the second internal passage 7".

Alternatively, the third radial bore 20 does not necessarily intersect wit the second radial bore 12, but may instead intersect with the second internal passage 7" whereby the second internal passage 7" is divided into two internal passages (not shown). The mechanical blocking means are e.g. needle valves although other valve types may be useable for installing into the radial bores. It may of course be possible to provide more than two, e.g. three, four or more, separate mechanical blocking means in additional radial bores arranged either upstream to the fusible plug and/or downstream to the first or second mechanical blocking means each for blocking the flow of hydraulic liquid in other positions.