ELECTRICALLY INSULATED BALL VALVE DEVICE AND ELECTRICALLY INSULATED SUPPLEMENTARY CAP FOR BALL VALVE

BACKGROUND OF THE INVENTION

The present invention relates to a ball valve device to be interposed between a couple of metallic pipes for supplying a fluid, more paticularly to a ball valve device capable of cutting off the current which flows through the couple of metallic pipes coupled with both sides of the ball valve. This invention relates also to an electrically insulated supplementary cap for such a ball valve device.

BACKGROUND ART

Liquefied Natural Gas(LNG) is universally used as fuel for cooking, heating and so on. The LNG is generally provided from a large-scale source of supply to each of users through metallic pipes. Since such pipes are electrically conductive, pipes are corroded due to several kinds of current such as earthing current by consumer goods, leakage current, static electricity and so on. Such corrosions shortenize the life of pipe and are able to cause a big accident by the leaked LNG due to the corrosions. Accordingly, one

of important things in supplying LNG is to cut off the current flowing through pipes. A conductive pipe for supplying an nonconductive fluid is always raised a problem on such an electric corrosion. In order to cut off such current flowing through the pipe, it has been known that a flange coupling including an insulating sheet and insulating spacers is interposed between pipes only for the purpose of insulating. However, this type of conventional way has a drawback in that additional costs and efforts are required for the purpose of insulating because of interposing the flange coupling additionally, and has a further disadvantage in that an enough insulating effect is not guaranteed for a long time because of deteriorating the function of the insulating element such as the insulating sheet or the insulating spacers of the flange coupling due to a twisting appearance of the pipe derived from the ground subsidence.

SUMMARY OF THE INVENTION

Accordingly, a principal object of the present invention is to provide an improved ball valve device, which is generally used to a pipe line for supplying fluid, capable of electrically insulating the device, thereby cutting off the current to be flowed along the pipe line without using an additional insulating utensil.

Another object of the present invention is to provide an electrically insulated supplementary cap, which can be added to a ball valve device already interposed or to be interposed in a pipe line for supplying fluid to guarantee economically electrical insulation of

the device, thereby cutting off the current to be flowed along the pipe line.

According to one aspect of this invention, there is provided a ball valve device comprising a ball having a penetration; a valve body, rotatably accommodating the ball therein, including a first threaded portion formed at its one end for coupling a first pipe, a second threaded portion formed at the other end and a first ball seat for supporting one side of the ball; a valve cap including third threaded portion at its one end for engaging with the second threaded portion, fourth threaded portion formed at the other end for coupling a second pipe and a second ball seat for supporting the other side of the ball; and an insulating layer, formed on and conforming to at least one of the first, second, third and fourth threaded portions, for electrically insulating the first and second pipes from each other. According to another aspect of this invention, there is provided a supplementary cap for a ball valve comprising, a first threaded portion formed at its one end for engaging with a threaded portion formed at one end of the ball valve; a second threaded portion formed at the other end for coupling a pipe; and an insulating layer, formed on and conforming to at least one of said first and second

threaded portions, for electrically insulating the ball valve and the pipe from each other.

Other features and operations of the present invention will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a disassembled perspective view of the electrically insulated ball valve device according to the present invention;

Fig. 2 is a partially cutaway cross- sectional view of the present invention,"

Fig. 3 is an enlarged view of part A in Fig.2; Fig. 4 is a cross-sectional view of a part corresponding to part A in Fig. 2 in order to illustrate another embodiment of the electrically insulated ball valve device according to the present invention;

Fig. 5 is a partially cutaway cross-sectional view of the other embodiment of the present invention showing an upper part of a valve body,"

Fig. 6 is a cross -sectional view of a supplementary cap; Fig. 7 shows a ball valve and a pipe connected by the supplementary cap of Fig. 6 in a partially cutaway cross -sectional view;

Fig. 8 is a cross- sectional view of another embodiment of the supplementary cap; and

Fig. 9 is a cross -sectional view of a third embodiment of the supplementary cap.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figs. 1 and 2, the ball valve device of the present invention comprises a ball 11 formed of a penetrating hole for controlling a fluid flow, a valve body 10 rotatablely accommodating ball 11 therein and providing a path of flowing fluid from one side to the other side through the penetrating hole of the ball 11 and a valve cap 20 to be spirally coupled to one side of valve body 10. Valve body 10 is formed with female thread 14 and 15 with its both sides each of which is coupled with a pipe (not shown) or one side of valve cap 20. Valve cap 20 is formed of a male thread 23 with its one side to be coupled with one of female thread 14 and 15 of valve body 10 and a female thread 25 with its other side for coupling a pipe. The ball valve device also has an electrically insulated layer 24 surrounding male thread 23 of valve cap 20 and an 0-ring 21 for hermetically coupling valve body 10 and valve cap 20.

Ball 11 is rotatablely held in valve body 10 in such a manner that the surface thereof is contacting with a first ball seat 12 formed at an inner side of valve body 10 and a second

ball seat 22 formed at one end and inner portion of valve cap 20. Ball 11 is moved between two positions of which one position is the openning position for permitting the fluid flow by lining up the penetrating hole of ball 11 with pipes coupled to both sides of the ball valve device and the other position is the closing position for shutting the fluid flow off, by mannually operating an operating lever 13. Ball seats 12 and 22 are made of a plastic material, for example "teflon", having the magnetic lubrication properties, thereby providing the electric insulation between ball 11 and valve body 10 or valve cap 20.

Fig. 3 is an enlarged view of part A in Fig.2. As can be seen from Fig. 3, an electric insulating layer 24 is formed in such a manner that it surrounds male thread 23 of valve cap 20 in order to provide the electric insulation between valve body 10 and valve cap 20. The electric insulating layer 24 can be formed by an insert injection molding process using materials of the glass fiber reinforced plastics or the engineering plastics so as to guarantee an enough degree of coupling strength. In some cases, after forming the electric insulating layer 24 by an injection molding process, the electric insulating layer can be hermetically assembled onto the thread of the valve cap 20. Furthermore, in order to prevent the fluid leakage due to the difference of the heat expanding coefficients between the insulating layer 24 and the valve cap 20, an O-ring 27 can be, as described in Fig.4, interposed between the insulating layer 24 and the male thread of

valve cap 20.

As the source material of the electric insulating layer 24 a bonding agent may be used by uniformly laminating it onto the corresponding thread and assembling valve body 10 and valve cap 20

with maintaining of the thickness of laminated insulating layer 24. Preferably, the bonding agent insulating layer consists of at least two sub -layers which are seperately laminated with a time lag. Primary sub-layer, which is initially laminated and appropriately hardened before laminating of secondary sub-layer, maintains insulating thickness of insulating layer during assembUng, while secondary sub-layer serves as adhesive to guarantee firm bonding between corresponding threads.

In order to prevent the possibility of occuring arc between valve body 10 and valve cap 20, it is preferable to expand electric insulating layer 24 up to ball seat 22 of valve cap 20. Otherwise, baU seat 22 may be integral with electric insulating layer 24.

As described above, aU contacting portions between valve body 10 and valve cap 20 are completely insulated, therefore, both fluid supplying pipes of which one is coupled to valve body 10 and the other is coupled to valve cap 20 are electricaUy insulated each other. The electric insulation between valve body 10 and valve cap 20 may also be guaranteed if ball 11 is formed of electricaUy insulated materials instead of ball seat 22 formed of electricaUy insulated materials. It is also understood that

whole surface of valve cap 20 can be formed of electricaUy insulated materials.

Fig. 5 shows another embodiment of the present invention. Although it is convenient in manufacturing a baU valve device that the electric insulating layer is ^" to be formed onto the male thread of valve cap 20, an electric insulating layer can be formed onto one of female threads 14 and 15 formed with both end of valve body 10 or female thread 25 of valve cap 20. In Fig. 5, the electric insulating layer 26 is formed onto the female thread 15 of valve body 10.

Fig. 6 shows an electricaUy insulated supplementary cap 40 according to another aspect of this invention, which is substantiaUy identical with the valve cap 20 of Fig. 4 and has an insulating layer 42 formed on it's male thread 41. This supplementary cap 40, as shown in Fig. 7, can be easUy interposed between pipe 45 . and conventional baU valve device to provide electrical insulation therebetween. Supplementary cap 50 of Fig. 8 has male threads 51 and 53 at its both end and an insulating layer 52 formed onto one of the male threads, whUe supplementary cap 60 of Fig. 9 has female threads 61 and 63 at its both end and an insulating layer 62 formed onto one of the female threads. These examples can be approprately appUed in accordance with the thread type of baU valve device and pipe line end. The supplementary caps 40, 50 and 60 provide advantage that it can be simply added to a baU valve device already instaUed or to be instaUed in pipe Une to guarantee economicaUy

electrical insulation of the ball valve device.

As Ulustrated above, the present invention provides economically an electricaUy insulating function to a baU valve device. While the invention has been Ulustrated and described with the

preferred embodiments, it is recognized that variations and changes can be made without departing from the scope and spirit of the invention as set forth in the claims.