FR2512158A1 - ANNULAR SEAL FOR A BALL STOP VALVE - Google Patents

Abstract

ANNULAR SEAL FOR A BALL SHUT-OFF VALVE. THE MAIN ANNULAR SEAL ACCORDING TO THE PRESENT INVENTION TO ENSURE THE PERFECT TIGHTNESS OF A BALL STOP VALVE IS IN ELASTOMERIC MATERIAL AND HAS A SENSITIVELY TRIANGULAR STRAIGHT SECTION WITH THE TOPS ARE ROUNDED AND THE BASE 6 IS CURVED. THIS GASKET IS RETAINED IN A FRONT CAVITY 7 OF A FLOATING SEALING ELEMENT 2 BY MEANS OF A METAL RETAINING RING 8.

Description

Annular Seal for a Ball Stop Valve This

  The invention relates to a novel type of annular seal which makes it possible to obtain a perfect, efficient, reliable and durable seal in a ball stop valve, even when the ball valve is mounted on a large diameter pipe and is therefore strong pressure differences. It is known that at present the sealing in a ball valve is ensured by means of a floating annular element comprising suitable cavities which respectively house the main annular seal ensuring sealing towards the ball of the valve and the seal. annular sealing sealant towards the valve body Said floating annular element is pushed towards said ball by a set of springs which keeps said main annular seal in contact with the ball thus ensuring a seal even in the absence of a pressure difference, this sealing becomes all the more perfect as the operating pressure increases by the fact that the latter generates a progressive additional load on the seal

principal by a piston effect.

  It goes without saying that to obtain a perfect and effective seal, it is necessary that said main annular seal

  ideally very soft and that it protrudes

  In this respect, the more the joint is soft and the more it protrudes, the more likely it is to

  remedy any defect in the surface of the ball due to imperfections

  construction defects, scratches or nicks caused by foreign matter entrained by the conveyed fluid. On the other hand, the fundamental problem raised by such valves when they are subjected to high pressure differences is the tendency of the annular main seal to be extruded, that is to say to be expelled from its housing during the opening. of these valves by the fluid which, as a result of its

  strangulation, rushes at great speed through the body.

  In the current state of the art, joints are used.

  sealing rings made of elastic material

  and having a circular cross section.

  However, such a type of seal does not have of course any of the aforementioned characteristics necessary to ensure a tight seal, that is to say perfect, effective on this subject, the fact that the seal has a section circular right means that only a small part of this seal protrudes from the housing if it is desired that the seal is effectively retained in said housing In addition, to prevent the aforementioned extrusion, it is necessary to use gaskets which, instead to be soft, are on the contrary sufficiently rigid for a harmful contraction of the joint

can not happen.

  Finally, a seal having a circular cross section, can rotate in its seat during the displacement of the ball, which results in a possible deformation of the seal and a consequent loss of this seal The object of the present invention is to overcome the disadvantages mentioned above by providing a main annular seal ball valve that does not rotate in its seat during the movement of the ball, which is not subjected to extrusion during the throttling of the conveyed fluid when the valve is partially open, even if said seal is of a soft material, which protrudes from its seat so as to seal even against partially damaged surfaces of the ball and which, finally, can be installed

simply and quickly.

  This result is achieved essentially by means of an annular seal of elastomeric material having a cross-section which, instead of being circular, widens rearwardly so that the seal can not be removed. escape from its housing, said seal being retained in its housing by a

  metal retaining ring.

  by assembling, in a particular manner, a normal O-ring with another O-ring whose diameter is

  much larger than the other joint.

  More particularly, the main annular seal for a ball stop valve comprises a floating annular sealing member which houses said seal in a

  front cavity that it holds and that keeps it pressed elastically

  against the ball of the valve is characterized in that it is formed by an elastomeric element whose cross section is substantially triangular with its rounded tops and its curved base and which is retained in said front cavity, which also has a cross section triangular, by means of a metal retaining ring supported by said annular floating element. We will now describe in detail the present invention with reference to the accompanying drawings which show a preferred embodiment given purely by way of illustration and not limitation as constructional variants can be made without departing from the scope of the present invention. In particular, the annular seal according to the present invention can be mounted on a valve with

  direct passage instead of a ball valve.

  In the drawings: Fig. 1 is a partial perspective view of a ball stop valve using the annular seal according to the present invention; Figure 2 is a front section, on a larger scale, of the part of Figure 1 in which the annular seal according to the present invention is mounted; FIG. 3 is a front section of the annular seal according to the present invention on a scale still

bigger.

  In the figures, the reference 1 designates the body of a ball stop valve and the reference 2 designates an annular floating sealing element which is disposed between the body 1 of the ball valve 3 and is pushed elastically by a

  circumferential assembly of springs 4 against said ball 3.

  Said annular floating element 2 serves to support an annular seal 5 sealing towards the body 1 of the valve and a main annular seal 6 providing a perfect seal to the ball 3, the latter being housed in a front cavity 7 of the floating element 2 and being retained in this cavity by a metal retaining ring 8 which is also supported by the floating element 2. The main annular seal 6 is made of elastomeric material and is essentially made of by assembling, in a particular manner, a normal O-ring of radius r (see FIG. 3) with another O-ring having a radius R which is much larger than that of the other seal so that one obtain a resulting straight section which widens rearward In short, said annular seal

  6 is, in practice, an elastomer of triangular cross-section

  gully whose vertices are rounded and whose base 6 'is

curve.

  According to a preferred embodiment, said triangular cross section of the annular seal 6 is in the shape of an isosceles triangle.

Claims (2)

  1 main annular seal for a ball stop valve comprising an annular floating sealing element (2) which accommodates said seal (6) in a front cavity (7) and keeps it pressed elastically against the ball (3) of the valve, characterized in that it is formed by an elastomeric element which has a substantially triangular cross-section with rounded tops and a curved base (6 ') and is retained in said front cavity, which also has a triangular cross-section, by means of a metal retaining ring (8) supported by said annular floating element.   2 main annular seal according to claim 1, characterized in that its triangular cross-section and the corresponding straight section of the front cavity of said annular floating element have substantially shape of an isosceles triangle.