JP2005106116A - Seat for ball valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seat reducing parts count, generating initial fastening surface pressure on an outer periphery of the seat at the time of assembling of a ball valve, and improving sealing performance. <P>SOLUTION: The seat for the ball valve is provided with grooves 3, 9 inwardly extending from a front surface or a back surface of the seat 1, and a fastening margin wherein the initial fastening surface pressure is generated on the seat outer periphery at the time of assembling of the ball valve. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a seat for sealing the outer periphery of a ball within a ball valve body.

  In order to improve the sealing performance between the ball valve main body and the ball, various proposals have been made regarding the structure of the seat.

Since the ball valve 11 of the trunnion structure has a ball fixed, it cannot be sealed unless a force is applied to the seat by a spring 14 or the like and the seat is pressed against the ball. For this purpose, the sheet is placed in the seat box 12 or the like, and the spring 14
Is attached and pushed from the back to generate a surface pressure between the ball and the seat and seal it.

  Since the seat box 12 is made of metal, an O-ring (rubber) 13 is attached to the outer periphery to seal the seat box 12 and the main body (see FIG. 7).

  In the case of fluids such as solvents, if the O-ring attached to the outer periphery of the seat box 12 is corroded and cannot be used, use a packing 15 with a spring inside the PTFE to seal the seat box and body. (See Figure 8).

  FIG. 9 shows a structure normally used in a floating structure, in which a sheet insertion portion 16 is provided in the main body, a sheet is inserted into this, and a surface pressure is applied to the back surface of the sheet for sealing.

Further, the ball valve 10 having a floating structure is sealed on the back surface of the downstream seat. However, when the fluid pressure is low or the wear period is long, the ball valve 10 easily leaks from the back surface of the seat.
JP-A-8-247306, valve seat

  The present invention is intended to provide a structure for properly sealing the outer peripheral surface side of the seat when the ball valve is used, and is not intended to provide a seal between the ball and the seat.

  In the structure shown in the above Japanese Patent Laid-Open No. 8-247306, a relatively large seat chamber is provided on the back side, but the outer periphery of the seat is screwed and fixed to the ball valve body. The effect is completely different from the seal.

  According to the first aspect of the present invention, the ball valve seat is provided with a groove directed inward from the front surface or the back surface of the seat, and provided with a tightening margin that generates an initial tightening surface pressure on the outer periphery of the seat when the ball valve is assembled.

  In the second invention, the tightening allowance when assembling the ball valve is 15% to 50% of the groove width.

  In the third invention, in the PTFE (tetrafluoroethylene resin) sheet, the thickness of the lip formed between the outer periphery of the sheet and the groove is 1.5 mm to 6 mm, and the groove width is 1.5 mm to 6 mm. And a seat in a ball valve in which the tightening allowance during assembly is 15% to 50% of the groove width.

  In the present invention, since a clamping allowance is provided so that an initial clamping surface pressure is generated on the outer periphery of the seat when the ball valve is assembled, the seat is applied with a force that pushes and widens the groove by the force of the initial clamping surface pressure and the fluid pressure. The outer periphery of the seal is surely performed.

  Compared to the conventional example, since an O-ring is not required, measures that depend on the corrosion resistance of the O-ring material are not required, the number of parts is small, and the structure is simple.

In the case of the trunnion structure, a spring is attached to the back surface of the synthetic resin sheet, and an elastic force is given by this spring to seal between the ball and the sheet. Further, the outer periphery of the seat is sealed by the spring effect of the lip portion 4 provided on the seat itself and the fluid pressure applied to the groove (see 1 in FIG. 6).

When assembling, a groove parallel to the outer periphery of the sheet is provided so that the initial tightening surface pressure is generated on the outer periphery of the sheet,
By providing the tightening allowance, the sheet outer periphery can be sealed by the initial tightening surface pressure and the fluid pressure entering the groove portion of the sheet.

In the case of the floating structure, since the ball floats, it can be dealt with if the groove direction is reversed (see 1 in FIG. 5).

Sealing performance can be ensured by setting the tightening allowance during assembly of the ball valve to 15% to 50% of the groove width. Although it can be used at 15% or less, it is inferior in durability. When it exceeds 50%, permanent deformation of the lip portion is large and inferior in durability, and sheet mounting becomes difficult.

In PTFE sheets, the thickness of the lip formed between the outer peripheral surface of the sheet and the groove is 1.5 mm to 6 mm, the groove width is 1.5 mm to 6 mm, and the tightening allowance during assembly is the groove width. 15% of
By setting it to -50%, the sealability on the outer peripheral surface of the seat is durable and can be easily assembled.
Embodiments shown in the drawings will be described below.

  In FIG. 1, a groove 3 is provided in parallel with the outer periphery 2 from the back surface of the seat 1 inward, and a tightening margin is given so that an initial tightening surface pressure is generated on the seat outer periphery 2 during assembly. Reference numeral 4 denotes a lip portion. A spring 6 was provided via a sheet presser 5 attached to the back of the sheet. The material of the spring 6 is made of metal (for example, SUS).

  In this structure, an initial tightening surface pressure is applied to the lip portion 4, and fluid pressure enters the deep portion of the groove 3, and the lip portion 4 comes into close contact with the wall surface of the ball valve body 7 by trying to expand the groove portion. Generate power. Accordingly, the outer periphery of the seat can be sealed and a stable sealing property can be secured.

  In FIG. 2, the basic structure is the same as that of the first embodiment. An elastic body such as rubber is applied as the material of the back sheet 8 mounted on the back of the sheet.

  In FIG. 3, the spring is not attached to the back surface of the seat 1.

  In FIG. 4, a groove 9 is provided on the front surface of the sheet 1. This is used when sealing with a downstream seat as in the ball valve 10 with a floating structure or when the upstream side is evacuated with a trunnion structure ball valve 11.

The material of sheet 1 is PTFE (tetrafluoroethylene resin), but PTFE or PEEK with filler
Engineering plastic synthetic resin materials represented by (polyether, ether, ketone) and the like can be applied in the same manner.

In the above embodiment, only a two-way valve having a trunnion structure and a floating structure is shown, but the present invention can also be applied to a multi-way valve.

  As the seat made of synthetic resin, there are few components and a tightening allowance is provided at the time of assembling the ball valve so that the initial tightening surface pressure is generated on the outer periphery of the seat, which contributes to the improvement of ball valve productivity and sealing performance Is big.

Sectional drawing which shows the principal part which shows Example 1 of this invention sheet | seat. FIG. 6 is a cross-sectional view of a main part showing a second embodiment. FIG. 6 is a cross-sectional view of a main part showing Example 3; FIG. 6 is a cross-sectional view of a main part showing a fourth embodiment. The principal part sectional drawing which shows the case where it applies to the ball valve of a floating structure. The principal part sectional drawing which shows the case where it applies to the ball valve of a trunnion structure. Sectional drawing which shows the principal part which shows one of the prior art examples. Sectional drawing which shows the principal part which shows the other example of a prior art example. The principal part sectional drawing which shows the other example of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seat 2 Seat outer periphery 3, 9 Groove 4 Lip part 6 Spring 8 Back seat 10 Floating structure ball valve 11 Trunnion structure ball valve

Claims (3)

  A seat for a ball valve, wherein a groove is provided inwardly from a front surface or a back surface of the seat, and a fastening allowance is generated on the outer periphery of the seat to generate an initial fastening surface pressure.   2. The seat for a ball valve according to claim 1, wherein a tightening allowance during assembly of the ball valve is 15% to 50% of the groove width.   In the PTFE sheet, the thickness of the lip formed between the outer peripheral surface of the sheet and the groove is 1.5 mm to 6 mm, the groove width is 1.5 mm to 6 mm, and the tightening allowance during assembly is 15 mm. 2. The ball valve seat according to claim 1, wherein the seat is in a range of from 50% to 50%.

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