JP3367965B2 - Fittings with overtightening gaskets - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint, and more particularly to a face seal pipe joint used in an ultra-clean environment.

[0002]

BACKGROUND OF THE INVENTION There are many types of fittings that can be joined to packing retainers or conduits. A joint that can be used in an ultra-clean environment or in a very clean room (hereinafter referred to as VCR) is combined with an annular seal bead protruding from the end of the tubular member to form a gasket. Are using. US Patent No. 4,854,557 and U.S. Pat. Nos. 4,838,583 disclose that a gasket is used between tubular members having annular seal beads protruding in the axial direction in a surface seal joint. Minimizing the generation of particulate matter is of particular importance in industries such as semiconductor manufacturing, and numerous joints have been developed for these special uses. The joints required in an ultra-clean environment or VCR are specifically designed to join tubular members in a manner that minimizes the ingress of particulate matter. One successful design is a joint that uses an annular bead intended to reduce the clearance between the non-seal surface of the gasket and the radial end surface of the tubular member. These fittings, known as dead-zero volume fittings, reduce the clearance and thus reduce the trapping of particulate matter through the fitting in the clearance. When particulate matter is trapped in the gap,
Later, it is released rapidly and a high concentration of particulate matter enters the superclean environment.

As a joint designed for a VCR, when the components of the joint are pulled together so as to reduce the friction between the seal surface of the tubular member and the seal surface of the face gasket, the components There are things that control the position of. It is believed that the friction and excessive pressure between the seal members caused by the force applied to the gasket causes scratches and deformations on the seal surface, which leads to unwanted ingress of particulate matter. Since the optimum level of particulate matter in a super-clean environment is zero, any method of reducing particulate ingress is a preferred improvement. Face seal developed for VCR
Refurbishment improvements were still limited. Modification of these joints to reduce dead zero volume results in
Area decreased. US Application No. 07 / 652,22
As disclosed in US Pat. No. 5,242,242, an improved version of the semicircular seal bead in a conventional face seal joint has an arcuate outer profile of the seal bead and a reduced seal area. Also disclosed is an improved gasket having a bevel, the gasket being designed to engage a new bead structure. The new joint reduces the surface area forming the seal, thus increasing the unit force on the surface area or the pressure on the unit area on the part.

In joints using this new design, the number of times the joint was disassembled was often limited before the gasket or tubular member was deformed to the extent that it could not be sealed. When assembling the parts,
It has been found that parts are often over-tightened. The over-tightening problem was exacerbated in joints with reduced seal surface area. In these joints, it is difficult to accurately grasp the point where sufficient sealing is performed by the tubular member and the gasket, and as a result,
The assembler will continue to tighten the parts even after sufficient sealing has been performed. Further rotation of the coupling nut after sufficient sealing will cause the tubular members to continue to be pulled together and pushed into the gasket. The continued pressure on this part causes the seal surface to deform beyond its elastic limit. Such deformations are an undesired source of particulate matter. Further, the deformation causes the seal surface to be unnecessarily worn and permanently deformed, thereby shortening the life of the component. Worn or deformed parts are
When repeatedly assembled, it is impossible to continuously provide effective sealing. Excessive tightening of the gasket will permanently deform the components and increase the wear rate,
As a result, the life of the seal surface component is reduced. Also, over-tightening can be a source of particulate matter as extreme metal pieces are released into the system due to extreme deformation of the components. Also, over-tightening of the seal surface can impart unnecessary stress to other components of the joint. For example, the tie bolt and the tubular member will accelerate fatigue of the entire assembly.

In fittings that use other types of gaskets where overtightening is a problem, a simple spacer outside the gasket may be used or the assembler may use a torque wrench. Was recommended. In the past, the problems associated with overtightening of face seal joints were often simply ignored. Various methods have been tried to determine the proper tightening by trial and error, or to evaluate how much the coupling nut should be rotated for finger tightening.

[0006]

However, in the ultra-clean environment, there is a technical problem to be solved in terms of preventing excessive tightening by these inaccurate methods. Therefore, an object of the present invention is to effectively prevent excessive tightening of the face seal joint.

[0007]

In order to achieve the above object, a surface seal joint of the present invention comprises a gasket and at least one tubular member, and the tubular member is a radial member of the tubular member. A sealing bead projecting from the end face in the direction, the gasket having an inner beveled section and a non-sealed outer section, the inner beveled section receiving the seal bead and sealing. An axial dimension that defines a seal and wherein the non-seal outer section limits compression of the seal bead beyond the elastic limit of the seal bead by engagement with the radial end face. It is characterized by having.

[0008]

In the present invention, the tubular member has a seal bead protruding from the radial end surface of the tubular member. The gasket also has an inner beveled section and a non-sealed outer section. The inner beveled section receives the seal bead to form a seal. Further, the non-seal outer section has an axial dimension which, by engagement with the radial end surface, limits compression of the seal bead beyond the elastic limit of the seal bead. ing.

That is, the non-seal outer section has an axial dimension that limits compression of the seal bead beyond the elastic limit of the seal bead by engagement with the radial end face. As a result, after sealing, further axial movement of the tubular member with respect to the gasket is prevented, and deformation beyond the elastic limit of the seal bead is prevented.
As a result, the present invention can effectively prevent excessive tightening of the face seal joint.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a joint according to the present invention. In FIG. 1, 11 is a gasket, which is an annular seal beer.
Between the tubular members 27 and 29 having the terminals 23 and 25, it is used for a face seal joint. The joint shown in FIG. 1 is an improvement over the conventional joint having a semi-circular annular seal bead and uses a seal bead having an arcuate outer cross section.
In cross section, the inner cross sections of the seal beads 23, 25 define the shape of the conduit 26, and the outer arc cross sections of the seal beads 23, 25 engage the gasket 11. The illustrated engagement is known as a zero dead volume joint because there is no gap between the gasket and the tubular members 27,29. As shown in FIG. 3, the conduit 26 defined by the inner surfaces of the tubular members 27, 29 and the inner cylindrical surface 20 of the gasket 11 results in two conical surfaces being the gasket 1
They will intersect at one cylindrical surface 20. Therefore, the conduit wall is a continuous streamlined surface that promotes laminar flow and is only interrupted by a slight seam between the gasket 11 and the tubular members 27,29.

As shown in FIG. 2, the gasket according to the present invention is an annular ring having three different sections. The section is the inner width section 1
3, an intermediate section 15 with bevels 17, 18 and an outer wide section 19. Slopes 17 and 18
Engages with an annular seal bead for sealing. The outer section 19 acts as a spacer to limit the pressure exerted on the seal surface. Both the inner surface 20 of the gasket and the outer surface 21 of the gasket defining the conduit are cylindrical in shape. FIG. 2 shows a first embodiment of the invention in which the seal bead first engages the beveled surface of the gasket and prior to tightening. FIG. 3 shows the first embodiment after it has been tightened and completely sealed.

FIG. 4 shows a second embodiment of the present invention before sealing, and FIG. 5 shows a second embodiment of the present invention after sealing. In this embodiment, the inner walls 43 of the tubular members 45, 47 are coaxial and the perimeter formed by the gasket and the tubular member is the same over the entire joint. When the member is clamped as shown in FIG. 5, the shape of the conduit is defined by a substantially continuous cylindrical surface.

As shown in FIG. 1, tubular members 27 and 2
9 are pulled together by turning the coupling nut 31. The seat 35 is engaged with the integral tubular flange member 35 by the rotation of the coupling nut 31. Cylindrical members 27 and 2
As 9 is pulled together, gasket 11 is pinched between the ends of tubular members 27 and 29. When the nut 31 is turned and the tubular members 27, 28 are both pulled, the annular seal beads 23 and 25 projecting from the ends of the tubular members 27 and 29 are the slopes 17 of the gasket 11 respectively.
And 18 to engage. Continued rotation of the coupling nut 31 brings the tubular members 27, 28 closer together, increasing the pressure on the members of the fitting. The metal forming the seal bead and the gasket is slightly deformable, and the helium-tight sheath is used.
Making it easy. As shown in FIG. 2, as each seal bead engages the beveled surface 17 of the gasket 11, the bead exerts a force on the gasket having axial and radial components. Since the surface is a slope,
The radial force pushes the gasket outward as the reaction force pushes the beads inward toward the conduit 26. See
When the ruby force and the slope force are combined, the surface of the member constituting the seal is slightly deformed, as exaggerated in FIG. A slight deformation is necessary to achieve the seal and is beneficial as the metal fills any gaps. When the joint is disassembled, the bead returns to its stress-relieved shape.

In a joint using the improved gasket of the present invention, after sealing, the radial sidewalls 40 of the gasket outer section 19 engage the radial sidewalls 41 of the tubular member. When these flat surfaces come into contact,
Further axial movement of the tubular members 27, 29 relative to the gasket is prevented and deformation of the seal beads 23, 25 beyond the elastic limit is prevented. The resistance of the coupling nut 31 increases rapidly so that the assembler can easily detect when the two radial side walls meet.

In order for the improved gasket assembly to function efficiently, the dimensions of the gasket should be such that the tubular member has an annular seal.
It is necessary to accurately manufacture the ruby. As shown in FIG. 2, the distance between the radial sidewalls of the outer section of the gasket has a constant axial dimension and its radial surface is flat and perpendicular to the axis of the conduit. The inner circumference of the outer section 19 should be equal to or greater than the outer circumference of the annular seal bead. An intermediate beveled section 15 extending axially inward intersects the inner section 13 having a narrow uniform axial dimension. Inner section 1
3, like the outer section 19, has radial side walls perpendicular to the axis of the conduit. The axial distance Y between the side wall of the inner section and the side wall of the outer section is
It is slightly smaller than the distance Z defined by the distance that the ruby 23 extends axially from the side wall 41 of the tubular member 27.
The side wall 40 of the outer section of the gasket is tubular member 27.
When in contact with the side wall 41 of the, further axial movement is prevented.

The foregoing description has been provided for a preferred embodiment of the present invention, and modifications can be made without departing from the scope of the claimed invention.

[0017]

According to the present invention, further axial movement of the tubular member with respect to the gasket after sealing is prevented and deformation of the seal bead beyond the elastic limit is prevented. Therefore, excessive tightening of the surface seal joint can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a joint using a gasket according to the present invention.

FIG. 2 is a cross-sectional view of a tubular member having a part of the gasket of the present invention and an annular seal bead.

FIG. 3 is an enlarged view of a part of the gasket of the present invention and a tubular member having an annular seal bead.

FIG. 4 is a cross-sectional view of a second embodiment of the joint of the present invention before sealing.

FIG. 5 is a cross sectional view of the second embodiment after sealing.

[Explanation of symbols]

15: Inner beveled section of gasket 17: Gasket non-seal outer section 20: Gasket 23, 25: Seal bead 27, 29: tubular member

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-62-75188 (JP, A) JP-A-5-126285 (JP, A) JP-A-2-501587 (JP, A) International Publication 92/7213 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16L 19/00-19/03

Claims (7)

(57) [Claims] 1. A surface seal joint comprising a gasket and at least one tubular member, wherein the tubular member has a seal bead protruding from an end face in the radial direction of the tubular member, and the gasket An inner beveled section and a non-seal outer section, the inner beveled section receiving the seal bead forming a seal, and the non-seal outer section engaging with the radial end surface. the case, possess an axial dimension that limits the compression of the sealing bead exceeding the elastic limit of the sealing bead, before
A bead engages the beveled section to form a seal
When the unsealed section is slightly deformed,
The axial dimension is selected so as to engage the end face in the radial direction.
Face seal joint characterized by being selected . 2. The face seal joint according to claim 1, wherein the seal bead is an annular ring. 3. A face sheet according to claim 2, wherein the axial section of the annular seal ring has an arcuate surface.
Le fitting. 4. The surface seal joint according to claim 1, wherein the annular seal bead has an arcuate cross-section having an arcuate outer shape and a straight inner shape. 5. The surface seal joint according to claim 1, wherein the gasket and the seal bead are made of metal. 6. A surface seal joint comprising a gasket and a plurality of tubular members having an end face in a radial direction provided with an integral seal bead, wherein the gasket has a cylindrical wall defining a circular hole, and An inner section having a radial side wall perpendicular to the axis of the conduit defined by the tubular member and the cylindrical wall, and an intermediate section extending radially from the inner section and having opposite sloping walls, A shaft comprising a radial wall and an outer section having an outer cylindrical wall, said outer section capable of stopping axial movement of said gasket relative to said tubular member within a predetermined distance. A face-seal joint having a directional dimension, wherein the predetermined distance is less than an amount that compresses the seal bead beyond its elastic limit. 7. A surface seal joint comprising two tubular members, each of said tubular members having a radial end wall and an annular seal bead extending from said end wall, said gasket comprising: An inner section having a bevel surrounded by an outer section, the bevel being arranged to engage the seal bead for sealing, and the outer section being the bevel.
After engaging the seal bead to form a seal,
A surface seal joint having an axial dimension for engaging a radial side wall of the tubular member.