GB2091364A

GB2091364A - Fluid-tight seal

Info

Publication number: GB2091364A
Application number: GB8101625A
Authority: GB
Original assignee: LEYGARD Ltd
Current assignee: LEYGARD Ltd
Priority date: 1981-01-20
Filing date: 1981-01-20
Publication date: 1982-07-28
Also published as: GB2091364B

Abstract

A seal between tapering surfaces of pipes or tubes 1, 2 is effected by an elastomeric O-ring 6 which is located in a circumferential channel 5 in one of the surfaces. As shown, the pipes 1, 2 are locked together by a threaded shoulder nut 3 engaging a threaded portion 1a of pipe 1. Alternatively threaded parts (7, 8, Fig. 2 not shown) of the pipes themselves are used as locking means. The tapering surfaces may be part-spherical (Fig. 3 not shown) to permit the pipes to be inclined at an angle to each other. <IMAGE>

Description

SPECIFICATION Improved fluid-tight seal This invention relates to an improved fluid-tight seal between interconnected parts of pipe or tube joints or couplings, and to joints or couplings incorporating such seals.

A primary object of the invention is the provision of a method of and means for effecting a seal as set forth in the preceding paragraph which is capable of resisting hydraulic and pneumatic pressures of up to about 10,000 Ib per sq. inch without necessarily having to use considerable force, e.g. by using a spanner or other turning tool, to turn and tighten the joint, and which in fact permits a satisfactory seal to be obtained by tightening the joint by hand.

According to this invention there is provided a fluid-tight seal between connecting ends of pipes or tubes, wherein said ends are respectively formed or provided with male and female complementary tapered surfaces, one of which includes a circumferential channel and an O-ring of elastomeric material within the channel but standing proud of said one surface, and means for locking said surfaces in abutting relationship.

The tapered surfaces are preferably conical.

Said locking means is preferably screwthreaded, but complementary cammed surfaces, or bayonet-type means, are also possible.

To enable the invention to be clearly understood preferred embodiments thereof will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a longitudinal section through a connection between the ends of two pipes which are fixedly secured together co-axially; Figure 2 illustrates a modification of Figure 1; and Figure 3 is a longitudinal section of a second embodiment in which the ends are angularly adjustable with respect to a co-axial position.

Referring firstly to the embodiment illustrated by Figure 1, the seal has a concave cone threaded adaptor 1; a convex coned nipple 2; and a shoulder nut 3, the adaptor 1 being externally threaded at 1 a and the nipple 2 being fitted with the shoulder nut 3 which is internally threaded for screwing over the thread 1 a of the adaptor.

The concave surface 4 of the adaptor is formed with a circumferential groove or channel 5 within which is located an O-ring 6 of rubber or other suitable distortable material such as Nylon or P.V.C. The size of this O-ring 6 is such that a circumferential portion 6a projects a predetermined distance beyond the mouth of the groove 5. When the members 1 and 2 are urged together by screwing the nut 3 over the threaded surface la of the adaptor member 1, the two conical surfaces are brought closely together. The projecting portion 6a of the O-ring 5 is caused to bear against the conical surface 2a of the nipple 2 and tightening of the shoulder nut 3 causes the O-ring to distort to effect a fluid-tight seal between the two conical surfaces of the adaptor 1 and the nipple 2 and with the bores of these parts in axial alignment.

According to a preferred form of the invention the angle of the coned portions of the adaptor and the nipple is 60 , and a mismatched is allowed of a maximum angle of 15 minutes between the two mating faces. However, an angle between 500 and 70C is probably both technically and commercially feasible.

The O-ring 6 is set into the groove 5 in the concave coned adaptor 1 so that when undistorted the portion 6a projects by .002"-.005" so as to expose approximately 15% of the surface of the O-ring for engagement with the surface 2a of the nipple, which assists in forming a good seal.

Referring next to Figure 2, the same reference numerals are used to denote similar parts. In this embodiment the shoulder nut 3 is not used and the coned adaptor is constituted by the open end portion of an end cap 7 which is screw threaded internally at 7a and receives a threaded part 8 projecting forwardly from the coned nipple 2. The action is so efficient that turning of the cap 7 which is plain externally is sufficient to effect a required seal.

Referring lastly to Figure 3, this illustrates a construction wherein the seal is effected between a concave adaptor 8 having a part spherical sealing surface 9 formed with a groove 10 housing an O-ring 1 1 having a portion 1 a which projects from the groove 10. The nipple in this embodiment comprises a substantially spherical member 12 which is complementary to the surface 9 of the adaptor, and a shoulder nut 13 which is threaded on to the outside of the adaptor 2.This shoulder nut 13 is formed with a partspherical bearing surface at 1 3a that bears against the nipple when the members are tightened together so as to lock the nipple in position with the axis of the nipple aligned with the axis of the adaptor, or alternatively, inclined at any required angle thereto while maintaining a seal by way of the O-ring sandwiched between the opposed contacting faces of the nipple and the adaptor.

The seal provided by this invention can be effected quickly and easily and will resist and withstand high pressures, e.g. of the order of 10,000 Ib per sq. inch although the parts are screwed together by hand only to finger tightness.

The required efficient seal is obtained without recourse to using considerable force by use of a tool such as a spanner, and this allows simple installation even in confined spaces.

It is believed that this is due to the fact that with conical faces of reasonable accuracy, the two faces can be brought into abutting relationship with substantially no gap. At the very high pressures considered, the projecting portion of the O-ring is then only distorted radially outwards to fulfil its sealing function. If the gap were present, the O-ring would be totally dislodged by outward extrusion under the pressure. It is possible to achieve this necessary abutting relationship by finger pressure alone due to the mechanical advantage inherent in the tapering of the surfaces.

The parts forming the fluid-tight seal may be made of metal or any suitable synthetic plastics material.

Claims

1. A fluid-tight seal between connecting ends of pipes or tubes, wher'ein said ends are respectively formed or provided with male and female complementary tapered surfaces, one of which includes a circumferential channel and an O-ring of elastomeric material within the channel but standing proud of said one surface, and means for locking said surfaces in abutting relationship.

2. A seal according to claim 1, wherein the locking means is screw-threaded.

3. A seal according to claim 2, wherein an internally-threaded shoulder nut is fitted around one of the pipes or tubes, the internal thread locking with an external thread on the other pipe or tube.

4. A seal according to any preceding claim wherein the tapered surfaces are frusto-conical.

5. A seal according to claims 2 and 4, wherein one of the pipes or tubes has a generally cylindrical internally-threaded portion which locks with a generally cylindrical externally-threaded portion of the other pipe or tube.

6. A seal according to claim 5, wherein the threaded portions of the pipes or tubes are provided at the narrow end of the tapered surfaces.

7. A seal according to any of claims 1 to 3 wherein the tapered surfaces are part-spherical.

8. A seal according to any preceding claim, wherein the channel is in the radially outer tapered surface.

9. A fluid-tight seal between connecting ends of pipes or tubes substantially as herein described with reference to Figure 1, or Figure 2, or Figure 3 of the accompanying drawings.