Pipe joints or couplings – With indicator – alarm or inspection means
Patent
1995-04-20
1996-06-25
Arola, Dave W.
Pipe joints or couplings
With indicator, alarm or inspection means
285363, 285910, 277 2, F16L 3500
Patent
active
055293468
DESCRIPTION:
BRIEF SUMMARY
The present invention is concerned with joints and, in particular joints having gaskets between complementary faces thereof.
As is well known, the purpose of a gasket is to seal a joint. There are many methods of sealing a joint but the most common way is by employing bolts extending perpendicular to the joint to exert pressure on the gasket. The pressure exerted within the gasket must exceed the pressure within the system, or else the gasket will not perform its function and therefore whatever the gasket is trying to contain will inevitably escape.
A problem with the use of bolts to cause components to engage on the face of a gasket is that the bolts are tightened individually, with the inevitable effect that the applied torque, and therefore the resulting force, is not evenly distributed throughout the gasket, thus causing local variations in applied pressure around the gasket. For example, in the case where there are four bolts equispaced around a joint, the tightening of one bolt inevitably causes some distortion of the diametrically opposed bolt. It is thus difficult to achieve equalised distribution of force. Although torque indicators can be used with the tightening spanners, these indicate the torque applied rather than the resultant force in the gasket.
The present invention seeks to provide a joint in which such disadvantages can be at least alleviated.
According to the present invention, therefore, there is provided a joint comprising a first joint component having an axial aperture, a second joint component having an axial aperture arranged to be coaxial with the first mentioned aperture, a gasket arranged to be interposed between said components, and a plurality of bolts arranged to secure said first joint component to said second component with said gasket interposed therebetween with opposed faces in contact with respective joint components, wherein said gasket incorporates a plurality of stress or strain responsive elements substantially equispaced around the entire periphery of said gasket, each of said responsive elements comprising a pair of electrodes having a stress or strain responsive material sandwiched therebetween, each said responsive element having opposed faces which are spaced from the respective opposed faces of said gasket, and means for connecting each of said responsive elements to an output display so as to give detectable indication of the stress or strain applied to each individual one of said responsive elements corresponding to the torque force applied to a proximate bolt.
The responsive elements therefore do not respond to the torque applied to the bolts, but to the force induced in the gasket during installation.
The joint components are typically tubular members and the gasket is then annular.
It is preferred that the responsive elements are encapsulated within the gasket. Advantageously at least four equispaced responsive elements are provided.
Preferably the gasket is provided with throughbores extending therethrough arranged to be complementary to throughbores provided for the bolts in said first and second joint components.
It is particularly preferred that the plurality of responsive elements are equal in number to the number of the plurality of bolts.
Typically the strain responsive elements are of the type suitable for inclusion in a strain gauge. In a preferred embodiment of the present invention the joint comprises a plurality of piezoelectric elements each comprising a pair of electrodes having a piezoelectric material sandwiched therebetween.
In one embodiment of the invention, the plurality of responsive elements is arranged around the entire periphery of the gasket such that a line drawn from the axis of said aperture radially outward through each bolt passes through a respective responsive element.
Further preferred features of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1 is a longitudinal sectional view of an exemplary embodiment of a joint according to the inventio
REFERENCES:
patent: 1569837 (1926-01-01), MacDonald
patent: 3151258 (1964-09-01), Sonderegga et al.
patent: 3358257 (1967-12-01), Painter et al.
patent: 4573351 (1986-03-01), Wiener
patent: 5121929 (1992-06-01), Cobb
patent: 5380014 (1995-01-01), Schaperkotter
Arola Dave W.
Intellectual Property Holdings Pte Limited
McGlynn Bliss
LandOfFree
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