GB2349677A

GB2349677A - Earthquake resistant pipe coupling

Info

Publication number: GB2349677A
Application number: GB9927894A
Authority: GB
Inventors: Masaaki Yamaguchi
Original assignee: Shinwa Industry Co Ltd
Current assignee: Shinwa Industry Co Ltd
Priority date: 1999-05-06
Filing date: 1999-11-25
Publication date: 2000-11-08
Also published as: JP2000320760A; KR20000075397A; CN1273338A; GB9927894D0

Abstract

An earthquake resistant pipe coupling has swaged flange ends 2 and 2a formed on pipe ends 1 and 1a with an interposed sealing ring packing 4 with annular restraining ring 5. Channel shape housings 6 and 6a embrace flange rims 2 and 2a. A gap a is formed between the flange rims 2 and 2a and the edges of ring 5 to allow deflection to absorb stress whilst retaining the sealing properties when bending force is applied.

Description

TITLE Pipe Coupling This invention relates to a pipe coupling primarily for supply of water or other liquid or gas. The pipe coupling is intended to have enhanced earthquake resistance and sealing properties.

If loads are applied to pipes due to earthquake subsidence or the like it is important to absorb the said load as far as possible and to prevent leakage from any broken parts and connected portions.

For such a purpose if a load acts on a pipe, the pipe coupling should yield to absorb the load and to prevent breakage.

In a known construction of pipe coupling (JP H8 190018) the ends of two pipes having the same cross section have flared rims which are butted together and have a holding clamp band around the rims and a band tightening device to shorten the circumferential length of the band. The end faces of the rims are brought together and held by tightening the band using a tightening means, thus connecting the two pipes while absorbing the expansion or shrinkage and deflection of pipe. In this way the mutually butting ends of two pipes of the same cross section can bend towards the outer circumference of the rims thus absorbing the expansion, shrinkage, deflection and vibration of the pipes.

In the prior art the sealing property is high when the bending force acts against the connecting portion. However, as the curved parts of the rims are closely connected the tolerable range of the sealing property is small if pull and bending forces act together. In this case the sealing material used may break.

One object of this invention is to provide a pipe coupling having good resistance to deformation together with good sealing properties, especially when pull forces are encountered and when pull forces and bending forces act together.

According to this invention there is provided means for coupling together the ends of two pipes each of said ends being outwardly flared to form flanges having mutually facing annular sealing surfaces, the means comprising a resilient sealing ring for location between and contacting each said sealing surface, a retaining surface encompassing the outer periphery of the sealing ring to constrain lateral movement of said ring, and a clamping ring of U-shaped channel cross-section embracing the flanges to bring the sealing surfaces and sealing ring together into sealing engagement, the said retaining surface being normally spaced from each said sealing surface to permit limited relative displacement between the pipes through deformation of the sealing ring.

This invention is further described and illustrated with reference to the drawings showing embodiments by way of examples.

In the drawings: Figure 1 shows an exploded view of a pipe and coupling according to this invention, Figure 2 shows a side of a pipe and coupling, Figure 3 shows a cross section on A-A'of Figure 2, Figure 4 shows a cross section on B-B'of Figure 4, Figure 5 shows a cross section as Figure 4 but with applied bending force, Figure 6 shows a partial cross section of a second embodiment according to this invention, Figure 7 shows a cross section of a further embodiment and example of packing ring, Figures 8a and 8b show a cross section of further embodiments of pipe couplings.

Figure 1 shows an exploded view of a pipe coupling of this invention, wherein 1 and 1a are the pipes to be joined, 2 and 2a are the flange rims formed by swaging the pipe ends 1'and 1 a'of pipes 1 and 1 a outwardly. The peripheral parts 3 and 3a of the flange rims 2 and 2a are convexly curved and thus the opposing flange faces form convex curved surfaces 3'and 3a'.

An annular seal packing 4 has an extemal metal ring 5 around the peripheral surface of packing 4. Split housings 6, 6a each of semicircular shape have flanges 9 with apertures 10 for securing bolts 7 and nuts 8. A channel 11 of U-shape is formed on the inside of the housings 6 and 6a, with tapers 13 and 13a whereby the inside of both the side walls 12 and 12a forming the channel 11 narrow towards the base.

The pipes are coupled with the packing 4 and ring 5 between the flanges 2 and 2a as shown in Figure 2 and Figure 3. The clamp formed by housings 6 and 6a is tightened using bolts 7 and nuts 8 and the flange rims 2 and 2a are pressed together by the action of tapers 13 and 13a of channel 11. The packing 4 is compressed as shown in Figure 4, but a gap a is maintained between the flange rims 2 and 2a and the ring 5. As a result, if the bending load acts from the side of pipe 1a, for example as shown by the arrow b in Figure 4, the upper part of the packing 4 and ring 5 move towards the side of flange rim 2 and the gap a reduces whilst the gap increases at the lower part. If a longitudinal deflection angle e occurs between pipes 1 and 1a the sealing property and gap a are maintained by the elasticity of packing 4. The load is absorbed around the 360 of the circumference.

The embodiment of Figure 6 has the ring 5 integrally formed on the inside surface of the channel 11 of housings 6 and 6a against the packing 4. In this embodiment also the packing 4 is prevented from expanding in diameter and deforming in a radial direction by the ring 5.

In the embodiments shown in Figures 1 to 6, the cross sectional shape of packing 4 and ring 5 are not limited to those shown. Furthermore the packing 4 may be integrated with the ring 5 or they may be given profiles so that they do not separate and may be concave or convex. For example a cross section of X-form may be provided for the packing 4 as shown in Figure 7 with a circular cross section given to the ring 5.

Further, in the embodiments shown the housings 6 and 6a are in two parts but they may be split into three or four parts according to circumference, size, weight or use. The housings split into two pieces maybe connected as shown in Figures 1 to 6 using bolts and nuts.

Figure 8 (a) shows an embodiment of pipe coupling that has perpendicular flanges 1'and 1a'on the outside and the ring 5 and packing 4 is located between these pipe end flanges to reduce the outside diameter width of housings 6 and 6a and also to improve the earthquake resistant and sealing property. Figure 8 (b) shows an embodiment of pipe coupling that increases the tightening force through the housings 6 and 6a, forming a V-shape taper 1c inside of the pipe end flanges 1'and 1a'. This also enhances the earthquake resistance and sealing property.

This invention, as described above, forms a flange rim on the pipe ends with interposed packing and a ring between the flange rims. The gap between the ring and flange brim, thereby absorbs the bending stress. As a result, the sealing performance can be maintained at a maximum even if the pull and bending forces act on the piping and the joint strength can be increased. In addition, the packing can be prevented from moving in a radial direction by the pressure of the ring on the outside circumference of packing.

Claims

CLAIMS : 1. Means for coupling together the ends of two pipes each of said ends being outwardly flared to form flanges having mutually facing annular sealing surfaces, the means comprising a resilient sealing ring for location between and contacting each said sealing surface, a retaining surface encompassing the outer periphery of the sealing ring to constrain lateral movement of said ring, and a clamping ring of U-shaped channel cross-section embracing the flanges to bring the sealing surfaces and sealing ring together into sealing engagement, the said retaining surface being normally spaced from each said sealing surface to permit limited relative displacement between the pipes through deformation of the sealing ring.
2. Means in accordance with claim 1, wherein the retaining surface is formed by a ring located around the sealing ring.
3. Means in accordance with claim 1, wherein the retaining surface is formed by an annular protuberance on the inside of the clamping ring.
4. Means in accordance with any preceding claim, wherein the internal side walls of the U-shaped channel of the clamping ring are divergent towards the open side of the channel, whereby tightening the clamp by reducing the diameter applies a longitudinal compressive force to the sealing ring through the flanges.
5. Means in accordance with any preceding claim, wherein the clamping ring is formed from a plurality of segments.
6. Means in accordance with claim 5, wherein the clamping ring is formed from two parts.
7. Means in accordance with any preceding claim, wherein the retaining surface is formed by a metal ring and is integral with the sealing ring.
8. Means in accordance with any preceding claim 1 to 6 wherein, the retaining surface is formed by a metal ring engaging profile parts of the salins ring and retained thereon.
9. Means for coupling pipes substantially as herein described and illustrated with reference to the drawings.