GB2032032A

GB2032032A - Flexible coupling pipe

Info

Publication number: GB2032032A
Application number: GB7929557A
Authority: GB
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 1978-08-24
Filing date: 1979-08-24
Publication date: 1980-04-30
Also published as: IT1162576B; NL7906355A; GB2032032B; IT7925267A0

Abstract

A flexible coupling pipe for interconnecting pipe lines for conveying dredged material, comprises an inlet pipe (3) provided at its inlet end with a flange (2) for connection with the end of one of the pipe lines to be interconnected, an outlet pipe (6) provided at its outlet end with a flange (5) for connection with the end of the other pipe line to be interconnected, and a flexible barrel-shaped central pipe (7) secured to and bridging the inlet and outlet pipes, the inner diameter of at least one of the inlet and outlet pipes converging in the direction from the inlet to the outlet of the coupling pipe. <IMAGE>

Description

SPECIFICATION Flexible coupling pipe This invention relates to a flexible coupling pipe, particularly for resiliently interconnecting pipe lines for conveying a medium such as rock, mud and sand dredged by a pump suction dredge ship.

A pipe line for conveying a medium such as rock, mud and sand dredged by a pump suction dredge ship (hereinafter referred to as a pump ship) suitably comprises a portion disposed on a float adapted to be connected to the pump ship and locating a medium conveying pipe on the sea and a portion disposed on a holding frame and locating the medium conveying pipe partly on the land and partly on the sea, and has an overall length of for example 5,000 m.

In general, that portion of the pipe line which is disposed on the holding frame is rectilinearly arranged and two pipe lines are directly connected to each other. In the case of changing the direction of the pipe line, use is made of a bent pipe so as to connect the pipe lines. That portion of the pipe line which is disposed on the float is required to move in response to the movement of the pump ship and to the movement of the float due to wind or waves, thereby bending the pipe line. Such bending of the pipe line must be absorbed by a flexible coupling pipe.

Such a flexible coupling pipe has a pressure gradient from its inlet portion near the pump ship toward a delivery opening thereof, the pressure being high at its inlet portion near the pump ship.

In addition, the inner portion of the flexible coupling pip is deformed due to bending of the pipe line in response to the movement of the float and becomes severely worn and damaged by mud, sand and crushed rock pieces. These damaged flexible coupling pipes must be replaced by new ones while stopping the operation of the pump ship.

The pipe line is rendered inoperative mainly due to damage to the flexible coupling pipe. As a result, the quality of the flexible coupling pipe exerts considerable influence upon the operational efficiency of the pump ship. In particular, when a flexible coupling pipe is used for a pipe line for conveying dredged mud and sand containing crushed rock pieces, the flexible coupling pipe is subjected to premature wear. As a result, the wear resistance of the flexible coupling is very important.

Heretofore, it has been the common practice to use a flexible coupling pipe mainly consisting of a rubber pipe or a flexible coupling pipe having a steel spherical surface. Both such flexible coupling pipes have numerous constructional defects and undergo premature wear in the case of conveying sharp objects.

The flexible coupling pipe having a steel spherical surface induces a throttling phenomenon as in the case of reducing the pipe diameter by the angle formed between the bent portions, thereby increasing the resistance against the medium conveyed through the pipe.

In the flexible coupling pipe having a steel spherical surface, in order to make the sectional area of the pipe line the same as that of a rectilinear pipe portion, it is required to use a large steel spherical surface type flexible coupling pipe so that the flexible coupling pipe becomes heavy in weight.

As a result, it is impossible to use an existing float or the heavy weight of the coupling pipe causes the pipe line to bend excessively so that it becomes difficult to convey various mediums with good efficiency. In addition, the spherical surface type flexible coupling pipe tends to undergo local wear at its engaging portions so that it is difficult to use it for a long time.

The present invention provides a flexible coupling pipe for interconnecting pipe lines for conveying dredged medium, comprising an inlet pipe provided at its inlet end with a flange for connection with the end of one of the pipe lines to be interconnected, an outlet pipe provided at its outlet end with a flange for connection with the end of the other pipe line to be interconnected, and a central pipe formed of a flexible material and bridging those ends of the said inlet and outlet pipes which are remote from the said flanges, wherein the said flexible main pipe is barrelshaped and secured to the inlet and outlet pipes so as to interconnect the inlet and outlet pipes, and wherein the inner diameter of at least one of the inlet and outlet pipes converges in the direction from the inlet to the outlet of the coupling pipe.

The invention will be further described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 pizza side elevational view, partly in section, of one embodiment of a flexible coupling pipe according to the invention for interconnecting pipe lines for conveying dredged material; Figure 2 is a partial longitudinal sectional view of another embodiment of a flexible coupling pipe according to the invention; and Figures 3 to 6 are longitudinal sectional views of further embodiments of flexible coupling pipes according to the invention.

Throughout the drawings like reference numerals indicate like parts.

The flexible coupling pipe shown in Figure 1 is composed of an inlet pipe 3 formed of steel or a wear resistant and rigid synthetic resin and provided at its inlet end with a flange 2, an outlet pipe 6 formed of steel or a wear resistant and rigid synthetic resin and provided at its outlet end with a flange 5, and a barrel-shaped central pipe 7.

The barrel-shaped central pipe 7 is composed of an inner surface rubber 1 2a having an excellent wear resistance, a reinforcing layer 1 2b formed of for example canvas cords and superimposed about the inner surface rubber 1 2a, and an outer cover rubber 1 2c having an excellent weather resistance and superimposed about the reinforcing layer 1 2b.

The central pipe 7 extends over ribs 8, 9, 11 projecting from the outer periphery of the inlet and outlet pipes 3, 6 and is provided at those end portions thereof which are located outside the ribs 8 and 9 with bead wires 13 and 14 respectively.

These bead wires 13, 14 are surrounded by the ends of the reinforcing layer 1 2b. The pipe 7 is firmly secured to the inlet and outlet pipes 3, 6 by baking the inner surface rubber 1 2a onto the inlet and outlet pipes 3, 6.

The inner diameter of the inlet end of a pipe portion 1 of the inlet pipe 3 and the inner diameter of the outlet end of a pipe portion 4 of the outlet pipe 6 are made equal to the inner diameters of the ends of adjacent pipe lines to be interconnected (not shown), for example 730 mm.

The inner diameter of the pipe portion 1 of the inlet pipe 3 gradually converges in the direction of advance of the medium conveyed therethrough and reaches, for example, 700 mm. Similarly, the inner diameter d2 of the pipe portion 4 of the outlet pipe 6 gradually converges from its inlet end in the direction of advance of the medium conveyed therethrough and reaches, for example, 700 mm.

As a result, the taper angle of the pipe portions 1, 4 of the inlet and outlet pipes 3, 6 is relatively small. In general, the loss in those pipe portions 1, 4 is wear loss only. In addition, the inner diameter d, of the outlet end of the pipe portion 1 of the inlet pipe 3 is smaller than the inner diameter d2 of the inlet end of the pipe portion 4 of the outlet pipe 6.

The medium conveyed through the inlet pipe 1 in the direction shown by an arrow Al is accelerated and decelerated when delivered from the outlet end of the inlet pipe 3. In other words, the medium conveyed through the inlet pipe 3 reaches the enlarged diameter inlet end of the outlet pipe 6 at a time when the stream lines are separated from each other so that there is no risk of the inner surface rubber 1 2a being worn by the medium flowing therethrough.

It is a matter of course that the distance between the inlet and the outlet pipes 3, 6 may be changed within a range which allows the pipe lines to be interconnected to effect the relative angular displacement through a desired angle.

In the embodiment shown in Figure 2, the inner diameter d3 of the inlet end of the inlet pipe 3 is made larger than the inner diameter d4 of the outlet end of the outlet pipe 6 so as to prevent the medium conveyed therethrough from accumulating therein.

In addition, the inner diameter of an inlet pipe portion 1 a of the inlet pipe 3 is made uniform for a length / so as to make the flow of the medium conveyed therethrough steady. The inner diameter of the remaining outlet pipe portion 1 b of the inlet pipe 3 converges in the advance direction of the medium conveyed therethrough so as to accelerate the flow of the medium. In the present embodiment, the outlet pipe 6 has substantially the same construction as the outlet pipe 6 shown in Figure 1.

If the inner diameter of the outlet end of the inlet pipe 3 is d5, then the length / of the uniform inner diameter pipe portion 1 a of the inlet pipe 3 is given by

If the length of the pipe 7 is considerably shorter than its inner diameter, it is possible to omit the uniform inner diameter pipe portion 1 a of the inlet pipe 1.

In the present embodiment, if the relation between the taper angle of the converging pipe portion 1 b of the inlet pipe 3 and the inner diameter of the inlet end of the outlet pipe 6 is determined such that an angle a formed between an imaginary extension line of the converging pipe portion 1 b which passes through the vertical centre line of the pipe 7 and a segment connecting a crossing point between the vertical centre line of the pipe 7 and an imaginary extension line from the converging pipe portion 1 b to the inlet end edge of the outlet pipe 6 is larger than a maximum bending angle p of the main pipe 7, the medium conveyed through the coupling pipe can directly reach the inside of the inlet end of the outlet pipe 6, thereby significantly reducing the wear of the inner surface rubber 1 2a.

The maximum bending angle P of the pipe 7 is 1 50 to 20 , so that the taper angle of the converging pipe portion 1 b and the inner diameter of the inlet end of the outlet pipe 6 are so selected that the angle a is larger than the maximum bending angle p.

The configuration of the inner flow path of the inlet and outlet pipes 3, 6 in section is not always circular, but may be square.

In the embodiment shown in Figure 3, the outlet end of the pipe portion 1 of the inlet pipe 3 projects beyond the firmly fastened portion of the central pipe 7 so as to form a projection Ic and define a space A between the outer periphery of the projection 1 c and the inner surface of the bulged centre portion of the barrel-shaped central pipe 7. It will be noted that in this embodiment there is provided a further rib 10 in addition to the ribs 8, 9 and 11. In the present embodiment, it is preferable to make the inner diameter d, of the pipe portion 1 a equal to the inner diameter d2 of a rectilinear pipe portion 4a of the outlet pipe 6.

In the flexible coupling pipe shown in Figure 3, the flexible central pipe 7 is capable of absorbing displacement produced when a pipe line connected to the inlet pipe 3 becomes bent with respect to a pipe line connected to the outlet pipe 6. In addition, when the pipe line connected to the inlet pipe 3 becomes bent with respect to the pipe line connected to the outlet pipe 6, the space A functions to prevent the sectional area of the coupling pipe from becoming smaller than the sectional area of the pipe portion 1 (of inner diameter d1) and becoming smaller than the sectional area of the rectilinear pipe portion 4a (of inner diameter d2). As a result, mud or the like conveyed through the coupling pipe is not subjected to pressure loss.In addition, dredged mud and sand, and sharp objects such as crushed rock pieces are conveyed from the pipe portion 1 of the inlet pipe 3 through a converging pipe portion 4b of the outlet pipe 6 to the rectilinear pipe portion 4a and hence do not make contact and collide with the inner surface rubber of the flexible central pipe 7. As a result, it is possible to prevent the inner surface of the pipe 7 from being worn or damaged.

When the inlet pipe 3 and the outlet pipe 6 become bent with respect to each other, water in the space A acts as a water cushion so as to compensate for the pressure change.

In the embodiment shown in Figure 4, a pipe portion 1 of an inlet pipe 3 is composed of a rectilinear pipe portion 1 a and a converging pipe portion 1b. A pipe portion 4 of an outlet pipe 6 is made rectilinear and the inner diameter d, of the rectilinear pipe portion 1 a is made equal to the inner diameter d2 of the pipe portion 4.

In the flexible coupling pipe shown in Figure 4, even if the inlet pipe 3 becomes bent with respect to the outlet pipe 6, the deformed wall portion of the central pipe 7 does not project between the converging pipe portion 1 b of the inlet pipe 3 and the pipe portion 4 of the outlet pipe 6 so that the conveying path in the coupling pipe becomes smooth. In addition, use of the converging pipe portion 1 b ensures an increase of the local flow rate of the medium conveyed therethrough.

In the embodiment shown in Figure 5, a pipe portion 1 of an inlet pipe 3 is composed of a rectilinear pipe portion 1 a and a converging pipe portion 1 b in the same manner as in the case of the embodiment shown in Figure 2. An outlet pipe 6 is provided at the inner end of a rectilinear pipe portion 4a of its pipe portion 4 with a converging pipe portion 4b. The present embodiment functions to improve smoothness of the conveying path and to make the local flow rate of the medium conveyed therethrough high if compared with the previous embodiment shown in Figure 4.

In the embodiment shown in Figure 6, an inlet pipe 3 is composed of a rectilinear pipe portion 1 and an inner pipe portion 15 slideably insertable into and removable from the rectilinear pipe portion 1. The inner pipe portion 15 is provided at its inlet end with a flange 16 adapted to be snugly fitted into an annular groove 17 provided in the flange 2 of the inlet pipe 3. In addition, the central pipe 7 is provided at one end of the inner peripheral surface thereof with a projection 7a which is tightly sealed together with the outer peripheral surface of the inner pipe portion 1 5, thereby preventing mud and sand from penetrating into the gap formed between the inner pipe portion 15 and the rectilinear pipe portion 1.

An outlet pipe 6 is composed of a rectilinear pipe portion 4a and a converging portion 4b.

The inner diameter d, of the inner pipe portion 15 of the inlet pipe 3 is made equal to the inner diameter d2 of the rectilinear pipe portion 4a of the outlet pipe 6.

In the present embodiment, when the inner pipe portion 15 becomes worn it can be replaced by a new one and the flexible coupling pipe as a whole may be used for a long time.

As stated hereinbefore, the flexible coupling pipe according to the invention has a number of advantages. In the first place, the use of a simple construction wherein the inner diameter of at least one of the inlet and outlet pipes converges in the advance direction of the medium conveyed therethrough prevents contact of the conveyed medium with the inner surface rubber of the central pipe of the coupling pipe with a lower pressure loss and hence prevents wear. Secondly, the use of the flexible barrel-shaped central pipe interconnecting the inlet and outlet pipes ensures sufficient absorption of bending or displacement of the pipe lines connected to the inlet and outlet pipes, respectively.Third, even if the flexible central pipe becomes deformed when the pipe lines are bent, the space formed between the outer periphery of the optionally projecting front end of the pipe portion of the inlet pipe and the inner surface rubber of the central pipe is capable of preventing the sectional area of the pipe path in the coupling pipe from becoming smaller than the sectional area in the pipe portions of the inlet and outlet pipes and hence there is no risk of the medium conveyed therethrough being subjected to pressure loss. Fourth, water in the abovementioned space functions to cushion the pressure change and causes dredged mud and sand, and sharp objects such as crushed rock pieces to flow from the inlet pipe to the outlet pipe without making contact or colliding with the inner surface rubber of the central pipe of the coupling pipe, thereby improving the wear resistance of the flexible main pipe and hence of the coupling pipe as a whole. Fifth, the use of a converging inlet pipe portion renders it possible to make the local flow rate of the conveyed medium high. Finally, the use of an inner pipe portion adapted to be slidably inserted into and removed from the inlet pipe permits replacement of the inner pipe portion of the inlet pipe by a new one, thereby prolonging the life of the coupling pipe as a whole.

Claims

1. A flexible coupling pipe for interconnecting pipe lines for conveying dredged medium, comprising an inlet pipe provided at its inlet end with a flange for connection with the end of one of the pipe lines to be interconnected, an outlet pipe provided at its outlet end with a flange for connection with the end of the other pipe line to be interconnected, and a central pipe formed of a flexible material and bridging those ends of the said inlet and outlet pipes which are remote from the said flanges, wherein the said flexible main pipe is barrel-shaped and secured to the inlet and outlet pipes so as to interconnect the inlet and outlet pipes, and wherein the inner diameter of at least one of the inlet and outlet pipes converges in the direction from the inlet to the outlet of the coupling pipe.

2. A flexible coupling pipe as claimed in Claim 1, wherein the inner end of a pipe portion of at least the said inlet pipe projects into an inside space of the said central pipe so as to form a space between the outer periphery of the said projection and the inner surface of the central pipe.

3. A flexible couplingpipe as claimed in Claim. 1, wherein the said inlet pipe is slidably insertable into and removable from the said central pipe.

4. A flexible coupling pipe as claimed in Claim 3, wherein the said inlet pipe is provided therein with an inner pipe portion adapted to be inserted into and removed from the inlet pipe.

5. A flexible coupling pipe substantially as herein described with reference to, and as shown in, Figure 1, Figure 2, Figure 3, Figure 4, Figure 5 or Figure 6 of the accompanying drawings.