EP0964965B1

EP0964965B1 - Sewer pipe

Info

Publication number: EP0964965B1
Application number: EP98908307A
Authority: EP
Inventors: Aloysius Gerardus Maria Roggekamp
Original assignee: Waco Liesbosch Beton BV
Current assignee: Waco Liesbosch Beton BV
Priority date: 1997-02-21
Filing date: 1998-02-23
Publication date: 2001-01-24
Anticipated expiration: 2018-02-23
Also published as: DE69800509T2; AU6636998A; WO1998037282A1; DE69800509D1; NL1005336C2; EP0964965A1

Description

The invention relates to a method for manufacturing a pipe suitable for use in a sewage system made from concrete and to be coupled with other pipes of the same type for the construction of a sewage system, which pipe is being provided with a seamless inside wall, having rising side wall elements which in a cross-sectional view taper towards the bottom of the pipe and extend in a substantially straight course, which side wall elements merge into one another at the bottom side of the pipe to form a curved wall portion whose curve is defined by a first radius, and which at the top side of the pipe merge into one another to form a curved wall portion whose curve is defined by a second radius, the second radius being larger than the first radius.

Such a pipe is known from DE-A-28 54 224. According to DE-A-28 54 224 the first radius may be considered as small relative to the second radius.

Such a pipe is further known from the Dutch patent application NL-A-286170. This publication also discloses a round pipe. The characteristic of the known pipe is an ability to cope with rather large debits of waste water. However, this large capacity detracts from the performance when there is a small supply of waste water. Particularly when there is little flow to be processed it is desirable that the flow of liquid in the pipe is maintained at a sufficiently high level in order to avoid corrosion of the pipe due to sediment deposit. Sediment deposit occurs especially at slower flow rates and results in the corrosion of the sewer of which the pipe is a component. A sufficiently high flow rate prevents sediment deposit but ensures also that possible sediment deposit is carried away sooner. To this end the use of egg-shaped pipes has already been known for some time from the prior art. Such egg-shaped pipes are known, for instance, from the Dutch patent application NL-A-6514445 and the Dutch patent NL-B-43859. In comparison with the known round pipe, an egg-shaped pipe will exhibit an improved flow rate at a certain supply flow in the low range.

The objective of the invention is now to further improve the pipes known from the prior art and to provide a pipe which, especially in the low flow range, discharges the liquid more quickly while maintaining the capacity. This objective is achieved by the method as defined by claim 1.

The pipe manufactured according to the invention is such that the first radius is more or less constant and small relative to the second radius such as to provide a sufficiently high flow rate under low debit conditions, and independent of the second radius, whereby the inclination of the side wall elements with respect to a horizontal base is fixed at a constant value which is independent of the second radius. This results in the flow profile in the bottom of the pipe being more or less constant and small and independent of the diameter of the pipe or of the pipe's capacity.

Gauging the first radius at a more or less constant and low value, ensures that even at a low supply flow the flow rate will be as high as possible. The second radius of the pipe is gauged depending on the desired capacity. As the inclination of the side wall elements with respect to a horizontal base is fixed at a constant value, the distance between the centre pertaining to the second radius and the centre pertaining to the first radius depends on the second radius determined by the desired capacity.

By this measure a pipe is provided which, as well as being able to realize a sufficiently high flow rate of waste water to be processed under low debit conditions, it has also sufficient capacity to process said waste water without fail under high debit conditions, while in addition affording sufficient storage capacity.

It has been shown that at any debit that may occur in practice, the pipe manufactured according to the invention realizes the highest flow rates so that under all operational conditions the pipe manufactured according to the invention proves to be superior compared with the prior art.

To ensure a stable and controlled installation of the pipe manufactured according to the invention, said pipe should possess an outside wall, a portion of which forms a substantially flat base. As the pipe having such a base can always be positioned quite horizontally, the pipe manufactured according to the invention achieves reproducible performances.

The invention will now be explained in more detail with reference to the drawing which

in Fig. 1 shows a cross section of a pipe manufactured according to the invention;

in Fig. 2 shows schematically the profile of a pipe manufactured according to the invention as well as a round pipe and an egg-shaped pipe in accordance with the prior art;

in Fig. 3 shows a graph of results of the pipe according to the invention for comparison with the prior art pipes shown in Fig. 2; and

in Fig. 4 shows in cross section five pipes manufactured according to the invention having different processing capacities.

Identical reference numbers used in the Figures refer to identical parts.

Fig. 1 shows the pipe manufactured according to the invention generally indicated by reference number 7. Said pipe is suitable for use in a sewage system and is made from concrete and can be coupled with other pipes of the same type for the construction of a sewage system. Said pipe 7 has a seamless inside wall 8 which is characterized in that it possesses rising

side wall elements

9 and 10 which in cross section taper towards the bottom of the pipe. The

side wall elements

9 and 10 merge into one another at the bottom side by means of a curved wall portion 11 whose curve is defined by a first radius. At the top side the

side wall elements

9 and 10 merge into one another by means of a curved wall portion 12 whose curve is defined by a second radius. The second radius 12 is larger than the first radius 11. The second radius 12 determines the maximum discharge and storage capacity, while the first radius 11 is more or less constant, small and independent of the diameter. The objective of said first radius 11 is to keep the flow rate as high as possible at low discharge conditions. The

side wall elements

9 and 10 furthermore, extend in a substantially straight course. The pipe 7 finally, is at the outside provided with a substantially flat base 13.

Fig. 2 shows schematically the profile of the pipe 7 manufactured according to the invention, a pipe 14 having a round cross section, and a pipe 15 having an egg-shaped cross section respectively. The differences between these respective embodiments are clearly recognizable in this Fig. 2.

Fig. 3 shows in a graph how the performance levels of the pipe manufactured according to the invention compare with pipes of the prior art, as schematically shown in Fig. 2.

In the graph of Fig. 3 the results of the pipe manufactured according to the invention are represented by the level square dots.

The graph shows on the X-axis the discharge in litres per second, while the Y-axis shows a measure of the flow rate. In addition to the results of the respective embodiment of the pipe manufactured according to the invention, the graph shows results of pipes according to the prior art which, with regard to capacity, correspond to the pipes manufactured according to the invention, i.e. the results of a pipe with a round cross section are represented by triangular dots, and the results of an egg-shaped pipe are represented by square dots standing on a corner. The graph of Fig. 3 shows clearly that under all conditions the flow rates of the pipe manufactured according to the invention is superior compared with the two pipes of the prior art.

Fig. 4 finally shows in sub-figures 4A-4E the pipe 7 manufactured according to the invention with a from Fig. 4A to Fig. 4E increasing processing capacity. The Figs. 4A-4E clearly show that the first radius 11 has a constant value in each of the Figs. 4A-4E while likewise, the

side wall elements

9 and 10 exhibit a constant inclination in relation to the base 13. The value of the second radius 12 increases from Fig. 4A-4E in correspondence with the increasing processing capacity, and the distance between the centres pertaining to the first and the

second radius

11, 12 increases correspondingly from Fig. 4A to Fig. 4E.

Claims

Method for manufacturing a pipe suitable for use in a sewage system made from concrete and to be coupled with other pipes of the same type for the construction of a sewage system, which pipe is being provided with a seamless inside wall, having rising side wall elements (9, 10) which in a cross-sectional view taper towards the bottom of the pipe and extend in a substantially straight course, which side wall elements merge into one another at the bottom side of the pipe to form a curved wall portion (11) whose curve is defined by a first radius, and which at the top side of the pipe merge into one another to form a curved wall portion (12) whose curve is defined by a second radius, the second radius being larger than the first radius, whereby the first radius is more or less constant and small relative to the second radius such as to provide a sufficiently high flow rate under low debit conditions, and independent of the second radius, and the inclination of the side wall elements with respect to a horizontal base is fixed at a constant value which is independent of the second radius.
Method for manufacturing a pipe according to claim 1, characterized in that said pipe is provided with an outside wall, a portion of which forms a substantially flat base (13).