ZA200505712B - Steel pipe section - Google Patents

Description

. nN ol 2005/05 y 5

STEEL PIPE SECTION

TECHNICAL FIELD:

This invention relates to steel pipes for fluid reticulation and is concerned with socketed steel pipes and dimensioning therefor.

BACKGROUND ART:

It is known to use either steel or plastics pipes for water reticulation, plastic or steel being chosen depending on the intended application and cost of installation. Generally, plastics pipe is used because of its ease of installation, using pipes with integral sockets and elastomeric seals or plastics pipe couplers of varies types. Steel pipes, while having many advantages over plastics pipes, are not widely used, because of the cost of making, fitting and using flanged ends or suitable couplers, and are used only where the application demands the properties of steel pipe. Integral sockets are not common with steel pipe because of the cost of forming the socket either using rolling and hydraulic or explosion techniques.

The use of steel pipe is also inhibited by the fact that conventional pipe steel pipe sizes or diameters are incompatible with plastics pipe, fittings therefor and valves used for water reticulation. This size incompatibility 2s has a historical origin. Steel, cast iron, ceramic, asbestos fibre and other existing fluid conveying pipes have been available for more than a century and thus normally have imperial measurement sizes for the bore of the pipe. The bores of such existing pipes is important, as it determines the capacity or flow rates of such pipes. More recently some metric sizes are used for some square and rectangular section pipes, but such pipes are not used for conveying fluid or used with pipe fittings and thus the sizes may be chosen freely. On the other hand plastics pipe and fittings therefor, which are of more recent technology, has set or fixed, metricated outside diameter sizes based loosely on standard bore sizes of existing 3s pipe and required wall thickness for required performance characteristics,

E the size then being rounded to convenient numbers. Thus plastics pipe has outside diameter sizes of 50, 63, 75, 90, 110, 140, 160, 200, 225, 250 and 315 mm. Of this range 50, 63, 90, 110, 140, 160, 225, and 315 mm outside

C2487EPNS'ENG 18.07.2005 page 2

: : ' ' 2 TN } WO OCs & Uo/7 12 diameter plastics pipe correspond loosely to 1%, 2, 3, 4, 5, 6, 8 and 10 inch existing pipes, with the 75, 200 and 250 mm sizes being added for desired size increments based on flow rate. Incompatibility is evidenced in that the outside diameter of 8 inch steel pipe is about 219.1 mm, which will not easily fit with 200 mm outside diameter plastics pipe.

Thus this invention seeks to provide a steel pipe that can be used more widely and that will be compatible with plastics pipe if required.

DISCLOSURE OF THE INVENTION:

One aspect of the invention provides a steel pipe of round section having a socket formation at one €nd for receiving an end of a similar pipe, the outside diameter of the steel pipe being substantially the same as the outside diameter as that of notionally similarly dimensioned plastics pipes.

Preferably the socket formation is formed from the material of the steel pipe.

Another aspect of the invention provides a fluid reticulation steel pipe of round section having an outside diameter that is substantially the same as the outside diameter as that of notionally similarly dimensioned plastics pipes.

Further features, variants and/or advantages of the invention will emerge from the following non-limiting description of an example of the invention made with reference to the accompanying schematic drawings and from the claims, which are to be regarded as an integral part of this description. so BRIEF DESCRIPTION OF THE DRAWINGS:

Figure 1 shows a longitudinal section through coupled plastics and steel pipes; and

Figure 2 shows a longitudinal section through a series of coupled pipes. 3s DESCRIPTION OF ILLUSTRATED EMBODIMENTS:

In the drawings the same or similar parts have the same reference numbers, certain parts having sub-numbers to identify them as part of a component or as substantially equivalent parts in different embodiments.

C2487EPNS'ENG 18.07.2005 page 3

CEPI

Figure 1 shows a longitudinal section through a steel pipe 10 coupled to a plastics pipe 12 via a widened diameter socket 14 formed integrally on one end of the steel pipe 10. An elastomeric sealing ring 18 is located in an annular groove 20 formed in the socket to prevent fluid leakage when the pipes are coupled. Preferably the sealing ring has an anti-extrusion formation and is of the type disclosed in co-pending South African patent application No 2005/1495. The steel pipe is protected against corrosion by epoxy coating, paint or galvanising as is known in the art.

Figure 2 shows a possible combination of steel and plastics pipes obtainable using the invention.

The wall thickness of the pipes differ in that the plastics pipe ranges from 3 to 38 mm, while steel pipe ranges from 1 to 3 mm thick over the 1s range of outside pipe sizes from 50 to 315 mm. The wall thickness is largely dictated by the intended use and diameter of the pipe.

In accordance with the teachings of this invention, the outside diameter of the steel pipe 10 is made to be substantially the same as the outside diameter of the plastics pipe 12. This is in contrast to conventional teachings which postulate that steel pipe sizes are set according to the bore of the pipe.

Thus using the invention the steel pipes may be coupled spigot and socket fashion to similar steel pipes, as well as plastics to steel pipe and vice versa, and steel pipe to valves and pipe fittings dimensioned for plastics pipes. This enables steel pipe to be used more widely, such as for water reticulation, and to be used in place of plastics pipe where the properties of steel pipe are required. A major benefit of steel over plastics pipe is that smaller outside diameter steel pipe may be used instead of larger outside diameter plastics pipe to achieve the same flow rate or capacity.

Such smaller outside diameter steel pipe are then used with smaller pipe fittings, valves and the like, so that significant cost savings (up to 30%) of pipes and fittings can be achieved on a project.

The invention is not limited to the precise details described above and shown in the drawings. Modifications may be made and other embodiments developed without departing from the scope of the invention as defined in the claims.

C2487EPNS'ENG 18.07.2005 page 4

Claims (9)

a ) y ’ * 4 ” CLAIMS:

1. A steel pipe of round section having a socket formation at one end for receiving an end of a similar pipe, the outside diameter of the steel pipe being substantially the same as the outside diameter as that of notionally similarly dimensioned plastics pipe.

2. A steel pipe as claimed in claim 1, wherein the socket formation has an annular groove for receiving an elastomeric seal.

3. A steel pipe as claimed in claim 2, wherein an elastomeric seal is located in the annular groove of the socket formation.

4. A steel pipe as claimed in any one of claims 1 to 3, wherein the socket formation is formed from the material of the steel pipe.

5. A fluid reticulation steel pipe of round section having an outside diameter that is substantially the same as the outside diameter as that of notionally similarly dimensioned plastics pipe.

6. A fluid reticulation steel pipe as claimed in claim 5, wherein a socket formation is provided at one end of the pipe.

7. A fluid reticulation steel pipe as claimed in claim 6, wherein the socket formation is formed from the material of the steel pipe.

8. - A steel pipe as claimed in any one of the preceding claims, wherein at least one of the inner and outside surfaces of the pipe has a corrosion resistant coating.

9. A steel pipe substantially as herein described with reference to and as illustrated in Figures 1 and 2 of the drawings. » 3s DATE 18 July 2005 a LES FISHER & CO. Applicant's Agents C2487EPNS'ENG 18.07.2005 page 5