GB2052362A

GB2052362A - Apparatus for coating the outside surfaces of hollow bodies

Info

Publication number: GB2052362A
Application number: GB8018569A
Authority: GB
Original assignee: Arbed SA
Current assignee: Arcelor Luxembourg SA
Priority date: 1979-06-06
Filing date: 1980-06-06
Publication date: 1981-01-28
Also published as: FR2458737A1; IT8022266A0; DE3019778A1; NL8002863A; IT1130661B; LU81366A1; BE883651A

Abstract

The invention provides a mould for moulding a coating around a body, e.g. a concrete coating around a steel pipe. The mould comprises a base trough formed by elongate members (30) extending side by side between and resting on spaced supports (10) of channel section (11), and a top closure therefor comprising further elongate members (30) extending between and carried by arm members (20) pivoted to the supports (10) for pivoting of the closure between an open position for placing of a tube (0) in the trough and a closed position in which the trough and closure surround the tube (0). The elongate members (e.g. wooden bars) are replaceable and so can be chosen to define any one of a variety of mould cross-sections. Pipes of different sections can thus be coated without the need for a complex adjustable mould or for a series of moulds of different section. <IMAGE>

Description

SPECIFICATION Apparatus fdr coating the outside surfaces of hollow bodies The present invention relates to apparatus for coating the outside surfaces of hollow bodies, in particu larforcoating steel pipes with concrete.

Steel pipes which are laid in the ground or under water are increasingly being provided with concrete sheathings which are of greater or lesser thickness, depending on whether the sheathing seeks to provide mechanical protection, protection from corrosion or a combination of these two actions. Thus for example steel pipes which are about 1 metre in diameter and which are provided for carrying gas under stationary or flowing water are provided with a sheathing of concrete which is 5-12 cm in thickness. The sheathing of concrete is intended to protect the pipe line from corrosion and from pressure and impact loadings; it is also intended to increase the weight of the pipe and to counteract the bouyancy effect which would give rise to the danger of rupture in flowing or moving water.

In accordance with the state of the art, thick layers of concrete may be applied to large-size steel pipes (diameter about 1 metre; length 10-20 metres) by rotatably mounting the individual segments of the pipe and carrying out the coating operation by means of a nozzle which moves along the axis of the pipe, the concrete being applied in successive layers of 6to 10mm in thickness.

In this process, a considerable amount of power has to be applied to rotate the pipe segment, because of the mass of the pipe. It must also be stated that the method involving the application of a plurality of coating layers on the one hand results in the finished coating of concrete having uneven surfaces and on the other hand, which is much more serious, very frequently results in the concrete peeling off the steel substratum due to the lack of homogeneity of the coating.

Attempts have been made to counteract this by incorporating expensive reinforcing means comprising wire into the layer of concrete which was found to be unsatisfactory as a result of the wire projecting out of the surface of the concrete at some positions, and by adding glass fibres to the concrete, which, besides increasing the cost, did not have any substantial effect on the cohesion of the coating.

In order to avoid these problems, it has been proposed that the pipes should be sheathed in vertical moulds, which is unrealistic when dealing with pipe segments which are 10 to 20 metres in length, in view of the moulds required to be employed. Furthermore, a process of this kind would have the result of a considerable difference in pressure between the layers of concrete applied right at the bottom and right at the top in the moulds, and there is no doubt that such pressure difference would result in non-uniform conditions in regard to the quality of the sheathing, from one end of the pipe to the other.

Apparatus according to the invention comprises a substantially stationary mould and is characterised in that a casing which preferably comprises a plurality. of shaped members forms a mould bottom which is of substantially semicircular cross-section and which lies on at least two support means which are independent of each other and which are arranged at a spacing from each other in the form of substantially semicircular support frames, the support frames preferably being provided on both sides with arms which are in the form of segments of a circle and which also have a casing and which can be pivoted up and closed and which in the closed condition define a circular mould with the mould bottom.

The invention also provides a method of moulding a coating over the outer surface of an elongate body (e.g. a tube) which comprises assembling a mould using closure and elongate members selected to provide a mould cross-section corresponding to that of the required coated body, disposing the body along the mould trough and spaced therefrom by the coating thickness, forming over the body a coating of unset coating material defined between the outer surface of the body and the inner surface of the closed mould, and causing or allowing the moulded coating to set.It also provides a mould for accommodating a tube for use in coating the outer surface of the tube, the mould comprising a base trough formed by elongate members extending side by side between and resting on spaced supports of channel section, and a top closure therefor extending between and carried by arm members pivoted to the support sides for pivoting of the closure between an open position for placing of a tube in the trough and a closed position in which the trough and closure surround the tube.

It is extremely expensive to build and maintain fixed moulds which are respectively suitable for coating large-size pipes of different lengths and diameters, while it is both expensive and also technically difficult to produce equipment which would have the flexibility required for coating different pipes.

Instead of providing either a multiplicity of moulds of different size and geometry, or an adjustable mould, the invention uses shaped members of suitable geometry, which can be selected to represent any desired mould bottom when they are properly arranged together on inexpensive support means.

According to the invention, the shaped members may comprise (e.g. substantially square or rectangular section) wooden bars. However, it is also possible to use shaped members of iron or other material.

These bars which are both inexpensive and also easy to produce may be readily cut to the desired length. When dealing with particularly long pipes to be coated, a plurality of series of bars can be arranged together in a lengthwise arrangement, with a support frame which is generally somewhat wide being disposed below the bars at the boundary between two series.

It is generally possible to use unworked commercially available wooden bars which are cut to the same length and which are marked as being associated with each other to form a given mould.

Obviously, a larger number of bars with a small sectional area is betterforforming an approximately circular shape, than a smaller number of bars of larger sectional area. Experience has shown that commercially available bars which are from 6 to 10 cm in width and from 5 to 10cm in height are useful for producing an approximately circular mould with a diameter of for example 124 cm (pipe diameter 1 metre, thickness of coating 12 cm).

A support frame may comprise a steel plate which has a semicircular recess cut therein and which is secured, preferably welded, to a stand for example in the shape of a wide U-shaped support member.

Sheet metal arm members can be secured by means of pivots on respective sides of the recess, and also serve as support means for the closure casing and can be pivoted over.

In order to ensure that the layer of concrete does not adhere to the beams, the latter are covered with a sheet, e.g. of plastics film or special paper.

The apparatus further may have two end support members which are vertically adjustable and which engage the free ends of the pipe to be coated.

Usually, concrete-free regions are left at the ends of the pipe, as the individual pipe segments have to be welded together before the pipe is laid. The support members are fitted at said ends and are so adjusted vertically as to allow for the thickness of the layer of concrete to be applied, in relation to the height of the individual support frames and the elongate mem bers lying thereon.

The apparatus according to the invention has the advantages of being a simple modular system, it is also satisfactory from the point of view of maintenance, as cleaning is restricted to individual elongate elements which can be protected by plastics films.

The elongate closure and elements are preferably interchangeable with others, i.e. removable and replaceable, according to the mould cross-section required.

Further features and advantage will be apparent from the description of the drawings in which Figure 1 shows a view in a cross-section through an apparatus according to the invention, while Figure 2 shows a view in cross-section through a support frame and Figure 3 shows a plan view of the same support frame with some beams. Figure 4 shows a diagrammatic view in a longitudinal section through the entire apparatus.

Figure 1 shows the pipe 0 to be coated which is mounted at a spacing 1 corresponding to the thickness of the coating of concrete, above the bars 30 which rest on the support frames 10. The support frames 10 have a semicircular recess 11 and two side flap members 20 which are secured by means of hinges 21 to the steel plate forming the frame 10.

The individual bars 30 are laid into the recess until the recess is filled up. Awide film or foil 31 is then laid thereon and the concrete pouring operation is effected. During the pouring operation, the concrete is treated at the same time by means of a bar-type vibrator (not shown) which can be conveniently inserted into the intermediate layer 1 and moved backwards and forwards. A vibrator may also be secured to the pipe. After the pouring operation has progressed, the flap members 20 are now also fitted with bars 30 and pivoted over, stop means (not shown) defining the end position of the flap members 20. It will be appreciated that a free region extending in the longitudinal direction of the axis of the pipe is left at the highest point of the pipe 0, for introducing the concrete and inserting the vibrator.

Figure 2 primarily shows the supportframe 10 with the recess 11 and the U-shaped support member 12, while Figure 3 shows the manner in which the adjoining bars 30 are mounted on the frame. At the ends of the pipes the bars are suitablytermin-- ated by means of sheet metal rings which prevent the concrete from flowing out laterally.

Figure 4 shows the apparatus in its entirety. Thd drawing shows the adjustable end support members 40 and the support frames 10 which are independent of the end support members 40 and of each other, with the side flap members 20.

As the entire apparatus according to the invention accordingly comprises individual components which can be simply put together, it may also be easily transported and operated at any desired locations, in conjunction with a concrete producing and pouring apparatus.

Itwill be appreciatedthatwhilstthe method and apparatus according to the invention will commonly be used for coating hollow bodies such as pipes, they are of course applicable whether the body is hollow or not.

Claims

1. A mould for accommodating a tube for use in coating the outer surface of the tube, the mould comprising a base trough formed by elongate members extending side by side between and resting on spaced supports of channel section, and a top closure therefor extending between and carried by arm members pivoted to the support sides for pivoting of the closure between an open position,for placing of a tube in the trough and a closed position in which the trough and closure surround the tube.

2. A mould according to claim 1 which when closed is of substantially circular cross-section:

3. A mould according to claim 1 or 2 wherein the closure comprises elongate members extending side by side between and carried by the arm members.

4. A mould according to any of claims 1 to 3 including a lining sheet extending over the exposed inner face of the trough and closure.

5. A mould according to any of claims 1 to 4 wherein the elongate members are wooden bars.

6. A mould according to any of claims 1 to 4 wherein the elongate members are channel section irons.

7. A mould according to any of claims 1 to 6 wherein the elongate members are removable and replaceable for altering the cross-section of the mould.

8. A mould according to any of claims 1 to 7 wherein the closure is in two parts, one carried on arm members pivoted to one side of the supports, and the other carried by arm members pivoted to the other side of the supports.

9. A method of moulding a coating over the outer surface of an elongate body which comprises assembling a mould according to any of claims 1 to 8 using closure and elongate members selected to provide a mould cross-section corresponding to that of the required coated body, disposing the body along the mould trough and spaced therefrom by the coating thickness, forming over the body a coating of unset coating material defined between the outer surface of the body and the inner surface of the closed mould, and causing or allowing the moulded coating to set.

10. A mould substantially hereinbefore described with reference to the accompanying drawings.

11. A method of coating a pipe, the method being substantially as hereinbefore described with reference to the accompanying drawings.

12. Apparatus for coating the outside surfaces of hollow bodies which comprises a substantially stationary mould in which a casing which preferably comprises a plurality of shaped members forms a mould bottom which is of substantially semicircular cross-section and which lies on at least two support means which are independent of each other and which are arranged at a spacing from each other in the form of substantially semicircular support frames, the support frames are preferably being provided on both sides with arms which are in the form of segments of a circle and which also have a casing and which can be pivoted up and closed and which in the closed condit-on define a circular mould with the mould bottom.

13. Apparatus according to claim 12 characterised in that the shaped members comprise square or rectangular wooden bars.

14. Apparatus according to claim 12 characterised in that the shaped members comprise Ushaped irons.

15. Apparatus according to claims 12, 13 or 14 characterised in that a plurality of series of shaped members are arranged together in a lengthwise arrangement, with a respective support frame which has a generally wider support surface being disposed below the shaped members at the boundary between each two series of shaped members.

16. Apparatus according to any of claims 12 to 15 characterised by a plurality of series of shaped members which are associated together to represent a given cross-sectional shape, the series of shaped members being suitably marked.

17. Apparatus according to any of claims 12 to 16 characterised in that the support frames comprise steel plates which have a semicircular recess cut therein and which are carried by a respective stand in the form of a wide U-shaped support member.

18. Apparatus according to any of claims 12 to 17 characterised in that the shaped members are covered by a plastics film or by special paper.

19. Apparatus according to any of claims 12 to 18 including vertically adjustable support members to engage the ends of the body and which are independent of the support frames.