GB2136763A

GB2136763A - A sealing cap for pipes

Info

Publication number: GB2136763A
Application number: GB08407756A
Authority: GB
Inventors: Walter Stucke
Original assignee: Mannesmann AG
Current assignee: Vodafone GmbH
Priority date: 1983-03-25
Filing date: 1984-03-26
Publication date: 1984-09-26
Also published as: FR2545578A1; IT1173601B; GB8407756D0; IT8419742A0; FR2545578B3

Abstract

A sealing cap 1 of synthetic material for the end of a steel pipe to protect the interior surface of the pipe from soiling and corrosion and to permit venting during coating of a string of such capped pipes comprises a plurality of the openings closable fully or to a predetermined extent by an apertured covering member 13 slidable over the openings. As shown, the covering member is guided for rectilinear sliding movement by cap ribs 14 and pin and slot connections 16, 17. Rotatable cams 18 control various positions of the covering member corresponding to full closure, two degrees of partial closure, and full opening, coacting ribs and grooves (32, 33) retaining the covering member in the selected position. In another embodiment, (Figs. 1-4) various sized openings (3, 4) in the cap are selectively all or individually closed by an apertured rotary covering member (2) retainable in the desired position by a member extension (22) co-operating with respective ends of opposed spaced ramps (23, 24, 25). <IMAGE>

Description

SPECIFICATION Caps for pipes, made of synthetic material The invention relates to caps of synthetic material which are fitted to the ends of pipes. Such caps are useful in the sheathing of steel pipes with thermoplastic synthetic material using for example the tube extrusion method, where caps on the pipe ends are used to join successive pipe lengths in a line, thereby enabling such lengths of pipe to be sheathed in a continuous coating operation.

During cleaning of the pipe surface by for example a blasting method, before coating, the pipes ends should be sealed so as to be dust-tight. This is a primary purpose that the end caps used are designed to fulfil. The caps may also be used to couple pipe lengths axially together. In such applications caps are designed to interlock with each other in such a manner as to ensure alignment.

Coating processes normally cause an increase in the temperature of the air enclosed in the pipe and possibly to the intrusion of humidity. Sufficiently large ventilation holes in the synthetic material caps make possible an equalization of pressure between coupled pipe lengths, thereby minimizing or preventing the inclusion of air between the pipe surface and the coating in the region of the joint between contiguous pipes. The ventilation holes should though, only be so large that the interior space of the pipes is sealed, on sheathing, to such an extent that the reduced pressure, produced for the tight application of the tubular sheathing onto the outer surface of the pipe, between sheathing and pipe, is largely maintained.After separation of the sheathed, but still warm pipes the pipe ends should be able to be sealed so as to be watertight, to enable additional cleaning of the individual pipes with pressure water following the cooling in the pipe string.

During storage of the sheathed pipes the caps serve to protect the interior of the pipe from the intrusion of dirt and humidity, and from corrosion.

They also serve to maintain a sufficient evacuation of air. Any ventilation of the pipes during storage should be restricted by the caps to such an extent that a fixed atmosphere is largely retained in the interior of the pipe, which ensures the operability of the inhibitor substance.

In German Patent Specification No: 2728498 sealing caps are disclosed which are suitable as coupling elements, and which have openings on the cap bases covered by surfaces constructed in the manner of tongues. The inner side of the cap bases have an inhibitor substance for protection against corrosion. In a particularembodimentthetwo sealing caps interlocking with each other are of equal shape. The dust-tight seal of the pipes during the cleaning process is achieved in that the cap bases do not initially have any opening, when they are placed onto the pipe ends. Only after the cleaning are the openings made. The cap base is divided through; e.g., at points marked by corresponding weakenings in the wall, and is opened by folding backthetongue-like piece which is thus produced.

A disadvantage of the above design is that the opening of the ventilation holes is a hindrance in the production sequence. The maximum size of the ventilation holes is determined by the given shape, but how large the openings in fact are depends on the position in each case of the tongue-like pieces which is not predetermined. Thus, it is not guaranteed that the ventilation holes are opened sufficiently wide during the coating process, and that during storage they are sufficiently tightly closed. To protect against the intrusion of rain into the pipes it has indeed been proposed to cover an opening obliquely above by an additional surface projecting in the manner of a tonque from the base of the cap.

However, a complete screening is not achieved by this, because the rain-water can penetrate into the pipe through the lateral openings of the ventilation hole, particularly in sealing caps which have a position in which the bent edge of the tongue of the ventilation hole deviates more sharply from the horizontal direction.

In order to open the ventilation holes in the simplest possible manner and to assure their effective size, the openings may be burnt into the cap base with a branding iron after cleaning of the pipes.

Problems however occur during additional cooling of the coated and already re-separated pipes with pressure water and for the storage of the coated pipes, with regard to the intrusion of humidity of volatility of the inhibitor atmosphere, because the holes cannot be sealed again.

The invention is therefore directed at the problem of providing on sealing caps of the type described ventilation holes in the cap base which can be completely closed in the production sequence simply and quickly; i.e., without the use of special tools, and can be opened as wide as necessary. Furthermore, the invention is concerned with the establishment of sufficient ventilation during storage, without inviting intrusion of rain-water or deterioration of the inhibitor atmosphere in the interior of the pipe.

A sealing cap acording to the present invention is couplable to another similar cap to connect two pipe lengths in a string and comprises a base with openings therein for passage of air to and from the pipe interior, and at least one covering member slidable over the openings to close same. Both rotational and linear sliding of the covering member is specifically described herein.

The invention will now be described by way of example and with reference to the accompanying drawings wherein: Figure 1 shows in plan view a portion of the base of a sealing cap according to the invention with a disc-shaped covering member; Figure 2 shows a section through the sealing cap of Figure 1 in a secured initial position of the covering member; Figure 3 shows a section through two wedgeshaped elevations on the base of the sealing cap to fix the covering member of Figure 1; Figure4shows a section through the covering member of Figure 1; Figure 5 shows in plan view a portion of the base of another sealing cap in accordance with the invention with ventilation openings which are adjustable by rotatable cam discs; and Figure 6shows a section through the sealing cap of Figure 5.

As can be seen from Figure 1,the base of the sealing cap 1 has two circular cut-outs 3, 3' for the ventilation of the pipe during the coating process.

Their size, together, amounts to approximately 5% of the area of the pipe cross-section. A further cut-out 4, which is necessary for the ventilation of the pipe during storage of the pipe, has a size of approximately 0.5% of the area of the pipe cross-section.

The disc-shaped covering member 2 is held rotatably by an annular guide rail 6 projecting over the rim of the disc and by a centering plug 31. The covering member has on its side facing the base of the sealing cap 1, in the vicinity of its rim, an annular groove 26 (Figure 1), into which engages a corresponding annular bulge 26a (Figure 2) on the base of the sealing cap 1. Its position (position a) is clearly fixed by the bracket 22 (Figure 2) which is firmly connected therewith, the free end of which is engaged into the interstice (Figure 2) formed by two wedge-shaped elevations 23, 23'. In the position drawn, which is held in the phase of the pipe cleaning, the cutouts 3,3',4 are completely closed by the covering member 2, so that no dirt penetrates into the pipe.

After the cleaning process, the covering member 2 is rotated by a simple manipulation into a second position, which is clearly preset by the detention position b of the bracket 22 between the wedgeshaped elevations 24,24'. In this position the two circular openings 5,5' in the covering member 2 lie concentrically over the cutouts 3,3' in the base of the sealing cap 1, so that there is ventilation of the pipe.

In the embodiment illustrated, the openings 5,5' are larger than the cutouts 3,3'. The purpose of this is that the same covering members 2 can also be used with sealing caps 1 which are provided for larger pipes and therefore require larger ventilation openings.

In order that, if required, the already coated pipes can be further cooled with pressure water after they have been separated, without humidity penetrating into the pipes, the ventilation openings 3,3' can be completely closed again by rotation of the covering member 2 into position a.

During the storage of the coated pipes it is necessary to protect the interior of the pipe from the penetration of dirt and humidity and to ensure the minimum ventilation necessary owing to fluctuations in temperature. For this, the covering member 2 is rotated by a further manipulation into the position pre-set by the detention position c of the bracket 22 between the wedge-shaped elevations 25,25'. In this position the two cutouts 3,3' are again completely covered; instead of this, the cutout 4 which takes up approximately 0.5% of the area of the cross-section of the pipe, is exposed by the opening 5 of the covering member 2 lying concentrically above.

At the same time, the cutouts 7,8, of equal size, in the base of the sealing cap 1 or in the covering member 2 become superimposed. A securing plug 9 is introduced through the cutouts 7,8 and is engaged therein, so that a rotation of the covering member 2 is no longer possible. To further secure the originality of this setting, the head 10 of the securing plug 9 is closely surrounded by a sleeve-like superelevation 11 on the covering member 2, whereby a subsequent removal of the securing plug 9 is prevented.

To preclude the penetration of pouring rain through the opening 4, the cutout 5 is screened externally by a tube-like extension 21. The screening effect is independent of whether the cutout 5, in relation to the bearing position of the sealing cap is situated, at random, above, below or to the side. In addition, through the overlapping guiding rail 6 a very good protection exists against the penetration of water running down the cap base.

In order to ensure an even better seal between the base of the sealing cap 1 and the covering member 2, particularly in the detention positions a and c, it may be expedient to provide the side walls of the groove 26 and the edges of the cutouts 5,5',8 and the cutout for the centering plug 31 in the covering member 2 on the side facing the base of the sealing cap 1 with an elastic sealing material 27,27',28,29,29' or 30 (eg. rubber, polyamide).

Owing to the simple opening and closing of the sealing caps 1 a further possibility is produced for usage. Through the openings 3,3', after the pipe coating has been completed, heat-transmitting media can be introduced into the pipe and enclosed there, in order to obtain a heating of the pipe or to maintain this over a longer period of time, which is necessary, for example, for the hardening of a pipe coating with a thermosetting layer component.

Figures 5 and 6 show the invention in another form of embodiment. Here, in the base of the sealing cap 1 rectangular openings 12 are arranged parallel, adjacent to each other. These may be completely closed by means of a strip-shaped covering member 13, which has the same number of rectangular openings 15 of at least the same size as in the base of the sealing cap 1. The openings 12 and 15, which may also have a different shape (eg. oblong hole, oval), have in each case the same centre-to-centre distance between them. The cross-pieces remaining between two adjacent openings 12 are wider than the openings 12 and 13. The covering member 13 is slidable parallel in guiding rails 14,14'. Through two oblong holes 16,16' arranged in longitudinal direction of the covering member 13, two securing plugs 17,17' are passed, which are connected, locked in place, with the base of the sealing cap 1, and which hold the covering member 13. On the side facing the base of the sealing cap 1 the covering member 13 has a bulge 32 running around the zone of the openings 15 in the manner of a rectangle and parallel to its side lengths.

By rotation of two cam discs 18,18' of equal shape which in each case touch the sides of the covering member 13 lying vertically to the guiding rails 14,14', the covering member 13 can be brought into 3 defined positions in relation to the openings 12, in which the bulge 32 in each case locks into a corresponding groove 33, which runs around in a rectangular shape, in the base of the sealing cap 1.

In a first position a, for cleaning the pipe the openings 12, as drawn in Figure 5, are completely closed by the cross-pieces between the openings 15 of the covering member 13. In a second position b, for the actual coating, the openings 12 (approximately 5% of the cross-section area of the pipe) are fully exposed by the openings 15 lying above them. For the storage of the pipes, finally, a position c is set, in which the openings 12 are covered by the crosspieces of the covering member lying between the openings 15 up to a remainder, which corresponds to approximately 0.5% of the area of the crosssection of the pipe. To secure this setting, the grip ridges 19,19' which are required for the rotation of the cam discs 18,18', are broken off by bending at a predetermined breaking point 19,19' (weakening of wall thickness) at the foot of the grip ridges 20,20'.A securing in original position would also be possible by means of a securing plug as in Figure 2.

Furthermore, the securing plugs 17,17' could be dispensed with if the covering member 13 is held for example by rails 14,14' which project over the edges of the covering body.

Since depending on the position of the covering member 13 to the cutouts 12 between the extreme values which are predetermined in terms of construction technology, ventilation openings of any chosen size may be used, the same combination of cutouts 12 and covering member 13 may be used in sealing caps 1 for pipes of different diameter, in which the opening widths can be adapted in each case optimally to the pipe diameter by cam discs 18,18' modified accordingly.

In the case of sealing caps for pipes with smaller diameters, the arrangement of the proposed sealing mechanism on the base of the sealing cap 1 can cause difficulties for reasons of space. In this case it may be advantageous to make use of the invention idea such that the ventilation holes are moved into the superficies of the sealing caps 1 and the sealing mechanism is modified accordingly.

Claims

1. A sealing cap of synthetic material for the ends of pipes, which cap is couplable to another similar cap to connect two pipe lengths in a string and comprises a base with openings therein for passage of air to and from the pipe interior, and at least one covering member slidable over the openings to close same.

2. A sealing cap according to Claim 1 including a securing mechanism for locking said at last one covering member in at least one orientation with respect to the base.

3. A sealing cap according to Claim 1 or Claim 2 wherein the base is formed with at least two openings of different size and wherein the covering member takes the form of a disc having itself at least one opening at least as large as the largest of the openings in the base, the covering member being rotatable to bring one or more of the openings respectively in the base and covering member into registration.

4. A sealing cap according to Claim 3 including an annular guiding rail on the base having a lip which projects over the edge of the disc.

5. A sealing cap according to Claim 3 or Claim 4 wherein one of the contact surfaces of the covering member and the base has an annular bulge for sealing the gap therebetween.

6. A sealing cap according to Claim 5 wherein the bulge engages in a corresponding annular groove in the opposite contact surface.

7. A sealing cap according to Claim 6 wherein the side walls of the groove are formed from an elastic sealing material and wherein the edges of any opening on the covering member on the side facing the base, is surrounded by an elastic sealing material.

8. A sealing cap according to any of Claims 3 to 7 wherein the covering member is fixable in defined positions by a bracket connected with and extending radially from the rim of the disc, the outer end of which reaches the base, which said positions are defined by the location of the end of the bracket in the interstice formed between two wedge-shaped elevations of respective pairs on the base.

9. A sealing cap according to any of Claims 3 to 8 including a rim around said at least one opening in the covering member, the height of which is smaller than half the distance between the covering members of two coupled sealing caps.

10. A sealing cap according to any preceding Claim including a securing plug engaged in congruent apertures in the covering member and base to secure a given relative orientation thereof, the installed plug having a head which is closely surrounded by sleeve-like elevation from the base of substantially the same height.

11. A sealing cap according to Claim 1 or Claim 2 wherein the openings in the base are arranged in a line and spaced from one another by distances greater than the dimension of the opening along the line, and wherein the covering member is a rectangular strip slidable in guiding rails parallel to the line of arrangement of the base openings, the covering member having openings corresponding to the base openings, whereby the covering member can be slid to locate the interstices between its openings at least partially over the base openings, the covering member being secured to the base by plugs passing through at least two oblong holes in the covering member and aligned parallel to the guiding rails.

12. A sealing cap according to Claim 11 including cam discs mounted on the base adjacent the ends of the covering member for adjusting the position of the covering member.

13. A sealing cap according to Claim 11 or Claim 12 wherein the covering member has a bulge extending between the guide rails adjacent eitherend thereof, and wherein the base member is formed with a plurality of grooves which bulge in each case engages in a corresponding groove in the base, a plurality of grooves at each end of the rails defining the range of predeterminable orientations of the covering member with respect to the base.

14. A sealing cap according to Claim 11 or Claim 12 wherein each cam disc has a grip ridge, the foot line of which has a weakened wall as predetermined breaking point.

15. A sealing cap according to any preceding Claim wherein the covering member is selectively locatable in at least three positions relative to the base, in the first of which the base openings are completely closed; the second open area constitutes substantially 5% of the pipe cross-section area; and in the third position the open area constitutes substantially 0.5% of the pipe cross-section area.

16. A sealing cap according to any preceding Claim including a corrosion inhibitor substance on the inner side of the base.

17. A sealing cap of synthetic material substantially as described herein with reference to Figures 1 to 4 or Figures 5 and 6 of the accompanying drawings.