Technical Field

The invention relates to a pipe end fitting for mounting on a folded pipe-shaped of plastics, preferably polyethylene.

Background Art

It is known to line a pipe by inserting or placing a pipe-shaped therein, the latter being folded, i.e. compressed in one side, prior to the insertion. As the pipe-shaped is provided with an end fitting in form of a plate at each end, said liner of balloon. When supplying steam to the interior of the pipe-shaped liner, it is heated and unfolds, and when compressed air is supplied, the pipe-shaped liner expands slightly. The steam and the compressed air are supplied to and escapes from the interior of the liner through holes in said plates, said holes usually being made on the site. As a result, plastics chips may accumulate in the pipe-shaped liner and cause the holes to be blocked at a later stage, whereby the steam/compressed air are not able to pass satisfactorily. Making the holes on site is also rather time-consum¬ ing.

Brief Description of the Invention

The object of the invention is to provide a pipe end fitting of the type stated in the introduction ready for use (without initially having to drill holes) and which may be used several times.

The pipe end fitting according to the invention is characterised in that it comprises a plastics plate, preferably of polyethylene, with one or more preformed, through- going holes and a first pipe stub member extending from one side of the plate essentially perpendicular thereto, the cross-section of said pipe stub member having

an outer profile corresponding to the outer profile of the folded pipe-shaped liner, said pipe stub member circumscribing the portion of the plate provided with the hole(s), and a second pipe stub member extending from the other side of the plate essentially perpendicular thereto and having an essentially circular cross-section, said pipe stub member circumscribing the portion of the plate provided with the hole(s). As a result, subsequent to welding the first pipe stub member of the end fitting to the folded liner, the pipe end fitting may be used immediately, as no drilling on the pipe end fitting is required.

The pipe end fitting may be used several times. Subsequent to use, the end fitting is sawed of the pipe-shaped liner on the welding point or close thereto. The pipe end fitting may then be used once again with another liner.

According to the invention, the first pipe stub member may have a wall thickness essentially corresponding to the wall thickness of the pipe-shaped liner and prefer¬ ably by welding, and the second pipe stub member may be connected to a pulling head provided with an eye member, said pulling for instance being formed with an essentially dome-shaped body with at least one small vent, through which hot gas, such as steam, condensed water and compressed air, leaving the liner, may escape. As a result, the pipe end fitting may be pulled (passed) through the eye of the pulling head immediately subsequent to being welded on the pipe-shaped liner, if need be.

Moreover, according to the invention, the pipe end fitting may be intended for pipe- shaped liners having a diameter of 50 to 500 mm, preferably 100 to 400 mm, and most preferred 150 to 30-0 mm. The pipe end fitting have proved particularly advantageous when used for liners of the above dimensions.

Furthermore, according to the invention, the first pipe stub member may have varying wall thickness, and the size and form of the internal cross-sectional area(s) correspond to the size and form of the hole(s) in the plate. As a consequence, a comparatively large amount of plastic material is available for welding of the first

pipe stub member.

According to the invention, the first pipe stub member may have the shape of an essentially solid C, wherein to each of the arms of the C a through-going hole, preferably being kidney-shaped, is provided. This shape of the first pipe stub member has proved particularly practical.

The invention further relates to a pipe-shaped liner being at least at one end provi¬ ded with a pipe end fitting according to the invention, whereby a very reliable way of removing the steam, condensed water, etc. is obtained.

Moreover, said liner may be provided with a pipe end fitting according to the invention at both ends, whereby the folded pipe-shaped liner is ready for supply of steam, compressed air, etc.

Furthermore, the invention relates to a fixing jaws device for mounting a pipe end fitting according to the invention on a pipe-shaped liner by means of welding, said fixing device comprising a first set of fixing jaws and a second set of fixing jaws jointly retaining said liner, and a third set of fixing jaws, in which said pipe end fitting according to the invention may be fixed, the pipe stub member of the latter facing the liner, said set of fixing jaws being parallel displaceable on a frame to such an extent that smoothing tools and plastics welding tools may be inserted between the second and third set of fixing jaws. The fixing jaws device is charac¬ terised in that when the jaws in each set are joined, the first and/or second set of fixing jaws each determine a hole having a form and size corresponding to the outer profile of the cross-section of the folded pipe-shaped liner, preferably a hole with an essentially C-shaped cross-section. In practice, such a fixing jaws device has proved particularly advantageous for mounting the pipe end fitting according to the invention.

Finally, according to the invention, the number of jaws in each set of fixing jaws may be two, and the jaws in the second set of fixing jaws may be of such a thick-

ness, preferably approximately 9-30%, most preferably 15-20%, of the largest dimension of the hole determined by the two co-acting jaws, that they may retain as well as form the end of the pipe-shaped liner in connection with the welding on to the first pipe stub member of the pipe end fitting. As a result, during welding, i.e. while the plastics is comparative soft, the jaws may obtain a particularly well forming grip about one end of said liner and the first pipe stub member of the pipe end fitting, the pipe-shaped liner and the pipe stub member being arranged end to end.

Brief Description of the Drawings.

The invention is explained in detail below with reference to the drawings, in which

Fig. 1 is a front view of an embodiment of the pipe end fitting according to the invention,

Fig. 2 is a side view of the same embodiment,

Fig. 3 is a rear view of the same embodiment,

Fig. 4 illustrates a second embodiment of the pipe end fitting according to the invention provided with a pulling head.

Fig. 5 illustrates a pipe-shaped liner prior mounting of the pipe end fitting according to the invention,

Fig. 6 illustrates the same liner subsequent to mounting of the pipe end fitting,

Fig. 7 illustrates a fixing jaws device according to the invention for mounting the pipe end fitting on a pipe-shaped liner, and

Fig. 8 is a perspective view of a set of fixing jaws, the thickness thereof being evident.

Best Mode for Carrying Out the Invention

The pipe end fitting shown in Figs. 1 and 2 for mounting on a folded liner of plastics is formed of a plastics plate 4 with one or more through-going holes, in the present example two holes 4a, 4b, confer in particular Fig. 2. These holes may for instance by provided by moulding of the pipe end fitting. One side of the plate (in Fig. 2 on the right hand side) a projecting pipe stub member 5 is provided being essentially perpendicular to the plate 4. The cross-section of the pipe stub member 5 has an outer profile corresponding to the outer profile of the folded pipe-shaped liner, confer the reference numeral 12 in Fig. 5. The pipe stub member 5 circum- scribes the portion of the plate 4 provided with the hole (s) 4a, 4b. A second pipe stub member 7 projects from the other side of the plate 4 and has an essentially circular cross-section, said pipe stub member circumscribing the portion the plate provided the hole(s) 4a, 4b. The circular cross-section of the second pipe stub member is shown in particular in Fig. 3.

The first pipe stub member 5 may have a wall thickness essentially corresponding to the wall thickness of the pipe-shaped liner. A pulling head 10 provided with an eye member 13 may be mounted on the second pipe stub member 7 for instance by welding, confer Fig. 4 As can be seen, the pulling head 10 may be formed with essentially dome-shaped portion 15 and an essentially cylindrical portion 11. The portion 11 may have at least one small vent 14, through which hot gas (e.g. steam), condensed water, and compressed air may escape from said folded liner, when the pipe end fitting is mounted thereon. Typically, three vents are provided about the portion 11.

The pipe end fitting may be formed in such a manner that it may be used for pipe- shaped liners having a diameter of 50-500 mm, preferably 100-400 mm, most preferred 150-300 mm.

As shown in Fig .1, the first pipe stub member 5 may have varying wall thick¬ nesses, the wall thickness being t, at one point, and being t ₂ at the end of the

cross-section, where t ₂ is considerably larger than t _j . It should be noted that in the present case the size and shape of the internal cross-sectional area(s) 2a, 2b of the pipe stub member is identical to the size and shape of the hole(s) 4a, 4b in the plate 4. However, this is not imperative. The internal cross-sectional area 2a, 2b is always larger or equal to the internal cross-sectional area of the holes 4a, 4b and is always arranged in such a manner that the internal cross-sectional areas 4a, 4b are within the internal cross-sectional areas 2a, 2b.

As it appears from Fig. 1, the first pipe stub member 5 may have the shape of an essentially solid C, wherein to each of the arms of the C, a through-going hole lc, preferably being kidney-shaped, is provided. This embodiment of the first pipe stub member has proved particularly practical.

Fig. 5 illustrates a pipe-shaped liner 12 and a pipe end fitting 1 prior to assembling. In this embodiment, the pipe end fitting 1 is provided with a plate 4 radially extending considerably beyond the first pipe stub member 5 (this was not the case in Fig. 1). The appearance of the pipe end fitting when mounted on one end of the folded liner 12 is shown in Fig. 6. The second pipe stub member 5, circumscribing the portion of the plate provided with the holes 4a, 4b, is quite visible . On the other end of said liner 12, a plate known per se (not shown) may be mounted (e.g. welded thereon), through which steam and compressed air may be fed into said liner 12. Another option is to mount (e.g. by welding) a pipe end fitting (not shown) according to the invention on the other end of the pipe-shaped liner, (i.e. on the left end of the liner 12), possibly without the parts 11 and 15 shown in Fig. 4, steam and compressed air being fed to said liner 12 through said pipe end fitting.

Fig. 7 illustrates the design of a fixing jaws device for welding of a pipe end fitting on a pipe-shaped liner. The device comprises a first set of fixing jaws 21 and a second set of fixing jaws 22 jointly gripping about and retaining said liner to be mounted with a pipe end fitting. As shown, a third set of fixing jaws 23 is also provided, in which the pipe end fitting may be fixed. In the fixed position of the pipe end fitting, the first pipe stub member thereof faces the liner. The three sets

of fixing jaws 21, 22, 23 is parallel displaceable on a frame 20. Especially, the third set of fixing jaws may be parallel displaceable to such an extent x that in the space between the second set of fixing jaws 22 and the third set of fixing jaws 23, tools for smoothing the end faces to be welded together and necessary plastics welding tools, such as heat reflector, etc. , may be inserted.

As shown in Fig. 8, when joined, the fixing jaws in each set of fixing jaws (i.e. the fist and/or the second set of fixing jaws) determine a hole having a form and size corresponding to the outer profile 16 of the cross-section of the folded pipe-shaped liner 12. The hole is preferably provided with an essentially C-shaped cross-section.

As shown in Fig. 8, the number of fixing jaws in each set of jaws may be of a considerably thickness θ and preferably corresponding to approximately 9-30%, most preferred 15 - 25%, of the largest dimension of the hole determined by the two co-acting jaws, θ is of a such extent that the jaws may retain as well as form said liner 12 in connection with the welding to the first pipe stub member of the pipe end fitting.

The pipe-shaped liner and the pipe end fitting may advantageously be made of polyethylene.

The invention may be modified in many ways without thereby deviating from scope of the invention.