DE8812596U1 - Fitting for re-insulating a branch point of district heating pipes - Google Patents

Description

Description

The innovation relates to a shaped part according to the preamble of claim 1.

From the German patent application P 37 35 228.8, an arrangement for re-insulating a branch of a district heating line, which is made in particular by the so-called tapping technique, is known. In this case, a plastic molded piece is pushed onto the branch line to be connected, which, after completion of the connection of the

and is connected in a fluid-tight manner to the jacket of the district heating line and the jacket of the branching line. The fitting is a plastic pipe, into one end of which a plastic disc with a passage for the branching line is welded and into the other end of which a plastic sleeve is welded. In one embodiment, the sleeve is provided with a plastic saddle piece, which is welded onto the outer jacket of the district heating line. In another embodiment, a band is welded to the sleeve, which is placed around the district heating line and welded in the area of its band edges.

The plastic molded part is a complicated component that can only be manufactured by hand using laborious labor. Another disadvantage of this

known arrangement is that both metal welding and plastic welding must be carried out at the assembly site, which experience has shown requires various skilled workers.

The aim of the present innovation is to further develop the known arrangement in such a way that the molded part can be assembled from commercially available components and that plastic welding at the assembly point is dispensable.

This problem is solved by what is covered by the characterising part of claim 1.

Further advantageous embodiments of the innovation are covered in the subclaims.

The innovation is explained in more detail using the embodiments shown schematically in Figures 1 and 2.

Figure 1 shows a perspective view of an arrangement according to the teaching of the innovation.

Here, 1 designates a district heating pipe, which consists of a medium-carrying inner pipe 2 made of steel, a thermal insulation layer 3 made of polyurethane foam and an outer jacket 4 made of polyethylene.

The branch line 5 can be constructed in the same way, whereby the dimensions of the components 2 to 4 are correspondingly smaller.

However, the branching line 5 is preferably designed as a flexible line, i.e. the inner pipe 2 is a corrugated stainless steel pipe, the insulating layer 3 is a

flexible polyurethane foam and the outer casing 4 is designed as a corrugated steel pipe on which a plastic casing sits. Between the corrugated steel pipe and the plastic casing there is a bitumen-based corrosion protection layer.

The medium-carrying inner pipe 2 is connected to the inner pipe 5 of the branching line 5 via a branch line section not shown in the figure. As will be explained in more detail later

&rgr; are the ones used for the purpose of welding

The inner pipe sections, which have been freed from insulation material, are surrounded by I plastic mouldings, which are

■■ Inner pipe sections form a gap that

'■-. is then filled with polyurethane foam. The

» Seams of the plastic molded parts and the annular gaps between

the plastic molded parts and the jacket of the district heating pipe 1 and the branch pipe 5 are [' with a shrink tube 6 or around the

I branch line and district heating line 1

!; wrapped shrink bands 7 and 8 sealed. The

* Shrink articles 6, 7 and 8 have on their inner

], surface a sealing compound which at shrink temperature

I becomes plastic and fills all the cavities. The

I Shrink bands 7 and 8 are provided with overlapping band edges

I as indicated at 9 and 10, wrapped around, and the

' Overlap areas 9 and 10 are each marked with a

I Adhesive strips 11 and 12 are covered, which during the shrinking process

* to hold the band edge areas 9 and 10 in position.

Passage openings 13 and 14 are cut into the shrink bands 7 and 8, which allow the passage of the branching parts of the molded parts.

The arrangement shown is permanently sealed against moisture penetration, since all the joints and annular gaps are covered by the shrink articles 6, 7 and 8.

Figure 2 shows a section through the branch point. A branch line section 15 is welded onto the inner pipe 2, which is welded to the inner pipe 2 of the branching line 5 as shown at 16 and to the inner pipe 2 of the district heating line 1 as indicated at 16a. The free end of the branch line section 15 is closed as shown at 17, so that the inner pipe 2 of the district heating line 1 is tightly connected to the inner pipe 2 of the branching line 5.

The plastic piece required for the foam filling consists of two plastic T-pieces 18 and 19, which are commercially available as prefabricated components or are easily manufactured by welding.

Each plastic molded part 18 and 19 consists of a T-beam 20 and 21 and a branch pipe 22 and 23, whereby the inner diameter of the T-beam 20 before assembly is larger than the outer diameter of the district heating pipe and the inner diameter of the T-beam 21 is larger than the outer diameter of the branch pipe 22. Before the plastic molded part 18 is applied to the district heating pipe 1, the T-beam 20 is slit lengthwise and slipped onto the district heating pipe 1. The edges of the longitudinal slit are placed on top of one another and the inner diameter of the T-beam 20 is reduced by means of tensioning straps (not shown) until the two ends rest on the casing 4 of the district heating pipe 1. The overlapping band edges are then drilled through in at least two places and a plastic plug 24 is welded into each hole.

The plastic T-piece 19 rests with the end of the branch pipe 23 on the outer casing of the branching line 5 and with its T-bar 21 surrounds the branch pipe 22 as well as a plastic cap 25 inserted into the opposite end.

The T-beam 21 is also slotted so that it can be guided around the branch line section 15. Using tensioning straps (not shown), the T-beam 21 is clamped with overlapping band edges on the branch pipe 22 and the plastic cap 25, the overlapping band edges are drilled through, and the plastic plugs 26 and 27 are welded into the holes.

The molded part consisting of the plastic T-pieces 18 and 19 is still surrounded by the shrink bands 7 and 8.

The production of the arrangement shown proceeds as follows:

After the jacket 4 and the insulating layer 3 have been removed from the district heating line 1 at the point intended for the branch, the branch line section 5 is welded onto the inner pipe 2.

The plastic T-piece 18 is then slit lengthwise in the area of its T-beam 20, slipped over the district heating line 1 and secured to the plastic casing of the district heating line 1 using tensioning straps so that the branch pipe 22 runs concentrically to the branch pipe piece 15. The overlapping band edges of the T-beam 20 are drilled through in two places and the plastic plugs 24 are welded in using mirror welding.

After removing the clamping straps, the plastic T-piece 19 is pushed onto the branching pipe 5. So that the end of the inner pipe 2 of the branching pipe 5 exposed from the insulating material can be welded at 16, the plastic T-piece 19 has a through-opening (not shown) in the area of the T-beam 21, from which the end of the inner pipe 2 of the branching pipe 5 protrudes.

After the weld seam 16 has been produced, as is known per se, the area of the inner pipe 2 of the district heating line 1 surrounded by the interior of the branch line section 15 is drilled through and, after drilling through the plug 17, is welded to the branch line section 15 in a fluid-tight manner. This work, i.e. welding on the branch line section 15, drilling through the inner pipe 2 and sealing with the plug 17, can be carried out without the district heating line 1 having to be taken out of service, but is only applicable to smooth-walled pipes, i.e. non-corrugated pipes.

After checking the tightness of the weld seams, the T-beam 21 is slit lengthwise and placed around the branch line section 15 so that the branch pipe 22 is enclosed. After the plastic cap 25 has been inserted, the T-beam 21 is clamped onto the branch pipe 22 and the plastic cap 25 using tensioning bands (not shown) to form overlapping band edge areas, the overlapping seam is drilled through and the plastic plugs 26 and 27 are welded in as described above.

After this work, a plastic molded part is available, mechanically assembled from the two T-pieces 19 and 20, which can serve as a mold for the foam. However, since the interior of the plastic molded part is not fluid-tight to the outside, sealing must still be carried out. For this purpose, a heat-shrinkable band 8 is provided with an almost circular cutout 14 and this cutout is connected to a longitudinal edge in a known manner by a cut (not shown) in the shrinking direction of the band 8. The band 8 is then placed around the T-beam 20, with the ends of the band 8 projecting beyond the T-beam 20 on both sides. The cutout 14 accommodates the branch pipe 22. When placing the band 8 around, care must be taken that the longitudinal edges of the band S

overlap each other. A plastic strip 12 is then placed over the overlapping strip edges over the entire length, the surface of which is coated with a hot-melt adhesive facing the strip 8. During shrinking, the plastic strip 12 is first heated and the hot-melt adhesive layer is activated. The plastic strip 12 now holds the strip edge area in position. The strip 8 is then heated over its entire surface until it has shrunk down to the plastic casing 4 or the T-beam 20. During shrinking, the sealing compound on the inner surface of the strip 8 becomes plastic and penetrates into any cavities that may be present and seals them. This work seals the annular gaps between the T-beams 20 and the casing 4 of the district heating line, the longitudinal slot of the T-beam 20 and the cutout 14.

In the same way, the band 7 with a cutout 13 is placed around the T-beam 21, provided with the plastic strip 11 and shrunk. After the shrink tube 6 has shrunk, although a shrinking band can also be used instead, the arrangement is sealed to the outside.

A pressure test is then carried out and a foamable plastic mixture based on polyurethane is filled into an opening 28 in the plastic cap 25 and the opening 28 is closed, for example by means of a welded-in plastic plug (not shown). If foam comes out of the opening 29 in the plastic cap 25, it can be assumed that the cavity is completely filled with foam.

The main advantage of the arrangement according to the invention is that a fairly complex component can be created at the assembly site using relatively simple components, which does not require any craftsmanship.

is required. The shrinking technique is a technique that has been used in district heating pipeline construction for many years and is considered safe.

Claims (2)

Patent claims 1. Moulded piece for re-insulating a branch point of district heating lines, in which a branch line piece is welded to the inner pipe of a district heating line exposed by the insulating layer, to which the inner pipe of the branching line is welded, and in which the branch point is surrounded by a plastic moulded piece, which is connected at the end to the jacket of the district heating line and the jacket of the branch line in a pressure-tight manner and the space between the inner pipes and the branch line piece and the moulded piece is filled with foam, characterized in that the moulded piece consists of two moulded parts (18, 19) designed essentially as T-pieces with T-beams (20, 21) and branch pipe (22, 23), the T-beams (20, 21) of which are slotted in the longitudinal direction, wherein one moulded part (13) with its T-beam (20) surrounds the district heating line (1) and its branch pipe (22) surrounds the branch pipe section (15) at a distance from it and the other moulded part (19) with its T-bar (21) envelops the branch pipe section (15) at a distance from it and rests with one end on the branch pipe (22) of the other moulded part (18) and with its other end on a plastic cap inserted into the end (25) and its branch pipe (23) surrounds the inner pipe (2) of the branching line (5) at a distance from it and that each molded part (18, 19) is surrounded in the area of its T-beam (20, 21) by a heat-recovered band (7, 8) made of plastic, which is located at the end on the jacket (4) of the district heating line (1) or on the branch pipe (22) and the plastic cap (25) and wherein the respective branch pipe (22,23) is guided through an opening (13,14) in the bands (7,8) and the overlapping longitudinal edges of the heat-recovered band (7,8) are covered by an adhesive strip (11,12). 2. Arrangement according to claim 1, characterized in that the longitudinal slot in the T-beam (20, 21) of the respective molded part (18, 19) is designed to overlap and the overlapping strip edges are connected by at least two plastic plugs (17, 26, 27) passed through bores in the strip edges, the peripheral surface of which is welded to the bores of the overlapping strip edges.