CZ1597A3 - Flexible piping intended for burying and process for producing thereof - Google Patents

Abstract

Gas pipe extenders to compensate for movements in ground-laid gas supply pipes caused by mining operations have been found to leak owing to their construction or have been inadequately extendible or capable of insufficient lateral movement. Greater axial extendibility and lateral movement are obtained with the aid of a metal bellows (1) and a corrosion-protection jacket (2) wound from strips and penetrating into the corrugation interstices (3) of the metal bellows. For use in supply pipes likely to be shifted by building operations and especially mining or earth tremors.

Description

A corrosion-proof tape is wound around the corrugated pipe or bellows (20) on the one hand, and on the other hand in the form of a helical screw-like element with the overlap of the individual threads, and then the corrugated pipe is stretched and wound. or the bellows (20) axially compresses and shortens to the desired length.

(54) Title of the invention:

Flexible pipelines for laying in the ground and method of its production (57)

The flexible conduit for connecting buried pipes, in particular gas pipes in the ground penetration areas, consists of a metal corrugated pipe or bellows (20) provided with connecting elements (21) at both ends and a corrosion protective sheath (22) after along the length of the corrugated pipe or bellows (20) and along part of the connecting elements (21). The corrosion protective sheath is formed from belts or a belt assembly (2), follows the wave peaks (6) and submerges so deeply into the interspaces (3) between the waves that the protective sheath takes the shape of a pleated bellows (2) and o The cylindrical shape (5) assumes the nominal value. On the portions of the fasteners (21) covered by the belt assembly (22) and at least on the first wave peaks (6), a rubber-metal connection means and a corrugated pipe or bellows (20) are applied together with the fasteners (21) connected to the corrugated pipe. or a bellows (20) extends axially so as to increase the spacing of the vertices (6) to form larger interspaces (7), and then onto the elongated corrugated pipe or bellows (20) starting from app.

Flexible piping for laying in the ground and method of its production

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a flexible conduit for connecting rigid ground buried distribution conduits comprising a metal corrugated pipe or bellows provided with connecting elements at both ends, and a corrosion protective sleeve extending over the entire length of the corrugated pipe or bellows. parts of connecting elements.

BACKGROUND OF THE INVENTION

In mine areas, the surface of the earth sinks and the earth surface cracks and pressures. As a result, there are displacements, stretches and upsetting of the distribution pipes that are buried in the ground. If compensating elements are not built into these pipelines to compensate for these movements, these pipelines are often damaged. Gas pipelines are potentially particularly dangerous, as leakage of gas from the pipeline can result in a gas-air mixture that is flammable.

The newly installed low pressure manifolds with nominal diameters of up to approximately 150 mm are mostly plastic. Existing distribution pipelines for longer periods and newly laid pipelines with a ground clearance of more than 150 mm and for higher pressures are usually made of steel.

Steel pipes are usually provided with a plastic corrosion protection layer. DE-OS 39 37 956, DE 28 53 726 and DE-OS 37 02 693 disclose gland compensators which essentially consist of inner and outer tubes which are telescopically displaceable relative to one another.

The gas leakage seal consists of an elastomeric seal or a packing gland. A substantial disadvantage of the compensating element with the seal becomes apparent when the compensating element is incorporated one or more times. The seal then ceases to seal. The gas then escapes into the surroundings and threatens the surroundings.

Greater danger arises from leakage of gas that flows along the pipeline and may, under certain circumstances, penetrate into a building that is connected to the pipeline.

A further disadvantage of the compensating element with the seals is that it gives little or no possibility of retaining lateral or angular movements. If lateral forces occur during pipe operation, leakage should be considered.

The known structures of the aforementioned compensating elements comprise two flanges which must be tightened together to achieve compression of the seal. Taking into account that the compensating element must be insulated for corrosion protection, all components that protrude from the cylindrical shape are disturbing.

From the standpoint of insulation, it is further disadvantageous that all the stretching of the compensating element takes place only at the point where the inner tube is introduced into the outer tube.

A sheath must therefore be produced which must handle the entire stroke at the point of introduction. Consequently . in this case, a good and cost-effective solution cannot be achieved.

Corrugated pipes, corrugated hoses and compensators are known to compensate for movements in steel pipes. They are made of stainless steel and are characterized by excellent flexibility. They do not need any seals. For corrugated pipes up to 100 mm in diameter, corrugated hoses are preferably used. The following solutions are known in the hose industry:

DE 25 58 478 discloses a corrugated hose with sleeves at both ends, which is provided with a shrink hose sleeve for corrosion protection. The corrugated metal hose inside is well suited to compensate for longitudinal, transverse and angular movements. However, the shrink tubing sheath has only limited elongation. The shrink hoses consist of thin-walled polyethylene hoses with radial cross-linking and a pre-expanded diameter which, upon heating, shrink to a diameter prior to expansion.

The axial elongation of polyethylene shrink tubing, which is suitable for grounding on corrugated hoses, does not reach the elongation value of the stainless steel corrugated hose when adjacent to the corrugated hose.

DE 97 46 08 describes a coiled metal hose with a polyvinyl chloride sheath. Problems with axial elongation are the same.

DE-OS 37 02 676 further describes a corrugated hose braided with a shrink hose. Due to the braid, no axial extension is possible.

Sheathing of metal corrugated hoses by the application of dense liquid bitumen is also known. After the bitumen mass has cooled down, only a slight elongation of such a hose is possible.

An important step to increase the axial elongation was the introduction of the corrosion protection tape to be wound onto the corrugated bodies.

A multi-layered corrosion-proof tape consisting of rubber and polyethylene layers is wound onto the corrugated hose. The rubber layers of the tape are welded together. However, these rubber layers are able to allow the threads of the corrosion protection tape to slide over each other without affecting the tightness. The winding allows the longitudinal extensibility of such a corrosion protective jacket in the longitudinal direction to be greater than that of the polyethylene material in the corrosion protective tape itself.

Thanks to the tape described, the expansion in the ground has also made progress with compensators with stainless steel bellows. The tape has so far been wound smoothly with the overlap of the individual threads. G94 04 814.2 describes the possibility of achieving axial elongation by means of an extended sheath of corrosion protection tapes which is separated from the corrugated surface of the pipe or hose to be protected.

Since the axial elongation is the most important parameter in compensators and the existing sheathing did not achieve the axial elongation of the metal bellows, it is necessary to find a sheath construction with higher elongation.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a stainless steel bellows compensator for ground-based gaseous and liquid media manifolds having higher axial ductility than prior art solutions, side movements and corrosion protection for bellows and connection points. . Another object is to achieve cost-effective production of such a structure.

SUMMARY OF THE INVENTION

This problem solves and the deficiencies of the known flexible conduits largely eliminate flexible conduits for connecting buried pipes, especially gas pipes in areas of ground fall, which consists of a metal corrugated pipe or bellows provided with connecting elements at both ends and a corrosion protective jacket which extends along the entire length of the corrugated pipe or bellows and part of the connecting elements according to the invention, which consists in that the corrosion protection jacket is made of strips or strips, following the peaks of the waves and immersed so deeply into the interstices between the waves According to the invention, the protective jacket takes the form of a pleated bellows and, when the elastic element is pulled by the nominal value, the protective jacket takes a cylindrical shape.

The strip is preferably a multi-layered corrosion protection strip consisting of at least one rubber layer and a polyethylene layer.

It is also advantageous that the belt assembly consists of a rubber belt and one or more two-layer belts consisting of a rubber layer and a polyeltylene layer.

The rubber layers are cold-welded when rolled up and can be permanently plastically deformed.

Preferably, the width of the strip is greater than the spacing between the wave peaks and the width of the strip and the overlap width are selected such that at maximum permissible elongation of the resilient element the protective sheath remains tight and the shear force exerted in the rubber layer during elongation is slightly less tear force. carrier layers. The corrugated pipe or bellows is suitable for large stroke movements and is preferably protected against bulging by one or more inner guide tubes.

Said guide tubes are preferably mounted in the connecting elements so that angular movement of the guide tubes relative to the longitudinal axis of the connecting elements is possible.

The connection elements are preferably so long that the assembly is not damaged by the welding heat when connecting the flexible pipe to the pipe.

The invention also relates to a method for producing a flexible bellows-like cladding according to the invention, characterized in that a means for connecting the rubber to the metal and a corrugated pipe or bellows together are applied to the parts of the connecting elements covered by the belt system. with the connecting elements connected to the corrugated pipe or bellows extending axially so as to increase the mutual spacing of the wave tops and create larger interstices, and then to the elongated corrugated pipe or bellows starting from the connecting element on one side, this corrugated pipe or bellows and A corrosion protection tape is wound on the other side of the helical connector on the other side of the individual threads, whereupon the stretched and wound corrugated pipe or bellows is axially compressed and shortened to the desired length.

The inherent stiffness of the polyethylene backing layer in the tape prevents the tape from adapting to the shape of the folded bellows during winding. A method is used to bend the web somewhat into the interstices between the bellows waves. Using narrow strips would cause them to fall into these interspaces. Roller winding tools cannot be used quite well because the belt surface is very sticky and therefore the belt adheres to the rollers.

In order to achieve the necessary partial bending of the tape into the interspaces between the waves, a certain manufacturing process is used according to the invention. This procedure consists of the following steps:

1. stretching the bellows

2. winding the tape

3. bellows tamping

As a result of this production method, the sheathing takes the form of a folded bellows. Axial elongation is compensated by the corrugated casing, similar to the metal bellows itself. Maximum axial elongation is due to the profiling of the bellows-shaped casing

Větší significantly greater than the ductility of the material itself.

A particular advantage of such an embodiment of the jacket is that the permissible extension of the jacket is increased to correspond to the permissible extension of the corrugated pipe or bellows.

Full immersion of the sheath into the interstices between the waves is neither necessary nor expedient. When laying in the ground, it must be taken into account that the compensator surroundings will deteriorate over time. The sheath completely embedded in the corrugated pipe or bellows would then have the disadvantage that the interstices between the waves would be completely filled with sand, preventing movement when the compensator is shortened axially.

When the sheath is partially submerged in said interspaces, the volume of sand in these interspaces between the waves is considerably smaller and this sand can also move slightly outwards and inwards as the waves approach each other, so that, as experiments have shown, only a thin layer remains.

According to the invention, therefore, a particularly advantageous use is made of a combination of the ductility of the spiral wound tape with the ductility of the sheath which is applied in the shape of a bellows.

By fully extending the elastic member, both elongation possibilities, i.e. both sliding of the rubber layers and movement within the folded bellows, are utilized, thereby achieving greater axial elongation of the elastic member than in the prior art solutions.

The web should be at least as wide as the corrugations of the corrugated pipe or bellows relative to each other to prevent the web from falling into the interspaces between the waves.

The elongation of the sheath also depends on the width of the overlap or the overlap of the threads of the sheath. If the overlap is small, only a short slideway is available and the wrap is soon opened or opened. If the overlap is large, a significant elongation and finally tearing of the belt support layer occurs before a noticeable slip is achieved.

The width of the belt and the width b for the overlap or overlap should be chosen primarily

1. that the cladding remains tight at the maximum elongation of the elastic member

2. that the shear forces occurring when the elastic element is drawn in the rubber layer are slightly less than the force required to tear the backing layer.

The optimal width b for the overlap or overlap can be determined experimentally or, if material parameters are available, can be calculated as follows:

^ k is shear stress at creep of rubber layer dt is tear stress of the support layer st is the thickness of the support layer

For equilibrium of forces in axial direction, * bk * d = dt * st * d from which it can be deduced that bk = dt * st / 't

From the above requirement the condition bk <ït * st / 77k

It is particularly advantageous if, according to the invention, the maximum elasticity of the band wrapping is utilized.

Furthermore, it is advantageous that by using a corrugated pipe or bellows which is provided with a pleated bellows according to the invention, due to the bearing of the jacket on the wave tops, a distribution of the overall elongation of the flexible pipe is achieved. section.

A particular advantage of the solution according to the invention is also the fact that the tape can be wrapped in a bellows of any diameter. The nominal diameters considered start at approximately 50 mm and end at 1600 mm. The advantage in manufacturing is also the low cost of maintaining the packaging material, i.e., the tape, in stock, and the fact that the sheathing material is readily available, which in addition brings greater availability of the flexible element at the customer.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further elucidated with reference to the accompanying drawings, in which:

- in FIG. 1, a corrugated metal bellows,

FIG. 2 shows a section of an expanded metal bellows,

- a three-layer strip wound on one another in FIG.

FIG. 4 shows a two-layer structure, and

FIG. 5 shows a flexible pipe with a corrugated pipe or bellows.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a corrugated metal bellows 1 between the peaks 6, the waves of which extend into the interspaces 3 between the waves, the corrosion protective sheath 2.

FIG. 2 shows a section of an expanded metal bellows 4 with enlarged interspaces 7 between the waves and a wound corrosion protective sheath 5.

In Fig. 3, a three-layer tape 10 with a width of 15, with a polyethylene backing layer 9 and rubber layers 8, is wound with overlap 16.

FIG. 4 shows a two-layer structure which consists of a rubber layer 14 and a two-layer tape 11 arranged above it, which consists of an outwardly disposed polyethylene backing layer 12 and an inwardly disposed rubber layer 13.

FIG. 5 shows a flexible conduit with a corrugated pipe or bellows 20 by connecting elements 21, inner guide tubes 12 and a flexible sheath 22.

Represented by:

Ing.J.Chlustina

03.01.97 i2- & y

- 11 of 02173/96-GB

PATENT CLAIMS

Claims (10)

1. Flexible conduit for connecting buried pipes, in particular gas pipes in ground-penetration areas, consisting of a metal corrugated pipe or bellows provided with connecting elements at both ends and a corrosion protection sleeve running along the entire length of the corrugated pipe or bellows and along the part of the connecting elements, characterized in that the corrosion protective sheath is formed from the strips or the strip assembly (2), follows the peaks (6) of the waves and delves into the interspaces (3) between the waves so deep that the protective sheath obtains the shape of the folded bellows (2) and the cylindrical shape (5) assumes the protective sheath when the elastic element is pulled by the nominal value. Flexible pipe according to claim 1, characterized in that the strip (2) is formed by a multi-layered corrosion protection strip (10) consisting of at least one rubber layer (8) and a polyethylene layer (9). Flexible pipe according to claim 1, characterized in that the belt assembly consists of a rubber band (14) and one or more two-layered bands (11), consisting of a rubber layer (13) and a polyethylene layer (12). Flexible pipe according to claims 2a3, characterized in that the rubber layers (8, 13, 14) are cold-welded during winding and can be permanently plastically deformed. Flexible pipe according to claims 1 to 4, characterized in that the strip width (15) is greater than the spacing between the wave peaks (6) and that the strip width (15) and the overlap width (16) are selected such that When the elastic element is allowed to stretch, the protective sheath remains tight and the shear force occurring in the rubber layer upon elongation is slightly less force to tear the backing layer. Flexible pipe according to claim 1, characterized in that the corrugated pipe or bellows (1, 20) is suitable for large stroke movements. Flexible pipe according to claim 1, characterized in that the corrugated pipe or bellows (1, 20) is protected against bulging by one or more inner guide pipes (12). Flexible pipe according to claim 7, characterized in that the guide tubes (12) are fastened in the connecting elements (21) such that angular movement of the guide tubes (12) relative to the longitudinal axis of the connecting elements (21) is possible. Flexible pipe according to claim 1, characterized in that the connecting elements (21) are so long that the assembly (22) is not damaged by welding heat when connecting the flexible pipe to the pipe. Method for producing a pleated bellows-shaped flexible sheath according to any one of claims 1 to 9, characterized in that means for applying the parts of the connecting elements (21) covered by the belt system (22) and at least on the first wave peaks (6) are applied. the connection of the rubber to the metal and the corrugated pipe or bellows (20) together with the connecting elements (21) connected to the corrugated pipe or bellows (20) extends axially so that the spacing of the wave peaks (6) is increased and larger interspaces (7) then on the elongated corrugated pipe or bellows (20) starting from the connecting element (21) on one side, to the corrugated pipe or bellows (20) and up to the connecting element (21) on the other side in the form of a helical overlap wind the corrosion protection tape, whereupon the stretched and wound corrugated pipe or bellows (20) is axially compressed and shortened to the desired length. Represented by: Ing.J.Chlustina 03.01.97 1/1