WO2004092638A1

WO2004092638A1 - Expansion device

Info

Publication number: WO2004092638A1
Application number: PCT/DK2004/000270
Authority: WO
Inventors: Rolf Rasmussen
Original assignee: Belman Production A/S
Priority date: 2003-04-15
Filing date: 2004-04-15
Publication date: 2004-10-28

Abstract

An expansion device (1) suitable for fitting in pipelines for compensating for axial, relative rotational and/or lateral movements in a pipeline, wherein the device (1) has an internal passage in an axial direction, and that the device (1) in the axial direction has a first and second end and that in each end of the device fastening means are provided for fastening the device (1) to a pipe end, and that the interior wall of the internal passage has a bellows structure (5) comprising corrugations having crests and troughs, wherein the troughs has a cylindrical section (M).

Description

EXPANSION DEVICE

Field of the Invention

The present invention relates to an expansion device suitable for fitting in pipelines for compensating for axial, relative rotational and/or lateral movements in a pipeline. These types of devices are usually used to protect a pipeline system from damaging expansions in the pipe system due to differences in temperature which may arise in a production plant facility.

The present invention is especially suitable in installations where the requirements to the hygienic standard and, consequently, the ability to clean the pipelines is very high.

Description of the related Art

In the art, devices which take up the expansion in pipelines have been known as expansion bend pipes (Tako-bend), bellows pipes, slip pipes and the like are examples of this type of devices. The latter two of these examples, bellows pipes and slip pipes, are special in that the distance between the connecting surfaces at the ends of a connecting passage such as a flange can be very small.

One problem especially with the bellows pipe type device is that when fluid including particles, bacteria or the like travel inside the bellow, impurities and other settlements will be caught in the groves of the bellows making it substantially impossible for the bellow to perform its primary role, which is to expand and subtract in response to the movement of the pipe section and, in severe cases, it might even lead to breakage of the bellow. Furthermore, the sedimented particles being bacteria or other impurities cannot be flushed out during normal cleaning procedures of the bellows pipe type device due to the corrugated nature of the interior wall of the bellows. It is hereby impossible to obtain a hygienic standard suitable for e.g. food, drug and biotech industries.

Also, in other types of expansion devices known from the art, for example where two pipes are arranged coaxially, one inside the other, and thereby allowing for an expansion, respectively contraction, the seal which is usually fitted between the two moving pipe sections also give rise to the collection of impurities which can contaminate the fluids which are supposed to be transported in the internal passage of the expansion device.

One such prior art device is known from GB 1109900 wherein a S-shaped compensation device is described. The device has a corrugated structure comprising crests and troughs. In order to relieve tension and stresses arising due to compensation movements of the device, resilient material is placed in each trough and crest. Although lessening the tension, this device is very difficult to manufacture due to the adhesion of different materials under severe conditions to which such devices are exposed, and furthermore the device is not developed for longitudinal expansion, but is designed to absorb dimension changes as a bending of the S-shape. Although the cylindrical sections in the troughs has a cylindrical section, due to the resiliency this is not the case in the use situation where buckling of the section due to thermal expansion will create a non cylindrical section, such that keeping the hygienic standard as required is not possible.

Another example of a prior art device is illustrated in DE471118 wherein a pipe section having a wall thickness corresponding to the desired height between crest and trough is worked such that the crests and troughs are formed by removing material.

Hereby is created a rather stiff expansion member with limited movement, and furthermore due to the removal of material whereby thin walls are created, a costly process requiring precision working and an elevated risk of faults is required. The number of corrugations and thereby the relative depth of each trough in relation to the length makes it very difficult to effectively clean this type of device, and on the other hand, as the material is comparatively stiff, rather deep troughs and a substantial number of these are required in order for the device to be able to absorb the expansion in use.

The present invention therefore aims at solving these problems by providing an expan- sion device which is especially hygienic and easy to clean and thereby provides for the maintenance of the quality of the fluids to be transported through the interior passage in such an expansion device, and at the same time is very flexible such that it may absorb expansive and retractive movements in the pipe system. Summary of the Invention

In order to achieve the above mentioned objects of the invention, the present invention provides an expansion device suitable for fitting in pipelines for compensating for axial, relative, rotational and/or lateral movements in a pipeline, where said expansion device has an internal passage in an axial direction, and that the device in the axial direction has a first and second end and that in each end of the device fastening means are provided for fastening the device to a pipe end, and that the interior wall of the internal passage has a bellows structure, comprising corrugations having crests and troughs, wherein the troughs has a cylindrical section (M_y).

The provision of a cylindrical section between two corrugations allows for the cleaning process to effectively flush out any contaminants or other sediments which would otherwise accumulate at the bottom of the troughs in the corrugated structure. Furthermore, due to the hydraulic flow in such a pipe system comprising a bellows having cylindrical sections between the corrugations it is avoided that dead zones in the bellows structure are created. By dead zones is meant areas in the bellows structure where the liquid/fluid has a velocity approaching zero whereby sedimentation could occur.

The corrugations are necessary in order for the device to be able to expand and con- tract due to influences from the pipeline system.

In order to protect the corrugations surrounding the internal passage, a further preferred embodiment of the invention provides that the fastening means in the first end is connected to a first tubular member, and that the fastening means in the second op- posite end is connected to a second tubular member, and further that a jacket is provided which jacket coaxially surrounds the first and second tubular members on at least a section of the tubular members, and further that the bellows structure is arranged and fastened coaxially inside the first and second tubular members.

In this manner, the expanding/contracting bellows structure is protected by two coaxially arranged tubular members such that any mechanical, or chemical for that matter, impact or influence on the device is absorbed, deflected or in any other way taken care of by the tubular members such that the bellows structure hereby is protected from external influences. Also, the entire structure is more cleaning friendly.

In a further advantageous embodiment the jacket is fastened to the first or second tu- bular member and opposite to the fastening of the jacket, the jacket is provided with a flexible seal between the jacket and the tubular member. Hereby is achieved that a firmer structure is provided such that the jacket will remain in a substantially fixed position relative to at least one tubular member such that the other tubular member will move telescopically in relation to the jacket. By further providing the flexible seal between the jacket and the moving tubular member, it is achieved that foreign matter, dust, liquid and other contaminants will not be able to enter into the expansion device which could thereby hinder the proper functioning of this device. Also, the protecting and sealed nature of this expansion device construction in this embodiment provides a cleaning friendly structure.

In a still further preferred embodiment of the device the combined length of the first and second tubular members in the axial direction is less than the distance between the two fastening means arranged in opposite ends of the device thereby creating a gab between the first and second tubular members.

This embodiment is especially advantageous in that it provides for the tubular members to be in closer proximity to the bellows structure along the entire internal passage. Hereby is achieved that the support for the bellows structure is improved. If the tubular member, as is the case in other embodiments, overlap, i.e. that the tubular members are coaxially arranged, the bellows structure will be closely supported on a part of the internal passage, namely that part which is adjacent the tubular member which is inside of the coaxially arranged tubular members, whereas the part of the bellow structure which is supposed to be supported by the other tubular member will have a lesser support in that a space may necessarily be provided between the bellows structure and tubular member for accommodating the coaxially arranged tubular member.

By providing the gab, the tubular members can be arranged at the same distance in relation to the bellows structure and thereby the internal passage such that a substan- tially uniform support for the bellows structure is provided along the entire internal passage. The size of the gab and thereby the length of the two tubular members in relation to the distance between the two fastening means arranged at opposite ends of the device shall be designed such that movements in the pipeline system should not cause the two tubular members to close the gab and thereby created tension in the pipeline systems which might lead to breakage, bending or other undesired effects in the entire pipeline system.

By having knowledge of the length of the pipes and the material of the pipes being connected to the expansion device, it is possible to calculated and thereby design the size of the gab such that it will be avoided that the gab will be closed due to expansion in the pipeline system. This is common knowledge to the person skilled in the art knowing the thermal expansion coefficients of the materials in question. In practise, however, the expansion device is manufactured in one or more standard sizes such that a certain standard device can be selected for a certain purpose according to the use, the size of the pipeline, length of the pipes being connected, etc.

In a further advantageous embodiment of the invention the construction is such that a cylindrical section between two corrugations arranged coaxially inside and superposed with the gab between the tubular members, has a length corresponding to at least twice the length of the gab at the intended use temperature for the expansion device. In this manner it can be effectively avoided that the corrugation during use becomes stuck or jammed between the two adjacent edges of the tubular members such that when the expansion device contracts, damage could occur to the bellows structure. Furthermore, in order to allow for a certain movement, the length of the gab and thereby the length of the corresponding cylindrical section of the bellows structure should be substantially larger than the production size of the gab.

As these types of devices are used in many different applications, they should be able to compensate for relative movements in the pipes being connected to the expansion device. These movements can be axial, i.e. in the flow direction of the liquid, steam or vapour passing through the interior passage of the device, or they can be lateral movements which is movements substantially perpendicular to the axis of the device that is that is perpendicular to the intended flow direction of the liquid through the expansion device or they can be rotational movements where one pipe section connected to the device is slightly angled with respect to the pipe section being connected at the opposite end of the device. Furthermore, combinations of these movements, which for ex- ample can arise in the shape of vibrations or shock waves in the system, extreme temperature gradients or other factors must also be accommodated by the device.

In a further advantageous embodiment especially suitable for compensating for relative rotational movements or combination movements, the expansion device is con- structed such that the fastening means in opposite ends are connected by a resilient member coaxially surrounding the bellows structure. The bellows structure is by nature a relatively flexible structure in that the corrugations of the bellow allow for a large degree of movement, especially in the axial direction. In the other directions differential movements are also allowed by the corrugations, but in the embodiment of the invention described above, the less flexible/substantially rigid tubular members and jackets, which otherwise provide a good support and protection for the bellows structure and thereby improve the integrity of the entire device, have some shortcomings when it comes to relative rotational movements of the pipe ends as well as lateral movements. For this purpose a resilient member coaxially surrounding the bellows structure is provided. As the bellows structure performs in response to the movements of the pipe ends connected to the fastenings means in both ends of the device, the resilient member will conform to this movement and provide the necessary support for the bellow structure in order to absorb the influences transferred to the expansion device. In this manner the expansion device is both provided with a very flexible con- struction and at the same time, due to the structure of the bellows, i.e. corrugations of alternating troughs and crests, it is still very hygienic friendly in that the ability to clean the structure in comparison to prior art devices is vastly improved.

In further preferred embodiments of the invention the expansion device can be manu- factured to any suitable pipe size. In a preferred embodiment the interior diameter (Dj) of the pipe connection means is 5 mm to 500 mm preferably 25 mm to 400 mm, and the distance "w" from trough to crest of the bellows structure perpendicular to the axial direction of the device is 0 mm to 25 mm and that the cylindrical section (M_y) be- tween two corrugations in the axial direction of the device is 0 mm to 50 mm more preferably 2 mm to 45 mm.

By the geometrical relationships described above a range of expansion devices can be manufactured for different purposes. For high temperature applications or where the pipe system shall be able to work with fluids having large differences in temperature, it is advantageous to have a very flexible bellows structure which will be able to expand and contract over a long distance. For this purpose it is advantageous to have a "W" as large as possible with due respect to the requirement of being able to clean the expansion device. Also, by being able to fit more corrugations inside the device per unit length gives the device an extra ability to expand. Therefore, it will be advantageous that the cylindrical section M_y between two corrugations is as small as possible. In other applications for other liquids or fluid materials, other relationships will be advantageous. For example with fluids having a high viscosity, i.e. fluid that are not very free flowing, W should be smaller and the length of the cylindrical section should be longer.

In a still further advantageous embodiment of the invention the bellows structure is made from a corrugated metal material such as steel, stainless steel, copper, alumin- ium, titanium or a polymer based material, and that the bending radiuses for shaping the corrugations and/or cylindrical sections is between 1 mm and 25 mm preferably between 3 mm and 15 mm.

The choice of material obviously limits the freedom in shaping the material in that by for example using steel materials and having too sharp bending radiuses, the number of movements of the expansion device over time will destroy the material in the bends, for example where a corrugation is formed.

Furthermore, also in order to create a flow of liquid, steam or vapour through the inte- rior passage such that the resistance against flow during normal operation is minimized and the cleaning effect of the cleansing fluid during the cleaning operation is maximised. Tests have, therefore, shown that the above mentioned bending radiuses provide for relatively sharp bends, long service life, minimized flow resistance and maximised cleaning possibilities.

In a further advantageous embodiment, resilient rings are arranged on the outside of the bellows structure in the corrugations, but inside either the first and second tubular members or inside the resilient member coaxially surrounding the bellows structure.

There resilient rings, which are often made from nylon, rubber or another resilient polymer based material, serve the purpose of distributing the forces evenly between the corrugations such that no single corrugation will be activated during expansion/contraction, but that the entire movement, due to the provision of these rings, will be distributed to substantially all corrugations.

The movement could otherwise be absorbed by one corrugation due to tolerances in the material thickness, unevenness in the material, stiffness, etc. Due to the provision of these rings, once a corrugation begins to contract due to expansion in the pipe system, the corrugation will meet the resistance of the resilient ring, whereby the force will be absorbed in a neighbouring corrugation until an even force distribution has been achieved in all the corrugations comprised in the bellows structure.

In this manner the forces acting on the bellow structure will be substantially distributed to all corrugations and thereby the tension in a single corrugation will be minimized and thereby the life expectancy of a bellows structure of this nature incorporated in an expansion device will be substantially prolonged.

Although the expansion device as described above has been designed in order to, among other thing, to improve the effective service life of the device, it will eventually be worn down and will need to be replaced.

In most installations it is difficult to predict when replacement or breakage takes place.

Traditionally, the replacement of these expansion devices is carried out as a compromise between the risk of having a breakdown, whereby the entire production facility needs to be shut down for a period of time, often with high costs involved, and costs involved with replacing the devices regardless of whether or not they are worn out or not.

In order to improve the predictability and the registration of when a device is worn down, a drainage and/or control means is provided, such that the means is in connection with the space between the outside of the bellows structure and the inside of the surrounding structure, i.e. the tubular members or the coaxially surrounding resilient member, and the outside of the expansion device.

By these means it is possible to detect the first slight leakage in the bellows structure such that, unless the leakage happens dramatically, the expansion device can be replaced at the most opportune time after the leakage is detected.

By furthermore providing the possibility of drainage of the space between the bellows structure and the inside of the surrounding structure, the production process in the installation comprising an expansion device according to the invention can be carried on for a period of time only with the additional loss of the material being drained off.

In one advantageous embodiment of this control means, the means is in the shape of an electronic moisture detector or the combined drainage and control means is a fluid connection in the shape of a pipe socket means.

When the control means is in the shape of an electronic moisture detector it is possible to hook up each and every expansion device in a complex installation such that from the central monitoring station also the status of the expansion devices can be monitored. Furthermore, an alarm system can be connected to such an electronic moisture detector, such that the personnel monitoring and servicing the installation quickly can identify the expansion device in question and replace the device at the first opportunity.

By having the drainage and control means in a combined unit as for example a pipe socket piece connected to the exterior tubular members, it is possible to detect by simple means that fluid is being drained of the installation. This indicates that there is a leakage in the bellows structure such that liquid being transported through the interior passage into the device is leaking through the expansion device and out into the space between the outside of the bellows structure and the inside of the tubular members. This a very simple and effective way of detecting that leakage is occurring and that immediate replacement or maintenance should be planned. It is advantageous to have leakage detection means in that expansion devices of this type often are integrated in rather complex constructions and not always are easily accessible, whereby inspection, maintenance and replacement may be cumbersome tasks.

Although the bellow has been described as a unitary as a unitary structure above, it may in fact comprise a layered structure, where the layers may be of the same material or each layer may be a different material. Using a layered construction, i.e. each distinct layer is arranged coaxially in/outside another layer, provides a number of advantages. A construction comprising a metal layer, a polymer layer and a metal layer where the thickness and choice of material is selected for the specific purpose, the material characteristics can be utilised such that a better expansion/contraction characteristic of the device can be achieved for the specific purpose. Also, for large or particularly small (narrow) devices the weight, strength and flexibility of the device can be designed to an optimum by using/selecting the appropriate materials.

Brief Description of the Drawing

The invention will now be described with reference to the accompanying drawing, but it should in this context be mentioned that the detailed embodiments of the invention described with reference to the figures should not be construed as limiting the inven- tion, but the invention should only be limited by the appending claims.

Fig. 1 illustrates a first embodiment of the device according to the invention, fig. 2 illustrates a second embodiment according to the invention, and fig. 3 illustrates different configurations of the bellows structure.

Detailed Description of the Drawings

In fig. 1 is illustrated a device 1 according to the invention. In opposite ends of the expansion device 1 , connections means in the shape of flanges 2,3 are provided. These flanges can, typically, be suitable for bolt connections to the adjoining pipe system or be welding flanges. Within the context of the present invention the exact configuration of these flanges is not important, as long as it is provided that a fluid tight and force transmitting connection is provided between the expansion device 1 and the adjoining pipe system.

Both in fig. 1 and in fig. 2 the upper part of the figure is a cut-away section exposing the interior of the device and the bottom half of each figure depicts the outside configuration.

Inside the internal passage 4 is provided a bellows structure comprising a number of corrugations 5, each corrugation comprising a crest 6 and a trough 7. Between each corrugation a cylindrical section M_y is provided (see fig. 3). Surrounding the bellows sections and connected to respective flanges 2,3 are two tubular members 8,9. Coaxi- ally arranged around these two tubular members 8,9 is a jacket 10. In the illustrated example the jacket 10 is fastened to the tubular member 9, for example by a weld 11. In order to render the connection between the jacket 10 and the tubular member 8 substantially air and fluid tight, a seal 12 is provided between the jacket and the tubular member.

In the illustrated example the connection means in the shape of flanges 2,3 are connected to the tubular members by welds 13,14.

When the expansion device according to the invention as illustrated in fig. 1 is built into a pipe system, expansions and contraction in the adjoining pipe system will be transferred to the expansion device via the flanges 2,3 and the tubular members 8,9. As the bellows structure is fastened to both tubular members 8,9, the expansion/contraction force deriving from the adjoining pipe system will push or pull the two connection means 2,3 towards, respectively apart, from each other whereby the bellows structure will be elongated or compressed. In order to accommodate this movement a gap 15 is provided between the tubular members. In the bellow structure superposed inside the gab, the cylindrical section between two corrugations is prolonged such that relative movement of the two tubular sections 8,9 will be accommo- dated by narrowing, respectively widening, the gab 15 by sliding the tubular member 8 in relation to the tubular member 9 and the jacket 10. The prolonged cylindrical section 18 eliminates the risk of a corrugation being squeezed or jammed in the gab between the two tubular members.

In order to detect leakage which can indicate that the expansion device needs to be replaced, a leakage detection and control means 16 is provided. In the illustrated example the drainage socket 16 is superposed with the gab such that any leak deriving from the internal passage 4 can flow in the space between the bellows structure and the tubular members 8,9 into the gab 15 and thereby arrive at the drainage socket 16 for easy detection of a leakage.

Furthermore, the expansion device is provided with resilient rings 17 arranged in each corrugation on the outside of the bellow structure. These rings serve to distribute the forces transmitted to the expansion device from the adjoining pipe structure due to expansions/contractions in that adjoining pipe structure. When the expansion device is activated by expansion/contraction in the pipe system, the softest corrugation 5 will be activated first. As the corrugation for example is squeezed due to expansion in the pipe system, the resilient ring placed on the outside of said corrugation will build up resistance, whereby the once softest corrugation will not necessarily be the softest any longer, but another corrugation in the bellows structure will be activated until this corrugation has been compressed sufficiently such that the material of the corrugation and the respective resilient ring 17 will provide sufficient resistance such that the movement will be absorbed in a third corrugation, etc. In this manner the forces being trans- mitted to the expansion device can, substantially, be evenly transferred to every corrugation in the device. Hereby is achieved that an even force distribution will even out the wear and tear on the device whereby the life expectancy of the device can be maximised.

Turning to fig. 2 a device according to the invention is disclosed which in addition to being able to absorb forces in the axial direction also will be able to compensate for lateral movements as well as rotational movements. The bellows structure comprising corrugations 5 having crests 6 and troughs 7 is substantially identical to the structure depicted in fig. 1. Instead of the tubular members a resilient member 19 is coaxially arranged around the bellow structure and connected to both fastening means 2,3 arranged at respective ends of the device.

Due to the construction of the bellows structure having crests and troughs it is relatively flexible and will be able to accommodate angular displacement arising from rotation of one fastenings means 2 in relation to the other fastening means 3. These angular displacements can derive from vibration in the adjoining pipe system, connected vessels, equipment or machines, accumulated tolerances when installing the pipe system, unforeseen expansion in the adjoining pipe system creating non-axial expansion forces being transferred to the expansion device 1 or erroneous construction of the pipe system. The coaxially arranged resilience member 19, although being flexible, also provides the necessary support for the bellow structure to be able to maintain its expansion function.

In table 1 is listed different geometric parameters which all, depending on the pipe system into which the expansion device is incorporated, provide the advantages, i.e. absorption of expansion and ease and security of cleaning and thereby improving the hygienic standard of the products conveyed inside the pipe system by reducing the contamination danger.

Table 1

In fig. 3 are illustrated the different geometrical parameters listed in table 1.

For most applications the expansion device will be manufactured in stainless steel in that, especially in the food production process, it is very important to achieve the hygienic standard which this device makes possible. It should, however, also be noted that the device can be made in any suitable material which will be able to expand and retract sufficiently without breaking. Among these materials are polymers, fibre reinforced polymers and other modified polymer materials. The embodiment of the invention described with reference to fig. 2 does comprise a coaxially arranged resilient/flexible member. This member can advantageously be made from a reinforced polymer material.

Claims

1. An expansion device suitable for fitting in pipelines for compensating for axial, relative rotational and/or lateral movements in a pipeline, wherein the device has an internal passage in an axial direction, and that the device in the axial direction has a first and second end and that in each end of the device fastening means are provided for fastening the device to a pipe end, and that the interior wall of the internal passage has a bellows structure, comprising corrugations having crests and troughs, wherein the troughs has a cylindrical section (M_y).

2. Expansion device according to claim 1, wherein the crest has a cylindrical section

(M,).

3. Expansion device according to claim 1 or 2, wherein the fastening means in the first end is connected to a first tubular member, and that the fastening means in the second opposite end is connected to a second tubular member, and further that a jacket is provided which jacket coaxially surrounds the first and second tubular members on at least a section of the tubular members, and further that the bellows structure is arranged and fastened coaxially inside the first and second tubular members.

4. Expansion device according to claim 1, 2 or 3, wherein the jacket is fastened to the first or second tubular member and opposite to the fastening of the jacket, the jacket is provided with a flexible seal between the jacket and the tubular member.

5. Expansion device according to any preceding claim, wherein the combined length of the first and second tubular members in the axial direction is less than the distance between the two fastening means arranged in opposite ends of the device thereby creating a gab between the first and second tubular members.

6. Expansion device according to claim 5, wherein a cylindrical section between two corrugations arranged coaxially inside and superposed with the gab between the tubu- lar members, has a length corresponding to at least twice the length of the gab at the intended use temperature for the expansion device.

7. Expansion device according to any preceding claim, wherein the fastening means in opposite ends are connected by a resilient member coaxially surrounding the bellows structure.

8. Expansion device according to any preceding claim wherein the interior diameter (Dj) of the pipe connection means is 5 mm to 500 mm preferably 25 mm to 400 mm, and that the distance "w" from trough to crest of the bellows structure perpendicular to the axial direction of the device is 0 mm to 25 mm and that the cylindrical section (M_y) between two corrugations in the axial direction of the device is 0 mm to 50 mm more preferably 2 mm to 45 mm.

9. Expansion device according to any preceding claim wherein the bellows structure is made from a corrugated metal material such as steel, stainless steel, copper, aluminium, titanium or a polymer based material, and that the bending radiuses for shaping the corrugations and or cylindrical sections is between 1 mm and 25 mm preferably between 3 mm and 15 mm.

10. Expansion device according to any preceding claim wherein resilient rings are arranged on the outside of the bellows structure in the corrugations, but inside either the first and second tubular members or inside the resilient member coaxially surrounding the bellows structure.

11. Expansion device according to any preceding claim wherein a drainage and/or control means is provided, such that the means is in connection with the space between the outside of the bellows structure and the inside of the surrounding structure, i.e. the tubular members or the coaxially surrounding resilient member, and the outside of the expansion device.

12. Expansion device according to claim wherein the control means is an electronic moisture detector or the combined drainage and control means is a fluid connection in the shape of a pipe socket piece.