GB2038472A - Pipe assembly and method for its manufacture - Google Patents
Pipe assembly and method for its manufacture Download PDFInfo
- Publication number
- GB2038472A GB2038472A GB7943371A GB7943371A GB2038472A GB 2038472 A GB2038472 A GB 2038472A GB 7943371 A GB7943371 A GB 7943371A GB 7943371 A GB7943371 A GB 7943371A GB 2038472 A GB2038472 A GB 2038472A
- Authority
- GB
- United Kingdom
- Prior art keywords
- pipe
- bending
- shaped
- bent
- outer pipe
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 title claims description 5
- 238000005452 bending Methods 0.000 claims abstract description 27
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 abstract description 3
- 239000011796 hollow space material Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 239000002826 coolant Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000007665 sagging Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D7/00—Bending rods, profiles, or tubes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D53/00—Making other particular articles
- B21D53/02—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers
- B21D53/06—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers of metal tubes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L9/00—Rigid pipes
- F16L9/18—Double-walled pipes; Multi-channel pipes or pipe assemblies
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D7/10—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically
- F28D7/106—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically consisting of two coaxial conduits or modules of two coaxial conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
- F28F9/26—Arrangements for connecting different sections of heat-exchange elements, e.g. of radiators
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Bending Of Plates, Rods, And Pipes (AREA)
Abstract
A pipe assembly particularly for use as a heat exchanger or as a chemical reaction tube, comprises an inner, U-shaped, cold-bent pipe capable of withstanding a relative high internal pressure, the straight limbs of the U each having a length of at least 5 times the external diameter of the pipe, and an outer seamless, J-shaped pipe coaxial with and enveloping the bend and one limb of the U-shaped pipe to form an annular passageway between the pipes. The invention also comprises a method for making the pipe assembly comprising the steps of (i) positioning a straight length of pipe over the U-shaped, cold-bent pipe; (ii) locating the outer pipe in a pipe- bending apparatus so that it is gripped by the pipe-bending elements thereof and so that the inner pipe is free to move within the outer pipe; and (iii) bending the outer pipe around the inner pipe. h
Description
SPECIFICATION
Pipe assembly and method for its manufacture
This invention relates to pipe assemblies and to a method for their manufacture.
Coaxial, U-shaped pipes which define between themselves on annular passageway are conventional components for the construction of heat exchangers. Such heat exchangers may include a complex system of pipework up to 3000 m in length and may be in the form of a plurality of generally parallel lengths of coaxial pipe connected one to another in series by such Ushaped pipe units.
If an exothermic or endothermic reaction takes place inside the inner pipe, and if cooling or heating is required, such a heat exchanger is known generally as a tubular reactor. The hollow space between the inner and outer pipe of the double-walled tubular reactor serves for the passage of coolants or heating agents for the purpose of influencing the reaction temperature inside the tubular reactor. In order to achieve a cooling or heating effect which is as uniform as possible, attempts are made to achieve concentricity of the inner and outer pipes, since this creates defined flow conditions in the hollow space between the pipes.
Whereas it is relatively simple to meet this requirement in the case of straitht pipes, considerable difficulties are encduntered in the case of coaxial, U-shaped pipes. The known, U-shaped cold-bent high-pressure pipes for operating pressures of over 1000 bar generally have a bending radius of about 7 times the external diameter of the pipe or more and the straight limbs of the U have a length of at least 5 times the external diameter. This straight length of pipe is required for the threaded joint with the next straight lengths of pipe and for masons of fabricating techniques.It has been found, however, that the bending radius cannot always be kept constant over the 1 80-degree bend, and that it fluctuates within a tolerance of + 0.10 m to 0.20 m. the reason for such non-uniformity is that such highpressure pipes are cold-bent and have nonuniform elastic recoveries. However, subsequent adjustment to the precise bending radius is not permissible. The procedure used hitherto for jacketing such a U-shaped, high-pressure pipe consisted of bending the outer pipe separately to the required bending radius without allowing for any straight limbs, and then cutting through the pipe either at the two lateral neutral bending lines, or at the inner and outer extremities of the bend.
The two resulting shells were then placed around the U-shaped high-pressure pipe and adjusted to the actual shape of the bend by applying heat and by pressing. The cuts were then welded. This was followed by welding straight lengths of pipe to the ends of the outer pipe. The inner, high-pressure pipe could be centered in the outer pipe by means of spacers. The process used hitherto for jacketing an inner pipe is extremely costly and timeconsuming because of the necessity to cut the outer bend and subsequently to weld the two shells together. Moreover, during the course of welding, the outer pipe could become distorted, resulting in a non-uniform hollow space within the bend. This, in turn, could result in non-uniform flow of the coolant or heating fluid, which will affect the heat transfer, thus causing unequal temperatures at various points within the Ushaped, high-pressure pipe.In addition to the stresses caused by the high operating pressure, there will also be additional stresses due to temperature differences.
The present invention seeks to overcome the disadvantages of the known pipe assemblies by providing an assembly in which the outer pipe is seamless and can be positioned over the Ushaped, high-pressure pipe by a simple bending operation.
According to the invention, there is provided a pipe assembly comprising an inner, U-shaped, cold-bent pipe capable of withstanding a relative internal pressure of at least 1000 bar, the straight limbs of the U each having a length of at least 5 times the external diameter of the pipe, and an outer seamless, J-shaped pipe coaxial with and enveloping the bend and one limb of the U-shaped pipe to form an annular passageway between the pipes.
The present invention also provides a method for the manufacture of such a pipe assembly which comprises the steps of
(i) positioning a straight length of pipe over the
U-shaped cold-bent pipe;
(ii) locating the outer pipe in a pipe-bending apparatus in such a manner that it is gripped by the pipe-bending elements thereof that the inner pipe is free to move within the outer pipe; and
(iii) bending the outer pipe to the required shape around the inner pipe.
An especially preferred method of bending the outer pipe over the high-pressure pipe is to force the former into a roller-type bending apparatus or to draw it through a slide-type bending apparatus, suitably while applying localized heat. The outer pipe is most suitably deformed over the exposed high-pressure pipe in such a manner as to impart a "mean" curvature to the outer pipe; the "mean" curvature corresponding to the "mean" curvature of the high-pressure pipe. The "mean" curvature is to be understood to mean the neutral axis of the bend.
The advantage achieved by the method according to the present invention is that the high pressure pipe is enclosed by the outer pipe in a single bending operation without the need for any additional cutting or welding steps. Also, the coldbent, high-pressure pipe is not subjected to any additional thermal stress. Even if the high-pressure pipe bend is not perfectly circular, it is possible to bend the outer pipe on a roller-type qr slide-type bending apparatus in such a manner that the "means" curvature of bot,h pipes is substantially identical at all points, thus achieving a uniform annular passageway between the pipes throughout the entire pipe bend.
In the case of pipe bends of large bending radius it is, of course, possible to include centering pins in the outer pipe to prevent any sagging of the high-pressure bend.
The following figures illustrate the dimensions and deviations of a typical pipe assembly according to the present invention:
U-shaped, high-pressure pipe:
internal diameter of pipe: 50 mm
wall thickness of pipe: 60 mm
mean diameter of pipe bend: 4 mm
deviation from mean bending
radius of 2 m: approximately
+ 100 mm
length of straight limbs; 1 m each
J-shaped, outer pipe:
internal diameter of pipe: 270 mm
wall thickness of pipe: 8mm
means diameter of pipe bend: 4 m
deviation from mean bending
radius of 2 m: approximately
+ 100 mm,
corresponding to
deviations of inner
pipe at all points.
Claims (8)
1. A pipe assembly comprising an inner, Ushaped cold-bent pipe capable of withstanding a relative internal pressure of at least 1000 bar, the straight limbs of the U each having a length of at least 5 times the external diameter of the pipe, and an outer seamless, J-shaped pipe coaxial with and envelopping the bend and one limb of the Ushaped pipe to form an annular passageway between the pipe.
2. A method for the manufacture of a pipe assembly according to claim 1, which comprises the steps of
(i) positioning a straight length of pipe over the
U-shaped, cold bent pipe;
(ii) locating the outer pipe in a pipe-bending apparatus in such a manner that it is gripped by the pipe-bending elements thereof and that the inner pipe is free to move within the outer pipe; and
(iii) bending the outer pipe to the required shaped around the inner pipe.
3. A method according to claim 2, wherein the outer pipe is bent in a roller-type pipe-bending apparatus.
4. A method according to claim 2, wherein the outer pipe is bent in a slide-type pipe-bending apparatus.
5. A method according to claim 3 or claim 4, wherein the outer pipe is heating during the bending step.
6. A method according to any one of claims 2 to 5, wherein the outer pipe is bent to a mean curvature identical to that of the inner pipe.
7. A method according to claim 2 carried out substantially as hereinbefore described.
8. A pipe assembly according to claim 1 manufactured by a method according to any one of claims 2 to 7.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2854548A DE2854548C2 (en) | 1978-12-18 | 1978-12-18 | Method for producing a substantially circular arc-shaped double tube with an intermediate cavity |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2038472A true GB2038472A (en) | 1980-07-23 |
| GB2038472B GB2038472B (en) | 1983-09-01 |
Family
ID=6057493
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7943371A Expired GB2038472B (en) | 1978-12-18 | 1979-12-17 | Pipe assembly and method for its manufacture |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5584221A (en) |
| AT (1) | AT365488B (en) |
| BE (1) | BE880691A (en) |
| DE (1) | DE2854548C2 (en) |
| FR (1) | FR2444518A1 (en) |
| GB (1) | GB2038472B (en) |
| IT (1) | IT1125815B (en) |
| NL (1) | NL7908119A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102011010385A1 (en) * | 2011-02-05 | 2012-08-09 | Eads Deutschland Gmbh | Double-walled pipe and manufacturing process |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3253326A (en) * | 1962-10-11 | 1966-05-31 | Combustion Eng | Method of bending concentrically arranged tubes simultaneously |
| FR1376997A (en) * | 1963-12-03 | 1964-10-31 | Stein & Roubaix | Process for simultaneously bending coaxial pipes |
| US3546917A (en) * | 1968-09-30 | 1970-12-15 | T O Paine | Technique of elbow bending small jacketed transfer lines |
-
1978
- 1978-12-18 DE DE2854548A patent/DE2854548C2/en not_active Expired
-
1979
- 1979-11-06 NL NL7908119A patent/NL7908119A/en not_active Application Discontinuation
- 1979-11-13 AT AT0724579A patent/AT365488B/en not_active IP Right Cessation
- 1979-11-16 IT IT27368/79A patent/IT1125815B/en active
- 1979-12-17 GB GB7943371A patent/GB2038472B/en not_active Expired
- 1979-12-17 FR FR7930832A patent/FR2444518A1/en active Granted
- 1979-12-18 JP JP16365179A patent/JPS5584221A/en active Pending
- 1979-12-18 BE BE0/198621A patent/BE880691A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| AT365488B (en) | 1982-01-25 |
| NL7908119A (en) | 1980-06-20 |
| IT7927368A0 (en) | 1979-11-16 |
| GB2038472B (en) | 1983-09-01 |
| BE880691A (en) | 1980-04-16 |
| ATA724579A (en) | 1981-06-15 |
| IT1125815B (en) | 1986-05-14 |
| JPS5584221A (en) | 1980-06-25 |
| FR2444518B1 (en) | 1983-12-23 |
| FR2444518A1 (en) | 1980-07-18 |
| DE2854548C2 (en) | 1986-07-03 |
| DE2854548A1 (en) | 1980-07-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |