GB1559291A

GB1559291A - Electrically insulated pipe coupling

Info

Publication number: GB1559291A
Application number: GB3121276A
Authority: GB
Original assignee: Caunned AG
Current assignee: Caunned AG
Priority date: 1975-08-11
Filing date: 1976-07-27
Publication date: 1980-01-16
Also published as: CA1047063A; DE2636402A1; JPS5222786A; CH595580A5; ES450575A1; BR7605135A; FR2321087A1

Description

(54) ELECTRICALLY INSULATED PIPE COUPLING (71) We, CAUNNED A.G., a Company organised under the Laws of Liechtenstein, of Im Stidtle 35, Vaduz, Liechtenstein, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be described in and by the following statement: It is known that to interrupt the electrical continuity between connected metal pipes or conduits, there are used insulating joints generally formed by a tubular metal sleeve, in which are inserted, so as to provide its perfect insulation, two tubular metal members which constitute the duct of the joint and both having a deformed end, for example a flanged end. The two adjacent deformed ends are spaced by a spacing insulating and sealing member which is compressed by the tubular metal members. The compression force may be derived, in such a manner that the insulating and sealing member, compressed between the opposite surfaces of the ends of the tubular members of the joints, must not only provide the function of an insulating spacer but must also achieve the sealing function. It should therefore be sufficiently elastic to have the characteristics of a sealing gasket.

It is evident that in this case said spacing insulating and sealing member, after undergoing severe mechanical stresses in the direction of the joint axis, tends to expand and to enter into the flow path of fluid through the joint with the result of hydraulic leakages. Furthermore, if said insulating annular spacer is formed even in a rigid unelastic material, it is extremely difficult to obtain a perfect sealing which anyway, in the long run owing to mechanical or thermal stresses, can leak.

To obviate this inconvenience it has been thought to make the joint rigid and in other cases to locate into annular grooves, formed in the opposite surfaces of the ends of the tubular metal members, O-rings so as to form a good seal between each of the said surfaces and an adjacent face of the insulating annular spacer made of a material having a high mechanical strength.

In this latter case, however, an eventual permeability to gas or an accidental break of the insulating spacer causes a leakage in the joint since the sealing given by the O-rings would be by-passed.

According to the invention, there is provided an electrically insulating pipe coupling comprising: a first metal pipe having an end portion which is symmetrically deformed in a direction away from the axis thereof: a second metal pipe having an end portion which is symmetrically deformed in a direction away from the axis thereof. said first and second pipes being coaxial and spaced with their respective deformed end portions mutually adjacent; a tubular metal sleeve coaxial with said first and second pipes, and being positioned so as to define an annular space between the-inner surface thereof and at least the end portion of said first pipe; a spacer formed of electrically insulating material and positioned between and in contact with the end portion of the first pipe and the end portion of the second pipe; an elastic sealing gasket positioned in said annular space and in contact with said spacer, said inner surface of said tubular metal sleeve and the outer surface of the end portion of the first pipe; and a blocking element in the form of a sleeve of electrically insulating material positioned in said annular space and in contact with said sealing gasket to press said sealing gasket against said spacer, said blocking element having a truncated conical portion and said tubular metal sleeve having a portion capable of being deformed into a corresponding truncated conical shape to hold said blocking member in position.

The tubular metal sleeve may either be integral or non-integral with one of the pipes. In the case where the sleeve is separate from both first and second pipes, the deformed end portion of each of the pipes may be constituted by a flange formed on the respective end portions.

Alternatively the deformed end portion of each pipe may be constituted by a bell-shaped end portion.

Preferably the coupling further comprises a second elastic sealing gasket positioned in said annular space and in contact with said inner surface of said tubular metal sleeve, the outer surface of the end portion of the second pipe and said spacer on the face thereof remote from the first elastic sealing gasket and a second blocking element in the form of a sleeve of electrically insulating material positioned in said annular space and in contact with said second sealing gasket to press said second sealing gasket against said spacer, said second blocking element having a truncated conical portion and said tubular metal sleeve having a second portion capable of being deformed into a corresponding truncated conical shape to hold said second blocking member in position.

Advantageously the spacer is an annular ring with a T-shape cross-section. Alternatively the spacer may be an annular ring with an Hshaped section having the radially inner arm of the "H" longer than the radially outer arm thereof, the spaces between the arms of the "H" being so dimensioned as to receive the bell shaped end portions of the respective pipes.

In the case where the metal sleeve is integral with one of the pipes, say the second pipe, then according to a preferred embodiment of the invention the deformed end portion of said second pipe is constituted by said tubular metal sleeve and by an annular intermediate portion connecting the said tubular metal sleeve to the remaining part of said second pipe. The spacer preferably has one face thereof, opposite to that face which is in contact with the sealing gasket, in contact with said intermediate portion of said second pipe. In this case the intermediate portion may be an annular shoulder formed on said second pipe and said spacer may be an annular ring of L-shaped section, one arm of the "L" bearing against said shoulder.

The invention will now be further described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a section through a coupling according to the invention, in a partly as sembled state; Figure 2 shows a section through the coupling of Figure 1, in the completely assembled state; and Figures 3 to 7, show partial sections through respective further embodiments of couplings ac cording to the invention.

Referring to Figures 1 and 2 there is shown a coupling which includes first and second metal pipes 1 and 1', provided at their adjacent ends with flanges 2, 2', extending away from the common axis of the pipes. Coaxially surrounding the end portions of the pipes 1, 1', is a tubular metal sleeve 3 having an inner diameter greater than the outer diameter of the flanges 2,2.

Positioned between the flanges 2, 2' and occupying a portion of the annular space defined between the sleeve 3 and the pipes 1,1' is an annular spacer 5 made of electrically insulating material having high mechanical strength, in particular a high resistance to compression. The spacer 5 is in the form of an annular ring of T-shaped cross section, the vertical leg of the "T" being positioned between the flanges 2,2' while the cross-piece of the T lies between, and in contact with the radially outer surfaces of the flanges 2, 2 and the radially inner surface of the sleeve 3.

Two annular gaskets 6, 6' made of rubber, asbestite or some other known sealing material are provided on either side of the spacer 5. Each gasket 6, 6' has a radially inner diameter corre spending to the outer diameter of the pipes 1, 1 ' and an outer diameter corresponding to the outer diameter of the spacer 5. The gaskets 6, 6' are in contact respectively with the ends of the crosspiece of the T-shaped section spacer 5.

In contact with those surfaces of the gaskets 6, 6' remote from the spacer 5 are two blocking elements in the form of sleeves 4, 4' formed of an electrically insulating material and having an inner diameter corresponding to the outer diameter of the pipes 1, 1'. That portion of the sleeves 4, 4' which is remote from the gaskets 6,6' has an outer surface defined by a truncated cone while that surface of the sleeve 4, 4' which is in contact with the gaskets 6, 6' is planar.

The sleeves 4, 4' extend in an axial direction, beyond the axial limits of the sleeve 3. The result of this formation is that, as shown in Figure 2, when the end portions 3' of the sleeve 3 are deformed radially inwards, they press against the frusto-conical portion of the sleeves 4, 4, pushing the sleeves 4, 4' towards each other.

The assembly of the joint takes place as follows. First of all the pipes 1, 1 are inserted into the tubular metal sleeve 3 with the interposition of the spacer 5, the flanges 2 and 2' being located in the spacer 5. The sealing gaskets 6, 6' are then inserted, followed by the sleeves 4,4'. The dimensioning of the sleeves 4, 4' and the gaskets 6, 6' are such that they are a force fit in the joint. Finally, the ends 3' of the tubular metal sleeve are strained inwards so as to maintain the various components of the joint in axial tight compression.

It is clear that one end 3' of the sleeve 3 can already be formed in its frusto-conical configuration before the joint is assembled.

Referring to the embodiment shown in Figure 3, the first and second pipes 7, 7' have bell-shaped deformed end portions 11, 11'. The insulating sleeves 10, which replace the insulating sleeves 4 of Figures 1 and 2, do not have a cylindrical inner surface but rather a shape determined by the bell-shaped end portions 11, 11'. The annular insulating spacer 5 is similar to that shown in Figures 1 and 2, while the sealing gaskets 9,9' are less wide than gaskets 6, 6.

When the pipes are formed of a material that can be easily deformed, such as copper or aluminium or when the flow path of fluid through the joint is not to be disturbed by an increase in pipe cross-section, an insulating spacer such as 12 in Figure 4 may be used. This spacer is an annular ring of H-cross section, the inner arm of the H being substantially longer than the outer arm so that it occupies the extra pipe cross-section defined by the bell-shaped end portions 11,11'.

In the embodiment shown in Figure 5, the tubular metal sleeve is integral with the second pipe. More particularly the second pipe is provided with an intermediate portion in the form of a shoulder 13 which connects the sleeve to the un-deformed part of the second pipe. The insulating spacer 14 is in the form an annular ring of L-section, one leg of the "L" being in contact with the shoulder 13. In this case only one sealing gasket 6 and only one sleeve 4 is provided. In this case this first pipe 1 is provided with a flange 2 as in Figures 1 and 2.

In Figure 6, the metal sleeve is again integral with the second pipe, in this case being connected by a frustoconical intermediate portion 15. The spacer 16 is an annular ring having a cross-section determined by the shape of the intermediate portion 15.

In Figure 7, the second pipe and metal sleeve are formed in the same manner as Figure 6. In this case however, the first pipe 17 has a longer bell-shaped deformed end portion, the edge of the first pipe 17 being bent in again at 18. The cross-section of the insulating spacer 19 is determined by the shape of the portions 15 and 18.

The method of assembly of the joints shown in Figures 2, 3 to 7, is similar to that described in connection with Figures 1 and 2.

Following the embodiments described in this specification we achieve insulating joints in which hydraulic leakages are practically impossible as the spacing insulating and sealing member is located and tightly compressed in a space whose volume does not undergo any changes under the mechanical stresses for which the joint has been designed and the areas having the task to perform the initial sealing are circular sections 5'. In realizing the joint of this invention it has been also foreseen that the couplings, particularly between flanges 2 and 2' and the annular spacer 5 and also every other coupling between components making up the joints, are provided with an adhesive or a hot or cold thermosetting resin so that the various couplings create integral parts among said different components of the joint.

In the case of conductive fluids, the tubular members may have an inner coating 8 provided by a paint or by an electrically insulating resin.

The various insulating sleeves 4, 4 and 10, 10' as well as the insulating annular spacers 5, 12, 14, 16 and 19 can be formed by a metal section provided with an insulating coating material, having a suitable thickness, on those sides where such a coating is essential to obtain the functionality of the joint.

WHAT WE CLAIM IS: 1. An electrically insulating pipe coupling comprising: a first metal pipe having an end portion which is symmetrically deformed in a direction away from the axis thereof; a second metal pipe having an end portion which is symmetrically deformed in a direction away from the axis thereof, said first and second pipes being coaxial and spaced with their respective deformed end portions mutually adjacent; a tubular metal sleeve coaxial with said first and second pipes, and being positioned so as to define an annular space between the inner surface thereof and at least the end portion of said first pipe; a spacer formed of electrically insulating material and positioned between and in contact with the end portion of the first pipe and the end portion of the second pipe; an elastic sealing gasket positioned in said annular space and in contact with said spacer, said inner surface of said tubular metal sleeve and the outer surface of the end portion of the first pipe; and a blocking element in the form of a sleeve of electrically insulating material positioned in said annular space and in contact with said sealing gasket to press said sealing gasket against said spacer, said blocking element having a truncated conical portion and said tubular metal sleeve having a portion capable of being deformed into a corresponding truncated conical shape to hold said blocking member in position.

2. An electrically insulating pipe coupling according to claim 1, wherein said tubular metal sleeve is non-integral with said first and second pipes.

3. An electrically insulating pipe coupling according to claim 2, wherein the deformed end portion of each of said pipes is constituted by a flange formed on the respective pipe.

4. An electrically insulating pipe coupling according to claim 2, wherein the deformed end portion of each said pipes is constituted by a bell-shaped end portion.

5. An electrically insulating pipe coupling according to any one of claims 2 to 4, further comprising a second elastic sealing gasket positioned in said annular space and in contact with said inner surface of said tubular metal sleeve, and the outer surface of the end portion of the second pipe and said spacer on the face thereof remote from the first elastic sealing gasket and a second blocking element in the from of a sleeve of electrically insulating ma

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cylindrical inner surface but rather a shape determined by the bell-shaped end portions 11, 11'. The annular insulating spacer 5 is similar to that shown in Figures 1 and 2, while the sealing gaskets 9,9' are less wide than gaskets 6, 6. When the pipes are formed of a material that can be easily deformed, such as copper or aluminium or when the flow path of fluid through the joint is not to be disturbed by an increase in pipe cross-section, an insulating spacer such as 12 in Figure 4 may be used. This spacer is an annular ring of H-cross section, the inner arm of the H being substantially longer than the outer arm so that it occupies the extra pipe cross-section defined by the bell-shaped end portions 11,11'. In the embodiment shown in Figure 5, the tubular metal sleeve is integral with the second pipe. More particularly the second pipe is provided with an intermediate portion in the form of a shoulder 13 which connects the sleeve to the un-deformed part of the second pipe. The insulating spacer 14 is in the form an annular ring of L-section, one leg of the "L" being in contact with the shoulder 13. In this case only one sealing gasket 6 and only one sleeve 4 is provided. In this case this first pipe 1 is provided with a flange 2 as in Figures 1 and 2. In Figure 6, the metal sleeve is again integral with the second pipe, in this case being connected by a frustoconical intermediate portion 15. The spacer 16 is an annular ring having a cross-section determined by the shape of the intermediate portion 15. In Figure 7, the second pipe and metal sleeve are formed in the same manner as Figure 6. In this case however, the first pipe 17 has a longer bell-shaped deformed end portion, the edge of the first pipe 17 being bent in again at 18. The cross-section of the insulating spacer 19 is determined by the shape of the portions 15 and 18. The method of assembly of the joints shown in Figures 2, 3 to 7, is similar to that described in connection with Figures 1 and 2. Following the embodiments described in this specification we achieve insulating joints in which hydraulic leakages are practically impossible as the spacing insulating and sealing member is located and tightly compressed in a space whose volume does not undergo any changes under the mechanical stresses for which the joint has been designed and the areas having the task to perform the initial sealing are circular sections 5'. In realizing the joint of this invention it has been also foreseen that the couplings, particularly between flanges 2 and 2' and the annular spacer 5 and also every other coupling between components making up the joints, are provided with an adhesive or a hot or cold thermosetting resin so that the various couplings create integral parts among said different components of the joint. In the case of conductive fluids, the tubular members may have an inner coating 8 provided by a paint or by an electrically insulating resin. The various insulating sleeves 4, 4 and 10, 10' as well as the insulating annular spacers 5, 12, 14, 16 and 19 can be formed by a metal section provided with an insulating coating material, having a suitable thickness, on those sides where such a coating is essential to obtain the functionality of the joint. WHAT WE CLAIM IS:

1. An electrically insulating pipe coupling comprising: a first metal pipe having an end portion which is symmetrically deformed in a direction away from the axis thereof; a second metal pipe having an end portion which is symmetrically deformed in a direction away from the axis thereof, said first and second pipes being coaxial and spaced with their respective deformed end portions mutually adjacent; a tubular metal sleeve coaxial with said first and second pipes, and being positioned so as to define an annular space between the inner surface thereof and at least the end portion of said first pipe; a spacer formed of electrically insulating material and positioned between and in contact with the end portion of the first pipe and the end portion of the second pipe; an elastic sealing gasket positioned in said annular space and in contact with said spacer, said inner surface of said tubular metal sleeve and the outer surface of the end portion of the first pipe; and a blocking element in the form of a sleeve of electrically insulating material positioned in said annular space and in contact with said sealing gasket to press said sealing gasket against said spacer, said blocking element having a truncated conical portion and said tubular metal sleeve having a portion capable of being deformed into a corresponding truncated conical shape to hold said blocking member in position.

terial positioned in said annular space and in contact with said second sealing gasket to press said second sealing gasket against said spacer, said second blocking element having a truncated conical portion and said tubular metal sleeve having a second portion capable of being deformed into a corresponding truncated conical shape to hold said second blocking member in position.

6. An electrically insulating pipe coupling according to any one of claims 1 to 5, wherein said spacer is an annular ring with a T-shaped section.

7. An electrically insulating pipe coupling according to claim 4, wherein said spacer is an annular ring with an H-shaped section having the radially inner arm of the "H" longer than the radially outer arm thereof, the spaces between the arms of the "H" being so dimensioned as to receive the bell shaped end portions of the respective pipes.

8. An electrically insulating pipe coupling according to claim 1, wherein said tubular metal sleeve is integral with said second pipe.

9. An electrically insulating pipe coupling according to claim 8, wherein the deformed end portion of said second pipe is constituted by said tubular metal sleeve and by an annular intermediate portion connecting said tubular metal sleeve to the remaining part of said second pipe.

10. An electrically insulating pipe coupling according to claim 9, wherein said spacer has one face thereof, opposite to that face which is in contact with the sealing gasket, in contact with said intermediate portion of said second pipe.

11. An electrically insulating pipe coupling according to claim 10, wherein said intermediate portion is an annular shoulder formed on said second pipe and said spacer is an annular ring of L-shaped section, one arm of the "L" bearing against said shoulder.

12. An electrically insulating pipe coupling according to any one of claims 1 to 11, wherein the contacting surfaces of the various components of the coupling are provided with a layer of an adhesive or of a hot or cold thermosetting resin.

13. An electrically insulating pipe coupling according to any one of claims 1 to 12, wherein the surfaces of the pipes are at least partially coated with paint or an insulating resin.

14. An electrically insulating pipe coupling according to any one of claims 1 to 13, wherein those surfaces in contact with the or each sealing gasket have circular configurations.

15. An electrically insulating pipe coupling substantially as herein before described with reference to and as illustrated in the accompanying drawings.