GB2196711A

GB2196711A - Electrically insulated pipe joint

Info

Publication number: GB2196711A
Application number: GB08709374A
Authority: GB
Inventors: Dr Wilhelmus Angustin Gruijter
Original assignee: Angli Holding BV
Current assignee: Angli Holding BV
Priority date: 1986-10-28
Filing date: 1987-04-21
Publication date: 1988-05-05
Anticipated expiration: 2007-04-21
Also published as: GB2196711B; GB8709374D0; NL8602709A

Abstract

An electrically insulated pipe joint comprises two similar tubular parts, the first having a bell, in which a flange of the second is received. A first insulating gasket lies between the front face of the flange and the flat bottom of the bell, and a second lies between the back face of the flange, the outer wall of the second tubular part and the inner wall of the bell. The bottom of the bell joins the cylindrical inner surface of the tubular part through a curved surface, which joining the first part through a shoulder. The first insulating gasket has a cylindrical appendix and the outer surface of the first gasket lies fittingly against the bottom of the bell, the curved surface and the first cylindrical surface part, and the inner diameter of the first gasket being equel to the inner diameter of the second cylindrical surface part of the first tubular part. The second gasket at the end directed towards the flange has a greatest diameter at least equal to the inner diameter of the ball and having a recess in the corresponding end face, in which the flange is fittingly received. The other end projects out of the bell and its outer surface goes from the end with the greatest diameter towards the other end in an S-shaped manner.

Description

SPECIFICATION Electrically insulated pipe joint The invention relates to an electrically insulated pipe joint of the monolithic type, comprising two similar tubular parts, the first tubular part having a bell, in which a flange of the second tubular part is received, wherein the outer diameter of the flange is smaller than the inner diameter of the bell, a first insulating gasket lying between the front face of the flange and the flat bottom of the bell, and a second insulating gasket lying between the back face of the flange, the outer wall of the second tubular part and the inner wall of the bell, wherein the diameter of the second insulating gasket going from the end adjacent the flange towards the other end decreases and the bell is substantially conically deformed towards the mouth of the bell.

Such a pipe joint. is known from Dutch patent application nr. 67.09100. In this known pipe joint the first tubular part with the bell is made by forging whereas the inner surface of the bell moreover is subject to a turning operation in order to obtain a flat bottom that is substantially perpendicular with respect to the inner wall. The production of this tubular part is thus relatively costly.

The invention has the object of providing a simplified pipe joint of the above-mentioned kind that can be obtained at low cost.

For this purpose the electrically insulated pipe joint is characterized in that both tubular parts are made of common pipe bars, the bell and the flange being formed by pressing, wherein the flat bottom of the bell joining the cylindrical inner surface of the tubular part through a curved surface, said cylindrical inner surface for the first part joining the curved surface having a greater diameter than the second part joining the first part through a shoulder, wherein the first insulating gasket has a cylindrical appendix and the outer surface of the first gasket lies fittingly against the bottom of the bell, the curved surface and the first cylindrical surface part, the inner diameter of the first gasket being equal to the inner diameter of the second cylindrical surface part of the first tubular part, wherein the second insulating gasket consists of hard insulating material slightly pliable under compression, said second gasket at the end directed towards the flange having a greatest diameter at least equal to the inner diameter of the bell and having a recess in the corresponding end face, in which the flange is fittingly received, wherein the outer surface of the second gasket going from the end with the greatest diameter towards the other end gradually decreases, the inner surface of the bell being pressed against the outer surface of the second gasket.

In this manner it is obtained that both tubular parts can easily and economically be made from common metal pipe bars without any subsequent machining being required.

Further the invention provides a method for manufacturing the electrically insulted pipe joint, wherein the tubular part with the flange is inserted into the bell of the other tubular part, in which the first insulating gasket is disposed, wherein the second insulating gasket is shifted on the tubular part with the flange and the connection between both tubular parts is obtained by deforming the bell, characterized in that both tubular parts are made of common pipe bars, wherein the flange and the bell are formed by pressing and during forming the bell, a flat surface is made, joining the cylindrical inner surface of the tubular part through a curved surface, wherein the first part of this inner surface has a greater diameter than the second part and wherein the bell with its inner sureace is pressed on the outer surface of the second insulating gasket likewise by pressing.

The invention will hereinafter be explained by way of the drawing in which an embodiment of the invention is shown.

Figure 1 shows a section of an embodiment of the pipe joint of the invention in separated state.

Figure 2 shows a section of the pipe joint of Fig. 1 in an assembled state.

In Fig. 1 and 2 an electrically insulated pipe joint of the monolithic type is shown in a separated state before assembling (Fig. 1) and in the assembled state (Fig. 2).

The pipe joint is provided with two similar tubular parts 1,2 each consisting of a common commercially obtainable pipe bar. Both tubular parts 1,2 each have the same inner and outer diameter. The tubular part 1 is provided with a bell 3, the inner wall. 4 of which being substantially perpendicular to the flat bottom surface 5. This bottom surface 5 joins the first cylindrical inner surface 7 through a curved surface 6, said surface 7 joining the cylindrical inner surface 9 of the tubular part 1 through a shoulder 8. The described form of the tubular part 1 with the bell 3 according to the invention is obtained by cold-pressing of the tubular part. As an alternative the tubular part can be provided with the bell 3 by warmpressing.

The tubular part 2 is provided with a flange 10 also by cold- or warm-pressing. The flange 10 in the shown embodiment is executed with a flat front surface. If required, the front surface of the flange 10 can be provided with at least one annular upstanding ridge.

The pipe joint according to the invention is further provided with a first insulating gasket 11 and a second insulating gasket 12. The first insulating gasket 11 comprises a cylindrical appendix 13 the inner diameter of which is equal to the inner diameter of the cylindrical surface 9. The outer surface of the insulating gasket 11 with the appendix 13 is accurately adapted to the bottom surface 5, the curved surface 6 and the cylindrical surface 7 of the tubular part 1, wherein the greatest diameter of the insulating gasket 11 substantially corresponds with the diameter of the inner wall 4 of the bell 3 so that the insulating gasket 11 may be fittingly reeived in the tubular part 1.

The insulating gasket 11 is made of a semirigid electrically insulating material.

The insulating gasket 12 made of a rigid insulating material that under compression is slightly pliable, has an internal diameter that is slightly smaller than the outer diameter of the tubular part 2, so that the second insulating gasket 12 may be disposed on this tubular part 2 with a pressfit. A recess 14 lies in the one end of the insulating gasket 12, in which the flange 10 fittingly can be received as appears from Fig. 2. The outer diameter of the insulating gasket 12 at least at the location of the part 15 surrounding the flange 10, is slightly greater than the diameter of the inner wall 4 of the bell 3. The outer diameter of the insulating gasket 12 gradually decreases from this greatest value to an outer diameter in the shape of a fattened letter 'S' when considering one half of the profile) that is about 6 mm greater than the outer diameter of the tubular part 2. The axial length of the insulating gasket 12 IS such that in the assembled state according to Fig. 2 the insulating gasket 12 projects out of the bell 3.

For assembling the pipe joint the insulating gasket 11 is pushed into the bell 3 of the tubular part 1, whereas the insulating gasket 12 is pushed on the tubular part 2 until the flange 10 falls into the recess 14. Hereafter the tubular part 2 is inserted into the bell 3 and by cold-pressing the bell 3 is pressed with its inner surface on the outer surface of the insulating gasket 12.

The invention is not limited to the previously enclosed embodiment, which may be modified in various manners within the scope of the invention.

Claims

1. Electrically insulated pipe joint of the monolithic type, comprising two similar tubular parts (12), the first tubular part (1) having a bell (3), in which a flange (10) of the second tubular part is received, wherein the outer diameter of the flange is smaller than the inner diameter of the bell, a first insulating gasket (11) lying between the front face of the flange and the flat bottom of the bell, and a second insulating gasket (12) lying between the back face of the flange, the outer wall of the second tubular part (2) and the inner wall of the bell, wherein the diameter of the second insulating gasket going from the end adjacent the flange towards the other end decreases and the bell is substantially conically deformed towards the mouth of the bell, characterized in that both tubular parts are made of common pipe bars, the bell and the flange being formed by pressing, wherein the flat bottom of the bell joining the cylindrical inner surface of the tubular part through a curved surface, said cylindrical inner surface for the first part joining the curved surface having a greater diameter than the second part joining the first part through a shoulder, wherein the first insulating gasket has a cylindrical appendix and the outer surface of the first gasket lies fittingly against the bottom of the bell, the curved surface and the first cylindrical surface part, the inner diameter of the first gasket (11) being substantially equal to the inner diameter of the clyindrical inner surface of the first tubular part (11), wherein the second insulating gasket consists of hard insulating material slightly pliable under compression, said second gasket at the end directed towards the flange having a greatest diameter at least equal to the inner diameter of the bell and having a recess in the corresponding end face, in which the flange is fittingly received, wherein the outer surface of the second gasket going from the end with the greatest diameter towards the othe end gradually decreases, the inner surface of the bell being pressed against the outer surface of the second gasket.

2. Pipe joint of claim 1, characterized in that the inner diameter of the second insulating gasket before assembling, is slightly smaller than the outer diameter of the tubular part.

3. Pipe joint of claim 1 or 2, characterized in that the outer diameter of at least the part of the second insulating gasket surrounding the flange, is slightly greater than the inner diameter of the bell before assembling.

4. Pipe joint as claimed in claims 1, 2 or 3, wherein the outer end of the second gasket projects out of the bell.

5. Method for manufacturing the electrically insulated pipe joint of any one of the preceding claims wherein the tubular part with the flange is inserted into the bell of the other tubular part, in which the first insulating gasket is disposed, wherein the second insulating gasket is shifted on the tubular part (1) with the flange and the connection between both tubular parts is obtained by deforming the bell, characterized in that both tubular parts are made of common pipe bars, wherein the flange and the bell are formed by pressing and during forming the bell a flat surface (5) is made, joining the cylindrical inner surface (9) of the tubular part (1) through a curved surface, wherein a first part of the inner surface of the bell has a greater diameter than a second part and wherein the bell with its inner surface is pressed on the outer surface of the second insulating gasket likewise by pressing.

6. Method of claim 5, characterized in that the forming of the flange and the bell is executed by cold-pressing.

7. Method of claim 5, characterized in that the forming of the flange and the bell is exe cuted by warm-pressing.

8. Method of claim 5, characterized in that the bell is deformed by cold-pressing.

9. Pipe joint as claimed in Claim 1 substantially as described with reference to the accompanying drawing.

10. Method of manufacturing an electrically insulated pipe joint as claimed in claim 5 substantially as described herein.