DEVICE FOR CONNECTING OF PIPES WITH A CLAMP RING CONNECTION

Abstract: A device for connection of hard conduits, e.g. steel conduits (1) with a clamp ring connection intended for soft or semisoft conduits, such as copper conduits, with a connection member. The connection member between the coupling means and the steel conduit is a so called reduction set (5), comprising a reduction collar (7) and one with this cooperating reduction cone (8). The reduction collar's (7) connection part (20) to the coupling means is at least one standard dimension larger than the reduction cone's (8) connection part to the steel conduit (1). The reduction collar is on the inside (2) provided with at least one groove (12) for a sealing means (4) for sealing cooperation with the outside (6) of the steel conduit (1).

Description: DEVICE FOR CONNECTING OF PIPES WITH A CLAMP RING CONNECTION TECHNICAL AREA The present invention concerns a device for connection of hard conduits, e.g. steel conduits, with a clamp ring connection intended for soft or semisoft conduits, such as copper conduits, which clamp ring connection comprises a coupling means, one to this fitting nut and a connection member. THE BACKGROUND OF THE INVENTION AND THE PROBLEM A clamp ring connection comprises a clamp ring, which is applied on the connecting soft conduit ahead of a nut, which internally is provided with one to the clamp ring adapted bevel. The connecting coupling means is also provided with a bevel corresponding to that of the clamp ring and has an external thread for cooperation with the above mentioned nut. When tightening the nut a radial deformation of the clamp ring occur, whereby its inner radius reduces somewhat at the same time as a certain deformation of the conduit occur. An effectiv sealing is achieved and a high resistance against drawing forces. Conduits of a hard material, such as steel, cannot normally be connected to a clamp ring connection for copper conduits, owing to the limited tendency of deformation of the steel conduit, occuring unevenness and unroundness. Efforts have been done to eliminate the above mentioned problem by producing clamp rings of other material than brass and by that achieve the possibility to use clamp ring connections intended for copper conduits also for steel conduits. One example of this is a clamp ring consisting of polyamide with an admixture of glass fibers and which is intended without further measures to be able to replace existing clamp rings in clamp ring connections intended for copper conduits. One drawback with these is that the resistance against drawing forces is low. Measurements have shown that the drawing force for such connections for normally occuring conduit dimensions, i.e. the force which is needed to cause an axial displacement of the conduit in relation to the connection is in the intervall 1100-3700 N. Measurements show not unexpectedly that an increased conduit diameter gives an increased drawing force, which with good reason can be connected to the increased contact surface between the conduit and the clamp ring. THEPURPOSEWITHTHEINVENTIONANDTHESOLUTIONOFTHEPROBLEM The purpose with the invention is to achieve a connection device of the type mentioned in the introduction, which with simple means fulfil the demands on tightness and has very high resistance against drawing forces. The device should also be inexpensive to manufacture, environmentally friendly and reusable. These tasks have been achieved through that the coupling means and the nut arc chosen in suitable sizes from a standard assortment, that the chosen coupling means is at least one standard dimension larger than that which fits to the steel conduit, that the connection member between the coupling means and the steel conduit is a so called reduction set, consisting of a reduction collar and one with this cooperating reduction cone, that the connection part of the reduction collar is arranged to fit in the chosen coupling means, that the inner cylindrical surface of the reduction cone is arranged to fit to the outer cylindrical surface of the steel conduit, that the reduction collar on the inside is provided with at least one groove for a sealing means for sealing cooperation with the outside of the steel conduit, and that the reduction cone consists of a softer material,preferably brass, than the steel conduit, whereby the reduction cone when tightening the nut on the coupling means adapt itself to occuring unevennesses or unroundnesses of the steel conduit. DESCRIPTION OF THE DRAWING The invention will in the following be more closely described with reference to the embodiment shown on the enclosed drawing. Figure 1 shows partly in cross-section a reduction set in accordance with the invention. Figure 2 shows a cross-section through a clamp ring connection with a reduction set belonging to it for assembly on a steel conduit, with the different parts for the sake of clearness shown apart form one another. Figure 3 shows the parts according to fiure 2 in assembled position. DESCRIPTION OF AN EMBODIMENT The principal part in the device according to the invention is a so called reduction set 5, shown in figure 1, which consists of a tubular reduction collar 7 and a tubular reduction cone 8. The reduction collar 7 has an outer diameter which is so adapted that it with good fit can be inserted in to the coupling means 13, whereby the axial displacement is limited by the end 9 of one on the outside extending, tapered collar 17, which also forms a part of a sealing cone which fits to the tapered seat 19 of the coupling means 13. The reduction collar 7 is on its inside provided with a pheripheral groove 12, in which a sealing means 4 in the form of an O-ring is applied. The reduction cone 8 has an inner cylindrical surface, which diameter essentially is the same as the outer diameter of the steel conduit 1 and an outer conical envelope surface 18 which fits to the inner tapered seat 11 of the reduction collar 7. Figure 2 shows all parts included in a clamp ring connection, namely a straight joint coupling 13, a reduction set 5, a nut 14 and a steel conduit 1, which shall be connected to the coupling means , shaped as a joint coupling. This is provided with external threads 15 and a tapered seat 19. The nut, which has internal threads 16 can be screwed on the external threads 15 of the coupling means 13 and is pro vided with a tapered seat 22, which is arranged to cooperate with a corresponding tapered bevel 23 at one end of the reduction cone. In the embodiment a coupling of a standard type has been chosen but with a dimension larger than one would normally have chosen for connection with a copper conduit. The coupling means 13 thus has a inner diameter a which exceeds the outer diameter b of the steel conduit with at least one standard dimension, i.e. with several millimeters, which makes it possible to arrange said groove 12 for the sealing 4 within the reduction collar. When assembly the device the nut 14 is screwed on the coupling means 13, which results in an axialy directed force on the reduction cone 8, which partly is pressed in under the reduction collar 7 and in contact with the seat 11. which results in a radially directed force against the steel conduit, see figure 3. As the reduction cone consists of a softer material than the steel conduit, the reduction cone will adapt itself to possible unevennesses or unroundnesses of the steel conduit 1, whereby a high resistance against axially directed drawing forces is achieved. As the steel conduit only to a limited extent can be affected by radially exerted forces of the reduction cor.e, a completely safe sealing cannot be quaranteed at high pressure in the conduit, and therefor the sealing ring 4 is arranged to effectively stop leakage. Measurements have shown that the above described connection gives a resistance corresponding to a drawing force of above 8000 N and a tight joint at pressures up to 32 bar. The invention is not limited to the above described embodiment but is of course adaptable also for other embodiments within the scope of the following claims.

Claims: PATENT CLAIMS A device for connection of hard conduits, e.g. steel conduits (1), with a clamp ring connection intended for soft or semisoft conduits, such as copper conduits, which clamp ring connection comprises a coupling means (1 ), one to this fitting nut and a connection member, characterized in that the coupling means and the nut are chosen in suitable sizes from a standard assortment, that the chosen coupling means (13) is at least one standard dimension larger than that which fits to the steel conduit (1), that the connection member between the coupling means (13) and the steel conduit is a so called reduction set (5), consisting of a reduction collar (7) and one with this cooperating reduction cone (8), that the connection part of the reduction collar (7) i s arranged to fit in the chosen coupling means (13), that the inner cylindrical surface of the reduction cone (8) is arranged to fit to the outer cylindrical surface of the steel conduit (1), that the reduction collar on the inside (2) is provided with at least one groove (12) for a sealing means (4) for sealing cooperation with the outside of the steel conduit, and that the reduction cone (8) consists of a softer material,preferably brass, than the steel conduit, whereby the reduction cone when tightening the nut on the coupling means adapt itself to occuring unevennesses or unroundnesses of the steel conduit 2. A device in accordance with claim 1 , characterized in that the reduction collar's (7) and the reduction cone's (8) with each other cooperating ends (9,10) are connected with each other and arranged to break said connection when they are axially displaced from each other. 3. A device in accordance with claim 1, characterized in that said sealing means (4) is an O-ring.

Inventors: BOERJESSON KURT, ENGELBREKTSSON ERIC, BOERJESSON, KURT, ENGELBREKTSSON, ERIC
Applicants: BOERJESSON KURT, ENGELBREKTSSON ERIC, GUSTAVSBERG VAARGAARDA ARMATUR, BOERJESSON, KURT, ENGELBREKTSSON, ERIC, GUSTAVSBERG VAARGAARDA ARMATUR AB
Application year: 1998
Main classification: F16L19
IPC codes: F16L19