GB2218769A

GB2218769A - Releasable pipe joint

Info

Publication number: GB2218769A
Application number: GB8911402A
Authority: GB
Inventors: Heinrich Eckermann
Original assignee: WAELZLAGER NORMTEILE VEB; VEB KOMBINAT WALZLAGER und NORMTEILE
Current assignee: WAELZLAGER NORMTEILE VEB; VEB KOMBINAT WALZLAGER und NORMTEILE
Priority date: 1988-05-19
Filing date: 1989-05-18
Publication date: 1989-11-22
Also published as: DD272344A1; DE3915011A1; GB8911402D0

Description

7 1, 1 m c 2218769 RELEASABLE PIPE.JOINT This invention relates to a

releasable or disconnectible pipe joint for use in any industrial plarit in which metal hydraulic and/or pneumatic pipes have to be assembled. It is preferably intended for use with flanged joints operating at normal pressures.

Joints are known in which pipes are clamped between a flange and a counterflange bolted together but these joints connect plastic pipes which are held by means of a flared end being pressed into the flanged joint with the aid of a clamping ring. Another known joint for connecting plastic pipes comprises a socket with an extended insert into the pipe to be connected, a diaphragm seal and a ring piece. The sealing ring has a frustoconical part which projects into the extended part of the socket and fits snugly against the outer surface of the pipe when the pipe joint is assembled. The other part of the sealing ring is a slip-on part and engages over the upper socket edge. This sealing ring _4S pressed against the outer cylindrical surface of the socket in a sealed manner by means of a ring piece.

1 2 - In yet another known pipe joint, an outwardly and inwardly tapered ring is pressed between two flange-like rings, the outer diameter being increased and the inner diameter being redJuced. This reduction in the inner diameter of the ring.means that the pipe is held in the pipa joint by the clamping action. This ring has no cutting edge. The pipe retaining forces are therefore small. Furthermore, an additional sealing element is required to seal the joint.

In many cases, pipe joints do not achieve their full service value or their full service life because the assembly moment achieved upon assembly of the sealing elements is too large or too small.

One disadvantage of sealing elements such as the cutting ring is the fact that in order to overcome large pipe tolerances, a correspondingly large axial distance must be covered,, and this can lead to defective assembly. In the applications described, the geometry of pipe Joints-of the 240 system is not explained. In yet another known sealing arrangement for a flanged joint,, the flanges are mounted on the Opposimg pipe ends, the flanges receiving a 111 1 Y frustoconical sealing ring.in correspondingly provided grooves. The seal has contact surfaces extending parallel to the central axis of the seal. A soft metal coating is applied to the outer and inner circumference of the sealing ring and, on assembly, these metal coatings come into contact with the lateral faces of the grooves,, while at the same time there is contact between the sharp edges and the corners of the grooves. This solution has several disadvantages in that not only does it involve a relatively high technological expenditure, but it also does not meet the requirements for the use of pipe joints, e.g. in the hydraulics industry with respect to welded pipe joints. Moreover, the sealing actio nis not produced directly at the pipe. Simple exchange of pipe joint elements is not possible.

The aim of the invention is to provide a joint for metal pipes which requires less material and which bridges larger pipe tolerances when an appropriately designed sealing element is used, thus ensuring very accurate assembly and high operational reliability, and ensuring that sealing is achieved with less effort being required for assembly.

1h 1 2.0 -V According to the invention. there is provided a releasable pipe joint comprising a body and a pressure piece to receive the pipe to be connected, securing means to draw the body and pressure piece together to clamp therebetween a tapered metallic spring ring seal for sealing the space produced between the pipe joint parts in the assembled state, the inner face of the ring surface having a toothed profile with at least one cutting edge, and the outer face of the ring acting as a supporting surface adapted to rest against a corresponding bearing surface in the body or pressure piece.

The invention provides a pipe joint which receives a radially acting resilient sealing element between the parts that are to be bolted together, said sealing element cutting into the pipe with material buildup.

In a preferred embodiment,, in its initial state, the spring ring seal is a known frustoconical sealing ring or is designed with a roof-shaped ring surface.

Al 1 1 is - n - The toothed profile on the inner face of the ring surface of the sealing ring is preferably disposed at an outwardly directed angle. A guide profile is preferably provided in the body in the region of the pip.6 seat. The sealing ring is cut-in with material build-up, the lower cutting edge face of the toothed profile, more particularly of the frustoconical sealing ring, resting against the guide profile in a sealed manner.

The pressure piece and the body have bearing surfaces which come together when the securing means, e.g. bolts, are tightened and cause a sharp increase in the assembly force, thus ending the assembly process. This prevents the sealing ring becoming ineffective owing to plastic deformation as a result of excessive expenditure of force on assembly.

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings,, in which:

1 Figure 1 shows an assembled pipe joint with an angular sealing ring, Figure 2 is a top view of the joint of Figure 1.

Figure 3 shows a pipe joint including a sealing ring with a sloping cutting edge, one half of the joint being shown in its unassembled state and the other half in its assembled state, Figure 4 is a cross sectdion of the sealing ring of Figure 3 showing its cutting edge, and Figure 5 is a cross section of t he angular sealing ring of Figure 1.

c :i The pipe joint shown in Figures 1 and 2 comprises a body 1, a pressure piece 2, a sealing ring 3 and a pipe 4 to be connected. The sealing ring 3 is disposed in a correspondingly provided recess 5 in the body 1. The body 1 and the pressure piece 2 are connected in a releasable or disconnectible manner by securing means such as bolts 6 so that they form one component which can itself be connected to another member such as a flanged joint. Several through-holes 7 (see Figure 2) serve for securing said component to the other member. The body 1 has an annular groove 9 on its underside for receiving an annular ring 8.

il 1 In its initial state, the sealing ring 3 has a roof-shaped cross section, i.e. the ring surface of the sealing ring 3 is formed by two contact surfaces tapered from the outside and the inside towards the pressure piece 2 and forming a point, each extending parallel with one another.

The inner face of the ring surface of the sealing ring 3 consists of a toothed profile 10 which comprises at least one concentric self-contained cutting edge 23 (see Figure 5) preferably disposed at an outwardly directed angle. A supporting surface 12 is provided on the outer face of the sealing ring 3 and extends parallel to bearing surface 11 provided in the recess 5 in the body 1. Before assembly, the diameter of the bearing surface 12 is smaller than that of the bearing surface 11. The toothed profile 10 has a larger diameter than the pipe 4,, so that the sealing ring 3 can be slipped easily over the pipe 4 and inserted into the recess 5.

When the bolts 6 are tightened. the pressure piece 2 transmits an axially acting force to the sealing ring 3. When they are tightened further, the toothed 1 Z profile 10 of the sealing ring 3 contacts the pipe 4 and cuts into it as a result of the forces-acting radially thereon. As the outer surface 12 of the sealing ring 3 rests against the bearing surface 11 of thebody 1, any outwardly directed radial extension of the seal 3 is prevented.

In the alternative embodiment shown in Figure 3, the annular seal 13 is disposed between the body laand pressure piece 2a and is frustoconical in shape. The outer face of the sealing ring 13 acts as a supporting surface 14 and corresponds with bearing surface 15 provided within a recess 16 in the pressure piece 2a.

The inner face of the sealing ring 13 is provided with a toothed profile 17. which is preferably disposed at an outwardly directed angle (Figure 5) and consists of at least one concentric self-contained cutting edge 24.

A guide surface 19 is provided in the body 1 at the entrance to pipe seat 18 which cooperates with the pipe 4 to be connected to ensure the sealing action of the spring ring seal (Figure 3).

1.1 1 1 is The assembly process for the flanged joint according to Figure 3 corresponds to that of theembodiment illustrated in Figure 1. The pressure piece 2a is first slipped on to the pipe 4 in such a way that the sealing ring 13 with the larger diameter is pushed into the recess 16. The pipe 4 is then inserted until it comes into contact with the pipe seat 18 in the body la. Consequently, the bolts 6 are guided through the pressure piece 2a and screwed into tapped holes 20 in the body la until the sealing ring 13 is firmly clamped between the pressure piece 2a and the body la and is pressed against seat 18 in the body la.

The increase in the assembly moment when the bolts 6 are tightened indicates the beginning of the cutting process. As the bolts are tightened further, a component of force directed radially towards the centre of the pipe and a radially outwardly directed component of force become effective as a result of the axial movement of the pressure piece 2a in the sealing ring 13 with increasing elastic deformation. However,, as it is impossible for the sealing ring 13 to extend further towards the outside owing to the bearing surface 15 of the pressure piece 2a, against which the 1 sealing ring 13 rests by- means of its supporting surface 17, only the component of force directed radially towards the centre of the pipe becomes effective so the sealing ring 13 cuts into the pipe 4 by means of its toothed profile 17.

The sealing ring 13 thus slides over the guide surface 19 acting as a sealing surface. When the bolts 6 are tightened further, bearing surface 21 of the pressure piece 2a (Figures 1 and 3) comes to rest against a bearing surface 22 of the body 1, la, thus bringing the assembly process to an end, indicated by a sharp increase in the assembly force- The invention has the following advantages:

Because they are flat, the sealing rings 3, 13 can be manufactured according to a processeconomizing on materials. The geometric position of the cutting-in point of the sealing rings 3. 13 in the pipe 4 is precisely defined. Fluctuations in tolerance in respect of the outer diameter of the pipe do not affect accurate assembly as larger distances can be bridged between the sealing rings 3, 13 and the pipe 4,, and f 'I W J - 11 thus pipes with larger tolerances can be used. Furthermore,, flanged joints can be produced with sealing rings 3, 13 with a minimum use of material, particularly in the case of larger dimensions, and there can be the minimum use of space as no lateral access is required for assembly.

There is no setting of the sealing rings 3, 13 as they maintain their resilient action during cutting-in so it is possible to use them even in the case of dynamic loads..

The assembly process has the advantage that there is no possibility of defective assembly due to subjective errors such as the destruction of the sealing rings 3, 13 as a result of excessive assembly forces. This is achieved by applying bearing surfaces 21, 22 to the pressure piece 2,, 2a and the body 1,, la so that the sealing rings 3. 13 only undergo elastic and not plastic deformation after the cutting-in process.

After the flanged joint has been dismantled,, the sealing ring 3, 13 springs back to a certain extent and can thus be removed from the recess 5, 16.

J

Claims

CLAIMS is 1. A releasable pipe joint comprising a body and a pressure

piece to receive the pipe to be connected,, securing means to draw the body and pressure piece together to clamp therebetween a tapered metallic spring ring seal for sealing the space produced between the pipe joint parts in the assembled state, the inner face of the ring surface having a toothed profile with at least one cutting edge, and the outer face of the ring acting as a supporting surface adapted to rest against a corresponding bearing surface or pressure piece.
2. A pipe joint as claimed in claim 1 wherein the sealing ring is frustoconical or includes a roof-shaped ring surface.
3. A pipe joint as claimed in claim 1 or claim 2 wherein the toothed profile ils disposed on the inner -j face of the ring surface of the sealing ring at an outwardly directed angle
4. A pipe joint as claimed in any one of claims 1-3 wherein the bearing surface is provided in a recess formed in the body or pressure piece.
5. A pipe joint according to any preceding claim wherein the body includes a pipe seat to receive the end of the pipe when inserted in the joint, a guide surface being provided in the body adjacent said seat.
6. A releasable pipe joint, substantially as herein described and illustrated in the accompanying drawings.

Published 1989 at The Patent Office, State House, 66,71 High Holborn. London WC I R. 4TP FluAher copies xnaybe obtainedfrom The Patent Office.

M= Mn miiitinipy tp.rhniaues ltd, St Mar-v Cray, Kent, Con. 1187