GB2103742A

GB2103742A - Improvements in or relating to welded flanged pipes

Info

Publication number: GB2103742A
Application number: GB08124267A
Authority: GB
Inventors: Cyril Barrie Greatorex
Original assignee: Stanton and Staveley Ltd
Current assignee: Stanton and Staveley Ltd
Priority date: 1981-08-07
Filing date: 1981-08-07
Publication date: 1983-02-23
Also published as: GB2103742B

Abstract

A welded flanged pipe has a flange mounted upon and welded to the pipe adjacent one end thereof, the flange configuration and the manner of welding being such that the part of the flange facing away from said one end of the pipe is prestressed in compression in the out-of-use condition of the pipe. Prestressing is achieved by making the internal diameter of the flange smaller than the external diameter of the pipe so that the flange may only be located upon the pipe by force-fitting or by expansion through heating.

Description

SPECIFICATION Improvements in or relating to welded flanged pipes This invention relates to welded flanged pipes of ferrous material of the kind in which a ferrous annular flange, by means of which the pipe is to be attached to an adjacent pipe, is secured by welding around the outer periphery of the pipe adjacent one end thereof.

Whilst at times such welded flanged pipes are intended and arranged for use in flanged connection with an axially juxtaposed pipe of similarly welded flanged construction, it is also at times a requirement to use welded flanged pipes with the flange located adjacent to a spigot of the pipe which is arranged for insertion into the socket of an axially juxtaposed pipe (usually with the interposition of an annular sealing member between the spigot and socket respectively), the flange in such arrangement being connectable by means of bolts or similar securing members to a member located behind or upon the socket so as to enable the joint to be locked together. The present invention is particularly, although not exclusively, concerned with welded flange pipes intended for the latter form of usage.

According to the invention there is provided a welded flanged pipe in which the flange is of such a configuration, and is mounted upon and welded to the pipe adjacent one end thereof in such a manner that the part thereof directed away from said one end of the pipe is prestressed in compression in the normal unused condition of the pipe.

It is to be understood that the word "pipe" as used herein includes any pipe like member such as a pipe, tube or hose, and hollow pipe fittings for use in pipe work such as elbows and "T"-junction members.

In configuration the flange may include a radially inner portion extending towards the end of the pipe. Thus the flange may throughout its thickness, deflect over its radially inner portion towards the end of the pipe. With such a configuration the flange may be welded to the pipe at the toe of the inward portion extending towards the end of the pipe and on the side thereof facing towards the end of the pipe.

The prestressing of the portion of the flange facing away from the end of the pipe may be assured by arranging the flange to be an interference fit on the pipe such that the flange requires to be pressed on or heated prior to fitting and then shrinks into a stress-creating fit upon the pipe. By this means and with the configuration described above, hoop compression is induced into the portion of the flange facing away from the end of the pipe. This compression is reinforced in use by the expansion of the pipe under internal pressure. The degree of prestressing so induced is controlled by varying the degree of interference between the flange and the end of the pipe.

We have found that by inducing the compression as provided by the invention, and thereby reducing at least part of the stress in the flange when utilised in the formation of a joint, a surprisingly lighter flange than has hitherto been possible can be utilised.

With the configuration of the flange described above, the weld around the pipe between the flange and the pipe is at all times in compression and can therefore be reduced in size.

The invention includes a pipe joint incorporating a welded flanged pipe as hereinabove defined.

In order that the invention may be more readily under-stood one embodiment thereof will now be described by way of example with reference to the accompanying drawing which is a part-sectional side elevation of part of a joint between two pipes incorporating a welded flanged pipe in accordance with the invention.

Referring to the drawing it will be seen that the joint comprises two pipes 1 and 2 incorporating a spigot and socket 3 and 4 respectively together with a resilient sealing member 5 located in the annular gap therebetween to prevent leakage of the contents of the pipe at the joint.

A flange 6 is mounted upon the pipe 1 adjacent the spigot 3 thereof. As will be seen the radially inner portion 7 of the flange 6 is deflected towards the spigot 3, and the flange 6 is welded (as shown at 8) to the pipe at the side of the toe 9 of this deflected portion facing towards the spigot 3. A plurality of strengthening webs 10 are disposed around the flange 6 on the side thereof facing towards the spigot 3.

Located around the socket 4 of the pipe 2 is a pressure applying annular gland member 11. The gland member 11, as can clearly be seen, is a loose fit upon the pipe but has a narrower internal diameter than the external diameter of the socket 4. The gland member 1 1 and the flange 6 have corresponding bores 12 and 13 (one of each of which is shown) through which bolts 14 are passed having securing nuts 15 on their ends. As will be appreciated tightening of the nuts and bolts forces the gland member 11 and the flange 6 together thereby holding the joint in a formed condition.

The flange 6 is an interference fit upon the pipe and when shrunk upon the pipe induces hoop compression into the back 16 of the flange 6.

Such compression is reinforced in use by the expansion of the pipe under internal pressure. The stress produced by the joint anchoring bolt 14 upon the flange 6 is therefore at least partially cancelled out by this hoop compression induced in the back of the flange. In addition, by locating the weld 8 at the nose of the flange, it is ensured that this is at all times in compression and therefore can be reduced in magnitude.

1. A welded flanged pipe in which a flange is mounted upon and welded to the pipe adjacent one end thereof, the flange configuration and the manner of welding being such that the part of the

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to welded flanged pipes This invention relates to welded flanged pipes of ferrous material of the kind in which a ferrous annular flange, by means of which the pipe is to be attached to an adjacent pipe, is secured by welding around the outer periphery of the pipe adjacent one end thereof. Whilst at times such welded flanged pipes are intended and arranged for use in flanged connection with an axially juxtaposed pipe of similarly welded flanged construction, it is also at times a requirement to use welded flanged pipes with the flange located adjacent to a spigot of the pipe which is arranged for insertion into the socket of an axially juxtaposed pipe (usually with the interposition of an annular sealing member between the spigot and socket respectively), the flange in such arrangement being connectable by means of bolts or similar securing members to a member located behind or upon the socket so as to enable the joint to be locked together. The present invention is particularly, although not exclusively, concerned with welded flange pipes intended for the latter form of usage. According to the invention there is provided a welded flanged pipe in which the flange is of such a configuration, and is mounted upon and welded to the pipe adjacent one end thereof in such a manner that the part thereof directed away from said one end of the pipe is prestressed in compression in the normal unused condition of the pipe. It is to be understood that the word "pipe" as used herein includes any pipe like member such as a pipe, tube or hose, and hollow pipe fittings for use in pipe work such as elbows and "T"-junction members. In configuration the flange may include a radially inner portion extending towards the end of the pipe. Thus the flange may throughout its thickness, deflect over its radially inner portion towards the end of the pipe. With such a configuration the flange may be welded to the pipe at the toe of the inward portion extending towards the end of the pipe and on the side thereof facing towards the end of the pipe. The prestressing of the portion of the flange facing away from the end of the pipe may be assured by arranging the flange to be an interference fit on the pipe such that the flange requires to be pressed on or heated prior to fitting and then shrinks into a stress-creating fit upon the pipe. By this means and with the configuration described above, hoop compression is induced into the portion of the flange facing away from the end of the pipe. This compression is reinforced in use by the expansion of the pipe under internal pressure. The degree of prestressing so induced is controlled by varying the degree of interference between the flange and the end of the pipe. We have found that by inducing the compression as provided by the invention, and thereby reducing at least part of the stress in the flange when utilised in the formation of a joint, a surprisingly lighter flange than has hitherto been possible can be utilised. With the configuration of the flange described above, the weld around the pipe between the flange and the pipe is at all times in compression and can therefore be reduced in size. The invention includes a pipe joint incorporating a welded flanged pipe as hereinabove defined. In order that the invention may be more readily under-stood one embodiment thereof will now be described by way of example with reference to the accompanying drawing which is a part-sectional side elevation of part of a joint between two pipes incorporating a welded flanged pipe in accordance with the invention. Referring to the drawing it will be seen that the joint comprises two pipes 1 and 2 incorporating a spigot and socket 3 and 4 respectively together with a resilient sealing member 5 located in the annular gap therebetween to prevent leakage of the contents of the pipe at the joint. A flange 6 is mounted upon the pipe 1 adjacent the spigot 3 thereof. As will be seen the radially inner portion 7 of the flange 6 is deflected towards the spigot 3, and the flange 6 is welded (as shown at 8) to the pipe at the side of the toe 9 of this deflected portion facing towards the spigot 3. A plurality of strengthening webs 10 are disposed around the flange 6 on the side thereof facing towards the spigot 3. Located around the socket 4 of the pipe 2 is a pressure applying annular gland member 11. The gland member 11, as can clearly be seen, is a loose fit upon the pipe but has a narrower internal diameter than the external diameter of the socket 4. The gland member 1 1 and the flange 6 have corresponding bores 12 and 13 (one of each of which is shown) through which bolts 14 are passed having securing nuts 15 on their ends. As will be appreciated tightening of the nuts and bolts forces the gland member 11 and the flange 6 together thereby holding the joint in a formed condition. The flange 6 is an interference fit upon the pipe and when shrunk upon the pipe induces hoop compression into the back 16 of the flange 6. Such compression is reinforced in use by the expansion of the pipe under internal pressure. The stress produced by the joint anchoring bolt 14 upon the flange 6 is therefore at least partially cancelled out by this hoop compression induced in the back of the flange. In addition, by locating the weld 8 at the nose of the flange, it is ensured that this is at all times in compression and therefore can be reduced in magnitude. CLAIMS

1. A welded flanged pipe in which a flange is mounted upon and welded to the pipe adjacent one end thereof, the flange configuration and the manner of welding being such that the part of the flange facing away from said one end of the pipe is prestressed in compression in the out-of-use condition of the pipe.

2. A pipe according to Claim 1 in which the flange includes a radially inner portion extending towards the end of the pipe.

3. A pipe according to Claim 2 wherein the radially inner portion throughout its thickness extends towards the end of the pipe.

4. A pipe according to Claim 2, or 3 wherein the flange is welded to the pipe at the toe of said radially inner portion on the side thereof facing towards the end of the pipe.

5. A pipe according to Claim 2, 3 or 4 wherein the flange is an interference fit upon the pipe.

6. A welded flanged pipe substantially as shown in and as hereinbefore described with reference to the accompanying drawing.

7. A pipe joint incorporating a welded flanged pipe according to any one of the preceding claims.