WO2001038778A1

WO2001038778A1 - Safe ring

Info

Publication number: WO2001038778A1
Application number: PCT/SE2000/002210
Authority: WO
Inventors: Hans Bertfelt
Original assignee: Bertfelt Teknik Ab
Priority date: 1999-11-22
Filing date: 2000-11-10
Publication date: 2001-05-31
Also published as: AU1652901A; SE0000765D0

Abstract

A spray shield for a pipe flange joint for preventing spraying of fluid, flowing through the pipe flange joint, in case of gasket failure, comprising a band (2), which covers the gap (5) which is present between two flanges (7) in the pipe flange joint and a gasket (6) provided in between the flanges (7) and at least a portion of each flange (7) that adjoin the gap (5). A porous material (3), is loosely or fixedly arranged on the side of the band that faces the flanges (7), at least of a width covering the gap (5), to slow down and spread out fluid which sprays outwards in case of gasket failure. The material (3) has a capacity of partly take up fluid. Also the fluid taken up by the material (3) slows down the spraying fluid. The spraying fluid trickles from the porous material (3) outwards between the flanges (7) and the band (2).

Description

Safe ring

The present invention relates to a spray shield for a pipe flange joint for preventing spraying of fluid, which flows through the pipe flange joint, in case of a gasket failure, comprising a band that in use covers the gap between two flanges in the pipe flange joint and a gasket, provided between the flanges, and at least a portion of each of the flanges that adj oin the gap .

BACKGROUND ART

Pipe systems are made up of a plurality of pipes and pipe bends. Normally these are connected to each other by providing the pipe ends with flanges and to attach these to each other with a gasket in-between the flanges, a so called pipe flange joint. In use, fluid flows in the pipe systems. If a gasket fails the fluid sprays straight out. Already at low pressures a powerful jet with considerable range arises. Additionally if the fluid is hot or corrosive, these suddenly occurring jets may be extremely dangerous and cause extensive damage. The spray shield is there to catch a jet of fluid from a damaged gasket so that the jet will not spray directly outwards of the joint.

EP 0 080 654 shows a spray shield for pipe joints, which spray shield comprises a preformed, to a ring, clamping band, which extends around the flanges and covers the flange gap. On the inside of and along the centre line of the clamping band, a C-shaped band is arranged. The band has slits along its sides to be bendable inwards and to be mountable in the clamping band and for letting leaking liquid through. The C-shaped band protrudes into the flange gap and the clamping band is tightened around the flanges when the spray shield is in use. The C-shaped band is there to disturb the flow of the spraying liquid so that the liquid flows out through the gap between the flanges and the clamping band instead.

As long as the clamping band corresponds to the circumference of the pipe flanges and the gap between the pipe flanges is filled by the C-shaped band so that its slitted edges bias against the insides of the flanges, this solution works. If the gap between the flanges is too big, a play will arise between the C-shaped band and the insides of the flanges, which means that the spraying liquid will only partly be disturbed and the liquid will spray with a high pressure outwards between the flanges and the clamping band. If the gap is too small, the spray shield according to EP 0 080 654 is not even usable.

A large number of different spray shields must be made and stored to be able to fit all different diameters and flange gaps. Additionally, since the spray shield is ring shaped, it takes up a large volume, both when stored and transported. All this lead to the fact that it is expensive to manufacture, store and transport these spray shields .

If the diameters of the flanges are different or if the pipes are mounted a bit out of line so that they are not concentric a play arises between the clamping band and the flanges so that the liquid sprays with a high pressure outwards between the flanges and the clamping band.

If only a band without having anything on its inside is mounted around a pipe flange joint, the fluid spraying due to a gasket failure will only be directed 90 degrees differently and spray powerful jets orthogonally to the plane of the flanges.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an inexpensive spray shield for pipe flange joints, which solves the problems of the known art .

This object is met according to the invention by a spray shield according to the preamble, which is characterised in that a porous material is loosely or fixedly arranged along the side of the band which in use is facing the flanges, at least having a width that covers the gap, for slowing down and spreading of spraying fluid from a damaged gasket, which material has a capacity to partly take up fluid, where also the uptaken fluid slows the spraying fluid down, whereby the fluid trickles from the porous material outwards between the flanges and the band.

This has the advantage that irrespective of the size of the gap between the pipe flanges or if the pipe flanges have different diameters or are not concentrically mounted, the gap is filled and covered by the porous material . The purpose of the porous material is to slow down and spread the spraying fluid fully in the porous material part and to partly take up the fluid. The uptaken fluid aids further to slow down the spraying fluid. Concurrently that more fluid is spraying out the porous material takes up the fluid, whereby the already taken up fluid is pressed out of the porous material, which fluid is trickling or running outwards between the flanges and the band.

The fluid is at first hand a liquid but may also be, e.g. a steam or a gas .

According to one embodiment, the porous material comprises a " knitted" , " crocheted" or woven material . Preferably, it is made of metal thread but may, for example, be made of nylon thread, such as fishing cord, instead. The material part may have the form of a strip, a stocking or hose, multiple layers of web or be " matted" of fibres, such as steel wool. If desired a fibrous material may be placed inside a " knitted" material .

According to another embodiment, the porous material comprises a sponge material with open pores, such as any type of foam rubber or plastic .

The band may be made of a bendable material which, when it is not in use, is elongated and flat. Preferably, the band is resilient, too.

This gives the advantage that the spray shields are not taking up a lot of space and may therefore be stored and transported easily and inexpensive contrary to preformed spray shields according to known art, which are stored and transported in the shape of space-consuming rings. Further, the spray shield may be mounted oval and rectangular flanges and at manholes and at applications where the gap between the flanges are negligible or non-existent.

Preferably, the spray shield is connectable by means of locking means in its end portions to form a ring. This may be performed in many different ways, which the person skilled in the art may understand, for example by means of snap-locks or a loop provided in one of the ends which is to hook onto one of a plurality of hooks provided at differently spaced positions from the other end and which loop is fixed in this position. Another example are hooks in one of the ends of the band that cooperates with recesses in the other end of the band and which is tightened by means of clamping means.

With a large number of hooks provided at differently spaced positions from the end edge, the spray shield may be used to pipe flange joints of widely spread diameters.

According to a further embodiment of the present invention, the spray shield is provided with guide pins, which, when the spray shield is used, protrude into the gap.

According to a variant, the spray shield is provided with a guide rail having creases, which, when the spray shield is used, protrude into the gap between the flanges .

According to a still further embodiment, the porous material may be provided with a crease along the circumference, which protrudes into the gap between the flanges and on its other side form a channel together with the band. This channel provides that the spraying fluid quickly may be transported out and be spread around the full circumference.

The advantage of having some kind of guidance that protrude into the gap between the flanges is that the spray shield securely is fixed even if the pipe flange joint, for example, vibrates heavily.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail by means of preferred embodiments together with references to the appended drawings .

Fig. 1 illustrates a spray shield according to the present invention from the side that faces the pipe flange joint in use,

Fig. 2 illustrates a cross section of a spray shield according to the present invention which is mounted on a pipe flange joint,

Fig. 3a illustrates an example of a locking means for connection of the ends of the spray shield according to the present invention, Fig. 3b, 3c illustrates another example, of a locking means, from the side and from above, respectively, for connection of the ends of the spray shield of the invention,

Fig. 4 illustrates guide pins provided at the spray shield of the invention,

Fig. 5a illustrates a guide rail provided at the spray shield of the invention from the side that faces the pipe flange joint in use,

Fig. 5b illustrates the guide rail from the side in use position,

Fig. 6a, 6b illustrates a porous material provided with a guide crease in two variants.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In fig. 1 a spray shield of the present invention is illustrated, which comprises a band 2 or a rail, a porous material 3 and locking means 4. The band 2 is bendable, substantially flat and elongated. Preferably the band 2 is resilient, too. On its one side, the side that in use will face the pipe flange joint, the porous material 3 is loosely or fixedly arranged along the length of the band, which material has a width which at least corresponds to the distance or the gap 5 between the two flanges 7 in the pipe flange joint, see fig. 2.

Between the flanges a gasket 6 is arranged. When this gasket 6 breaks, fluid sprays outwards between the flanges, which the present invention prevents by means of the porous material slowing down and spreading out the fluid along the periphery, whereby the material at least partly takes up the fluid. The fluid taken up by the porous material will also aid by further slowing down the spraying fluid. The porous material may, for example, be provided by means of adhesives or welding, of course depending of the type of material used. In use the band 2 is bent around the pipe flange joint, so that the side provided with the porous material 3 abuts the pipe flanges 7 and the gap 5 is covered by the porous material 3. The ends of the band 2 are connected by locking means 4.

The locking means may be of any type. As a first example, a suggestion of a locking device 4 is described in connection with fig. 3a. In one end of the band, a clasp 8 is pivotably provided. A small distance from the attachment of the clasp 8, on the clasp 8, a loop 9 is arranged. In the other end of the band, at least one row of hooks 10 are provided in differently spaced positions in relation to the end edge.

At connection of the band ends for forming a ring, the loop 9 hooks onto one of the hooks 10, thereafter the clasp 8 is pivoted downwards the band 2 so that the locking device 4 is tightened. Which one of the hooks 10 to be used depends on the diameter of the flanges 7. Due to the large amount of hooks 10, the spray shield 1 may be used for pipe flange joints of diameters differing vastly.

A second example of locking means is shown in figs . 3b and 3c. A small distance from one of the ends of the band 2, on the outside of the band when in use, two hooks 14 are provided. In the other end of the band 2 two rows of recesses 15 are arranged for cooperation with the hooks 14. In fig. 3b it is shown that the end provided with hooks lies inside of the other end provided with recesses 15. The hooks 14 protrude through the recesses 15. The end showing the recesses 15 is also provided with a clamping device 16, which is arranged, seen from the end, on the other side of the recesses 15. Of course one or multiple hooks 14 may be used with corresponding number of rows of recesses .

When the hooks 14 have hooked into the recesses 15 the clamping device 16 is clamped by screwing a screw 17 inwards, preferably a screw with a wing, which cooperates with a fixedly attached nut 18 so that the band 2 is tightened around the pipe flange joint and the hooks 14 hook into the edges of the recesses 15. In fig. 3b it is shown that the end of the band which is provided with hooks extends inside of the other end of the band so long that both the recesses 15 and the clamping device 16 are covered and thereby not disturbing the function of the spray shield 1.

The spray shield 1 ought to be tightened so much that it is kept in place by friction between the porous material 3 and the flanges 7.

In fig. 4 it is shown how guide pins 11 may be arranged along the band. They can be of use if the spray shield 1 is used, for example, in a vibrating environment. The guide pins 11 protrude into the gap 5 between the flanges 7 and keeps the spray shield 1 in place in such a way. If the spray shield 1 should be used around a pipe flange joint with a large gap 5 it could be advantageous to, for example, provide the guide pins 11 in a staggered way or in pairs .

Another example of guidance is illustrated in figs. 5a and 5b. A guide rail 12 is provided along the band 2, on top of the porous material 3, for example, by spot welding, if the material allows this. At a number of positions along the guide rail 12, the rail 12 is creased or bent so when the band 2 is bent to a ring these creases 13 protrudes out from the band 2 and the porous material 3. When the spray shield 1 is in use the creases 13 protrudes into the gap 5 between the flanges 7 and keeps in this way the spray shield 1 in place.

It has further been shown in tests that the guide rail 12 aids in quickly spreading the fluid along the periphery of the pipe flange joint at extremely high pressures and at extremely large damages to the gasket .

In figs . 6a and 6b a spray shield 1 is shown in a mounted position having a porous material 3 , which is provided with a crease 19. The crease 19 extends into the gap 5 between the flanges 7 so that the spray shield 1 securely stays in place . Further a channel 20 is formed on the other side of the porous material 3 together with the band 2. This channel 20 contributes to a quick spreading of the spraying fluid around all of the periphery. The crease 19 may have any desired shape. In fig. 6a a V- shape crease is shown and in fig. 6b a crease 19 is shown, which forms a channel 20 having a rectangular cross section.

Claims

1. A spray shield for a pipe flange joint for preventing spraying of fluid, flowing through the pipe flange joint, in case of gasket failure, comprising a band (2) , which covers the gap (5) which is present between two flanges (7) in the pipe flange joint and a gasket (6) provided in-between the flanges (7) and at least a portion of each flange (7) that adjoin the gap (5) , further a porous material (3) , having a capacity of partly taking up fluid, is loosely or fixedly arranged on the side of the band that faces the flanges (7) , at least of a width covering the gap (5) , characterized in that the porous material (3) is provided to slow down, spread out and together with the band (2) direct the fluid, which sprays outwards in case of gasket failure, where also the fluid taken up by the material (3) slows down the spraying fluid, whereby the fluid trickles from the porous material (3) outwards between the flanges (7) and the band (2) .

2. The spray shield according to claim 1, wherein the porous material (3) comprises a " knitted" material.

3. The spray shield according to claim 2 , wherein the porous material (3) is " knitted" of metal thread.

4. The spray shield according to claim 2 or 3 , wherein the " knitted" material (3) is filled with a fibre material.

5. The spray shield according to claim 1, wherein the porous material (3) comprises a sponge material.

6. The spray shield according to any one of the claims 1-5, wherein the band (2) comprises a bendable material, which is, when not in use, substantially flat and elongated.

7. The spray shield according to claim 6, wherein the band (2) is resilient.

8. The spray shield according to any one of the claims 1-7, wherein the band (2) is connectable by means of locking means

(4) in its end portions for forming a ring.

9. The spray shield according to any one of the claims 1-8, wherein the band (2) is provided with guide pins (11) , which protrudes into the gap (5) when the spray shield (1) is in use.

10. The spray shield according to any one of the claims 1-8, wherein the band (2) is provided with a guide rail (12) provided with a crease (13) , which protrudes into the gap (5) when the spray shield (1) is in use.