GB2212239A

GB2212239A - An inspection glass fitting

Info

Publication number: GB2212239A
Application number: GB8825919A
Authority: GB
Inventors: Wilhelm Schulz
Original assignee: Schulz & Co KG Wilhelm
Current assignee: Schulz & Co KG Wilhelm
Priority date: 1987-11-06
Filing date: 1988-11-04
Publication date: 1989-07-19
Also published as: DE3737695C2; GB8825919D0; FR2622953A1; DE3737695A1

Description

1 "An inspection glass fitting" 1;1 2212239 The present invention relates

to an inspection glass fitting for incorporation in pipelines, tanks or accoutrements, which mainly consists of a tube portion, from which tubular attachments of smaller diameter than that of the tubular member are seamlessly necked out on diametrically opposite sides, and its opposite apertures are hermetically sealed by glass discs releasably attached to the tube portion, with the insertion of packings.

Inspection glasses of the type referred to above are known, for example, from German OS 31 45 086.

Inspection glass fittings incorporated in pipelines or tanks upstream or downstream of shut-off fittings are used for observing the colour, consistency or degree of dirtying of the following medium. Known inspection glass fittings are produced by mould casting and have a tube portion to whose opposite open ends attaching flanges are moulded, welded or applied in one piece. In the central portion, spigots with flanges are also moulded or welded in one piece to diametrically opposite sides of the cylinder generated surface. The first-mentioned flanges serve for the incorporation of the inspection glass fitting in the pipeline and the last-mentioned flanges for the attachment of the glass discs, which are generally releasably attached by means of a flanged ring with the interposition of sealing rings, so that when damaged the discs can be interchanged or cleaned.

2 It is relatively expensive to produce inspection glass fittings by the mould casting process, since a special model must be prepared for each dimension and the casting must be performed individually. Since the inspection glass armatures must repeatedly be made of different materials, namely the same material as the pipeline into which they are to be incorporated, relatively expensive individual production is required. Since the wall thickness of the cast products is always relatively large, a correspondingly large amount of tube material must be used.

German OS 29 33 939 discloses a more economical method of producing such inspection glasses by providing flat bearing surfaces moulded-on in one piece for the glass discs on the tubular member in the zone around the apertures. This obviates dead spaces, so that vision through the glass discs is not affected by deposited dirt, even with prolonged use of the fitting. With this known inspection glass fitting, a portion of the pipeline in which the inspection glass fitting is to be incorporated can be used for its production. In that case the portion in question is made of the same material as the pipeline, so that no problems arise due to the pairing of different materials. The portion has a smaller wall thickness than a mould casting product, and therefore requires less material and is more inexpensive merely for that reason. The formation of the bearing surfaces for the glass discs of the inspection glass fitting, which must be hermetically sealed by the disc in the zone of the apertures provided on diametrically opposite li, F.

3 sides of the generated surface can also be manufactured in a very simple manner by contact pressure, something which reduces manufacturing costs.

In inspection glass fittings of the type referred to above problems are caused by the releasable attachment of the glass discs hermetically sealing the opposite apertures in the tube portion. According to German OS 31 45 086, the glass disc is enclosed by a ring which is hermetically inserted in the end portion of the tube portion via an annular seal in the external peripheral surface and axially located by means of a retaining ring. A method of this kind is also provided for the inspection glass fitting disclosed in US Patent Specification No. 2,681, 034, although in that case the seal is provided not in the peripheral surface of a ring enclosing the glass disc, but in the bearing surface thereof in the end portion of the tube portion. Neither of these similar methods ensure that the bearing surface of the glass disc against the tube portion is reliably sealed or remains so even under internal pressure, since the retaining ring in view of its function does not exert any axial force on the glass disc, but its force is radially directed. The glass disc has therefore a clearance in the axial direction which can lead to leakage if the packing between the disc and the tube portion is inadequately pressed.

In other known inspection glass fittings the glass disc is attached via screws to the tube portion by means of a contact pressure plate or a contact pressure ring. Examples 4 are disclosed in German Patent Specification 29 33 939, German Utility Model 78 28 731. German Utility Model 71 00 720 and, in a very expensive construction using a pair of flanges at each aperture, in German Utility Model 80 24 144.

The known attachment of the glass disc to the inspection glass fitting by means of screws has the disadvantage that special steps must be taken in the -inspection glass fitting in order to receive the screw. Either the inspection glass fitting itself must have such a large wall thickness that the screws can be screwed directly into the wall of such fittings, or blocks, or as disclosed in German Utility Model 80 24 144 flanges must be provided for receiving the screws. In the case of German Patent Specification 29 33 939, due to its large wall thickness the inspection glass fitting is very heavy, and this increases costs due to the large amount of material. In the cases of German Utility Model 78 28 731 and German Utility Model 80 24 144, extra machining expenses involved in the application of the respective rings or flanges. Moreover, there is the risk that the inspection glass armature will become warped when the rings or flanges are welded on.

In the method disclosed in German Utility Model 71 00 720 the two opposite flanges for fixing the glass discs are interconnected by common screws and pulled against one another when the screws are tightened, so that the glass discs bear hermetically against the apertures in the inspection glass fitting. However, this calls for long fl 3 screws which add to the weight of the inspection glass fitting. Furthermore, centring collars are required for the glass disc, and lastly the mounting of the two glass discs simultaneously is a laborious operation.

It is an object of the invention to provide an attachment of the glass discs to inspection glass fittings which requires the smallest possible number of light-weight components and can be put into effect in the simplest possible manner. The glass disc can also be released in a very simple and problem-free manner.

According to the present invention there is provided an inspection glass fitting for incorporation in pipelines, tanks or accoutrements, comprising a tube portion from which tube attachments of smaller diameter than that of the tube member are seamlessly necked out on diametrically opposite sides and whose opposite apertures are hermetically sealed by glass discs attached releasably thereto, with the insertion of packings characterized in that worked into each of the end portions of the tube portion is an annular depression into which an annular packing is completely inserted and thereabove the glass disc is partially inserted; the end portions are formed with an external screwthread on which a screw collar ring engaging around the edge of the glass disc is screwed; and an annular packing is laid between the glass disc and the screw collar ring.

It is a relatively simple matter, calling for only a few components, to produce the inspection glass fitting according to the invention. A tube portion of ordinary or 6 special steel, copper or other metals or metal alloys is first provided seamlessly with two tubular necks on diametrically opposite sides of the tube portions. The neck is performed in the cold state by known methods of press moulding. Flanges used for the incorporation of the inspection glass fitting in pipelines or tanks are welded to the necks, or else the neckings are formed with screwthreads for connection to adjacent tube portions. The two end portions of the tube portion are also provided with an external screwthread. The length of the screwthread must not be very large. To create the necessary wall thickness for the additional reception of the external screwthread. The end portions of the tube portion can also be upset prior to the working-in of the screwthread.

After these relatively simple machining operations the actual casing of the inspection glass fitting is ready. All that is now needed are two glass discs, four annular packings and two screw collar rings to complete the inspection glass fitting.

An annular packing is inserted into an annular depression in the tube member end portions, whose diameter is somewhat larger than the diameter of the glass discs, glass disc being laid upon the annular packing. Only a portion of the thickness of the glass disc lies in the annular depression, the glass disc projecting at least a small distance beyond the end faces of the tube portion. The screw collar ring, equipped at the contact surface with the glass and engaging over the edge thereof, is screwed on X I- 7 to the externally screwthreaded end portion of the tube portion until the two annular packings are pressed together on opposite surfaces of the glass disc, the gaps being sealed. The screwing-on of the screw collar ring and the resulting pressing can be facilitated and controlled by means of wrenches or if necessary dynamometric keys. In the case of manual actuation. It is recommended to knurl or flute the peripheral surface of the screw collar ring, to increase grippability. If a wrench is used for operation, conveniently the peripheral surface of the screw collar ring can be formed with longitudinal notches or surfaces to which the wrench can be applied.

The present invention will now be described in greater detail by way of examples, with reference to the accompany drawings, wherein:- Fig. 1 is a longitudinal section through a preferred from of inspection glass fitting; Fig. 2 is a side elevation, of the inspection glass fitting shown in Fig. 1; Figs. 3 to 6 show examples of the external contouring of the screw collar ring to facilitate screwing on and off.

Figure 1 shows a tube portion 1 whose end portions 2 have an external screwthread 3. Tube attachments 4 are seamlessly necked out on opposite sides of the tubular member 1 and serve for connection to a pipeline, a tank or an accoutrement (not shown).

Connecting flanges 6 or connecting screwthreads 7 can be provided on the tube extensions. The direction of flow 8 through the inspection glass fitting is indicated by arrows 5.

An annular depression 8 into which an annular packing 9 is inserted is worked into each of the end portions 2 of the tube portion 1. A glass disc 10 is laid on the packing 9 and partly lies in the depression 8, and partly projects, as can be clearly sen in Fig. 1.

The glass disc 10 is releasably attached to the tube portion 1 by means of a screw collar ring 11 which engages by a radial extension 12 over the edge of the glass disc 10. Another packing 13 is located between the screw collar ring 11 and the glass disc 10. When rotated, the screw collar ring 11 screws itself on to the external screwthread 3 on the end portions 2 of the tube portion 1 and as a result via the packings 9 and 13 presses the glass disc 10 against the tube portion 1 to provide a hermetic seal.

In order to facilitate the turning of the screw collar ring 11, its periphery can be formed with a knurled surface 14 or fluting, as shown in Fig. 3. Alternatively, as shown in Fig. 4, the external peripheral surface of the screw collar ring 11 can also be formed with notches 15 to enable a tool to be applied to turn the screw collar ring 11.

In another alternate form as shown in Fig. 5, the screw collar ring 11 can be formed with flattened portions 16 for engagement by a wrench. The screw collar ring 11 can also be constructed in the form of a polygonal screw or nut 17, as shown in Fig. 6.

il 9

Claims

CLAIMS:-

1 1. An inspection glass fitting for incorporation in pipelines, tanks or accoutrements, comprising a tube portion from which tube attachments of smaller diameter than that of the tube member are seamlessly necked out on diametrically opposite sides and whose opposite apertures are hermetically sealed by glass discs attached releasably thereto, with the insertion of packings characterized in that worked into each of the end portions of the tube portion is an annular depression into which an annular packing is completely inserted and thereabove the glass disc is partially inserted; the end portions are formed with an external screwthread on which a screw collar ring engaging around the edge of the glass disc is screwed; and an annular packing is laid between the glass disc and the screw collar ring.

2. An inspection glass fitting according to claim 1, characterized in that the periphery of the screw collar ring is formed with a knurled surface fluting or notches which act as a screwing aid when opening or closing and also when mounting or demounting the inspection glass.

3. An inspection glass fitting according to claim 1, characterized in that the periphery of the screw collar ring has flattened positions on its surface for engagement with a wrench.

4. An Inspection glass fitting according to claim 1, characterized in that the periphery of the screw collar ring has flat surfaces in the form of a polygon.

5. An inspection glass fitting constructed substantially as herein described with reference to and as illustrated in the accompanying drawings.

1 i Published 1989 atThe Patent Office, State House, 66,71 High Holborn. LondonWCIR4TP- Further copies maybe obtained from The Patent Office. Was Branch, St Mary Cray, Orpington, Kent BRS 3RD- Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con. 1/87