Blanking disc

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A glasses lens in the open position in a natural gas pipeline

A blank is used for the temporary separation of a pipeline . For this purpose, the blanking plate is installed in a specially prepared flange connection .

With blanking disks, a section of a pipeline or a container can be separated (isolated) from the rest of a chemical plant or pipeline network. Such a separation is necessary for maintenance work (especially when containers are entered by personnel) and for a pressure test .

Designs

Sketch of a lens for glasses

Designs without open disc are referred to as dummy wafer referred to as open slices open disc , with a bore such smaller nominal diameter than the throttle disc .

Spectacle blinds (to DIN EN ISO 10628: 2000 Umsteckscheiben ) combine reactive and open disks by two circular plates each welded are:

  • the closure part as a flat plate with the hole pattern of the prepared flange connection ( blind disk ),
  • the operating part with the same hole pattern and a hole with the same nominal width as the connected pipeline ( open disc ).

Adapter disks therefore only have to be converted for normal operation of the pipeline; The correct installation can be recognized immediately by the part protruding from the flange connection. Because of this shape, the lens is also called a spectacle lens .

Application example

A container with blanks

In the second photo on the right you can see a yellow container through which natural gas flows during operation. Before the lid can be opened, the following steps must first be carried out:

  1. Close both slides (with the black handwheels above the stage)
  2. Release the gas and thus lower the high pressure in the container to ambient pressure. A few smaller fittings and pressure gauges are available for this.
  3. Loosen the screws on the flanges on which the blanking washers are located.
  4. Turn the blanking disks so that the side (shown in the photo) is without a hole in the line and the side with a hole protrudes.
  5. Retighten the screws on the flanges with the blanking washers.

literature

  • Günter Wossog (Ed.): Handbook of pipeline construction. 3rd edition, Vulkan Verlag, Essen 2008, ISBN 978-3-8027-2745-0 .
  • Johann Mutschmann, Fritz Stimmelmayr: Pocket book of water supply. 13th edition, Friedrich Vieweg & Sohn Verlagsgesellschaft, Wiesbaden 2002, ISBN 978-3-663-12398-9 .

Web links

Commons : Glasses Blind  - Collection of images, videos and audio files