DE3123060A1 - Pipe for high temperatures - Google Patents

Abstract

On pipes which are subject to high stress resulting from heat, pressure and/or radiation, the occurrence of cracks is often assisted by the wall thickness being overdimensioned because of safety requirements. This is because the expansion stress is increasingly exacerbated with its thickness. More suitable materials are being looked for in order to avoid cracks. As a supplement to this, and in order to reduce the said stress, the present invention recommends a pipe whose wall consists of at least two layers (pipes) which lie one above the other and can be displaced axially with respect to one another when heat expansion occurs. In consequence, the said stress is reduced and thus the risk of fracture. The figure shows on the left the case in which the overpressure p in the pipe prevails. The pipe (1) can slide in the flange (2) and is sealed at (3). Short pipes (4) are pushed onto (1) in an unsealed manner. Elastic intermediate elements (for example spring washers) are located at (5). The pipes (4) support the pipe (1). On the right-hand side, the overpressure p is intended to be outside the pipe. The closed pipe (4) can slide on the pipe (1) and in the flange (2) and is sealed at (6). <IMAGE>

Description

Tubes for high temperatures.

Pipes, such as those installed in steam generator or nuclear systems and are exposed there to high stresses due to heat, pressure and radiation, occasionally suffer cracks, especially when the wall thickness is due to safety requirements are very oversized.

Because a pipe that has a temperature gradient across its wall has to the axis, is, preferably in its longitudinal direction, different want to expand.

Since it can only do this as a whole, tensions arise in the wall, which, together with others, can grow so large that cracks form. To do this avoid, better materials are on the lookout everywhere.

In addition to these efforts, the present invention recommends Pipe arrangements in which the above-mentioned tensions are significantly reduced that the wall is made of at least two superimposed layers that can move axially to each other. This will make the above described "Tensile stress" is reduced to the extent and the risk of cracking is reduced, such as layers available. Because of the now lower stress on the material this is also less high quality.

Some exemplary embodiments are shown schematically in the figures.

Fig. 1 shows two tubes inserted one inside the other. The inner 1 is between two fittings 2 and 3 firmly and tightly attached. The outer tube 4 is displaceable attached on the inner to a connector 3, but to the connector 2 it maintains an "expansion distance" 5.

The connecting piece has a support ring over the end of the tube 4 6th

In Fig. 2, the pipe 1 is also between two connecting pieces 3 firmly and tightly attached. On the tube 1, a metal band 7 is wound up and attached to the connecting pieces that flehnung distances 5 are observed.

In Fig. 3, 4 pipes were chosen as an example, which can be moved longitudinally among each other are connected to the connector 2. But only pipe 1 is with the connector 2 firmly and tightly attached. At the other end, not shown, are the tubes 1 and 4 firmly and tightly attached to a connection piece 3 as in FIG.

Iffl otützansatz 6 of the connection piece 2, the pipes 4 are arranged so that each maintains an expansion distance 5 and with the sealing rings 8 (asbestos and / or Carbon fiber) are sealed with each other and with tube 1.

Another execution is recommended if the two contact points the connection pieces are fixed points in the room.

Then a design like Fig. 4 is possible at both ends, where pipe 1 as well as the tubes 4 can be longitudinally displaced at both ends with expansion spacings 5 and sealing rings 8 are mounted in the support extension 6 of the connection piece 2.

This arrangement, which is then doubly flexible, is particularly advantageous when if the contact points represent stable fixed points (levels), but how mostly, can shift within limits due to stress. Also for the and expansion of the pipes, this flexible arrangement brings advantages.

Next is next to the expansion distance 5 for several sealing rings 8 shows the distance 9, which results from the ring width and an expansion distance 5 This makes inserting the rings easier and the support attachment 6 only needs to be divided once, as with part 10.

In addition, any advantageous combination of the examples described can be used can be applied.

L e r s e i t e

Claims (3)

Claims 1. Pipes for high thermal and mechanical loads, the walls of which consist of at least two superimposed layers, thereby characterized in that these layers are designed to each other that an axial Displacement between them through thermal expansion can take place by also reasonable i) freedom of information is provided. 20 pipes according to claim 1, characterized in that the over layers located in a middle tube are also tubes, but also bands or Wires are. 3. Pipes according to claims 1 and 2, characterized in that several tubes inserted one inside the other at both ends can be moved one below the other in Connection pieces and sealed with seals and stored with expansion distances are. 4o tubes according to claim 3, but characterized in that the tubes are slidably mounted only at one end, while at the other end End firmly and tightly attached to the connecting piece 0 50 pipes according to the claim 4, characterized in that one of the pipes is firmly afld in both connection pieces is tightly attached. 60 pipes according to claims 1 to 5, characterized in that the aforementioned pipes and layers in a general interpretation also include containers like boiler, gore or heat exchanger.