Flexible joint steel pipe/ceramic pipe

[TordFi]

Hello

I'm looking for a solution on joining a steel pipe til a ceramic pipe. Diameters are about 100mm. Air is flowing through the pipe at 4 bar and 800 degrees Celsius. More or less no leakage is accepted, and the steel pipe should be allowed to move 5mm relatively to the ceramic pipe.

Please let me know if you have any idea, suggestion, or know a company with competence. I assume there are already developed standard solutions in the marked.

 

[Onno]

Dear TordFi

Interesting construction scheme.
First of all, stainless steel and aluminim-oxide Al2O3 can be joined together using vacuum soldering/brazing. This method is used to produce electrical feedthroughs ie. a conductor insulated by a ceramic insulator. This brazingprocess is specialized and relies heavily on experience of the manufacturer. It will deliver leak free bonds: at 1 bar pressure difference, vacuum inside piping, leakrates smaller than 1e-10 scc/sec can be obtained.
You have the option of connecting removeable seals between the individual part for easy (dis)assembly.

Since bonding may not be a real problem, movement of your construction can be obtained by inserting a bellow.
Swagelok.com vacuum tubing may be of interest. They produce flexible bellows. A 1/4 inch bellow has a pressure rating of 100 psig (6.8 bar) Bigger than 3/8 in has 1.7 bar maximum pressure rating. Rolling a spring type tube may also solve your problem.

Of course 800 degrees C is somewhat high for using stainless steel. I know it can handle the temperature. However I am not up to date with all the specifics of your design and ideas. Yo masy consider heating to 800 C at the very last moment so starting at the position of the ceramic pipe when the metal parts have been passed.

Greetings from Onno