Maintaining the Tension on a Wire in Extreme Environment

With information in the OP, this is a good answer.

I am sure we will get more info that makes this impractical... in the meantime, GA.

That is actually what I am working on now. Unfortunately the space / weight is limited.

Another way would be to form the wire into a coil (or zigzag pattern) and place it in the solution under tension. As the wire expands (and contracts) the coil will lose (and regain) some tension but should still have enough to stay in place, even under repeated or rapid thermal cycling.

This solution will obviously not work for all situations (especially if the wire is not flexible enough or too flexible) but may be a viable alternative as it requires no further mechanisms unlike those indicated in post #1 (which is the other good way).

Also a good idea that I have tried. I am using ZrOx ceramic for support and it does not have enough flex to take up the slack. I wish there was a material that could stand up to the operating conditions and had more flex to it.

If wishes were horses beggars would ride. And if it was easy someone else would have don it already.

Good answer. That is what Edison used in his light bulb filiaments. (An extreme environment for sure!)

Use a wire that has a lower coefficient of thermal expansion that the structure that is supporting it or vice versa (note this will increase the tension on the wire as the whole thing is heated). For a constant tension, go for OzzyB's suggestion.

The easiest way I see is to apply a spring on one end of the wire to compensate the elongation at the maximum temperature.

It would be good to know the purpose of the wire and material

• what tension you require
• what is the diameter and
• length.

With this data you could calculate the thermal expansion.

A steel spring is not effected by caustic soda, hydrogen or oxygen. (I presume you are processing aluminium in the tank )

Good luck

Steal is readily attacked in dilute NaOH solution. The vessel is inconel 600 and every thing else is Ni 270, ZrOx or PTFE. I tried using some 625ss and rust forms on it. If you know of a spring or at least some what springy material that will function in dilute (0.1M - 1M) NaOH at 200C that would be great!

Maybe use pneumatic or hydraulic cylinder to maintain tension. Use spring at one or both end of the wire.

What about a temperature resistant silicon rubber tube or band that could be pretensioned to take up the slack?

How about a chunk of magnetic material holding one end of the wire, with a magnet outside the vessel to apply tension. Magnetic materials include ferrites, nickel, iron (this is a good chance), cobalt, magnetic alloys such as silicon steel (transformer steel).

If the vessel is magnetic, this may not work.

Got to agree with Ozzb.. its the easiest and the most simple of arrangements, in fact if you look at any electrified train supply, that exactly what you will see for tensioning the wires..

glass towers with glass beads with holes in all of them to allow easy passage larger or more of the beads higher tension one more tower .. for more tension movement

easy calc for weight = tension

right glass non reactive in situation.. so a Pyrex possibly

You did not mention how long the wire is, but would it be possible to connect one end of the wire to another wire which would be run over a pulley and then connected to a suspended weight? The weight would only need to be enough to maintain tension.

If this won't work, let me know and I'll try to come up with something better.

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My avatar picture is the device in which this is taking place. The internal dimension is a cylinder ~4"D X 5"L. There is a basket, stir and heat exchanger inside as well as the wire. I am looking into #9. I did not think Silicon tubing would work at 200C but I hope it will. That would be an easy solution - the best kind.