Elastic Hot Gas Seal - Up to 1200°F & 1 Atm Pressure

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Discussion Overview

The discussion centers around finding a suitable material to seal gas in a jet engine nozzle at high temperatures (up to 700°C or 1200°F) and pressures (up to 1 atmosphere). The context includes considerations for dynamic movement between the sealing surfaces and the need for effective sealing without excessive weight.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks a cloth material that can effectively seal gas at high temperatures and pressures, noting that the gas is mostly static in the sealed volume outside the nozzle.
  • Another participant suggests Grafoil as a potential sealing material, highlighting its use in high-temperature applications and its capability for both static and dynamic sealing.
  • A different participant mentions the difficulty in understanding the specifications of sealing materials without visual aids.
  • One participant proposes that a bellows type seal may be necessary depending on the surrounding geometry.
  • Another participant expresses a desire to avoid bellows seals due to weight concerns, emphasizing their role as an aerospace engineer.
  • A later reply counters that bellows seals are commonly used in many flying engines, suggesting a need for reconsideration of their use.
  • The original poster expresses optimism about a different sealing solution they found, indicating ongoing exploration of options.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and appropriateness of bellows seals, with some advocating for their use while others prefer to avoid them for weight reasons. The discussion remains unresolved regarding the best sealing material and approach.

Contextual Notes

Participants mention specific materials and manufacturers, but there is uncertainty regarding the performance characteristics of these materials under the specified conditions. The discussion also reflects varying priorities between weight savings and sealing effectiveness.

Aero Stud
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Hello people :smile:

Again I need some help...:shy:
I'm looking for a type of cloth that can be used to seal a gas at up to 700 degrees C (about 1200 F) and a pressure difference of up to 1 atmosphere.

Just to explain a bit more, I want to seal gas between two sections of a jet engine nozzle that can move a short ditance with respect to each other. The cloth is not directly exposed to the jet, just seals the whole thing on the outside, so the gas is mostly static in the emmidiate sealed volume ouside the nozzle, and pressure difference is actually probably less than even half an atmosphere (1 is just to be safe for now).

I found some fiberglass materials so far but I still don't know how well they can handle pressure or seal hot gas. I'll keep looking.

Thank you :smile:
 
Last edited:
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Hi Aero,
It sounds like you want a small amount of movement between the two parts you're sealing. Have you looked into Grafoil? It's commonly used on very high temperature valves, and can be used both as a static and dynamic seal. One manufacturer is UCAR Carbon, but I believe it's sold primarily through distributors:
http://www.usseal.com/Graphite.htm
http://www.grafoilsales.com/

You might also try posting your question at the engineering tips forum:
http://www.eng-tips.com/threadminder.cfm?pid=819
 
Thank you again Q_Goest. :)

I looked at Grafoil, but it seems to mostly be used for O-rings. Anyway, many of these specifications are so specific that it's difficult to understand what exactly you're supposed to use these materials for, unless you have a pic.

Anyway, I think I found something:
http://www.jameswalker.biz/group/categories/expansion_joints.html

Hope it works. :smile:
 
Depending on the surrounding geometry you may have to go with a bellows type of a seal.
 
That's exactly what I want to avoid. I'm supposed to be an aerospace engineer dealing with stuff that's supposed to fly not an armoured tank engineer... :wink:
 
Aero Stud said:
That's exactly what I want to avoid. I'm supposed to be an aerospace engineer dealing with stuff that's supposed to fly not an armoured tank engineer... :wink:
I hate to break it to you, but bellows seals are on a lot of flying engines.
 
I didn't mean that, I meant I want to save weight as much as possible and what I found looks promisng. Thanks. :smile:
 

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