High Temperature Sealant

[tom5145]

I am looking for a sealant that fits the following requirements:
- Withstand 1400 F for 10 seconds
- Withstand 400 F for 90 min
- Flexible (due to thermal expansion), watertight
- Must fill ¼” gap
- Adhere to steel
- Exposed to weather (UV degradation, rain/sea water, fuel/oil)

Is there anything that fits these specifications?

 

[Compositepro]

Standard silicone sealant will meet your requirements.

 

[tom5145]

Wont silicone become brittle with high temperatures? This will be exposed to the high temperature multiple times and needs to remain flexible for thermal expansion.

 

[Compositepro]

You won't find anything better than silicone. There are some differences in formulation of different products. The high temperature formulations are usually red/orange. Bathtub sealant may have other additives that hurt the high temperature stability.

http://www.mcmaster.com/#catalog/119/3403/=l91ci0

 

[KENAT]

You could talk to these folks

http://www.arcorepoxy.com/,

we played around with Arcor EE101HT for an application that required relatively high temps and solvent resistance. If you only need the temp they may have something else - 1400 F is pretty high though - we were down nearer your 400F range.

Does the seal really get heated to 1400 F for 10 seconds or is it exposed to 1400 F for 10 seconds? Depending what kind of heat sink it's attached to etc. the bulk of the seal may not get anywhere near that temp.

Not sure if Masterbonds products are really sealants as such but we looked at 10HT and EP125 for our application.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[ScottyUK]

I'm not sure if the 'standard' high temperature silicones are acetoxy types - i.e. they release acetic acid during curing - but if this is a problem in your application then Dow's 3145 RTV is a high temperature silicone with a neutral cure. A previous employer used it in continuous service at just shy of 300°C without noticeable degradation over many years.