High temperature bolts

[Jamesgtx]

I have a client that made a mistake when ordering valves. They need to order high temperature valves and instead ordered standard ones. The maximum temperature the bolts would see in a fire is 1875 deg. F. Inconel 718 would be a good choice up to 1600 deg F but I am concerned that from 1600 - 1875 deg F the bolts would anneal and fail, even if the time at temperature is a very short time (say 2 - 3 minutes). Is there any other material that may work for this application?

 

[metengr]

Jamesgtx;
Your design condition regarding fire exposure would prohibit the use of any high temperature bolting materials. Why are you even considering exposure to fire? This seems rather unique to me from a design standpoint.

 

[CoryPad]

I agree with metengr. AEREX 350 from SPS Technologies is used at 1350 [°]F, but 1875 [°]F is not a realistic use temperature for a fastener material.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Jamesgtx]

I find out in a meeting tomorrow (1/9) all of the particulars. The 1875 deg F came from the client. I will be sure to ask where this temperature came from. If the temperature was 1600 deg F or below Inconel 718 would work just fine. I appreciate the responses and will provide more information tomorrow.

 

[jehan17718]

Jamesgtx,

I concur with the views of metengr and Cory. I have encountered a specification for external fire condition on a particular project.

If your bolting needs to conform to an external fire condition then the allowables for this case will be different [more specifically greater] than the CODE allowables.

The allowables for the external fire case will have to be covered by a project/ client specification.

-jehan

 

[OTHGWayne]

Jamesgtx,

I can appreciate the need for hi-temp fasteners, I too have had the need to make them upon occasion. As a product manufacturer, fail-safe issues are important to some customers. For the temperature ranges you are looking to work in, especially since it is only for a few minutes, there are a few materials with anneal tempertures over 2000degF. You might Google these and talk to the manufacturers, they usually have very competent application folks.

Haynes HR-120
Haynes HR-160
Incoloy HT800
Hastelloy X

Some of these might be tough to procure in the sizes you need, but finding one of themn should be possible.