A36 Steel Structure at Elevated Temperatures

230F is not that high. The attached paper is for connections but the first part has a several tables for various materials at elevated temperatures.

I would be more concerned about thermal growth and making sure the thermal growth is not restrained in such a way as to overload the structure. Most analysis programs will handle elevated temperature but the hard part will be figuring out what temperature to use. A drawing of what you have would be helpful to provide more advice.

Here is an image of the mount that was designed. It will support 3 burners and 2 reflection panels. Guarding will be surrounding the structure but heat will be able to vent through the top and through the exhaust ducts attached to 2 of the burners. Thank you for the attached document and information. At this temperature, is creep a factor that should be considered? Also, what other material may be suited for this application?

I added a few comments.

I don't know how big this is or what kind of loads you have from burner weights and tension on the material going through it. I am assuming these things are fairly small. Like something less than 10' tall and 5' wide or so.

I am not sure about a creep factor. Looking at it I would guess stresses are low but again I am not sure about the size or weights you have here.

I noted in the attachment but one thing to consider is getting rid of the cantilevers and extend the support beam to each side.

I assume you are in the US since you noted A36 material. You are not going to find a true A36 I beam. They will mostly be A992 (50 ksi)

Check out the ASME BPVC (Boiler & Pressure Vessel Code). There are tables in there that define Fy and Fu at different temperature intervals.

At 300 degrees F your Fy is 31.8 ksi and your Fu is 58 ksi per Tables Y-1 and U.

Your 230°F is very low.  Barely warmer than boiling water.

ASME Section II Part D doesn't list creep effects until 700°F for A36. Most CS materials don't experience creep until this temp range, so A992 would be the same.

You may want to have a look at this thread. A number of sources are given (including AISC):

The structure is approximately 10ft tall and 6.75ft wide. The burners are 6ft wide and the can reach temperatures up to 320°F (the material going between the burners comes out at 230°F). The A36 will not be directly in front of the burners.

Ideem, you have a point. I will add some gusset plates to the cantilever beams to reduce the stress in the welded locations(supports). (And I am in the US)

The beams are well below the 31.8ksi yield strength.

If A36 doesn't experience creep until 700°F, does that mean that temperature is negligible regarding the amount of deflection and stress the beams will have?

Again looking at ASME Section II Part D, the modulus of elasticity E for A36 goes from 29.4e6 psi at 70°F to 28.3e6 psi at 300°F. Thus only a slight change in deflections.