Steel Limitations at -67F

[denniskostrzewski]

Can carbon steel be used for a non-pressure vessel application for an exhaust muffler that will see an ambient of -67F? During run, the gas temperature will be 850F. Maximum back pressure will be 10" w.c.
Some tell me that we have to build a code vessel and do SharpE testing and impact testing. Is this true for an exhaust system?

 

[metengr]

No, for an exhaust manifold that is open to atmosphere. The material of construction can be Corten steel. I would not worry about impact temperature because there is no significant load on this manifold when the engine is not running.

 

[gr2vessels]

The low temperature properties of any steel are refered to the ability to withstand the brittle fracture of the metal subjected to a level of stress at freezing temperatures. I don't believe that you expect the muffler made of any steel to fall off at -67F, without applying a serious mechanical stress on it. Also, 10" w.c. does not qualify for the name of "pressure" as accepted in the pressure vessel industry. Hence, the pressure vessel code doesn't apply to your muffler and no impact tests are required for the thin, sheet metal used for the muffler (and the rest of exhaust system;- that including the cast steel manifold).
cheers,
gr2vessels

 

[vesselfab]

and for future

it's Charpy V-notch testing same as impact testing

just so you'll know for later

 

[MintJulep]

You should be seriously concerned about the ability of the design to accommodate thermal expansion, and the rate of heating and cooling and associated thermal gradient.