Chromemoly vs St.St

[jason886]

Hi all,

Im a trainee engineer on my last year of a HNC so I still have a lot to learn, so any advice on the following would be helpful.

I would like some information on the plus and minuses of a stainless steel tubesheet vs. a CrMo tubesheet. The item is a small u-tube de-superheater bundle. However I do not have any technical information such as operating temp or operating pressure etc. So I suppose any basic info would be helpful. I will try and get more information off the customer if I can.

I have done some research and found out the following about CrMo ~ chromium provides improved oxidation and corrosion resistance and the molybdenum increases strength at elevated temperatures. CrMo steels have a tendency to long term embattlement in the approx. 370 to 580 degrees Celsius range.

Regards,
Jason

 

[metengr]

I would like some information on the plus and minuses of a stainless steel tubesheet vs. a CrMo tubesheet. The item is a small u-tube de-superheater bundle. However I do not have any technical information such as operating temp or operating pressure etc.

Material selection for a heat exchanger is based on suitability for service (which means you absolutely need to know operating conditions and the environment), cost of material and availability of material.

Most likely for a desuperheater, you will need elevated temperature strength properties and corrosion resistance. In pressure vessel design, the allowable stress values for material selection plays a significant role provided the materials can handle the environment (potential corrosion issues).