ASTM A-335 Grade P11 thermal conductivity? 1

[NCCaryME]

I found a calculator online (

http://www.hrsgdesign.com/page5_6.htm)

that claims to calculate the tube wall temperature. I believe this would give me an idea of the superheater tube wall temperature, given the process steam temperature at the superheater outlet. If so, I need to know the thermal conductivity of ASTM A335 Gr. P11, but I can not find this information online. Can anyone help?

Thanks in advance.

---
Scott Stamey
Project Engineer
CPM, Inc.

http://www.cpm-inc.com

 

[jte]

Scott-

You'll find the info you're looking for in II-D, table TE-1. For a 1¼Cr-½Mo-Si material you're in material group 1 which has mean coeff's of thermal expansion (10E-6*in/in/°F)in going from 70°F to the indicated temp of:

6.4 at 70°F
6.5 at 100
linear 'till
7.3 at 500
7.3 at 550
7.4 at 600
linear 'till
7.9 at 850
7.9 at 900
8.0 at 950
8.1 at 1000
8.1 at 1050
8.2 at 1100
8.3 at 1200
8.4 at 1250
8.4 at 1300

jt

 

[jte]

Scott-

I forgot to mention that I don't think you'll find that varying the conductivity will have much impact on your calc's. The heat transfer equation is most likely bottlenecked by convection/radiation on the outside or convection on the inside. Try running the calc's with conductivities of 1 and 10 and see what happens to your results.

jt

 

[metengr]

Typically, for superheater boiler tubes, the gas touched tubing in the boiler runs between 50 to 75 degrees F hotter in metal temperature than the steam temperature. This information is a good estimate, and is extracted from one of the EPRI Boiler Tube Failure Guides.

 

[jte]

Sheesh... I was thinking conductivity and posted thermal expansion... Gotta finish that first cup of coffee before posting.

Conductivity is in table TCD of II-D, material group C, and varies from 23.5 at 70°F to 21 at 800°F to 15.1 at 1500°F. That's BTU/(hr*ft*°F). So vary the conductivity from 10 to 100 and see what happens.

jt