ASME B31.3 Table C-3 Thermal Coefficients, U.S. Units

Hi David,

I am sorry that you are the only one I know from the code committee. Therefore I will shoot my question on you.

I was wondering if you can clarify the following:

The Table C-3 was introduced as the "Mean Coefficient of Linear Thermal Expansion Between 70 deg F and Indicated Temperature, min./in.-deg F". Is this really correct?

I can see that similar title is used for Table C-1, and I see that the linear expansion is zero at 70 deg F. So its title reflects what exactly it is.

The same does not look apply for the Table C-3. The coefficient is not zero for 70 deg F. I am guessing that the coefficients looks independent from 70 deg F, and the title is misleading or I am missing something. I would like to have your opinion on this.

Let us assume the table is correct, so how do you calculate the thermal expansion between 70 deg F and an arbitrary temperature?

Thanks in advance and kind regards,

Ibrahim Demir
Snr Mech Engineer

It works. Note that Table C-3 is per degree Fahrenheit. Multiply this mean value by temperature for both ends of the range and subtract to find thermal growth. You will see that this value matches Table C-1.

Hi David,

Thanks for your prompt answer. I have put my understanding in a simple spreadsheet. I have found that there are small discrepancies in the calculated values between values of Table C-3 and C-1. I may not be correct.

I have just wanted to introduce the speradsheet as an attachment, but I could not find the option for it. If you can send me an e-mail I will forward the spreadsheet.

Thanks and kind regards,

Ibrahim Demir
ibrahim.demir@worleyparsons.com

David,

I guess these discrepancies are the product of rounding the numbers. They are around 1-4 % and can be ignored.

I trust this is sufficient for the moment.
Thanks and kind regards,

Ibrahim Demir