## Thermal coefficient of expansion for S&T exchanger tubes

## Thermal coefficient of expansion for S&T exchanger tubes

(OP)

Hi guys,

I want to calculate the expansion that tubes of a shell and tube heat exchanger could be subjected to operating at a temperature of 200 Deg C. The tube material is SA 213 TP304L. The material has a nominal composition of 18Cr 18Ni. This categorizes as a group 3 material as per ASME Sec II, Part D, Table TE 1 (austenitic stainless steel).

However, this table lists down three different coefficients of thermal expansion, A (instantaneous coefficient of thermal expansion), B (mean coefficient of thermal expansion) and C(linear thermal expansion).

In order to calculate the expansion that can occur in the tubes, I am using the formula of "alpha*Lo*(delta T).

I am not sure what coefficient value should I be using. Should I go for mean thermal expansion coefficient since its values are quite high as compared to C, the linear coefficient.

Can anybody explain the difference and application of these three types of coefficients?

I want to calculate the expansion that tubes of a shell and tube heat exchanger could be subjected to operating at a temperature of 200 Deg C. The tube material is SA 213 TP304L. The material has a nominal composition of 18Cr 18Ni. This categorizes as a group 3 material as per ASME Sec II, Part D, Table TE 1 (austenitic stainless steel).

However, this table lists down three different coefficients of thermal expansion, A (instantaneous coefficient of thermal expansion), B (mean coefficient of thermal expansion) and C(linear thermal expansion).

In order to calculate the expansion that can occur in the tubes, I am using the formula of "alpha*Lo*(delta T).

I am not sure what coefficient value should I be using. Should I go for mean thermal expansion coefficient since its values are quite high as compared to C, the linear coefficient.

Can anybody explain the difference and application of these three types of coefficients?

## RE: Thermal coefficient of expansion for S&T exchanger tubes

expansion in inch / 100 ft. You could use one fifth this value for 20 ft tubes for example for a simplified calculation. Column A is the actual value (instantaneous) at the given temp. I don't really know what its most common use is.Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

## RE: Thermal coefficient of expansion for S&T exchanger tubes

## RE: Thermal coefficient of expansion for S&T exchanger tubes

@snTman: Actually I have calculated using both B and C and found almost similar results.

For a tube length of 6.2 meters, if I use coefficient B, for austenitic stainless steels at a temperature of 400 Deg C.

The B value at 400 Deg C is 18.1 * 10^-6. Delta T is 400-20 = 380 Deg C and L0 is 6.2 meters (the initial tube length).

Putting in the formula for linear expansion gives the result of 42.65 mm

Now, at the same temperature, the value of C is 6.9 mm / m. For a tube length of 6.2 m, this gives an overall linear expansion of 6.9*6.2 = 42.78 mm. This is almost the same result as obtained by using B.

However, this value is slightly higher in decimals.

## RE: Thermal coefficient of expansion for S&T exchanger tubes

No offense, but if this surprises you, you don't understand what you are looking at. Column C data is Column B data calculated on the basis of 100 ft length.

In/100 ftat the given temperature. Column B data isin/in/deg F.at the given temperature. (Sorry but I only have US units available). The slight differences are in significant figures / rounding.Look at the

UNITS.Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

## RE: Thermal coefficient of expansion for S&T exchanger tubes

Whereas, the value of column B is the coefficient in (mm/mm Deg C). If you use this value, you need to calculate using the formula vessexst mentioned. So, its basically upto you which column you wish to use depending upon you know what you are doing

## RE: Thermal coefficient of expansion for S&T exchanger tubes

The problem with sloppy work is that the supply FAR EXCEEDS the demand

## RE: Thermal coefficient of expansion for S&T exchanger tubes

Regards

## RE: Thermal coefficient of expansion for S&T exchanger tubes

## RE: Thermal coefficient of expansion for S&T exchanger tubes

Regards

## RE: Thermal coefficient of expansion for S&T exchanger tubes

It was mentioned wrongly in the above information

## RE: Thermal coefficient of expansion for S&T exchanger tubes

Regards

## RE: Thermal coefficient of expansion for S&T exchanger tubes

43mm is a lot of movement to accommodate, and this is a short unit.

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P.E. Metallurgy, Plymouth Tube