Allowable Stress for SA312 TP310

dear mahesh 4757

greeting to you

first in ASME sec II part D version 2010 it cover in material SA 312 up to temperature 825 degree centigrade ( equal to 1512 degree fahrenheit ).

in this case you can apply interpolation rules

the maximum allowable stress at 40 degree c is 138 MPa = 20000 PSI

the maximum alloweable stress at 825 degree c is 1.15 MPa = 166 PSI

SO the maximum allowable stress at 900 degree c ( 1652 F) is 1.04 MPa = 151 PSI

LOOK OUT : this values for material SA 312 tp 310S SMLS AND WLD PIPE

in most cases of furnaces and heaters the size of convection pipes is 5 inchs or 6 inchs.

when you calculate the required thickness for these pipes you will take into your considerations the value of maximum allowable stress from applying the interpolation rule.

AND you must check on creep stress in this case specially the design temperature is higher than 400 degree C

Dear blackpanic73, Thanks for replying. Still wounder whether the interpolation is recommended by ASME in this case. I am saying this and as mentioned by you, in Sec 2 Part D the the maximum temperature limit for this material is 1500 degree Fahrenheit!!!

Did you find the design thickness of the coils matching with the extrapolation values of allowable stresses as describe by blackpanic73?

Is the furnace's actual working temperature is near the design temperature, how is the performance of coils in actual functioning.

in the case using pipe 5 in diameter the thickness will be 120 mm using corrosion allow. 6 mm

in case of using pipe 6 in diameter the thickness will be 136 mm using corrosion allow. 6 mm

the joint efficiency = 1

note: you can take corrosion allow. = 0 mm in stainless steel materials

i want to say : the range of design pressure is very high in this applications of furnace in the main discussion so the thichness is very high. in the field of petroleum serivec the design pressure rating is less than from the mentioned design pressure so the schedule of pipe is less than the thicknesses which i calculated above.

for example : for crude oil petroleum furnace i use pipe with diameter 5in or 6 in sch. 80 material SA- 106 GR. B.

so what exact the application of this furnace ?

There is paragraph in ASME section II Part D Edition 2010 in STATEMENT OF POLICY ON INFORMATION PROVIDED IN THE STRESS TABLES.

Below mentioned is the paragraph:

The information in the Applicability and Maximum Temperature Limits columns is mandatory. Where a material is permitted for use in more than one Construction Code, and in the SI units version of these tables, the maximum use temperature limit in these columns is critical. The temperature to which allowable stress or design stress intensity values are listed is not necessarily the temperature to which use is permitted by a particular Construction Code. Different Construction Codes often have different use temperature limits for the same material and condition. Further, in the SI units version of the stress tables, values may be listed in the table at temperatures above the maximum use temperature limit. These stress values are provided to permit interpolation to be used to determine the allowable stress or design stress intensity at temperatures between the next lowest temperature for which stress values are listed and the maximum-use temperature limit listed in these columns.

Dear blackpanic73 , referring to above paragraph will you pls explain how you have arrived at the allowable stress value at the 900 deg cen?

Also the maximum temp limit for above material in sec.I and sec.VIII Div:01 is 816 deg cen.

Dear asd 23789

Greeting to you

If you check any material in ASME sec II part D (2010) you will find the temperature values in all tables begin in the first column from -20 to 100 F (-30 to 40 C) and listed in the last column in the next page 1650 F (900 C) . when the value of maximum allowable stress written as (….) it does not mean that this material have no value of maximum allowable stress at this temperature. But it mean may be the value of maximum allowable stress for this material as the same value of pervious temperature value .

For example in ASME sec II part D 2004 for material SA- 516 GR. 70 if you check the value of maximum allowable stress of this material at temperature 250 F you will find the value of stress written as ( ….. ) . is this mean that this temperature has no maximum allowable stress at this temperature ? Of course not, and if you check the value for the same material at the same temperature in version 2010 of ASME sec II part D you will find that the value of maximum allowable stress is 20000 PSI ( 138 MPa). This value is the same value of pervious value of stress at the perivious temperature and the same value at the next temperature. this way applied in all values of maximum allowable stress which written as (...) not only for values filled between similar values of stress.

In our material SA- 312 TP 310S the last temperature in the table listed as 900 C but the value of maximum allowable stress at this temperature written as ( …..), and the nearest value of maximum allowable stress listed under temperature of (1500 F) (825 C) we can take the same value of stress but we apply the principle of interpolation here in this case at high design temperature for more safety to increase the thickness of pipe to make good strength against the internal pressure during operating conditions at the operting temerature especially when design temperature exceed 400 C due to creep action.

The paragraph which asd 23789 transport above from ASME section II Part D Edition 2010, apply if ONLY the temperature design value exceed the temperature value Which listed in the last column in the tables.

For material SA-312 the last temperature value in the table is 900 C which equal to mentioned design temperature above.

Note: All requirements in the ASME code represent the minimum required rules for each parts of the designed equipment. You can not any way to ignore these rules. But you can apply the philosophy of code in some where you need more safety in the designed equipment to make your design more and more safety.

Dear Blackpanic73,

I am not able to understand.

Will you Please explain how to interpolate the value at 900 deg cen from 825 when there is no value avaialble beyond 900 deg cen.

Regards

ASD23789

i think the discussion is getting really interesting with the thoughts by you all. good question asd23789!!!