Vani

You assume a linear relationship between the temperatures and interpret the table as such.

Table A-1 says it is 20 ksi at 100 deg F and 20 ksi at 200 deg F, what would be the value when the temperature is 170 deg F.

For example sake, if it says 20ksi at 100deg F and 15 ksi at 200 deg F, then at 150 deg F, the allowable stress value would be 17,5 ksi.

Use interpolation as demonstrated at that example: Pipe_Wall_Thickness_-_Problem_Solution.

Dear Sir,

Thanks for your answer and attachement.

Thanks and regards

Vani.