A312 TP304 Stainless Steel above 1000 F

[Fidens]

Hi,

ASME B31.1 says that "The allowable stress values tabulated for temperatures over 1,000°F apply only if the carbon content of the material is 0.04% or higher" under note 10 for Table A-3, for A312 TP304

My question(s) is: Can I use the pipe being supplied if its carbon content is at or below 0.035%? I'm pretty sure the answer is a simple "no" since ASME B31.1 says you can only use those tabulated values for 0.04 and higher. And if the answer is "yes" then which allowable stress values should be used for lines above 1,000 F? (I have a 2" hot air exhaust line (A312 TP304) at 1202 F/low pressure--this will be the service conditions) The vendor has submitted their material test report sheets and all the reports state that the A312 TP304 being supplied is below 0.035 % for the carbon content. And they state that this is the carbon content required in accordance to ASME B31.1. Bottom line is that they should have noticed it on the drawings provided and supplied a higher carbon content for this specific line, right? (and yes we should have probably done a better job in specifying the difference in our specs or highlighted the "issue" better)

Also, the vendor says that the stainless steel being supplied is "dual stamped 304/304L" How can a material be dual certified to be "low" carbon (in the case of 304L) and "regular" (in the case of 304) at the same time? I know the "dual stamped" thing is common but this still confuses me a great deal.

I feel that these are such basic questions so thank you all for any help you can provide on my first questions ever to Eng-tips.

 

[Ripz]

304 - 8% max Carbon

304L - 3% max Carbon

304H - 4 - 10% Carbon

....

If a 304 Steel has, for example, 2% carbon content, then it satisfies the requirements for both 304 and 304L. Thus can be considered both and may be dual stanmped. There is no minimum Carbon content specified.

....

The table you are referring to is for 4% Carbon 304 which is 304H. The 304 you obtained, at 3.5% is your typical 304 stainless steel.

That's not to say you cannot use the pipe. You'll need to recalculate using the stress values for this grade of 304 and not 304H.

 

[XL83NL]

I'm pretty sure the answer is a simple "no" since ASME B31.1 says you can only use those tabulated values for 0.04 and higher

Correct.

And if the answer is "yes" then which allowable stress values should be used for lines above 1,000 F?

Please note that B31.1 temp. limits are real limits (you may not use that material above that limit - see 124.1.1), whereas B31.3 allows you to go further.

And they state that this is the carbon content required in accordance to ASME B31.1

B31.1 does not require that from then.

Bottom line is that they should have noticed it on the drawings provided and supplied a higher carbon content for this specific line, right?

No, it all depends what you purchase order spec'd. Generally, they will supply ASTM A312 material, as that's what most people order, and whats generally ordered.
It's probably dual certified with 304L and ASME SA marking, but that's not relevant as of now.
Most mills just make ASTM A312 TP304

Also, the vendor says that the stainless steel being supplied is "dual stamped 304/304L" How can a material be dual certified to be "low" carbon (in the case of 304L) and "regular" (in the case of 304) at the same time?

Just Google "dual certified 304/304L". This topic has been discussed at eng-tips numerous times. It's also covered in one of the Appendices of ASME II

Furthermore, please note that for B31.1 piping, you need ASME SA312 TP304 material instead of ASTM A312 TP304.

 

[Fidens]

Thank you guys for your feedback. This clarifies things a great deal !