SA-240 304L High & Low Strength Plate
SA-240 304L High & Low Strength Plate
(OP)
ASME Section II, Part D, page 82...the materials listed in lines 38 and 39 are both identified as SA-240 304L plate with the same P-No., Group No., min. tensile and yield strengths, and external pressure chart no. Their applicability and max. temp. limits (page 83) are the same except for the line 39 material isn't permitted in Section III applications. For the most part they have different notes.
Now, getting to their maximum allowable stresses...their values diverge after 100F. That is, one material (line 38) maintains a 16.7 ksi max. allowable stress up to 300F whereas the line 39 material is only good for 12.8.
I believe these materials are different and feel that this position is supported by the fact that our PV Code calculation software's material database contains "SA-240 Gr. 304L, High" and "SA-240 Gr. 304L."
I discussed this with our formed head supplier who takes the position that SA-240 304L is the only material spec and that there is only one product by that designation. After getting them to open Sec. II their claim became that the different lines (38 vs 39) just identified the allowable stress range that SA-240 304L has to meet. That is, for the 300F example the material can have an allowable stress between 16.7 and 12.8 ksi. (That kind of makes it had to design with.)
I don't agree with their assessment and think that I'm within my rights to specify either material and for lack of anything better would do so by using the clarifiers "high strength" or "low strength."
How far off in left field am I?
Now, getting to their maximum allowable stresses...their values diverge after 100F. That is, one material (line 38) maintains a 16.7 ksi max. allowable stress up to 300F whereas the line 39 material is only good for 12.8.
I believe these materials are different and feel that this position is supported by the fact that our PV Code calculation software's material database contains "SA-240 Gr. 304L, High" and "SA-240 Gr. 304L."
I discussed this with our formed head supplier who takes the position that SA-240 304L is the only material spec and that there is only one product by that designation. After getting them to open Sec. II their claim became that the different lines (38 vs 39) just identified the allowable stress range that SA-240 304L has to meet. That is, for the 300F example the material can have an allowable stress between 16.7 and 12.8 ksi. (That kind of makes it had to design with.)
I don't agree with their assessment and think that I'm within my rights to specify either material and for lack of anything better would do so by using the clarifiers "high strength" or "low strength."
How far off in left field am I?





RE: SA-240 304L High & Low Strength Plate
RE: SA-240 304L High & Low Strength Plate
I will provide a hint instead of telling you exactly because this forces one to look up information. Review carefully Note G5 followed by Notes T4 and T6.
RE: SA-240 304L High & Low Strength Plate
Thanks.
RE: SA-240 304L High & Low Strength Plate
This generalization needs to be reevaluated on each design.
RE: SA-240 304L High & Low Strength Plate
the lower values are for where distortion is not allowed, like a plate flange or bolted head.
the higher stress values are for where distortion can be tolerated, like a vessel head or shell.
We have never been questioned by a client or AI about this, so I am assuming we have been correct. LOL
RE: SA-240 304L High & Low Strength Plate
We don't play with stainless much so I'm sure our QC department would freak out if they had Code calculation reports listing the head material as "SA-240 Gr. 304L, High" (as APV does when that is what's selected) and the MTRs list just "SA-240 Gr. 304L."
RE: SA-240 304L High & Low Strength Plate
RE: SA-240 304L High & Low Strength Plate
If you browse Sec II, Part D for the stainless and some other materials you will find the same situation exists for product forms other than plate and also find forgings and bolting sorted by thickeness. It is important to CHECK that you (or your software) has selected the correct allowable stress.
And if your QC department freaks due to their own unfamiliarity with the Code, well, you'll just have to educate 'em.
Regards,
Mike
RE: SA-240 304L High & Low Strength Plate