ASME Section II vs. FFS-1 (API-579) Material Clarification

[InTheField]

Hi all, I have an interesting query as I have not noticed this before. Hopefully someone here has some background.

OK, as an industrial boiler specialist I was putting together an in house data base which compares ASME allowable stress in ASME Section II, table 1a to FFS-1 calculated stresses. We sometimes get into FFS on boiler components within the boiler setting. Under the creep range is fairly straight forward (by the way there are some interesting differences with ASME Section II and FFS-1 MPC and WRC values).

Within the creep range, the MPC creep coefficients (Strain Rate Parameters and Omega parameters) have different values for SA213 T11/T22 depending heat treatment (N&T and annealed).
I thought, OK Section II must state the fabrication and heat treatment for tubing supply. After checking Section II Part A and Part D, I could find no specific requirement for as supplied condition.
I also double checked section I and there is also no reference to the heat treatment of supplied tubes.

Does anyone have any experience in this and know if there is a requirement under Section II to have a standard heat treatment for supply of boiler tubes? I am looking and SA213 T11/T22, but there are likely other materials which fall under this question.

I ended up looking at low and medium carbon steels (those applicable to boiler construction). Short of having to take a field sample/etching and check the grain size, I am hoping there is another solution. Note: this is not an immediate problem, I am just putting this together out of interest. The goal is to quickly evaluate which stress governs failure of a material at a given temperature based on FFS-1 compared to ASME.

Thanks for the help all!

 

[DriveMeNuts]

I'm not sure if I can answer your question, however I created a spreadsheet some time ago which calculated the allowable stress in the creep zone using the ASME II Part D Appendix 1 and ASME FFS-1 omega method.
I got it to work precisely for 0.67xSRave and 0.8x SRMin, however there was a difference when calculating the 1% creep stress limit.
There seems to be slight differences between ASME II and FFS-1 when calculating allowable stresses.

 

[InTheField]

Yes, I noticed that as well. There are also some interesting differences below the creep range. I wonder if this should be a clarification question for ASME Section II Part D? It seems odd to me this is not addressed for materials operating in the creep range. For older equipment the original MTR's are not always available, making analysis a bit more difficult. I'm going to post this question in the materials topic sto see if there is anyone there that may have an answer.

 

[EdStainless]

I have supplied those alloys in both conditions as specified by the customer.
Our default in N&T.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy

 

[InTheField]

Is there a stress difference? As I mentioned there are some different creep constants in the FFS-1 code I find interesting. I would think there would not be a difference as ASME Section II Part D does not show different values for SA213 T22 or T11.