B31.3, Unlisted Material 303SS 1

[kcme2005]

We are trying to get a level control product a CRN (canadian registration number) through TSSA. The unit is made from a slug of SS, 2in in diameter by 5in length. It has NPT threads on the outside to engage in the process, and a 1 in hole bored half way in down the center axis for a float and magnet system.
We were able to perform design calculations (at 400°F) based from equations in B31.3 for the 316SS unit from allowable stress data in the code book. However, we also make an identical part out of 303SS, which isn't a recognized material in the code book. TSSA will not list the 303SS without the calculations.

Does anyone know where we can get an allowable stress value for 303SS at 400°F (without having to have a test lab do it for us)? Or does anyone know the code well enough to know another way we could get the 303SS listed?

We already have the 316SS listed, and we need to have the 303SS listed as well.

 

[metengr]

ASME Section II, Part D, Table 3 lists the allowable stress values for ASME SA 320 Grade B8F, which is AISI Type 303 SS. At 400 deg F, the allowable stress is 12.6 Ksi. This material is permitted for use at 400 deg F for ASME Section III (nuclear) applications. For ASME Section VIII Div 1 and 2, the maximum permitted service temperature is only 100 deg F.

ASME B31.3, paragraph 323.1.2 does permit the use of unlisted materials provided they are manufactured to a published specification. Allowable stresses can be calculated using the method in B31.3 or a more conservative approach.

Make sure that you have evaluated all service conditions for using this material.

 

[kcme2005]

Where in B31.3 does it show how to calculate the allowable stresses for unlisted materials?

I have found paragraph 302.3.2 (f) that states tensile at temperature is found by multiplying th average expected tensile at temperature (where to find this, make it up?) by the ratio of St (if it is unlisted, there is in St value in the code book) divided by the average expeted tensile at room temperature (can I use the ASTM value here?).

Maybe this is the wrong section of B31.3.

Is ASME SA 320 Grade B8F included in B31.3?

 

[metengr]

kcme2005;
SA 320 Grade 8BF is not listed in B31.3. My point of listing ASME Section II Part D, Table 3 is that the allowable stress value is derived for 303SS material. In B31.3 you have the option of calculating the allowable stress using the methodology in paragraph 302.3 (a-f) OR using a more conservative approach. The approach used by ASME B&PV Code, Section II would suffice.

 

[FSB01]

We had similar problem, and only solution we come up to was to send bar for testing in lab.