ASME II part D values

[MotorMan12]

We are to build a one-off pressure vessel out of a cast aluminum bronze material for submerged use. The aluminum bronze is selected due to good heat transfer capability and past experience. Past experience is, however, not based on applications where ASME VIII-Div 1 has been a requirement. According to ASME II-part D, Table 1B, UNS C95400 (B148) is the material with the highest allowable stress in this group, and our intention is to use this material. Material data sheets for UNS C95400 (and other similar materials) indicate that the material has much better properties in the TQ50 temper condition than in the "as cast". Enhanced properties due to heat treatment does not seem to be allowed according to ASME II. Is this really so, or is there an opening for heat treating the material and using the enhanced properties in the design? I find UG-10 hard to understand, but there seems to me that this might be the opening I am looking for. Is this correct? If yes, is difficult to achieve in practice from a "standard" foundry?

 

[gr2vessels]

The aluminium bronze you mentioned is listed in the Table D, ASME approved materials. Since ASME VIII is a design code/standard, you can only use the allowable stresses listed for approved materials in the Section II, Table D. You cannot design equipment in accordance with ASME VIII, using the actual measured UTS and Yield values to re-calculate higher allowables. You cannot use enhanced UTS and Yield values if not specifically allowed by the ASME code. You can only use the listed allowable stress for the nominated material. Also, you must refer to the notes specified in Table D for the selected material.
gr2vessels

 

[trottiey]

UG-10 allows you to recertify material with broken paperwork, for example material that was manufactured to a foreign material specification that is really close to an ASME one. It is not a loophole. If you really really want to use TQ50, you can take a look at Section II Appendix 5. But high strength heat treated materials are usually too brittle for use in pressure vessels.