This message indicates that the selected material does not qualify for impact test exemption as per ASME Section VIII Division 1, UCS-66.

• • UCS-66 defines the Minimum Design Metal Temperature (MDMT) limits for materials.
  • If the combination of material group (curve), thickness, and design MDMT falls outside the allowable exemption limits, impact testing becomes mandatory.
  • AutoPIPE Vessel triggers this message when the material fails to meet the exemption criteria (Rated MDMT<Design MDMT).

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Resolution / Workarounds

You can address this issue using one of the following approaches:

1. 1. Proceed with Impact Testing
      • Accept the requirement and ensure the material is impact tested in accordance with code requirements.
   2. Use Material with Better Toughness (Higher Curve)
      • Select a material assigned to a more favorable UCS-66 curve (e.g., Curve A instead of Curve D).
      • Materials with better toughness allow lower MDMT without impact testing.
   3. Reduce Thickness
      • Lower thickness may move the material into an exempt region per UCS-66 curves.
      • Verify allowable thickness vs. MDMT in the ASME charts.
   4. Increase Design MDMT
      • Adjust the design MDMT to a higher (less severe) temperature, if permissible for your design conditions.
      • This may bring the material within exemption limits.

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See Also

Bentley AutoPIPE Vessel

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