Appendix 2 Flange Calculations with Nubbins

[spayette]

Two existing girth flanges are mated together. One flange has a nubbin 1/64” high and 1/8” wide. The gasket used between the flanges is DJAF iron, that is 1/2” wide.

Question:
When considering the facing on the flanges as Type 2 (per Table 2-5.2, from Sec VIII, Div 1, Appendix 2), the joint is inadequate for the design pressure. If on the other hand, a Type 1C facing is selected in the analysis, the flanges are sufficient for the required pressure. Since the flanges appear to also meet the criteria of a Type 1C facing, is it acceptable to analyze this flange pair assuming a Type 1C facing?

 

[Christine74]

I don't believe you can consider this a type 1c facing. Every time I've reviewed calculations for a DJAF gasket with a nubbin, Column 2 with Facing Sketch 2 was used.

Appendix 2 should be more clear as to which facing sketch is applicable in this case, however.

-Christine