UCS 66 Cold Design Temperature and Charpy Testing

[JakeR82]

I am looking over a proposal for our company regarding a pressure vessel. The customer is stating that A516 Gr.70 does not need to be Charpy tested with a thickness less than 25mm for a design temperature of -50°C. I look at VIII Fig. UCS-66M and the lowest that A516 Gr.70 goes is to curve B, indicating -29°C. A516 Gr.70N (N = normalized) plate will fall under curve D indicating a -48°C design temperature.

Can anybody inform me if I am missing some part of code that allows plate to be used at -50°C without Charpy testing? The plate technically is going to be subjected to about 2 psi(g) because it is used more for casing around a pressure part.

 

[jtseng123]

That is possible. Table UCS-66 or Fig UCS-66M is based on fully stressed condition.
If your plate is not fully stressed (means you provide more thickness than required per code), go to Fig UCS-66.1 or 66.1M to calcualte how much reduction you can take.

 

[SnTMan]

JakeR82, it is possible that reductions per UCS-66 (b) are being taken. Perhaps only your customer knows.

Regards,

Mike