I am using Sec VIII-Div 2-para 220.127.116.11 for protection against local failure. The design is using SA-516-GR70N plate cold rolled to a cylinder. There is a ring welded on OD of this cylinder. Since the load on ring is high, calculation shows to prevent local failure, forming strain should be zero around the welding area. The code states if “If heat treatment is performed in accordance with Part 6, the forming strain may be assumed to be zero.”
The part that I need some guidance is what should be heat treated so we can assume the forming strain is zero the:
- If I heat treat the rolled plate before welding the ring, does it make the forming strain zero?
- If we heat treat the weld (post weld heat treatment) between rolled plate and ring , does it make the forming strain zero?
Let’s assume other than our design doesn’t require any heat treatment from part 6 and the only reason for heat treatment is to make the forming strain zero.
Additionally, I know how to calculate forming strain using Table 6-1.I am trying to make it zero by heat treatment. The part that I do not know is what should be heat treated to make the forming strain zero. Should the rolled plate itself to be heat treated or weld should be post weld heat treated? My understanding is that heat treatment of rolled plate (before welding the ring) will make the forming strain zero.
The heat treatment is Stress Relieving like PWHT
If forming stress is less than 5% SR is not required, depending of thickness.
The best practice is PWHT all the complete vessel.
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