Impact Test Exemptions, VIII/1
Impact Test Exemptions, VIII/1
(OP)
Per UCS-66, why doesn't doesn't the actual part thickness matter when exemption materials? For example a 3/4" shell welded to a 2" flat head. To exempt the head, the governing thickness is the thinner of the 2 parts.





RE: Impact Test Exemptions, VIII/1
If you want to apply to a non welded part, you need to apply the rules for governing thickness of non welded parts or materials as you put it, which are different.
Read UCS-66(a)(1), (2), and (3) because there are different criteria for each and each shall be treated as separate components.
There are three kinds of people in this world; those who can count and those who can't.
RE: Impact Test Exemptions, VIII/1
When the vessel design is complete, a review of all of the impact test evaluation results from every componenet will reveal the warmest value for all governing thicknesses. This will be your vessel MDMT.
As to why the governing thicknesses for welded and non welded parts are what they are? I don't know, I only enforce the requirements. I hope some engineer can shed light on the answer you need.
There are three kinds of people in this world; those who can count and those who can't.
RE: Impact Test Exemptions, VIII/1
RE: Impact Test Exemptions, VIII/1
I believe that the concern is more the weld and the weld HAZ as opposed to the base material. The thinking is that the base material will have a MDMT given by one of the curves in Fig UCS 66. The thinner of the two parts will be the more highly stressed, and if a thick shell is attached to a thin shell, the high stress will be in the thin HAZ of the weld. As the weld tapers to the thicker section the stress is reduced.
EJL
RE: Impact Test Exemptions, VIII/1
Regards,
Mike