API 650 Flanged Compression Ring

[andyross333]

I am looking into forming a compression ring as part of the top shell plates. From what I can tell, this was covered in API 650 10th edition, addendum 4, Figure 3-3A (pg 3-3) labeled as ALTERNATIVE ROOF-TO-SHELL JOINT; however, I have not been able to locate this in the current edition.

Does anyone know why it has been removed? Is this type of compression ring design still permitted?

Thanks.

 

[JStephen]

I'm not sure exactly what the detail in question was- but it sounds like the flanged connections that are allowed under Appendix J for shop-built tanks.

Note that for many tanks, this is not actually a compression ring.