Compression Ring Requirement as per API 650 1

[merton]

When the participating area at the roof to shell junction (without compression ring) is greater than then required participating area as per API 650, does this mean that the roof to shell compression ring may be omitted? (REF API 650 Edition 10, Addendum #4 Section 3.1.5.9 (e) and Section 3.10.5)

Thank you

 

[JStephen]

If you mean the top angle, refer to the Technical Inquiry Responses included with Addendum 4, Appendix D. This very question is asked, #650-I-11/02, Section 3.1. They say the angle can't be deleted.

The top angle isn't actually a compression ring unless there is adequate tension/pressure in the roof to put it into compression. It still helps round the top of the shell up and stiffens the shell somewhat between rafters.