How choose angle of backing device which is dovetail style?

[aprilgcl]

Hello, I'm a engineer working on Plant EPC company
When I study Heat exchanger, I found there is a backing device for floating head type(S&T Heat exchanger)
And Our company usually use 17 and 18 degree for backing device Style A dovetail.
I want to know that why should we use that degree, but people don't know detailed reason.
I tried to find out it through Vendor company, but they also don't know and not reply.
so if anyone know about the factor to choose dovetail degree, please give me some advice.
Thank you

 

[SandCounter]

It is difficult to comment without a diagram or photo. I would think the taper is to encourage a centered fit and the angle is dictated by available space and mass needed for strength to meet the service rating.

I used to count sand. Now I don't count at all.

 

[Christine74]

Here's a link to a diagram of a TEMA "Style A" split backing ring:

https://www.red-bag.com/ves/doc/ASME/ASME_APPEND2_SBR.htm

TEMA requires the dovetail angle to be between 15° and 45° from the vertical, presumably to help with alignment.


-Christine