Dear all
I have following doubts in design of backing ring in heat exchanger with floating heads (backing rings split into two halves - 180 deg diametrically)

1. As per Appendix:2 thickness of split flange has to be computed taking 200% of bending moment computed for a solid flange; What is the basis of this 200% ? The same is applicable to backing ring of floating head?

2. If we attach the two halves by bolting together using a strip the two halves become integral and hence will behave as a solid ring (integrity of attachment to be ensured); Can we then take only 100% moment leaving the split factor 2.?..or we must consider moment 200%?

3. Further backing device thickness given in RCB:5-141, split ring of style B needs factor 2 but style A or style D does not need the factor 2. This is not reflected in ASME Section VIII Div.1 appendices

4. Actually our cases is like style A and also we are attaching the two halves by bolting; wat split factor we should consider,1(will make moment 100%)or 2(will make moment 200%) ?.According to me,Backing ring is in two halves means that it has 1 split.No.of splits=1 ,will make the split factor=2.which in turn will cause the moment to gt doubled i.e.200%.
So,please do let me know, for style A,no of aplits cosidered shall be equal to 1 or equal to 2..??

Your prompt response is highly appriciated.
Thanking You in advance

Regards
Harshal Kolhe.
Deputy Manager
Essar Engineering Services Division,Mumbai.

For TEMA TYPE "A" split backing ring total moment to each ring is 100% of Mo.But you have to follow very carefully TEMA quidelines for the ring construction,allowances,dimensions etc.