Abdul,

Yes, unsupported mass ( i.e. no. of valves on the branch) is one of the parameters for LOF. But my question is " is the practise of using branch bracing for lines with 600 lb rating irrespective of other considerations,based on scientific vigor?". I guess not as you will not need bracing for 150/300 lb rating, where based on the MTD guideline , i.e. lesser wall thickness of the header, it may be required.Personally I agree with the MTD guideline.The reason for asking this question, is to get answer to the above as I felt that such specifications can result in vibration problem as all the parameters involved have not been considered, although apparently it appears that it is a conservative approach.


In AIV, the nature of vibration is circumferential i.e. shell mode, hence we require circumferential stiffeners to minimize this problem. In this context, I feel that the brach bracing is a source of asymmetric discontinuity.

Regards