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Lugs in Heads of vertical vessels using line loads-EN 13445/COMPRESS

Lugs in Heads of vertical vessels using line loads-EN 13445/COMPRESS

Lugs in Heads of vertical vessels using line loads-EN 13445/COMPRESS

(OP)
Hello,

I have a question regarding the methodology for using line loads for calculating stresses in lifting lugs in the head of vertical pressure vessels. We recently have compared our methodology to EN-13445-3 (via COMPRESS). We found that the equivalent calculation diameter from EN-13445-3 16.6.3 to be equal to what in my mind should be the effective radius. We have not been able to resolve why this is, and I was wondering if anyone has any knowledge as to why the European code is using the effective diameter as the radius in the calculations?  

Thanks

RE: Lugs in Heads of vertical vessels using line loads-EN 13445/COMPRESS

I am the other half of the "we" in the OP above.
Some further explanation:
Looking at calcs for lugs on a head, EN-13445 Section 16.6.3 defines equivalent diameter, Deq  as follows:
  Deq = Ri  for spherical sections
and again
  Deq = Di×SQRT(1-3((x/Di)^2))  for 2:1 S.E. heads

these numbers seems to be short by a factor of two and I believe should read

  Deq = 2×Ri  for spherical sections
and
  Deq = 2×Di×SQRT(1-3((x/Di)^2))  for 2:1 S.E. heads

I have sketched out the 2:1 head in CAD and checked the calculated Deq  against measuring the radius of the arc at varying offset distances, x
(I will try to post my sketches later)

The Deq calcs match the CAD measurement of the radius

The only real concern we have is COMPRESS* uses this Deq  calculation for lugs on a head, and my personal calcs have suggested this may result in non-conservative line load stresses in the head

Thanks in advance if anyone can share comments or experience about this

*Build 7110


 

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