Dinant Krijgsman
Mechanical
- Sep 7, 2017
- 1
Dear All,
I'm doing a fatigue analysis screening, according to ASME BPVC VIII DIV 2 section 5.5.2.4 (method B).
In my case I have both pressure fluctuations (STEP 3 and 4) and fluctuations from mechanical loads (step 8) (i.e. from thermal expansion of piping). Which this in regard I thought it is strange that there are different criteria, with no connection between them.
I would have thought, that if you would just barely satisfy for example step 3 (full range pressure cycles). That this would have a big influence on step 4 and 8 (other pressure cycles). I would have thought you would need to combine them (maybe using Miner's rule when they are independently) or even add the stresses in case of thermal expansion combined with pressure cycles when the cycles occur simultaneously (as for example mentiond in EN 13445-3 17.1.2).
Am i just wrong? Or are the criteria that conservative that you can look at them seperately?
Kind regards,
Dinant Krijgsman
I'm doing a fatigue analysis screening, according to ASME BPVC VIII DIV 2 section 5.5.2.4 (method B).
In my case I have both pressure fluctuations (STEP 3 and 4) and fluctuations from mechanical loads (step 8) (i.e. from thermal expansion of piping). Which this in regard I thought it is strange that there are different criteria, with no connection between them.
I would have thought, that if you would just barely satisfy for example step 3 (full range pressure cycles). That this would have a big influence on step 4 and 8 (other pressure cycles). I would have thought you would need to combine them (maybe using Miner's rule when they are independently) or even add the stresses in case of thermal expansion combined with pressure cycles when the cycles occur simultaneously (as for example mentiond in EN 13445-3 17.1.2).
Am i just wrong? Or are the criteria that conservative that you can look at them seperately?
Kind regards,
Dinant Krijgsman