Vessel life cycle, endurance strength & S-N curves for 316L

[scotchie78]

Hey All,

First post, so please be gentle....
I'm trying to familiar myself with determining life cycles for ASME BPVC VIII Div 1 for pharma/bio-pharma application.

First reaction to date has all been FEA, FEA, FEA....

To me, FEA is a relatively new technology and I've been researching how life cycle have been estimated before FEA.

Looking at endurance strenght/S-N curves etc.

As far as i can tell on reading to date, this topic is covered in detail in ASME III for nucleur applications. I don't have access to ASME III and wondering is there any other good reference I should be looking at.

Based on research to date I think I should be focusing on the endurance of seam welds/nozzle welds, HAZ and loading around these areas.
Typical cycling loading on vessel are due to sterilization processes at 121°C.
Unusual to have DP>+6bar/-1.0 or DT>150°C
Majority of vessel are all made up of A240/270/312/213 316L material with E=0.7 but some are E=1.0 inspection. Life cycles are generally <10^4 cycles

Based on initial research I think I won't have life cycle issue given the number of cycles but, I want to develop the paperwork to back this up.

Welcome comments/feedback that will point me in the right direction.

Thanks S.

 

[TGS4]

At those temperatures you want to be referring to Section VIII, Division 2 and not the Nuclear Code Section III.

The issue with cyclic service and cyclic analysis is determining the peak stress range over the cycle. For thermal cycles, that is governed by the heat up rate, the cool down rate, and the thermal mass.

Since you have less than 10,000 cycles, I would highly recommend a fatigue screening evaluation using the methodology (Method B) in ASME Section VIII, Division 2, Section 5.5.2.4.

Generally, we only speak of "endurance" and endurance limits and the like when we have cycles in excess (well in excess) of 1e6 cycles.

 

[scotchie78]

Thanks TGS4,

Much Appreciated: Saves me researching Section III in vane.