Section VIII DIV 1 paragraph U-2 requires the designer to address all conditions the vessel will experience.  I would have to look up Div 2, but it should have a paragraph that is similar.  These codes just don't supply a standard analysis for creep or creep fatigue, but it doesn't relieve the designer from its concerns.  Div 1 and Div 2 may also have lower temperature limits and stress limits that would protect against creep fatigue, that the nuclear codes don't have, you could compare in Section II.

 Dear C.H. Delee,

Thanks for sharing your views.

Let us say that the broad conditions given to me for design of a pressure vessel are operating temperature T deg C, pressure p bar (g), in X environment, with N number of startups through service life of t hours. Now same design conditions may be for a nuclear facility component and for a nonnuclear facility component. If it is part of a nuclear facility I will use ASME section III and if it is part of a non nuclear facility I will use section VIII. In reality if loading (temperature mainly) is significantly high to cause creep fatigue interaction it must be taken care in design. I completely agree with you (These codes just don't supply a standard analysis for creep or creep fatigue, but it doesn't relieve the designer from its concerns) and very strongly believe that section VIII will also be taking care of CFI. But I want to know How/where?

As you have pointed out temperature limits may be one cause. I am not very sure but my initial feeling tells it is not the reason because for Alloy 617, which is not permitted for nuclear application, allowable stresses are given up 900 deg C (ASME BPVC 2013 SECTION II page 227-229) for section VIII-1 and you can find so many papers on internet - where 617 was tested for VHTR application in the same temperature range creep fatigue interaction diagram intersected at (0.1,0.1). It means the design practices of section VIII div 1 (non nuclear code) take care of this interaction.

The ASME BPVC 2013 SECTION VIII - DIVISION 1 U2 (page 3) tells:

"The user or his designated agent shall establish the design requirements for pressure vessels, taking into consideration factors associated with normal operation, such other conditions as startup and shutdown, and abnormal conditions which may become a governing design consideration. Such consideration shall include but shall not be limited to the following"

Which are followed by some conditions now if I include such conditions also, I will be designing as per section VIII-1 only. As per my understanding whatever design condition I include, CFI calculations will not be the part of design directly for a non nuclear component. It may be there in some hidden form.

Regards

Section VIII division 1 allows the designer to choose the best method that the Authorized Inspector will agree to for conditions not covered specifically in the Code.  For instance, for regular fatigue, ASME Section VIII div 1 does not provide a method to perform the calculations, but U-2 and UG-22 require the designer to account for their effects.

 This is also true of external loads, the code does not provide a method to design vessels for earthquake loads, but that does not alleviate the designer of responsibility.

 In Section III the service is considered critical enough that the code committee feels it is necessary to decide on one method that everyone must follow.   If the Section III creep-fatigue method is applicable to your design case, then it will likely be an acceptable method to analyze the Section VIII Div 1 or 2 vessels to. (Given AI and engineering approval etc.)

Hello everyone

Dear Salvatore Nasisi and C.H. Delee thanks for your replies

@ Salvatore Nasisi - I just want understand the basis of the calculations of code in a better way (especially non nuclear as they seems not very clear to me…nuclear codes are more elaborative from design loads to procedures/calculations)......so many OEMs leave some portion of the load in design and consider that the factor of safety on the primary load takes care of this load...so I want to understand if same thing is applicable in case of codes also....when they don't do an exclusive calculation for a particular load case (CFI in this case)...is it also taken care or just ignored and designer has to take care of it separately…

@ C. H. Delee – 

It becomes difficult for me to interpret ASME-BPVC properly many times….sometimes language looks more legal (my problem only)….for example section VIII div 1 U2 (g) says “This Division of Section VIII does not contain rules to cover all details of design and construction. Where complete details are not given, it is intended that the Manufacturer, subject to the acceptance of the Inspector, shall provide details of design and construction which will be as safe as those provided by the rules of this Division”…. it is clear to me what code wants to tell...but I miss it many times till someone explains me...

I completely agree with you that unavailability of design procedure for some particular load in a particular section of ASME does not alleviate the designer’s responsibility. As you have pointed out that section VIII div 1 does not have a procedure for fatigue calculation and we used to use section VIII div 2 para 5.5 (protection against failure from cyclic loading – page 543 in 2013 edition) for fatigue assessment.

So in my opinion --> ”Designer should NOT assume that the procedure given in a section of ASME take care of all the loadings. He/she should do the necessary calculations (outside that section) for remaining loads that are part of design load but not covered in the design procedure/calculations of that section”

Did I get the correct message?

With best regards

Yes, I agree.  Be sure to use the allowables from ASME section VIII and combine loads appropriately.