Nozzle pad edge stress intensity factor (SIF) derived from Part 4.5.

[Greenbee]

Commercial software such as COMPRESS Codeware is using Part 4.5 in ASME Code VIII-2 to derive the SIF at pad edge.

It is easy to understand that nozzle with or without pad stress intensity factor (SIF) at intersection could be derived from per eq. 4.5.55 and 4.5.145. But to the pad, what the assumption to the inputs could get the pad edge SIF, such as Rn, tn, and etc.?

 

[DriveMeNuts]

For a Pad with a width greater than sqrt(Dx(T+t)), SIF = 1.
For a narrow pad, engineering judgement is required. I don't know of any design method which provides an adjustment factor.

 

[Greenbee]

DriveMeNuts

Thanks for your response. I found the COMPRESS Codeware report that SIF at pad edge is derived from Part 4.5 ASME Code VIII-2. I cannot figure it out how it is derived for a pad. Nozzle SIF can be figure it out.

 

[DriveMeNuts]

That is weird. I haven't used Compress in a while but I did study the nozzle loading design routine a lot and vaguely remember Compress assuming that the SIF at the edge of the pad is assumed to be 1.