Let's revisit the infamous F correction factor 1

[rww88]

There has been much discussion in this forum regarding the F correction factor of UG-37 and Figure UG-37. Through these discussions I have garnered a complete explanation and consequently, understanding, of the theoretical aspects of this factor.

I need no further explanations; what I do desire, and would be most appreciative of, is at least one single, real-world, practical, actual application of the F correction factor. One in which an economic or otherwise meaningful impact was derived from its use.

 

[jte]

rww-

One "real world" example including photographs is presented in the paper available at

http://store.asme.org/product.asp?c...tegory_name=&product_id=PVP2006-ICPVT11-93596

In the case presented, economic (reduced schedule) and physical (reduced likelyhood of warpage) drove the use of the F factor.

jt

 

[rww88]

Thank you jte. I will order a copy of the cited paper.

 

[TomBarsh]

JTE has shown application of use of the F factor to existing vessels (creative use of weld repair can save ones bacon for existing vessels...my apologies, JT if I misinterpret the paper).

But the F factor has important application to construction of new vessels as well.

For example, nozzle necks inserted through the shell may be either cut square or may be cut as contoured to the inside surface of the shell. If they are cut square then the resulting internal projection of the nozzle neck in plane theta=0° can be used for reinforcing area (F=1.0). But then the plane through the nozzle at theta=90° (F=0.5) must be considered separately as well.

Generally for a radial nozzle with "integral reinforcement" the plane at theta=0° will be the critical plane and there is no need to check reinforcing on other planes, they are good "by inspection".

But for this case where the (integral) reinforcing area provided actually varies around the circumference of the nozzle with angle theta, then at least the cross-sections at theta = 0° and 90° should be investigated. This is because it can no longer be determined by inspection that the section at theta = 0° governs the reinforcing.

This has real-world application for fabricators who work with expensive materials, or with nozzle forgings with very thick wall (eg: very thick walls for, say, the FVC type heavy barrel forgings). I see this regularly.

 

[rww88]

Thank you TomBarsh. Once again, your post is very informative and most appreciated. I will incorporate the new knowledge that you have imparted into my literary endeavors.

 

[jamesl]

Here is an example.

There are some process columns with very large inlet nozzle tangential to shell, you have much longer cord length (sometimes twice long) at 90 degree than the opening width at 0 deg, with F=0.5, a much smaller insert plate can be used for reinforment.