Hello Bajwa,

Well, context is everything in this question. In the context of the Lummus document that you are citing:

"In paragraph 4.2.1 the manner in which a bend develops its flexibility by a flattening of the cross section was described."

This alludes to the Flexibility Factor. Elbows and bends are more flexible under loading than a similar piece of straight pipe. When we are performing structural analyses of piping systems, we must address the additional flexibility of elbows and bends. Simply stated, the Flexibility Factor for an elbow is the ratio of the bending flexibility of an elbow segment to the bending flexibility of a straight pipe. Dave Diehl wrote about this in the October, 2002 issue of COADE Mechanical Engineering News. Please download the issue (pdf format) at:

http://www.coade.com/newsletters/oct02.pdf

and read it over several times.

The "Correction Factor" comes from B31.3, Appendix D, Chart B (also read note (5) in B31.3, Appendix D). While an elbow or bend is more flexible than a straight piece of pipe, some of that additional flexibility is diminished if a flange is attached at the weld line and even more of that additional flexibility is diminished if two flanges are attached, one at each weld line. The Correction Factor is used when one or two flanges are attached to the elbow (bend). The "correction factor" is a coefficient that is applied to the "flexibility factor" to REDUCE it, thereby addressing the "stiffening" effect of the flanges.

So, when you read in the Lummus document that:

"This correction factor C1 has value C1 = h^(1/6) when one end is flanged and CI = h^(1/3) when both ends are flanged. Note that this is a reduction factor."

....in that context, the "Correction Factor" actually is a "Reduction Factor" in that it reduces (adjusts) the calculated "Flexibility Factor" to address the installation of flanges (which makes the elbow or bend "stiffer").

Regards, John.