Variable tw in B31.1 Section 104.3.1(C.2)

[SG12345]

Hoping someone can help me on this one. Does anyone know where I can find the definition of variable 'tw' as called out in ASME B31.1 2010 Ed. Section 104.3.1(C.2)?

Any help would be most appreciated.

 

[SG12345]

Found it. Though it is shown in another Figure (Fig. 127.4.8(G)). It should be shown in Fig. 127.4.8(F) as well.