New release of ASTM 680 C adapted

In 2004, ASTM have modified again their standard 680 C, release 2003. The new ASTM C 680 formulas are adapted in SIMU-THERM within May 2005. 

It turns out that there is a good conformity of the new ASTM release with the German VDI heat atlas in case of free air convection. We recommend to use the new ASTM formula to calculate shell temperatures