A multitask experimental study was conducted to provide the petroleum industry with solutions to recurring incidents of cracking in the application of welded 1 ¼ Cr - ½ Mo steel for hydrogen processing equipment. The principal objective was to develop recommendations for the elimination of cracking that occurred during fabrication or early in operating life, was associated with repairs or was found after extended service exposure at elevated temperature. Vessel and equipment experience has shown that the majority of weld cracking problems have occurred at temperatures in excess of 850°F. Further, little or no problems have been found for operation at temperatures below 800°F. Thus, a cutoff temperature of 825°F has been suggested for invoking the precautions, considerations and recommendations regarding the potential for coarse grained weld HAZ (CGHAZ) cracking in 1¼ Cr-½ Mo steels.