Experimental study of the creep lifetime of the butt-welded 1.25Cr0.5Mo steel pipes M. Sajjadpour, F. Vkili-Tahami and M. Zehsaz EPJ Web of Conferences, 6 (2010) 43002 Published online: 10 June 2010 DOI: 10.1051/epjconf/20100643002