Cracking of a Field Girth Weld
During the construction of a large-diam pipeline, several girth welds had to be cut out as a result of radiographic interpretation. The pipeline was constructed of 910 mm (36 in.) diam x 13 mm (0.5 in.) wall thickness grade X448 (x65) line pipe. The girth welds were fabricated using standard vertical down stove pipe-welding procedures with E7010 cellulosic electrodes. The crack started partially as a result of incomplete fusion on the pipe side wall, which in turn was a result of misalignment of the two pipes. The crack was typical of hydrogen cracking. Girth welds can be made using cellulosic electrodes. For high-risk girth welds, an increase in preheat and/or a reduction in the local stress by controlling lift height or depositing the hot pass locally before lifting may be required.