Soft-soldered copper pipe joints used in refrigerating plants failed. The solder had not adhered uniformly to the pipe surface. In addition, there were some longitudinal grooves on the pipe surfaces, parts of which were not filled with solder. The unsoldered areas formed cavities within the joints, some of which had been in direct communication with the outsides via the grooves or interconnected cavities. On cooling, moisture condensed on the external surfaces. Some of this was drawn by capillary action into the cavities in open communication with the external surface. On continued cooling to below freezing-point, water that entered the...