The influence of welding procedures on bacterial colonization of stainlesssteel weldments

The US food processing industry requires that food contact stainless steel surfaces have a No. 4 surface finish, with welds having a surface finish eq uivalent to the parent plate. To meet this standard, most welds must be gro und and polished, which significantly increases the cost of fabrication. Tw o laboratories have independently compared colonization of seven plasma are welds, not subjected to grinding and polishing by either the human pathoge n Listeria monocytogenes, or a 3-member bacterial consortium containing Fla vobacterium spp. that were isolated from weldments in a seafood processing plant. Bacteria did not appear to preferentially colonize the surface of we lds over that of adjacent parent 304L stainless steel with a 2B finish (equ ivalent to No. 4). The results suggest that the current practice of grindin g and polishing welds to achieve a No. 4 surface finish that meets current food industry roughness standards may have no significant influence on shor t-term bacterial accumulation. (C) 1999 Elsevier Science Ltd. All rights re served.