A self-adhesive purge dam for retaining purge gas around a weld zone includes a base configured to substantially obstruct an air passage leading to the weld zone and an adhesive skirt extending from the base and configured to engage portions of the air passage. An adhesive on the adhesive skirt allows the skirt to be adhered to the air passage. An optional removable backing covers the adhesive prior to installation. The purge dam is installed by peeling the removable backing (if present) and exposing the adhesive for adhesion.