Systems and methods for safely repairing potable water tanks when submerged within a tank. The barrier may be shield structure defining a cavity and having an aperture and valve for injecting the coating material into the cavity, or the barrier may be a sheet preloaded with coating material and stored within and delivered via a transfer shield, or the barrier may be a continuous sheet delivered over the top of the coating material at the same time it is applied. The barrier layer, be it a shield structure sheet or continuous sheet, becomes adhered to the substrate being repaired so post cure removal is not required. Methods of repair include pressing the sealing edge of a barrier shield over an area, injecting coating material between the barrier shield and area, removing the source of coating material, and permitting the coating material to cure.

Systems and methods for safely repairing potable water tanks when submerged within a tank. Several barriers are used to separate the coating material after application to the area of the tank needing repair from the potable water. The barrier may be shield structure defining a cavity and having an aperture and valve for injecting the coating material into the cavity, or the barrier may be a sheet preloaded with coating material and stored within and delivered via a transfer shield, or the barrier may be a continuous sheet delivered over the top of the coating material at the same time it is applied. The barrier layer, be it a shield structure sheet or continuous sheet, becomes adhered to the substrate being repaired so post cure removal is not required.

A roll for a hot-dip metal coating bath has a substantially cylindrical shape. At least an outer peripheral surface of the roll is formed of a ceramic material. A relatively coarse groove is formed on the outer peripheral surface of the roll in a direction crossing the rotation axis. A plurality of relatively fine grooves is formed in the bottom surface of the coarse groove along the longitudinal direction of the coarse groove. In place of the fine grooves extending in the longitudinal direction of the coarse groove, a plurality of rows of fine grooves may be formed along the crosswise direction of the coarse groove.