Abstract: This invention relates to a method for applying preformed cellular glass insulation blocks to the exterior surface of a spherical metallic storage vessel by the steps of:(a) cleaning the exterior surface of the vessel;(b) maintaining the vessel at a temperature of 80.degree.-100.degree. F.;(c)(1) beveling the side walls of a preformed cellular glass insulation block,(2) dishing the inner surface of the preformed block to correspond to the contour of the spherical vessel to which the block is to be adhered,(3) applying uncatalyzed urethane-modified asphalt adhesive stored at 35.degree.-50.degree. F.