Primary containment problems in double wall steel tanks, and tanks with steel primary containments and non-corrosive secondary containments, can occur as the tanks age. The inner-tank, or primary containment, can develop corrosion permeations which can cause product migration into the interstitial space of the tank. Some of these permeations may develop at weld points on striker plates, under striker plates, at welded seams or under tank bottom sludge deposits. Perforations at weld points can sometimes be attributed to corrosion cells created by the interaction of dissimilar metals in the welds. Microbial action can cause accelerated corrosion potential in tank bottom sludge. Other failures can be caused by wear spots and/or corrosion points occurring at the tank bottom, attributed to years of contact by gauging sticks.
Double wall steel tanks and steel tanks with FRP or resin wraps which develop such problems can be returned to service quickly and safely by the application of the Armor Shield tank repair process. When studied through such tests as ultrasonic gauging at the time of repair and lining, virtually all of these tanks show structural integrity meeting or exceeding industry standards. In simple terms, other than small isolated problem areas, these tanks are sound and can be returned to full term useful life expectancy in the vast majority of cases.