REPAIR TECHNOLOGY FOR SINGLE DECK DISTORTION OF FLOATING ROOF TANK

The repair welding procedure and assembly method that is considered as the key of repair single deck distortion are pointed out in this paper. Also presented is the repair plan of single deck distortion which consists of four stages: stress release, distortion repair, stress adjusting, and sequential assembly. The steps and technical requirements of repair single deck distortion are as follows: Step 1: Installing repairing platform The platform should have enough stiffness, or else it will influence the repair effect of single deck distortion. Step2: Inspecting the stress and distortion or single deck plates The intention of inspecting the stress and distortion of single deck plates is in order to select the welds which should be retained or removed, and to confirm the sequence of removing the welds. The method of lattice is applied in inspection. Step3: Removing single deck plates The principle of removing single deck plates is to remove longitudinal welds and adjust the longitudinal distortion of single deck plates first, then removing transverse welds and adjust the transverse distortion of single deck plates. Step4: Eliminating the local stress of single deck The key of eliminating local stress of single deck is to control the skill of releveling the single deck plates, assembly of shaped single deck plates, dot welding of single deck plates and inspecting the distortion of the single deck plates. Step 5: Eliminating the integral stress of single deck The single deck is divided into nine parts. Small distortion of single deck is eliminated first, then the serious distortion. Step 6: Adjusting the distortion of assembled single deck plates Adjusting the distortion of assembled single deck is a very important process for single deck repair. The adjusting method is from integral to local and then from local to integral of single deck repeatedly. Step 7: Welding single deck plates The step is to weld short welds first, then long welds. From the center to all sides of single deck, the method of skip welding is applied. Step 8: Nondestructive examination Copyright (C) 2008 by ASME