Safety Assessment of Vertical Storage Tank Based on Robot Ultrasonic Online Inspection

Robot online inspection is a new technology for nondestructive and quantitative detection corrosion of vertical storage tank without emptying the liquid. The storage tank safety assessment methods for robot online inspection are still at the exploratory stage of development. An online inspection robot has been developed by the authors. This paper studies the evaluation methods of bottom plate corrosion with this robot detection. Aiming to characterize localized corrosion and pitting corrosion, multi-angle evaluation indices are proposed. Mathematical models based on reliability evaluation are derived. Above models and evaluation methods are then validated by a case study. Assessment results show that the maximum corrosion depth of storage tank floor is 2.44 mm, the residual useful life of the storage tank is 5 years, and the center coordinates of localized corrosion region of numbered A is (0.58 m, - 0.01 m), the area is 0.484 m(2), and the average corrosion depth is 2.03 mm. Abundant quantitative conclusions are obtained by using the proposed evaluation methods, instead of rough qualitative descriptions. This research provides references for storage tank safety assessments and formation standard based on robot online inspection.