Automated IBEX crawler for PAUT inspection for in-service ferromagnetic assets

Abstract

In order to guarantee the safety of the gas production plants, Air Liquide conducts NDT inspections regularly closely following the assets’ maintenance plans. One high criticality asset is the Pressure Swing Adsorber (PSA), found in the last stages of the hydrogen production process, where product purification takes place. These adsorbers are pressure vessels and need to be inspected for hydrogen enhanced fatigue cracks. Conventional inspection would require stopping site operation, building scaffolding for the totality of the height, which depending on design can be up to 15 meters tall and 6 meters in diameter, grinding of the inspection surface to remove the paint, conducting the inspection manually by 2 operators, and repainting once inspections are concluded. Commonly, inspection plans for these high-criticality assets outline a high inspection frequency, resulting in elevated costs associated with logistics, personnel and time and monetary resources required to plan and execute each inspection. This necessity is what drove Air Liquide R&D and INTACT to create a partnership and develop an automated crawler that can be deployed on in-service ferromagnetic assets for Phased Array Ultrasonic Testing (PAUT) inspection, using Total Focusing Method (TFM) with INTACT proprietary imaging and software. The robot, named IBEX Crawler, is deployed at the lowest part of the vessel and controlled safely at the ground level by a single operator. It is able to change directions to accommodate the inspection of longitudinal and circular welds. It includes an encoding system that enables operators to exactly locate any indications present. The crawler’s payload includes an electronic 128 elements PAUT board controlled by fiber optics, laser tracking and machine vision camera. The inspection results are analyzed by 3D reconstruction and managed by mechanical integrity assessments proprietary technology, calculating the stability of the found indications and using fracture mechanics and Fitness-For-Service (FFS) to estimate the residual lifetime of the indications and in consequence, the interval between inspections to develop a more accurate maintenance plan. Today INTACT’s IBEX crawlers travel worldwide between Air Liquide sites to ensure the integrity of the assets.