Asset integrity demands special people with special NDT tools

Staff responsible for asset integrity should be ‘cup half empty’ types; they should be intuitively sceptical and constantly expect the worst to happen because asset failure can have extremely serious safety, environmental and financial effects. In addition, these people need to possess a highly methodical, risk-based approach to asset management, with almost obsessive attention to detail. The pressure for ageing assets to perform for extended periods has probably never been greater, so the demand for effective, reliable inspections is enormous. However, there is also pressure for this work to be as fast and efficient as possible in order to minimise down-time. The protection of asset integrity therefore relies on the availability of inspection tools that meet this demand. As NDT Market Manager at Ashtead Technology, one of Steve Drake’s responsibilities is to ensure that the company’s fleet of rental and sale instruments meet the demands of the asset integrity testing community, so he is well placed to comment on the latest technological developments. “Many NDT technologies are high value items, so it doesn’t make financial sense to purchase this equipment for occasional use,“ Steve says. “We invest in these instruments so that our clients don’t have to. By making this equipment available for hire, we provide access to the latest technology without the burden of capital cost. But that’s not the only driver behind our investments; in addition to financial choice, we also aim to offer technology choice, which means that we continually invest in a variety of technologies so that customers can select the instrument that best suits their application.” A further advantage of instrument rental lies with the ability to call upon technology at short notice – when existing equipment is in use elsewhere or becomes unavailable for some reason. As a result, the ability to dip into a pool of rental instruments allows asset inspectors to avoid the costs of over-tooling. Corrosion Under Insulation (CUI) Corrosion under insulation has long been an insidious form of corrosion because traditionally it has been difficult to measure and predict without physically removing the insulation. The potential costs of CUI are also enormous, so the launch of the Eddyfi Lyft is highly significant because it provides asset inspection and maintenance staff with a fast, reliable, flexible tool for this vital work. The Eddyfi Lyft employs Pulsed Eddy Current (PEC) in a portable, rugged, battery-powered NDT instrument with connect-anywhere wired and wireless communications. Designed to improve the speed, ease and quality of inspections with real-time C-scan imaging, the Lyft offers fast data acquisition (up to 15 readings per second) grid-mapping and dynamic scanning modes. Three different sized standard probes and a specialised splash-zone probe enable the inspection of wall thicknesses up to 64mm, insulation up to 203mm thick (fibreglass, plastic wrap, concrete, or other non-ferrous materials), as well as stainless steel, aluminium, and galvanized steel weather jackets. The Lyft’s unique compensated wall thickness (CWT) tool improves inspection accuracy by quantifying the minimum wall thickness of a specific region in a C-scan, and specialised algorithms isolate a defect’s contribution to the signal to more precisely compute remaining wall thickness. The potential for CUI is greatest in marine environments, hot and humid environments, and in locations with high rainfall, aggressive atmospheres or steam tracing leaks. Intermittent wet and dry conditions, or systems that operate below the dew point can encourage CUI and some insulating materials may contain contaminants such as sulphides and chlorides, or may retain moisture, or be designed in a way that restricts moisture drainage. In addition to CUI, applications for the Eddyfi Lyft include corrosion under fireproofing, flow-accelerated corrosion, corrosion blisters and scabs, splash zone and underwater, surface corrosion, and corrosion under coatings and at waterworks. Corrosion Inspection The Olympus OmniScan phased array ultrasonic systems are some of the most popular instruments in Ashtead’s entire rental fleet. The OmniScan MX2 for example increases testing efficiencies, ensuring superior manual and advanced UT performance with faster setups, test cycles, and reporting, in addition to universal compatibility with all phased array and ultrasound modules. The MX2 unit is equipped with advanced features such as the ability to use PA and UT channels simultaneously. As a modular platform, the MX2 houses more than 10 different Olympus modules and Ashtead Technology’s engineers are able to advise on the best setup for every application. The Olympus HydroFORM corrosion mapping scanner employs an ingenious water-column concept that eliminates the need for a wedge, thereby providing the benefits of a phased array immersion-tank inspection. Designed for the detection of wall-thickness reductions due to corrosion, abrasion, and erosion the HydroFORM also detects mid-wall damage such as hydrogen-induced blistering or manufacturing-induced laminations, and can easily differentiate these anomalies from loss of wall thickness. In applications such as corrosion mapping, delamination or defect detection in composites, bond inspection and crack detection with eddy current arrays, the Phoenix ISL Tracer freehand scanning system calculates and outputs accurate X-Y positional data for C-scan inspections without the constraints of a scanning frame. The Tracer can be used on an inspection area of up to 2m x 2m from a single position, even in difficult to access areas. Importantly, it does not lose position when the probe is lifted off the surface and then replaced, so maximum scan coverage is achieved up to and around obstructions. The Silverwing Scorpion is a motorised magnetic inspection tool, able to inspect vertical, curved and even overhead surfaces. Designed for cost-effective A and B-scan inspections, the Scorpion is a dry-coupled UT crawler that connects with the UT Lite data acquisition instrument via a 30 meter umbilical cord. Dry coupling removes the need for a constant water supply and a magnet in front of the wheel probe removes the cost and safety issues associated with scaffolding or rope access. When combined with the UT Lite the Scorpion continuously records thickness measurements as it moves over the inspection surface. The recorded thickness information is presented in the software as an A-scan trace, a digital thickness measurement and a B-scan profile. Summarising, Steve Drake says: “Every tank, pipe or vessel is different; not just in age and material of construction, but also in build and maintenance quality. The environment can also have a significant impact on the quality and integrity of an asset, as can operational conditions. It is important therefore for inspection staff to deploy the most appropriate instrumentation, which is why our customers find it so useful to be able to select from a large fleet of the latest technologies and to seek our advice when making these important choices.”

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