In nearly any industry with tanks, pipes on supports, or pipes going to the surface, customers face inspection challenges and specific questions about how to inspect critical areas of these three asset components.However, restricted access phased array (RAPA) methods can inspect these traditionally challenging areas that have historically been known for not having easy inspection solutions.
RAPA is an ultrasonic inspection method that is a powerful corrosion screening tool.The benefits of RAPA are greatly reduced inspection time, limited excavation needs, and the ability to potentially extend tank inspection intervals or prioritize tank inspections.
Tank inspections are necessary for a number of reasons – from compliance with various regulatory standards, to ongoing detection and maintenance of issues such as corrosion and leaks.If left unchecked, storage tanks can become a major safety and environmental issue with potentially catastrophic consequences.
However, tank inspection is not an easy process, as many areas on a tank require the use of specific inspection techniques or screening for specific problems.One area that falls into this complex category is the annular ring in above-ground storage tanks, which is the area below the perimeter of the base.As corrosion hotspots, these annular rings and their welded joints tend to accelerate bottom corrosion given the considerable mechanical stress placed on this area.In addition, if there is internal upper corrosion in the critical region, it may make the region more vulnerable.
While inspection of these annular tank rings has traditionally required off-line inspection, restricted access phased array (RAPA) screening inspections allow the tank to remain in service throughout the inspection process.
RAPA is an advanced NDT technique proven to be an effective short-range corrosion scanning solution.The benefits of using RAPA scanning for annular tanks are two-fold – first, the tank can continue to be used, eliminating a major inspection limitation.Second, through RAPA, customers gain a better understanding of the integrity of tanks in critical areas.
By employing RAPA inspection screening when a tank is put into service, operators are able to understand any potential threats to the structural integrity of the tank and prioritize future inspections accordingly.This ability to anticipate threats makes RAPA inspections an effective pre-closure strategy for many customers looking to allocate inspection spending where it is most needed.
RAPA has proven to be a powerful detection method when it comes to protecting the safety and integrity of tanks, scanning the tank’s annular plate and providing “early warning”.However, as with any inspection technique, using RAPA scans for annular plates does require some consideration.Such considerations include cleaning the toroid to bare metal to eliminate method variables and improve signal transmission.Further considerations include that the annular protrusion should be 40mm or larger and should not corrode badly at the top or bottom.
The number one priority for tank inspections is to minimize disruption and protect production without compromising any quality.RAPA is an advanced detection method that helps achieve such results.With RAPA scanning the annular tank ring, inspections can be performed with minimal disturbance and optimized results.
All piping is mounted on some form of support, so all piping is susceptible to wear from movement during operation or to debris build-up under piping corrosion.This applies to both lag and non-lag pipelines.
In the past, the only way to inspect these areas was to conduct limited visual inspections or lift pipes, a safety hazard and financially intensive process.The process of lifting pipes for visual inspection is rigorous and certain pipe configurations cannot be lifted.
Using the RAPA method, the ALS can now screen the area beneath the pipeline and determine if there is damage, providing a more focused view of CUPS.Ultimately, this improves security and significantly reduces financial requirements.
One meter below the surface, the composition of moisture and oxygen is an ideal environment for corrosion of carbon steel pipes.Traditionally, the only way to inspect this area of the pipe was to dig a hole around the pipe for visual inspection.
The problem with this method of excavation inspection is that only pipes that show signs of corrosion need to be excavated.When using RAPA inspection screening, safety concerns associated with excavation are eliminated and inspection costs are significantly reduced, targeting only excavations that show signs of subsurface corrosion.
Overall, RAPA eliminates the potential for burrowing to find pipes in good working order.
Corrosion is complex, and mitigating and managing it is not a linear process.Having said that, RAPA makes it increasingly feasible to examine these three traditionally problematic locations.For all three applications above, RAPA is used as a cost-effective screening tool to improve safety and spend inspection budget funds in a more focused manner.Screening solutions are seen as increasingly valuable when used as an initial inspection method – to guide further inspections and identify needed remedial action.
Post time: Feb-25-2022