Author: Ing. Carlos Álvarez, August 26, 2023.
Introduction
Non-Destructive Testing (NDT) plays an important role in evaluating and monitoring corrosion. These techniques make it possible to identify the degree of deterioration of materials without compromising their integrity, which is necessary to guarantee the safety and durability of these structures. By using methods such as ultrasonics, x-rays, and eddy currents, corrosion can be accurately tracked under various environmental conditions.
In the oil and gas industry, offshore platforms make deep-water extraction possible. However, these structures are constantly exposed to adverse environmental conditions that can accelerate corrosion in their components, especially in the piles of these structures.
The detection of corrosion in these piles is essential to guarantee the safety of workers, the protection of the environment and the structural integrity of the facilities.
The inspection of piles in submarine platforms presents unique challenges due to difficult access and harsh environmental conditions, where traditional inspection can be expensive and dangerous, making the development of more advanced technologies essential to overcome the limitations of traditional techniques and improve the accuracy of the inspection. In this article, recent developments in Non-Destructive Testing (NDT) used for the detection of corrosion in piles of offshore platforms are exposed.
Traditional methods of corrosion detection in offshore platform piles
Before delving into the most current developments, it is important to understand the conventional methods used in the detection of corrosion in marine piles. These methods include visual inspections, ultrasonic thickness measurements, and current density tests, in which the inspector must access these areas by rappelling to the splash zone or by diving below it, not always presenting safe conditions. for the worker.
Although effective to some extent, these methods are often limited in terms of accuracy and ability to assess the true extent of corrosion in hard-to-reach areas, especially splash zones.
Challenges in the splash zone and underwater inspections.
The splash zone is a critical point on offshore platforms, as the combination of saltwater and changing conditions creates an environment conducive to corrosion. Constant exposure to water and moisture can weaken offshore platform pilings over time.
Most defects are found in areas where air and water are in contact with or under water; suspended technicians cannot reach this area and the waves make it very dangerous to use divers. The usual inspection method for these components is to lower technicians with rope and harness to make a visual inspection, but always above the waterline.
Underwater surveys often involve risks for divers due to the possibility of encountering dangerous marine life, exposure to marine wildlife, or the danger of becoming entangled in underwater structures. As well as the difficulties related to breathing, which limits the immersion time and the accessibility in these areas.
Recent Developments in Non Destructive Testing
Remote Ultrasonic Corrosion Mapping
The robotic ultrasonic corrosion mapping process combines the advantages of ultrasonic mapping with the mobility and versatility of underwater robots. Underwater robots equipped with ultrasonic sensors are submerged in the splash zones and the reflected ultrasonic pulses are picked up by the sensors and the time of flight is used to calculate the pile wall thickness. As the robot moves, it collects ultrasonic mapping data in real time. These data are used to generate accurate maps of the corrosion distribution in the piles. This is an excellent option to determine the degree of deterioration and useful life of offshore platform piles.
Remote eddy current corrosion mapping
They can be applied at or below the waterline. This method employs eddy currents to assess the thickness of the pile walls and detect thinning due to corrosion in combination with the mobility and versatility of underwater robots. Advances in this technology have made it possible to detect corrosion at an early stage in areas previously difficult to access, which has improved the effectiveness of inspections.
underwater robots:
Underwater robots, also known as Autonomous Underwater Vehicles (AUVs) and Remotely Operated Vehicles (ROVs), have revolutionized offshore platform inspection. These robots are designed to operate in harsh underwater environments and can perform a variety of inspections and maintenance. Each type is described below.
Autonomous Underwater Vehicles (AUV): These are unmanned underwater vehicles that move autonomously according to previous programming. These vehicles are equipped with sensors and navigation systems through which they carry out detailed inspections of offshore platforms.
Remotely Operated Vehicles (ROV): These are underwater vehicles that are controlled remotely by operators on the surface. They are connected by umbilical cables and are capable of maneuvering in difficult marine environments.
Benefits and future of advanced Non-Destructive Testing
The adoption of advanced non-destructive testing offers a number of benefits, including increased accuracy in corrosion detection, reduced downtime of inspection rigs, and improved worker safety. As technology continues to evolve, further automation of inspection processes and deeper integration of artificial intelligence for data analysis is likely.
conclusion
Recent developments in non-destructive testing are revolutionizing the way we detect and assess corrosion in offshore platform piles. These innovations not only improve the efficiency and accuracy of inspections, but also contribute significantly to safety and structural integrity in the offshore industry without risking the health of workers. With constantly advancing technologies, a promising future is glimpsed in corrosion and flaw detection to improve the efficiency and safety of these facilities.
Bibliographic references
CORDIS. Big Data to Replace Visual Corrosion Detection on Oil Rigs; Consulted on August 22, 2023; https://cordis.europa.eu/article/id/415492-big-data-replaces-eyes-for-high-resolution-corrosion-assessment-of-oil-rig-structures/en
INSPENET. Robotic Subsea Inspection in the Oil Industry: Benefits and Challenges; Consulted on July 23, 2023; https://www.linkedin.com/pulse/inspecci %C3% B3n-submarina-rob %C3% B3tica-en-la-industria-petrolera/?originalSubdomain=es
MARINE MAGAZINE. Robotics in naval systems, current affairs and challenges; Consulted on August 24, 2023; https://revistamarina.cl/es/articulo/la-robotica-en-los-sistemas-navales-actualidad-y-desafios
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