In the human body, the arteries deliver nutrients and oxygen from the heart to the different parts of our body, making them an important part of our blood system. In some ways, pipelines are the arteries of the oil and gas industry, as they ensure that those materials are being transported efficiently and reliably from one place to another – thus keeping the system running. One of the main threats to oil and gas assets is corrosion. Our RoCorr MFL service addresses this threat and helps mitigate risks. In this article, prepared by ROSEN experts from our Asia Pacific region, we would like to outline the history of the technology and discuss the most recent developments.


For thousands of years, pipelines have been constructed globally as a means to transport and distribute water for drinking, irrigation and agriculture. The first hydrocarbon pipeline that was recorded in history dates back to 500 BC; it was made from bamboo. But we have come a long way since then. Today, pipelines are the arteries of the oil and gas industry.

One crucial fact operators need to be constantly aware of is that pipelines are subject to flaws and start to deteriorate basically the moment they are manufactured. Corrosion and deterioration are a particularly critical threat, and, if not detected early on, they will eventually create irreparable damage to an asset.

As such, ROSEN is always prepared to be one step ahead in assisting operators in ensuring their pipelines are safe and able to run efficiently. To that end, the corrosion detection tool is utilized to ensure that our clients’ high-value assets maintain their structural integrity.


The powerhouse technology in terms of metal loss detection is based on the high-resolution magnetic flux leakage (MFL) method. State-of-the-art permanent magnets are used to magnetize the pipe wall to saturation levels (typically 10 kA/m to 30 kA/m). Achieving a high magnetization level is essential to differentiating critical corrosion from other non-critical pipeline features, such as inclusions and surface defects.

Figure 1 – The basic principle behind MFL involves magnetizing a ferrous metal object to saturation level with a powerful magnetic field. Where the object has no flaws, the magnetic flux will remain undisturbed.

Figure 1 – The basic principle behind MFL involves magnetizing a ferrous metal object to saturation level with a powerful magnetic field. Where the object has no flaws, the magnetic flux will remain undisturbed.

Under perfect conditions (in which no flaws are present), the magnetic flux can travel through the pipe wall undisturbed. But when internal or external metal loss is present, the flux “leaks” out and is recorded by hall-effect sensors. The hall sensors are oriented within the magnetic field and provide coverage of the entire circumference. The character, amplitude and various other measurements of the sensor signals are used to determine the depth, length and width of the detected metal loss.


Figure 2 – Where there is internal or external metal loss, the magnetic flux leaks from the object. MFL testing devices record the leakage.


Similarly to how pipelines have evolved over the time, ROSEN’s corrosion detection tool was also further enhanced and developed to not only detect the smallest pipeline defects but to also define the exact structure of defect groups and complex corrosion. The technological advances of our RoCorr MFL-A service over the last decades will be explained below.


The development of our RoCorr MFL (Magnetic Flux Leakage) tool in 1987 marks the beginning of our corrosion detection tool fleet. This was the first time corrosion or metal loss detection became a part of our service offerings. In 1993, our ROSEN experts started to improve our MFL service by developing a high-resolution technology. By the time the world hit the 20th century, MFL had been through rapid technological advancement. ROSEN started to step up its game by introducing digital high-density technology in 2020 – a sensory technology that definitely helps clients get more accuracy.

Figure 3 – RoCorr MFL-A tool

Figure 3 – RoCorr MFL-A tool


In 2005, another milestone was reached when the team started to combine technologies. The combination of ILI technologies and RoCorr MFL and extended geometry technology, and the combination of MFL and ultrasonic technology, were the start. But ROSEN did not stop at combining two technologies; instead, we begun to develop the quadruple combo, a combination of four technologies in one tool.


We hit another milestone when we started to use digital extended-density technology in MFL, another sensory technology improvement, to further improve both precision and reliability. Then, in 2008, ROSEN introduced MFL heavy-wall-thickness coverage aimed especially at offshore pipelines.

However, even with those advancements, it was virtually impossible to reliably detect and size minuscule defects, such as pinholes of 1 mm and less in diameter. It has been equally challenging to determine the exact shape and structure of defect groups such as complex corrosion, let alone pinholes in heavily corroded pipelines. At the same time, data evaluation is always subject to the human factor, which can impact the repeatability of results.


Especially when it comes to our MFL-A (axial MFL) service, recent technological developments have led to significant changes: In 2016, ROSEN launched a new in-line corrosion detection service, RoCorr MFL-A Ultra, which has a five times higher resolution than the previous service. The new technology, in combination with a perfected evaluation process, is designed to provide something not available before: a detailed and accurate representation of a pipeline’s structure by zooming into the smallest of pinholes in process called Pipeline Imaging™. This enables the client to produce less conservative integrity assessments, which in turn can minimize field verification expenses and lead to extended asset lifetimes.

The main advantages of the MFL-A Ultra technology are highlighted in this video:

The wide range of proven tool configurations available can address individual pipeline requirements, while the high magnetization levels of our robust tool fleet provide first-rate data quality. Special configurations are available for bi-directional movement, multi-diameter lines, low-flow/low-pressure systems, high-temperature/high-pressure systems and high-flow/high-flow velocities.


With pipeline corrosion features getting more and more complex and regulatory requirements tightening further, we are determined to adapt to those upcoming challenges by continuously improving our service offerings to secure a sustainable future empowered by technology.