How inline video inspection works

In inline video inspection, a camera system is inserted into the pipeline. Typical variants are:

• Robotic crawlers (for larger, walkable pipes)
• Self-propelled or media-driven inspection tools
• Pushable cable cameras (in smaller or domestic pipes)
• Cable-connected video systems that are either pulled or driven by the flow of the medium

The video material is usually recorded in high resolution and can be combined with additional sensors:

• LIDAR (for 3D profiling)
• Ultrasonic sensors (for wall thickness measurement)
• Gyroscopes and acceleration sensors (for geometry mapping)
• Hydrophones for acoustic leak detection

The data is transmitted in real time or stored for later evaluation and then examined by engineers for anomalies.

Specific requirements for use in water transport lines

Water transport pipelines, also known as long-distance pipelines, in Germany mainly have diameters ranging from DN 400 to 1800. Due to their function, they cover long distances, i.e., the pipeline sections are long. Total lengths of over 100 km are not uncommon.

A decisive factor in the selection of suitable inline inspection and diagnostic systems is the lack of redundancy in the pipeline system. Unlike branched supply networks, the affected pipe section cannot be replaced, or only with great effort, in the event of a failure or interruption due to maintenance work, which leads to supply failures or high costs for replacement routes. The same applies to the drainage of pipe sections to enable inspections. This rules out methods that require the drainage or decommissioning of the pipe.

Another important aspect is access to the pipe. Access to water pipes is limited and, in the case of transport pipes, only available at large intervals. This limits the use of cable-based systems.

However, the biggest obstacle for inline inspection devices is cross-sectional restrictions such as flaps and slides, which are found in every water pipe. A lack of passability, which requires removal before installation and reinsertion afterwards, leads to considerable costs and labor. Often, the costs for preparing the inspection section would exceed those for the inspection itself.

The ideal system for inline inspection of water lines:

• allows the devices to be inserted through existing installations such as T-pieces, manholes, etc.,
• allows measurements to be taken during operation,
• can pass butterfly valves
• is driven by the medium in the pipe,
• Allows long measurement runs over many kilometers
• Has stable, centered device guidance
• Enables precise positioning of the measuring device, diagnosed defects
• and the pipe trajectory in the x, y, and z directions.

Applications and advantages

Inline video inspection offers numerous advantages:

• Direct visualization: Immediate detection of damage such as root ingrowth, spalling, leaks, or misalignments
• Preventive maintenance: Early detection enables timely repairs
• Minimized downtime: Mostly non-destructive and less invasive than excavations
• Results documentation: Video recordings as a reference for planning, repair, and asset management

Typical cost advantages result from:

• Avoidance of unnecessary complete renovations
• Early detection of expensive pipe breaks
• Reduced downtime
• Targeted use of resources in network operation

Advantages of high-resolution video recordings for detecting cracks and defects

In addition to documenting visible defects, modern high-resolution video systems also enable the precise detection and documentation of defects and directional deviations in pipe connections. Given that more than 80% of leaks and pipe failures are due to defective pipe connections, this method is a cost-effective and efficient tool for predictive, condition-based maintenance of pipelines. It enables significant savings in repairs over the life cycle of the pipe while extending its useful life.

Compared to ultrasonic methods for measuring faults and directional deviations in pipe connections, qualified video methods offer the following advantages:

Direct visual confirmation

Video provides real visual context – the gap or misalignment is visible, not just indirectly measurable. This allows genuine misalignments to be reliably distinguished from image artifacts such as weld spatter or corrosion. Foreign objects can be clearly identified.

Damage to the pipe socket that indicates a failure of the pipe connection is also detected, which is not possible with indirect methods such as ultrasonic technology (UT)
 

Precise measurements in real units

Calibrated video systems enable measurements in millimeters. This allows, among other things, the exact evaluation of gap widths in socket connections and root openings of weld seams, as well as axial or angular misalignments.

High accuracy for complex geometries

Ultrasonic methods are often inaccurate in areas with complex geometries (e.g., on pipe bends or weld roots). Video recordings remain evaluable reliable even in such areas.

Immediate evaluation by operator or AI

Trained specialists or AI systems detect errors directly in the video image – without time-consuming signal interpretation. This enables quick decisions on site.

Documentation and archiving

Video recordings provide a permanent, repeatable representation of the actual condition – ideal for:

• Technical evaluation
• Insurance and regulatory compliance
• Before/after comparisons after repairs

Compatible with AI/computer vision 

High-resolution video is ideal for integration into automated AI processes: 
Fault classification, trend analysis, and predictive maintenance are possible. 
Data from UT systems, on the other hand, is more complex and more difficult to make AI-compatible.

Rosenxt Linegy MultiCam System

This innovative multi-camera inline video inspection solution provides a comprehensive assessment of water pipes by simultaneously capturing high-resolution images from multiple angles. This advanced system uses multiple cameras strategically positioned within the pipeline to provide a complete 360-degree view of the interior surfaces. The multi-camera setup enables real-time detection of anomalies that may be missed by single-camera systems. 

The outstanding features are:

• Complete 360° coverage of the pipe interior
• High-resolution multi-camera system
• Can be used from DN 300 to 1800
• Minimal bendability 1 D
• Flap and slide valve compatible from DN 500
• Free-floating, centrally aligned
• Precise detection of the position in the pipe enables accurate determination of pipe gaps and angles of deviation
• Precise detection of the pipe trajectory in the x, y, and z directions
• Easy insertion and removal via T-pieces, manholes DN 300–500 (depending on tool size)
• Modularly expandable for acoustic leak detection, for example
• Long measuring distances, >20 km
• AI-supported detection and quantification of anomalies, no interpretation required – “what you see is what you get”
• Fusion with other inspection data enables more comprehensive cause and effect analysis
• Interactive asset-centric and GIS-based measurement reports in the Rosenxt Customer Portal

The interactive report on the inspection results allows water pipe operators to easily visualize and analyze the data, enabling faster and more informed decision-making. It improves the ability to identify problem areas, prioritize repairs, and track maintenance activities.

Despite the advantages of modern video inspection systems, it would be wrong to classify them as a universal method that renders other methods obsolete. Every technology has its system-related limitations and its suitability for specific tasks. 

Ultrasonic and electromagnetic methods, for example, remain irreplaceable for:

• Detecting material defects inside pipe walls (e.g., inclusions, laminations)
• Measuring wall thickness to detect corrosion (internal and external) or erosion
• Leaching (asbestos cement pipes), wire breaks (prestressed concrete pipes)
• Inspection in opaque media