Initial Situation: Corrosion Detection via Intelligent Pigging

During a previously conducted pipeline inspection by the operator using a smart pig, a corrosion site was discovered. Augel’s task: expose the affected area, have the condition of the pipeline verified by an expert, and—if necessary—carry out a professional repair.

Excavation and verification pit in rocky terrain

First, the pipeline was pinpointed using search slots. The rocky terrain in the Eifel region made the on-site work particularly challenging. After excavating a verification pit, the section of pipeline could be inspected for external corrosion.

An expert subsequently inspected the identified area of corrosion and determined that it required repair, thus paving the way for the repair of the affected section of pipe.

Preparing the cut: Precision on the pipe

Performing a cut requires proper preparation of the pipe:

• Removal of the bitumen insulation, some of which contains asbestos
• Cleaning the exposed pipe
• Measuring the pipe to be replaced

Only then can the cutting operation take place. This area poses a potential explosion hazard, as residual product may still be present in the pipe. To protect employees, the machines are therefore operated remotely from outside the inspection pit.

In this project, a significant misalignment of the pipe ends became apparent after the cut—an effect that can result from stresses in the pipeline and had to be taken into account in the subsequent planning of the welding work.

Workplace Safety: Protection Against Potential Lightning Surges and AC Interference

Our employees' safety is always our top priority during all pipeline work. To minimize risks posed by potential lightning currents and AC interference transmitted through the pipeline, equipotential bonding chains with attached cables were installed around the pipe. In the event of an emergency, these ensure equipotential bonding and divert currents in a controlled manner—a key component of the construction site's safety plan.

After cutting away the corroded section, the cut edges were carefully prepared for the upcoming welding work. The weld joint connecting the new fitting to the existing pipe was allowed to be only five millimeters thick. Meticulous preparation is therefore essential.

Special features: spiral-welded, magnetized tube

The existing pipe was spiral-welded and had been magnetized during a prior inspection using a smart pig. This magnetic charge initially made standard welding work impossible, as it could interfere with the arc.

The problem was solved by using special sleeves that are attached to the existing end pieces. These “deflect” the magnetic field lines away from the actual weld joint, thereby creating stable conditions for the welding process.

Fitting the joint and welding

Due to the limited space available during the installation of the new pipe section, centering devices were used to position the fitting precisely between the two pipes.

After that, the crucial step began: welding the new fitting to the existing pipeline.

• Welding time: approx. 3–4 hours per weld
• Procedure: Two welders working simultaneously on a weld

Quality Assurance: X-ray, Ultrasound, and Visual Inspection

Once the welding work was completed, a comprehensive quality assurance inspection of the repaired pipeline section was conducted:

1. X-ray inspection of the weld
2. Ultrasonic testing to detect potential defects in the weld area
3. Visual inspection for leaks after refilling the product

Following successful inspection, the insulation was restored and the excavation was properly backfilled.

Outcome: Reliable operational safety in sensitive facilities

Thanks to their technical expertise, meticulous attention to detail, and unwavering commitment to safety and responsibility, the engineers were able to restore the operational safety of the oil pipeline in the Kelberg area on a lasting basis through this measure.