How can internal pipeline corrosion be analyzed in the laboratory?

An internal leak in a pipeline should never be treated as an isolated defect. In industrial operations, hydraulic networks, or heating and cooling systems, a localized perforation often reveals a broader deterioration: pitting, corrosion under deposits, premature corrosion, differential aeration phenomenon, galvanic attack, degradation of the passivation layer.

Analyzing internal corrosion in a pipeline in the laboratory makes it possible to trace the root cause, assess the true extent of the damage, and prioritize corrective actions before production stops or a major incident occurs.

The most revealing signs are the presence of deep pits, cavernous attack, localized areas directly beneath a deposit, a waterline, or a break in flow continuity, as well as oxidation gradients between neighboring surfaces.

A single perforation may correspond to the most advanced point of a mechanism already spread over several meters of piping.

Comparative observation between the perforated area, the adjacent area, and the sound area is essential to assess the systemic nature of the failure.

Le diagnostic s’appuie sur des techniques complémentaires.

La microscopie optique sur coupe micrographique met en évidence la profondeur d’attaque, la morphologie des piqûres et l’état microstructural du métal. Le MEB-EDX expertise finement la topographie de corrosion et la composition semi-quantitative des produits formés.

L’ICP recherche des éléments traces, la XPS précise la chimie de surface et l’état d’oxydation, tandis que la DRX peut aider à identifier certaines phases cristallines des dépôts et oxydes. Si nécessaire, la vérification de nuance matière, la dureté et l’analyse élémentaire complètent l’expertise défaillance canalisation.

MIC (bacterial corrosion) is suspected when the attack morphology, the nature of the deposits, and the operating context converge: biofilm, viscous or layered deposits, local enrichment in sulfur or other characteristic species, highly localized pits under deposits, fluid stagnation, favorable temperature, and low renewal rate.

The laboratory does not stop at visual observation; it characterizes the surface and deposits to look for signatures compatible with microbiological activity and its effects on local electrochemistry.

Laboratory expertise relies on a structured approach: visual and macroscopic examination of sound and failed areas, controlled opening of the pipeline, sampling of internal deposits, metallographic observations on cross-sections, surface analysis, and chemical micro-analysis. This approach cross-references the morphology of the attack, the composition of the corrosion products, the nature of the metal, any coating heterogeneity, and the service parameters.

The tools of SEM-EDX metals, ICP, XPS, XRD, optical microscopy, and electrochemical testing make it possible to see what the human eye misses and to substantiate a diagnosis of pipeline failure investigation.

Internal deposit analysis often provides the key to the diagnosis. A mineral, organic, or mixed deposit can create a differential aeration cell, concentrate chlorides, trap sulfur species, or promote microbiological growth. Chemical micro-analysis and SEM-EDX observation make it possible to identify the major and trace elements associated with corrosion products, sludge, scale, and contaminants originating from the fluid or the process.

When the context requires it, electrochemical tests strengthen the interpretation. Open circuit potential (OCP) measurement provides insight into the spontaneous behavior of the metal in a given environment.

LSV helps estimate a corrosion rate, EIS evaluates surface phenomena and coating defects, and the galvanic coupling test highlights interactions between dissimilar materials. Simulations of specific environments, including chlorides, extreme pH values, or inhibitors, also make it possible to verify the sensitivity of a grade or a process.

Differential diagnosis remains essential. Galvanic attack will be more closely linked to a combination of metals with different potentials and a favorable conductive geometry. Chemical corrosion will depend more on pH, chlorides, dissolved oxygen, oxidants, or degraded inhibitors.

By comparing surface, composition, metallography, and network operating data, the laboratory ranks the hypotheses and identifies the dominant mechanism.

Repairing without understanding the issue exposes you to a quick recurrence. Laboratory analysis makes it possible to decide whether the material should be changed, the surface treatment reviewed, water chemistry corrected, a stagnation zone eliminated, a deposit problem treated, galvanic coupling controlled, or the maintenance of the hydraulic network diagnosis adjusted.

It also helps define a monitoring plan, target the sections to inspect, and secure the restart. For both the operator and the claims expert, internal corrosion analysis on piping means turning a leak into actionable technical information.