What are slag inclusions, and how do they occur?
Slag inclusions are non-metallic particles that become trapped in steel during the manufacturing process. They form when an ingot becomes contaminated with slag. Most slag inclusions are removed early in the manufacturing process, such as during piercing and trimming the ingot ends. However, some inclusions may remain in the pipe wall. The shape and size of slag inclusions depend on the forging process. While most inclusions are small and structurally insignificant, surface-breaking inclusions can cause problems. These inclusions can damage the thin-film coatings applied to the pipe and should be removed by grinding before the coating is applied.1
What are the risks of slag inclusions?
Slag inclusions pose several risks, including:
- Coating defects: Surface-breaking inclusions can cause weak spots in protective coatings.
- Corrosion initiation: When contaminated with soluble salts, inclusions can serve as a starting point for pitting corrosion.1
Explore more on this topic
Pipeline Inspection Solutions
Would you like to learn more about how to address a specific challenge in pipelines? We take a holistic approach to addressing specific pipeline integrity risks:
The Competence Club
Looking to build practical knowledge beyond the Encyclopedia? Join The Competence Club to access exclusive learning modules, expert insights, and technical guidance on pipeline safety, defect assessment, and more.
Source reference
1 The Encyclopedia of Pipeline Defects, ROSEN UK, Edition 3, 2017.