What are manufacturing-related defects?
Manufacturing-related defects are imperfections in the pipe wall that originate during the production of steel plates or the pipe-forming process. These defects may appear as irregular shapes and can result from issues such as solidification flaws in the steel ingot or pieces of lapped material. Different defect types can occur depending on the pipe type (seamless or welded).1,2
Manufacturing-related defects can be categorized into four categories:
- Plate Defects – e.g., blisters, laminations, laps, segregations, indentations, and slivers.1
- Seamless Pipe Defects – e.g., slag inclusions, laminations, and laps.1
- ERW (Electric Resistance Welded) Pipe Defects – e.g., burn marks, inclusions, hook cracks, and lack of fusion.1
- DSAW (Double Submerged Arc Welded) Pipe Defects – e.g., cracks, hard spots, lamination, lacks, roof topping, slag inclusions, and porosity.1
How do manufacturing-related defects occur?
Defects related to manufacturing are usually introduced during steel production, in the form of solidification irregularities in the ingot, or during pipe manufacturing, in the form of errors during rolling, welding, or handling.1,2 While significant defects should be detected and removed during mill inspections or pre-commissioning hydrostatic pressure tests, minor imperfections can remain.1
Why are defects related to manufacturing a risk for pipeline safety?
Under normal conditions, pipelines operating below their maximum allowable operating pressure (MAOP) should not fail due to these defects. However, manufacturing-related defects can act as starting points for the development of in-service flaws. If left unchecked, these defects can compromise the integrity of pipelines and lead to leaks or ruptures.1,2
Would you like to find out more about specific manufacturing-related defects, such as blisters or slivers? Expand your knowledge by clicking through the 'Related Terms' section at the bottom of the page.
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Source reference
- The Encyclopedia of Pipeline Defects, ROSEN UK, Edition 3, 2017.
- Specification for Line Pipe, API Specification 5L, 2012.