Pipeline Geometry Defects

What are pipeline geometry defects?

Geometry defects, also known as geometric defects, refer to deviations from the ideal circular shape of a pipeline that lead to pipeline deformation. These changes in geometry can occur during manufacturing, construction, or operation and compromise pipeline safety. Geometric defects in pipelines can generally be categorized into two groups: local features and global deformation. Local features include dents, dents combined with metal loss, wrinkles and ripples, roof topping, ovality, buckles, and scale and wax deposits. These imperfections typically occur in specific areas of the pipeline. Global deformation, on the other hand, refers to large-scale changes in the pipeline's shape, such as bending. This impacts the overall alignment and performance of the pipeline system.1

Illustration of a pipeline's geometry.
  • Pipeline segment with a buckle

    Buckles: Severe deformation often linked to soil movement.

  • Picture of a dent with metal loss

    Dent with metal loss: Dents combined with corrosion or gouging.

  • Picture of a dent in a pipeline

    Dents: Depressions in the pipe wall.

  • Picture of a pipeline with an ovality anomaly.

    Ovality: Deviation from a perfect circular cross-section.

  • Picture of pipeline ripples.

    Ripples: Smaller wrinkles.

  • Illustration of how roof topping on a pipeline can look like.

    Roof topping: Flattening of the pipe crown.

  • Picture of pipeline wrinkles.

    Wrinkles: Folds or undulations in the pipe wall.

How do geometry defects arise?

Geometry defects often result from:

  • External influences, such as geohazards (e.g., landslides, soil settlement, or earthquakes), or accidental third-party actions.
  • Operational factors, such as internal pressure fluctuations or thermal expansion.
  • Manufacturing or handling issues during pipe production or installation.

These factors can deform the pipeline, creating localized irregularities or overall bending.1

What are the risks of geometry defects in pipelines?

Pipeline geometry defects can lead to stress concentration (localized areas of high stress), crack initiation, and pigging difficulties because internal irregularities can obstruct inspection tools or cleaning devices. Furthermore, they reduce structural integrity because severe deformation may result in buckling or rupture under operational loads.1,2

Would you like to find out more about specific geometric defects, such as dents or wrinkles? Expand your knowledge by clicking through the 'Related Terms' section at the bottom of the page.

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Source reference

  1. The Encyclopedia of Pipeline Defects, ROSEN UK, Edition 3, 2017.
  2. Introduction to In-Line Inspection - Defects and Loads, Beller & Reber, 2023.

Related terms

Picture of a dent in a pipeline

Dents

Pipeline dents are deformations in a pipe’s wall caused by an external force. They represent a common defect that occurs when the circular cross-section is permanently altered.
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Picture of pipeline wrinkles.

Wrinkles

Pipeline wrinkles are localized deformations of the pipe wall that resemble a waveform and are characterized by alternating inward and outward bulges. 
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Illustration of how roof topping on a pipeline can look like.

Roof topping

Roof topping, also referred to as tenting, peaking, or angular misalignment, is a geometric anomaly that occurs at the seam weld of longitudinally welded pipes.
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Picture of a pipeline with an ovality anomaly.

Ovality

Pipeline ovality refers to the out-of-roundness of a pipeline, meaning the pipe’s cross-section deviates from a perfect circle. 
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Pipeline segment with a buckle

Buckles

A buckle is a severe deformation, or partial collapse, of a pipe, caused by lateral instability. This defect occurs when a pipe experiences excessive bending.
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Image of a pipeline wall showing a crack.

Bending

Pipeline bending is a type of pipeline deformation. It refers to changes in a pipeline’s shape that deviate from its intended alignment. 
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Picture of a coating failure on a pipeline.

Mechanical damage

Mechanical damage is caused by external forces acting on a pipeline. This broad term includes defects such as dents, gouges, and coating damage. 
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Picture of a lack of fusion anomaly on a pipeline.

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. 
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Pipeline running through a landscape affected by ground movements.

Movement

Pipeline movement refers to the displacement or deformation of a pipeline from its original position, often caused by external forces, such as ground shifts or natural hazards.

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