Pipeline Dent

What are pipeline dents?

Pipeline dents are indentations or deformations in a pipe’s wall caused by an external force. They represent a common pipeline defect that occurs when the circular cross-section of a pipe is permanently altered. This change usually makes the inside of the pipe concave, reducing its internal diameter.1,2,3,4

How do dents occur?

Pipeline dents can occur during construction or while the pipeline is in service. Common causes include2:

  • Construction activities: Pipes that are laid directly on rocks in the trench or improper backfilling can create dents.2,3
  • Agricultural or excavation equipment: Heavy machinery striking the pipeline during maintenance or farming operations.1
  • Rock impingement: External pressure from surrounding materials without metal loss.2,3
Picture of a dent in a pipeline

Why are pipeline dents a risk for pipeline safety?

Dents compromise pipeline safety by creating localized stress and strain concentrations. These areas are more susceptible to crack initiation and fatigue crack growth. Even if a dent does not result in immediate failure, it can weaken the pipeline over time, thereby increasing the risk of rupture during normal operation.1

dent in a pipeline showing finite element analysis results.

Different dents in pipelines

Picture collage of different dents in pipelines.

  • A deep dent that obstruct inspection tools und cleaning devices

  • Dent, which has already caused a leak

  • Dent with metal loss

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Pipeline Deformation Management

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Source reference

  1. The Encyclopedia of Pipeline Defects, ROSEN UK, Edition 3, 2017.
  2. Introduction to Pipeline Defects, Angus Patterson, The Competence Club, ROSEN, 2025.
  3. Recommended Practice for Assessment and Management of Cracking in Pipelines, API Recommended Practice 1176, July 2016.
  4. Handbuch Molchtechnik, Bernd Skerra, 2000.

Related terms

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 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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Close up of a dent in the surface of a pipeline.

Geometry defects

Pipeline geometry defects refer to deviations from the ideal circular shape of a pipeline that lead to pipeline deformation.
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Picture of a coating failure on a pipeline.

Mechanical defects

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.

Pipeline 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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