Semless Steel Pipe and Tube

Why is Non-Destructive Testing (NDT) performed on seamless steel pipes? What is the difference between ultrasonic testing and eddy current testing?

 

Non-Destructive Testing (NDT) is essential for seamless steel pipes, acting as a crucial safety and quality assurance measure. It detects manufacturing flaws (e.g., cracks, inclusions, pores, folds) that threaten mechanical integrity and can lead to catastrophic failure in critical, high-stress applications (like boiler or hydraulic tubes).

 

1. Method Comparison and Selection

The two main NDT methods, Ultrasonic Testing (UT) and Eddy Current Testing (ECT), are differentiated by their principles and optimal use cases:

 

1) Ultrasonic Testing (UT)

•      Principle: Uses high-frequency sound waves. Defects reflect the waves, allowing accurate determination of location, size, and nature.

•      Strengths: High inspection depth, high sensitivity, accurate sizing.

•      Weaknesses: Requires a couplant, relatively slow speed, sensitive to surface finish.

•      Application Focus: Best for thick-walled and critical pipes, primarily detecting internal, volumetric defects (inclusions, porosity).

 

2) Eddy Current Testing (ECT)

•      Principle: Based on electromagnetic induction. A coil induces eddy currents, which are disrupted by flaws, indicating a defect.

•      Strengths: Very fast, no couplant required, highly automatable, high sensitivity to surface and near-surface defects.

•      Weaknesses: Shallow inspection depth, poor quantitative analysis, affected by material's electromagnetic properties.

•      Application Focus: Ideal for thin-walled pipes, focusing on surface quality and high production efficiency.

 

2.Optimal Application Strategy

The appropriate method must be selected based on the pipe's requirements:

•      Internal Flaws: UT is prioritized for thick-walled or critical pipes requiring internal flaw detection.

•      Surface/Efficiency: ECT is suitable for thin-walled pipes where surface quality and speed are paramount.

 

To ensure comprehensive quality control, a combined approach is often utilized: ECT performs a quick, preliminary surface scan, followed by UT performing a detailed re-inspection of any suspect areas to confirm internal defect status. This strategy leverages the strengths of both methods to guarantee product quality and operational safety.

 

ShangHai ShengQiu Materials Co., Ltd

Email：sales@sqsteelpipe.com

WhatsApp: +8613761124029

Website: www.sqsteelpipe.com