Published on 07-Nov-2023

Tubular Inspection and Techniques Involved in NDT

Tubular Inspection and Techniques Involved in NDT

Table Of Contents

  • Introduction
  • What is Inspection?
  • Basic Principles of Inspection: Ensuring Precision and ThoroughnessNon-Destructive Testing
  • Standards and Guidelines
  • What is Tubular Inspection?
  • How do you Inspect Tubing?
  • Top Tube Inspection Techniques
  • Tube Inspection Selection Chart
  • Benefits of Tubing Inspection
  • Conclusion
  • Key Takeaways


Tubular inspection is a fundamental aspect of numerous industries, ranging from oil and gas to construction and aerospace.

Tubular components, such as pipes, tubing, and pipelines, serve as the backbone of many critical infrastructures.

Ensuring their structural integrity and safety is paramount, and this is where Non-destructive Testing (NDT) techniques come into play.

This article explores the world of tubular inspection, the basic principles of inspection, the various methods used to inspect tubing, and delves into the top techniques in this field.

What is Inspection? 

Inspection is the systematic process of carefully examining and evaluating components to detect defects or irregularities.

These inspections are conducted to maintain the safety, reliability, and performance of structures and materials.

In the context of tubular inspection, this process becomes particularly crucial due to the critical role that tubular components play in a wide range of industries.

Basic Principles of Inspection: Ensuring Precision and Thoroughness

Inspection is a systematic practice that underpins the reliability and safety of various components, structures, and materials across different industries.

To understand the essence of inspection, it is essential to delve into the basic principles that govern this practice.

These principles provide a framework for conducting assessments, ensuring that inspections are thorough, precise, and consistent.

Here’s a detailed outlook into these principles with a specific focus on the tubular inspection of heat exchangers as an illustrative example.

  • Thoroughness

Thoroughness is a fundamental principle of inspection.

It entails the comprehensive examination of components or materials, leaving no aspect unexamined.

In the context of tubular inspection for heat exchangers, thoroughness means conducting a detailed assessment of all tubes, considering their internal and external surfaces, dimensions, and structural integrity. 

Heat exchangers play a critical role in various industries, including HVAC systems, chemical processing plants, and power generation facilities.

Ensuring the thorough inspection of heat exchanger tubes is essential to identify potential defects that could compromise their performance.

Thorough inspections involve meticulous scrutiny of the entire surface area of heat exchanger tubes, looking for signs of Corrosion, pitting, scaling, or any other anomalies that might affect their efficiency.

The principle of thoroughness is not limited to external inspections; it extends to internal examinations as well.

Technologies like the Internal Rotary Inspection System (IRIS) or Eddy Current Testing are employed to assess the condition of the tube's internal surface, detecting defects like pitting and erosion.

By adhering to the principle of thoroughness, heat exchanger tubes can be effectively evaluated for potential issues, ensuring their continued reliable operation.

  • Precision

Precision in inspection is vital for accurately measuring and evaluating components.

Precise measurements and assessments are crucial in identifying defects and assessing their severity.

In the context of heat exchanger tubes, precision is essential to gauge the thickness of the tube wall, the extent of Corrosion, or the depth of pitting accurately.

These factors directly impact the structural integrity of the tubes and, consequently, the efficiency of the heat exchanger.

Precision is especially critical when dealing with heat exchanger tubes that operate in demanding environments where thermal and chemical stresses are common.

Any imprecision in measuring the wall thickness or identifying defects could lead to incorrect assessments, potentially resulting in tube failures and, in some cases, system shutdowns.

To achieve precision in tubular inspection, Advanced Inspection Techniques such as laser measurement, ultrasonic testing, and Eddy Current Testing are employed.

These methods provide accurate and detailed information about the condition of heat exchanger tubes, allowing for precise evaluations and timely maintenance or replacements when necessary.

For a thorough understanding of Eddy Current Testing and its principles, check out Eddy Current Testing - A Complete Guide

Standards and Guidelines

Inspection procedures must adhere to established standards and guidelines.

These standards serve as a framework for Inspection Methodologies, ensuring consistency and quality in the assessment process.

In the case of heat exchanger tubes, adhering to industry-specific standards, such as those outlined by organizations like ASME (American Society of Mechanical Engineers) or ASTM (American Society for Testing and Materials), is essential.

Standards and guidelines provide clear instructions on inspection procedures, including the type of Inspection Method to be used, acceptable levels of defects, and reporting requirements.

They also establish the qualifications and certifications required for inspectors to perform these assessments.

Adhering to these standards ensures that tubular inspection for heat exchangers is consistent and meets industry best practices.

Furthermore, standards and guidelines often evolve to incorporate advancements in Inspection Technology and emerging industry challenges.

This adaptability ensures that inspections remain up-to-date and effective in identifying defects and anomalies in heat exchanger tubes.

Also, adherence to standards and guidelines provides a structured and consistent approach to tubular inspection, promoting quality and reliability in critical industries.

The basic principles of inspection, namely thoroughness, precision, and adherence to standards and guidelines, are vital in the evaluation of critical components such as heat exchanger tubes.

By applying these principles, industries can maintain the safety, reliability, and performance of their systems while minimizing the risk of unexpected failures.

Thorough inspections of heat exchanger tubes ensure the early detection of defects, while precision in assessment accurately gauges their severity.

What is Tubular Inspection?

Tubular inspection is a specialized and essential facet of Non-destructive Testing that centers on the assessment of tubular components, including pipes, tubing, and pipelines.

These cylindrical structures are the lifeblood of various industries, playing a pivotal role in sectors such as oil and gas, construction, and manufacturing.

The reliability and safety of these tubular components are paramount, as they underpin the integrity and efficiency of the industries they serve.

The practice of tubular inspection encompasses a comprehensive array of Non-destructive Testing Techniques and Methods meticulously designed to identify and assess defects or anomalies that may compromise the structural integrity of tubular components.

These methods are crucial for quality control, routine maintenance, and, most importantly, ensuring the safe operation of critical infrastructure.

For example, in the oil and gas sector, Pipelines are the arteries through which vital resources are transported over vast distances.

Any defect or flaw in these pipelines can have catastrophic consequences, not only in terms of environmental impact but also for the safety of personnel and the reliability of the energy supply.

Tubular inspection in this context is indispensable for detecting corrosion, material loss, or cracking that could jeopardize the pipeline's functionality.

Similarly, in construction and manufacturing, tubular components are used in structures and systems where their structural soundness is vital.

Tubular inspection is employed to assess the condition of structural supports, piping systems, and a variety of critical components to ensure they meet safety and quality standards.

In essence, tubular inspection serves as the frontline defense against potential failures, ensuring that these cylindrical components continue to perform their crucial roles without compromising safety or efficiency.

It is a practice that upholds the standards of industries reliant on these tubular structures, safeguarding the integrity and longevity of vital infrastructure.

How do you Inspect Tubing?

Tubing, a fundamental component in various industries, must undergo rigorous inspection to ensure its structural integrity, safety, and efficiency.

The inspection of tubing encompasses a variety of techniques, each tailored to specific applications, defects, or environmental conditions. 

Tubing inspection is a critical component of quality control, safety, and the longevity of critical infrastructure.

By employing a combination of Visual Inspection, precision measurements, hydrostatic testing, electromagnetic inspection, Magnetic Particle Testing, and Ultrasonic Testing, industries can ensure that their tubular components perform at their best and meet the highest standards of safety and reliability.

These techniques collectively contribute to the seamless operation of various industries, from the Oil and Gas Industry to construction, safeguarding the structural integrity of tubing and preventing potential issues that could compromise safety and efficiency. 

The choice of method depends on factors such as the type of tubing, the working environment, and the specific defects or anomalies being targeted.

Depending on the inspection's goals, one or more of these methods may be employed to ensure the structural integrity and safety of tubular components.

Here are the various techniques commonly employed for inspecting tubing, and their unique advantages and applications.

  • Visual Inspection

Visual Inspection, a fundamental inspection technique, is often the first step in assessing the condition of tubing.

This method involves a close examination of the tubing's external surface using the naked eye or optical devices like borescopes.

Visual inspection serves as the initial screening process to detect apparent surface defects, including corrosion, cracks, and physical damage.

It is a non-intrusive and cost-effective method suitable for evaluating the overall condition of tubing.

Visual Inspection plays a crucial role in identifying visible defects in tubing, offering a quick and efficient means of assessing surface integrity.

However, it may have limitations in detecting internal or subsurface defects that are not visible externally.

To address such flaws, more Advanced NDT Techniques are often required.

  • Caliper Measurements

Caliper measurements are employed to assess the external dimensions and wall thickness of the tubing.

This method is particularly important for verifying the dimensional accuracy of tubing, ensuring it adheres to specified standards and tolerances.

Caliper measurements help identify variations in the tubing's outer diameter and wall thickness, affecting its performance and compatibility with associated components.

Caliper measurements are especially valuable in manufacturing processes, where tight dimensional control is essential to meet quality standards.

By employing precision measuring tools, inspectors can ensure that the tubing meets the required specifications, guaranteeing proper fit and functionality in the intended application. 

  • Hydrostatic Testing

Hydrostatic testing is a robust method for evaluating the integrity of tubing, particularly when it comes to identifying leaks, weaknesses, or structural defects.

This technique involves subjecting the tubing to high-pressure liquid or gas, pressurizing it to levels that exceed its expected operating conditions.

By doing so, inspectors can pinpoint potential issues such as leaks, cracks, or material weaknesses.

Hydrostatic testing also helps in assessing the pressure containment capabilities of tubing, ensuring that it can safely handle the demands of its intended application.

This method helps identify vulnerabilities that could compromise the tubing's performance, allowing for preventive maintenance or replacement.

  • Electromagnetic Inspection

Electromagnetic inspection techniques, including Eddy Current Testing, are valuable tools for evaluating the condition of tubing.

Eddy current testing utilizes electromagnetic fields to detect surface and near-surface defects, making it suitable for a wide range of materials and tubing types.

This method is highly sensitive to changes in material conductivity and can identify defects such as cracks, Corrosion, and erosion.

Eddy current testing is non-invasive and can be applied to both ferromagnetic and non-ferromagnetic materials.

It is particularly useful in industries where materials vary widely and where the detection of surface or near-surface defects is critical for ensuring tubing integrity.

  • Magnetic Particle Testing

Magnetic particle testing is a Non-destructive Testing Techniques and Methods commonly employed to identify surface and near-surface defects in ferromagnetic materials.

This technique relies on the application of a magnetic field to the tubing and the use of finely divided magnetic particles applied to the surface.

These particles accumulate at areas where Magnetic Flux Leakage occurs, highlighting defects such as cracks, inclusions, or other irregularities.

Magnetic Particle Testing is highly effective in detecting defects that are perpendicular to the magnetic field direction, making it a valuable tool for assessing the structural integrity of tubing.

It is particularly relevant in industries where ferromagnetic materials are prevalent and where surface defects may compromise tubing performance.

  • Ultrasonic Testing

Ultrasonic testing is a versatile Non-destructive Testing method that plays a significant role in evaluating the condition of tubing.

This technique utilizes high-frequency sound waves, typically beyond the range of human hearing, to penetrate materials and identify internal defects or inconsistencies. 

Ultrasonic Testing measures the time it takes for sound waves to travel through the material and reflect, providing valuable information about the material's condition.

This method is particularly useful for detecting internal defects and inconsistencies in materials, making it a valuable tool for assessing the structural integrity of tubing.

It is non-invasive and capable of providing precise data about the size, location, and nature of defects, allowing for accurate assessments and timely maintenance or replacement when necessary.

  • Proper Handling of Tubing 

The integrity of tubing doesn't solely depend on the inspection process; it also relies on proper handling, care, and maintenance throughout its lifecycle.

Improper handling can lead to damage, which, if undetected, can compromise the tubing's performance and safety.

The proper handling of tubing includes several key aspects:

  • Shipment

Tubing often needs to be transported from manufacturing facilities to operational sites.

During shipment, it is crucial to secure the tubing to prevent physical damage or distortion.

Protective measures should be in place to shield the tubing from external factors like impact, moisture, and extreme temperatures.

  • Running and Pulling Tubing

In industries like the Oil and Gas Industry, tubing is frequently run into wellbores and later pulled out for maintenance or replacement.

These processes should be carefully executed to avoid mechanical damage to the tubing.

Proper techniques and equipment should ensure the tubing remains undamaged during these operations.

  • Thread Compound

The use of thread compounds, particularly in oilfield applications, is common for securing and sealing tubing connections.

Proper application and maintenance of thread compounds are essential to prevent leaks and maintain the structural integrity of the tubing to extend its operational lifespan.

Top Tube Inspection Techniques

While the previously mentioned techniques provide a solid foundation for tubing inspection, there are more advanced and specialized methods available for in-depth assessment.

These techniques are particularly valuable when dealing with complex or critical tubing components.

Some of the top tube inspection techniques include:

  • Remote Field Eddy Current Testing

Remote field eddy current testing is a specialized form of eddy-current testing that is primarily used for inspecting ferromagnetic tubing.

It is particularly effective in detecting corrosion and erosion in the tubing's inner surface.

This technique is commonly employed in industries like the Oil and Gas Industry to assess the condition of tubing in wellbores.

  • IRIS (Internal Rotary Inspection System)

The Internal Rotary Inspection System, or IRIS, is a high-resolution Ultrasonic Inspection Method used to assess the condition of tubing from the inside.

It is especially valuable for detecting and characterizing defects in the tubing's internal surface, such as corrosion, pitting, and wall thickness variations.

IRIS is commonly utilized in the inspection of heat exchanger tubing and other critical applications.

  • Transverse Field Inspection (TFI)

Transverse field inspection is an advanced electromagnetic testing technique used for inspecting tubing.

It is particularly effective in identifying defects such as corrosion, pitting, and cracks in ferromagnetic and non-ferromagnetic materials.

TFI offers high sensitivity and is well-suited for various industrial applications.

  • Magnetic Flux Leakage

Magnetic flux leakage (MFL) is an inspection technique that relies on the detection of magnetic flux leakage caused by defects in tubing.

This method is highly effective for identifying anomalies such as corrosion, pitting, and material loss.

MFL is widely used in industries where corrosion assessment is critical.

  • Laser Inspection

Laser inspection is an innovative approach to tubing assessment.

It employs laser technology to scan the tubing's surface and identify defects or irregularities.

Laser inspection offers high precision and can be used in various applications to detect surface defects.

These advanced techniques provide a more comprehensive and in-depth assessment of tubing components.

Depending on the specific requirements and conditions of the tubing being inspected, one or more of these techniques may be employed to ensure the highest level of quality and safety.

Tube Inspection Selection Chart

A Tube Inspection Selection Chart, often referred to as TISC, is a tool used in Non-destructive Testing for inspecting tubes, typically in industrial settings.

It helps determine the appropriate NDT Method based on the type of material being tested, the tube diameter, and the specific requirements of the inspection.

The chart provides guidance on which Advanced NDT Techniques are suitable for detecting various types of defects such as corrosion, cracks, or other irregularities in tubes.

The available methods might include techniques like ultrasonic testing, eddy current testing, visual inspection, Radiographic Testing, and others.

By consulting the Tube Inspection Selection Chart, inspectors can make informed decisions about which NDT technique to employ, ensuring accurate and reliable inspection results.

This tool helps streamline the inspection process and optimize resource allocation for tube testing.

Benefits of Tubing Inspection

Tube inspection, a crucial aspect of Non-destructive Testing, offers several benefits in various industries where tubes are extensively used.

Some of the key advantages include:

  • Safety Assurance:

Tube inspection helps identify potential defects, corrosion, or damage without the need for Destructive Testing, ensuring the integrity of the tubes and, subsequently, the safety of operations.

  • Prevents Failures:

By detecting defects early on, tube inspection helps prevent catastrophic failures that could lead to accidents, downtime, and costly repairs or replacements.

  • Extends Service Life:

Identifying and addressing issues in tubes promptly can extend their service life, saving on replacement costs and reducing downtime associated with maintenance.

  • Ensures Regulatory Compliance:

Many industries, especially those involving hazardous materials, are subject to strict regulations regarding the integrity of tubes.

Regular inspection helps ensure compliance with these regulations.

  • Maintains Process Efficiency:

Tubes play a critical role in various industrial processes (e.g., pipelines, heat exchangers).

Ensuring their integrity through inspection helps maintain process efficiency and productivity.

  • Reduces Environmental Impact:

Preventing leaks or failures in tubes that handle hazardous materials helps minimize the environmental impact and potential harm to ecosystems.

  • Cost Saving:

Early detection of defects allows for timely repairs or replacements, which are often less costly than dealing with the aftermath of a failure.

  • Optimizes Maintenance Schedules:

Scheduled tube inspections can be integrated into maintenance programs, helping to plan and allocate resources effectively.

  • Enhances Quality Assurance:

Inspection provides a reliable means of quality control for tubes, ensuring that they meet industry standards and specifications.

  • Provides Data for Informed Decisions:

Inspection data can be used to make informed decisions about the continued use, repair, or replacement of tubes, based on their condition and potential risks.

  • Supports Predictive Maintenance:

Data gathered from tube inspections can be used for predictive maintenance strategies, allowing for planned interventions rather than reactive ones.

  • Improves Reliability:

Knowing that tubes are in good condition increases confidence in the reliability of systems that depend on them.


Tubular inspection is a fundamental practice in various industries, ensuring the safety, reliability, and structural integrity of critical components.

The choice of Inspection Method and the proper handling of tubing can significantly impact the performance and longevity of these components.

Whether in the Oil and Gas Industry, construction, manufacturing, or any other industry, the quality of tubing inspection plays a pivotal role in maintaining operational efficiency and safety.

Key Takeaways

  • Inspection is a systematic process for assessing the condition of materials and structures to detect defects, anomalies, or irregularities.
  • Tubular inspection is crucial for ensuring the safety and reliability of tubing components in various industries.
  • Inspection methods for tubing range from basic Visual Inspection to advanced techniques like Eddy Current Testing and laser inspection.
  • Proper handling of tubing, including during shipment, running and pulling, and the use of thread compounds, is essential to prevent damage.
  • Advanced inspection techniques like IRIS, Magnetic Flux Leakage, and laser inspection provide in-depth assessment capabilities.
  • The choice of the right Inspection Method depends on specific conditions and requirements, and a selection chart can aid in this decision-making process.
  • Incorporating rigorous tubular inspection practices and leveraging Advanced NDT Techniques ensures the structural integrity and safety of critical components, contributing to the overall success of industries that rely on these tubular structures.


1. Fairtex Nigeria Ltd


3. Arotec


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Application Notes