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Understand how the pear-shaped decanting tube contributes to the precision and reproducibility in controlling the concentration of magnetic particles (MP) , in accordance with applicable technical standards.

The role of the per a type decanting tube

Magnetic particle testing (MPT) is widely used to detect surface and subsurface discontinuities in ferromagnetic materials. In wet
testing , the appropriate concentration of magnetic particles in the bath is crucial for the sensitivity and repeatability of the results.

One technical detail makes all the difference: the use of the “pear” type decanting tube , an essential accessory for measuring the bath concentration with precision, speed, and traceability .

Supermagna Pear-Type Decanter Tube: what it is and how it works

The Supermagna Pear-shaped Decanter Tube is an auxiliary accessory used to determine the quantity of magnetic particles per volume of fluid in the suspension used in wet dispersion testing. With a graduated scale, it allows for the reading of the volume of particles settled after a period of rest.

There are two main models , developed according to the type of particle:

• Supermagna Decanting Tube with a 0.1 ml scale (fine scale): suitable for colored particles ;
• Supermagna Decanting Tube with a full scale of 0.05 ml (most sensitive scale):suitable forfluorescent particles.

Main applications:

• Verification of the correct concentration of the magnetic particle bath before performing the test;
• Assessment of contamination levels in the bath during use.

Why concentration control is essential

With continuous use, the magnetic particle bath can undergo changes that directly compromise the reliability of the results. Among the main causes are:

• Evaporation of the liquid phase;
• Natural settling of particles;
• Contamination by oil, dirt, or metallic residue.

These variations can affect the sensitivity of the assay:

• Excess particles : generate false readings and increase background noise;
• Low concentration : reduces visibility and makes it difficult to detect actual discontinuities.

In addition to proper control, the quality of the magnetic particles used is a determining factor in the test’s performance.

Metal-Chek magnetic particles are developed with specific formulations to meet regulatory requirements .

How to properly use the Supermagna Pear-shaped Decanter Tube

The use of the Supermagna pear-shaped decanter tube
must follow the specific instructions for each product and vehicle, in addition to the guidelines of the qualified test procedure. Generally, the process involves agitating the suspension for homogenization, filling the tube to the indicated volume, and allowing it to stand for a sufficient time for the particles to settle by gravity.

After the defined period, the decanted volume is read, observing the interface between the fluid and the particles.
The reading must be performed according to the type of particle used:
– For colored particles , visible light should be used to provide good visibility of the separation line between the fluid and the particles.
– For fluorescent particles , the reading requires the use of ultraviolet (UV-A) light , in a darkened environment, according to the requirements established by applicable standards.

The results obtained serve as a comparison with the reference values ​​indicated by the manufacturer of the magnetic particles or according to the technical procedure approved by a Level 3 Inspector , ensuring that the concentration control is in accordance with the established practices for the test.

Normative references

Concentration control with the Supermagna pear-shaped decanter tube is supported by the main international and national standards applicable to magnetic particle testing, such as:

• ASTM E709 – Standard Guide for Magnetic Particle Testing
• NM 342 – Non-Destructive Testing — Magnetic Particles — Discontinuity Detection
• PETROBRAS N-1598 – Magnetic Particle Testing
• ASME Section V, Article 7 – Magnetic Particle Examination

Good practices and frequency of control

To maintain suspension stability , it is recommended to :

• Perform concentration checks daily (or before each inspection shift);
• Record the results in spreadsheets or quality control forms;
• Renew the bath whenever there is visible contamination, foam, or variation outside the defined limits ;
• Periodically check the physical condition of the settling tube (cracks, dirt, or illegible scale).

These practices contribute to reproducibility in testing and reliability in results , in order to avoid rework and waste.

Technical notice

This content is for educational purposes only. The application of the test methods and parameters must follow a qualified procedure approved by a Level 3 Inspector .

Metal-Chek Excellence

Excellence in products for those seeking reliable results.
Metal-Chek provides complete solutions for Non-Destructive Testing (END) : magnetic particles, contrast dyes, yokes, accessories, and settling tubes — all developed according to the main ASTM , ASME , NM , and PETROBRAS standards .

Talk to our experts
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The importance of technical standards in Non-Destructive Testing

Non-destructive testing (END) is essential to ensure the integrity of equipment and components used in various industrial sectors.
Among the most widely used methods are liquid penetrant testing (LP) and magnetic particle testing (PM).

Both allow the identification of discontinuities that could compromise the safety and performance of metal structures, welds, shafts, or castings, etc.

To ensure the quality and standardization of results, there is a set of national and international technical standards that establish criteria for execution, materials, and test conditions.

Next, see what these rules are and what each one determines in summary.

Standards applicable to Penetrant Testing (PT)

ASTM E1417 – Standard Practice for Liquid Penetrant Testing

It is the main international standard for the Penetrant Testing method .
It defines the essential parameters for the safe and accurate execution of the test, including:

• Classification of penetrants (fluorescent and colored);
• removal methods (water washable, post-emulsifiable, solvent removable);
• lighting and sensitivity requirements;
• stages of the process, such as cleaning, penetration, and development.
• process controls.

ISO 3452 – Non-Destructive Testing – Penetrant Testing

The ISO 3452 series establishes international standards for materials and equipment.
Among its main topics are:

• Part 1: General principles;
• Part 2: Penetrant material requirements;
• Part 3: Reference blocks;
• Part 4: Equipment;
• Part 5: Requirements for liquid penetrant testing at temperatures above 50 °C.

NM 334 – Non-destructive testing — Penetrant testing — Discontinuity detection

Mercosur standard that defines the main requirements for LP inspections in the national context, including:

• technical terminology and symbology;
• test stages (pre-cleaning, application, penetration, removal, development and evaluation);
• minimum lighting levels;

ASTM E165 – Standard Practice for Liquid Penetrant Testing for General Industr y

Standard that defines the general procedures and criteria for liquid penetrant testing (LP) in industrial applications.
Establishes requirements for:

• Classification of penetrants (fluorescent or colored);
• removal methods (water, solvent or post-emulsifiable);
• Control of lighting, temperature, and penetration time;
• Sensitivity testing and product quality control.

PETROBRAS N-1596

Define:

• test parameters and minimum/maximum process times;
• procedural requirements;
• lighting conditions;
• Product classification and traceability;
• Requirements for staff execution and qualification.

PETROBRAS N-2370

Provides:

• General guidelines for safety, documentation, and traceability;
• Penetrant testing.

ASME V – Art. 6

An integral part of the ASME Boiler and Pressure Vessel Code (BPVC) , it defines the requirements for penetrant testing applied to boilers, pressure vessels, and pressurized equipment.
It contains:

• Specifications for materials and equipment;
• sensitivity check of the test system;
• process control and inspection intervals;
• Acceptance according to manufacturing codes.

Standards applicable to Magnetic Particle Testing (MPT)

ASTM E709 – Standard Guide for Magnetic Particle Testing

The principal international standard governing magnetic particle testing .
It establishes best practices and application guidelines for:

• Magnetization techniques (yoke, electrodes, coil, center conductor and direct contact);
• use of colored and fluorescent particles;
• Electrical current control and field direction;
• Verification of particle concentration and illumination (visible and UV).

ASTM E3024 – Standard Practice for Magnetic Particle Testing for General Industry

It complements ASTM E709 and provides specific instructions for inspections in general industry .

NM 342 – Non-destructive testing — Magnetic particles — Discontinuity detection

It establishes technical parameters for conducting the test in accordance with international standards:

• Dry and wet application;
• characteristics of magnetic particles and liquid vehicles;
• Recommended concentration ranges for wet application (0.1 to 0.4 mL for fluorescent and 1.2 to 2.4 mL for colored);
• Light intensity control for visible and UV-A light.

ASTM E1444 – Standard Practice for Liquid Penetrant Testing for Aerospace

Specifically for the aeronautical and aerospace sector , it defines detailed practices for magnetic particle (PM) testing .
It establishes:

• requirements for magnetic materials and vehicles;
• concentration limits and bath control;
• UV-A and white light checks;
• Strict calibration and acceptance criteria.

PETROBRAS N-1598

It defines the criteria for performing the PM method on ferromagnetic materials.
It covers:

• magnetization techniques;
• UV lighting requirements and field strength;
• calibration procedures.

ASME V – Art. 7

Part of the ASME Boiler and Pressure Vessel Code , it defines the requirements for magnetic particle testing of pressurized equipment and welded components.
It covers:

• Types of electric current and magnetization techniques;
• magnetic field intensity control;
• detection methods;
• Acceptance and qualification criteria for the testing system.

ISO 9934 – Non-Destructive Testing – Magnetic Particle Testing

The ISO 9934 series establishes international standards for materials and equipment.
Among its main topics are:

• Part 1: General principles;
• Part 2: Detection method;
• Part 3: Equipment;

Importance of technical standards for the reliability of END (Non-Destructive Testing).

The standards governing liquid penetrant and magnetic particle methods are the technical basis that ensures reliability and regulation  of Non-Destructive Testing.
They guide everything from product development to practical application in the industrial environment, ensuring quality, safety, and standardization in every inspection.

Knowing these standards is essential for anyone working in quality control, maintenance, and inspection — whether in heavy industry, petrochemicals, aeronautics, or metallurgy.

Important notice:

This content is for educational purposes only. The application of the test methods and parameters must follow a qualified procedure approved by a Level 3 Inspector .

Solution in Non-Destructive Testing

Metal-Chek provides complete END solutions: penetrant liquids , magnetic particles , yoke and accessories , developed according to the main ASTM, ISO , ASME, NM, PETROBRAS standards, guaranteeing quality, safety and technical compliance in every inspection.

Discover the complete Metal-Chek product line.

Contact our team.

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THE POWER OF COMBINATION

Discover how the combination of Supermagna Yoke HMM6 , magnetic powder particles , BC 502 SN Conditioner and 104C Contrast ensures fast, compliant and safe magnetic particle inspections .

In industrial maintenance, the reliability of inspections is crucial to avoid rework, equipment failures, and costs associated with unscheduled downtime.

Among Non-Destructive Testing (END) methods, magnetic particle inspection (MPI) is one of the most widespread techniques for detecting surface and subsurface discontinuities in ferromagnetic materials .

For reliable results, good magnetization equipment alone is not enough. High-quality magnetic particles, a suitable conditioner, and an effective contrast agent are also necessary .

This is where Metal-Chek stands out, offering a robust combination for the industry: the Supermagna Yoke HMM6 , magnetic powder particles associated with the BC 502SN Conditioner and the 104C Contrast .

Supermagna Yoke HMM6: Robustness and Compliance

The Supermagna Yoke HMM6 is an electromagnetic yoke designed to generate the necessary magnetic field during inspection.

Main features:

• Portable and robust – ideal for field and factory inspections.
• Safe – it does not conduct current through the part, but induces a longitudinal magnetic field.
• Versatile – suitable for inspecting welds, castings, forgings, metal structures, etc.

Regulatory – complies with the main national and international standards.

Magnetic Particles + BC 502 SN Conditioner

The use of magnetic powder particles , combined with BC 502 SN Conditioner , is the most widely adopted method for forming stable and efficient suspensions.

Function of magnetic particles:

• They make surface and subsurface discontinuities visible by accumulating in regions where the applied magnetic field escapes.
• The concentration can be adjusted according to the procedure.
• Available in different options for visible or fluorescent inspections.

Function of BC 502 SN Conditioner:

• It guarantees corrosion protection .
• Allows for uniform dispersion of particles .
• It promotes proper moisturization and mobility  on the surface.
• Compliant with technical standards requirements.

104C Contrast: Enhanced Visibility and Precision

Contrast 104C is applied before magnetization and magnetic particle bathing, creating a uniform white background .

Main functions:

• It increases the contrast between the particles and the surface.
• Increased sensitivity of the assay.
• Compliance with technical standards.

How the Combination Works

1. Applying Contrast 104C – creates a contrasting and uniform white background.
2. Magnetization with the Supermagna Yoke HMM6 – generates the necessary magnetic field.
3. Application of the prepared suspension (particles + BC 502 SN) – the particles agglomerate in the leakage field regions, forming indications.
4. Interpretation – with a white background and highlighted particles, the inspector can quickly and reliably identify discontinuities.

Advantages of the Combination

• High sensitivity in detecting discontinuities.
• Operational speed , with results visible immediately.
• Regulatory reliability , in accordance with ASTM, ISO, AMS, ASME and PETROBRAS standards.
• Flexibility , allowing adjustments to particle concentration.
• Safety is ensured through the use of a robust and secure yoke in various environments.

Technical Standards Supporting the Set

The combination meets the requirements of international and national standards, such as:

• ASTM E709
• ASTM E3024
• ISO 9934 (1 and 2)
• NM 342
• ASME BPVC Section V, Article 7
• PETROBRAS N-1598

Magnetic particle inspection is an essential technique for industrial maintenance and quality assurance . However, its efficiency depends on choosing the right equipment and supplies .

The combination of the Supermagna Yoke HMM6 , magnetic particles with BC 502 SN Conditioner , and 104C Contrast ensures a fast, reliable, and safe inspection process.

With this complete solution, Metal-Chek reinforces its commitment to providing cutting-edge technology for Non-Destructive Testing , meeting the needs of the industry with excellence.

Speak with our  technical team  and discover how we can help transform your inspection routines into competitive advantages. 

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Discover how to plan and execute magnetic particle inspections, ensuring speed, reliability, and compliance with technical standards.

Industrial inspections can present challenges such as lack of infrastructure, space limitations, adverse conditions, and the need for fast and reliable results .

In this context, Non-Destructive Testing (END) using magnetic particles (MP) stands out as a practical solution for detecting surface discontinuities in ferromagnetic materials .

This practical guide is aimed at maintenance professionals, inspectors, and engineers , showing how to perform magnetic particle inspections efficiently, safely, and in compliance with regulations , even outside of controlled laboratory environments.

Surface Preparation

One of the biggest challenges in inspections is dealing with surfaces contaminated by grease, oil, welding spatter, or oxidation. Proper area preparation is essential to avoid false readings.

Recommended techniques:

• Steel brush (manual or rotary): quick removal of oxidation from welds and metal structures.
• Grinding: suitable for removing coatings and persistent oxidation.
• Solvents and clean cloths: remove grease and oils.

The better the preparation, the greater the reliability of the inspection.

Choice of Technique

The type of application of magnetic particles should consider environmental conditions, available time, and required sensitivity .

• Dry process:

Advantages → ideal for surfaces with high temperatures

Limitations → lower sensitivity to small discontinuities

• Wet method (water or oil):

Advantages → high sensitivity, suitable for detecting small discontinuities.

• Colored wet process

Advantages → visible under white light, no need for special lighting fixtures.

Limitations → operating temperature

• Fluorescent wet particles:

Advantages → maximum sensitivity under UV-A light.

Limitations → operating temperature, visible only under UV-A light.

Safety in Confined Spaces

Inspections of tanks, vessels, and confined structures require additional safety measures:

• Use portable and robust equipment , such as the Supermagna Yoke HMM6 , which works in different positions and does not conduct current through the workpiece.
• Respect occupational safety standards (e.g., NR-33 – Safety in Confined Spaces).

Choosing robust equipment is crucial for reducing risks and increasing reliability in challenging environments.

Technical Standards Governing Testing

Magnetic particle inspection can follow recognized standards to ensure reliable results:

• ASTM E709
• ISO 9934 (1 to 2)
• PETROBRAS N-1598
• ASME Section V, Article 7

Recommended Equipment for Inspections

For magnetic particle inspections, the ideal solution is to use equipment that combines durability, safety, and regulatory compliance.

The Supermagna Yoke HMM6 , for example, is designed to meet these needs:

• Portable and robust.
• Safe in potentially explosive atmospheres.
• Meets ASTM, ISO, ASME and PETROBRAS standards.
• Suitable for inspections of welds, metal structures, castings, forgings, etc.

Magnetic particle inspection is a strategic tool for industrial maintenance. When performed correctly — with proper surface preparation, appropriate technique selection, and the use of reliable equipment — it ensures operational safety, regulatory compliance, and cost reduction .

If your company operates in sectors such as oil & gas, energy, automotive or metallurgical , the Metal-Chek Supermagna Yoke HMM6 is the ideal solution to guarantee reliable results within standards .

Speak with our technical team.

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In industrial maintenance, the efficiency of a solvent goes far beyond cleaning. E-59 is a clear example: developed as an aliphatic solvent, it plays a strategic role in both non-destructive testing (END) and heavy-duty cleaning of industrial components, especially in environments where lubricating oil is a constant challenge.

E-59 in Non-Destructive Testing

In inspection and quality control processes, choosing the correct solvent directly impacts the effectiveness of the tests. E-59 is widely used as part of the surface preparation steps in liquid penetrant testing , ensuring that parts and components are properly cleaned and free of contaminants before the method is applied. This results in greater accuracy in detecting discontinuities.

Applications in Oil Cleaning and Lubrication

Beyond its use in inspection applications, the E-59 is recognized for its high efficiency in removing lubricating oil from engine blocks, mechanical parts, and impregnated surfaces. This versatility makes the product an ally in sectors that deal with high levels of oil contamination, such as engine rebuilding shops, heavy maintenance, and railway industries.

Use in Grinding Shops and the Railway Sector

Engine rebuilding companies use E-59 for the precise cleaning of engines and components, ensuring that the reassembly process occurs under ideal conditions. In the railway sector, especially in locomotive manufacturing companies , the product stands out for its ability to remove oil residue from large and complex parts, where cleanliness is critical for the reliability and durability of the equipment.

Advantages of the E-59

• High performance aliphatic solvent.
• Ideal for surface preparation in non-destructive testing.
• Excellent removal of lubricating oil and grease.
• Widely used in engine rebuilding shops and locomotive companies.
• Versatility: suitable for industrial maintenance, inspection, and heavy-duty cleaning.

E-59 is not just a solvent. It represents a practical and reliable solution for sectors that demand deep cleaning and precision in non-destructive testing. Whether in engines, industrial parts, or large railway systems, its application guarantees efficiency, safety, and reliability in day-to-day maintenance.

Want to learn more about the E-59 and its applications? Talk to our team !

Read also: High-Quality Industrial Inspections Begin with a Clean Surface

Follow us on Instagram: @metalchek

A practical guide for purchasers and supply engineers.

In industry, Non-Destructive Testing (END) is fundamental to ensuring the quality, safety, and conformity of parts and equipment. However, many Requests for Quotations (RFQs) fail because they do not correctly specify what is being requested—whether it is the  contracting of END services  or the  acquisition of supplies and equipment  to perform it.

Below, we present a practical guide to preparing clear and complete RFQs, with real-world examples from  Metal-Chek  and  Supermagna products .

1. Define what you are buying: a service or a supply.

First of all, determine if your RFQ will be for:

• END service  – the supplier performs the test and delivers the technical report.
• Materials/supplies/equipment for END  – your team or service provider will use the purchased products to perform the test.

This distinction avoids confusion and ensures that the specifications are suitable for what you want to buy.

2. Specifying the contracting of the END service

When hiring a service, describe  how the test should be conducted  and  what acceptance criteria  will be adopted.

a) Method and technique

Specify the method and technique:

• Example: Liquid penetrant testing, Type I, Method A, Level 2, using  Metal-Chek FP 91
• Example: Dry magnetic particle extraction, white powder, using  Supermagna WD 55

b) Reference standard

Define the applicable standard (ASTM E165, ASTM E709, ASME Section V, AWS D1.1 or internal standards such as Petrobras N-1596/N-1598).

c) Acceptance criteria

Determine codes and levels (e.g., ASME VIII Div.1, EN 1369, Level 2 or 3).

d) Inspector qualifications

Require  SNQC/ABENDI  or  ASNT SNT-TC-1A certification , Level II or III, depending on the method.

e) Implementation conditions

Include requirements such as cleanliness, adequate lighting (lux or µW/cm²), temperature, humidity, and application times.

f) Documentation and traceability

Request reports with photos, sketches, and part identification, ensuring traceability by batch or serial number.

3. Specifying the purchase of materials and equipment for END

When purchasing supplies or equipment, the RFQ (Request for Quotation) should contain  technical details of the product .

a) Penetrant Liquids

• Fluorescent: Metal-Chek FP 91 , Type I, Method A, Level 2
• Visible: Metal-Chek VP 30 , Type II, Method A
• Visible: Metal-Chek VP 31 , Type II, Method C

b) Developers

• Dry:  Metal-Chek D72 , form a
• Non-aqueous:  Metal-Chek D70 , form d, e
• Aqueous:  Metal-Chek D76 , form b

c) Removers / Cleaners

• Solvent: Metal-Chek E 59 , Class 2
• Solvent: Metal-Chek R 501 , Class 1

d) Magnetic Particles

• White dry track: Supermagna WD 55
• Yellow dry track: Supermagna YD 404
• Fluorescent wet process: Supermagna LY 2000
• Visible red wet path: Supermagna RW 222
• Visible black wet sample: Supermagna BW 333

e) Equipment

• Yokes:  Supermagna Yoke HMM6

4. Best practices for any END RFQ

• Be specific: avoid generic terms like “LP test” without specifying the method, type, and standard.
• Standardize the descriptions across all requests.
• Approve the technical proposal before the price.
• Include safety and environmental requirements (PPE, proper disposal of products).

Conclusion

A clear specification — whether for contracting END services or acquiring Metal-Chek and Supermagna supplies — ensures that the process is executed with quality, reduces risks, and avoids rework.

Want to learn more?   Read also: How to choose the ideal penetrant type for each application .

Speak to our technical team .

Follow us on Instagram: @metalchek

In penetrant testing, choosing the correct product is crucial for the  sensitivity, reliability, and compatibility of the test. Specifying an inappropriate penetrant can lead to incomplete detection of discontinuities, material damage, or even unnecessary rejections.

This guide will help you understand which factors to consider  and how to select the most suitable penetrant for your application, with real-world examples from the Metal-Chek line.

1. Begin by understanding the classification of penetrants.

Penetrant liquids are classified primarily by  type, removal method, and sensitivity level.

a) Type

• Type I – Fluorescent.
  High sensitivity, inspection under UV light. Ideal for detecting very fine discontinuities.
  Ex.:  Metal-Chek FP 91 , Type I, Method A, Level 2.
• Type II – Visible.
  Indications visible to the naked eye under white light. Simpler and faster, ideal for field inspections.
  Ex.:  Metal-Chek VP 30 , Type II, Method A;  Metal-Chek VP 31 , Type II, Method C.

b) Removal method

• A – Washable with water  (easy removal with water)
• B – Lipophilic post-emulsifiable  (emulsifier applied after the penetrant)
• C – Solvent removable  (removal with cloth and solvent, such as  Metal-Chek E 59  or  Metal-Chek R 501 )
• D – Hydrophilic post-emulsifiable  (water-based emulsifier)

c) Sensitivity level (Type I)

It ranges from  Level 1  (low sensitivity) to  Level 4  (ultra-high). The more critical the component, the higher the recommended level.

2. Consider the material to be inspected.

• Stainless steels, titanium, and special alloys : require penetrants with low halogen and sulfur content, and compatible developers.
  Ex.:  Metal-Chek FP 91  with contaminant certification according to ASTM E165.
• Carbon steel and ferrous materials : greater flexibility of choice, depending on the acceptance criteria.
• Porous materials : require care to avoid excessive penetration and false readings.

3. Inspection environment and conditions

• Environments with low, controlled lighting : fluorescent (Type I) is preferable.
• Field inspection or areas with restricted UV lighting : opt for visible (Type II).
• Locations without running water : consider method C (removable solvent) for cleaning up excess water.

4. Compliance with standards and criteria

Always align the penetrant and developer with the required standard:

• ASTM E165, ISO 3452, ASME Section V, Petrobras N-1596.
  And include in the RFQ the requirement for a batch certificate and SDS (Safety Data Sheet).

5. Combining penetrant, developer, and remover

For an effective test, choose a compatible set:

• Metal-Chek FP 91  (fluorescent) +  Metal-Chek D70  (non-aqueous developer) +  Metal-Chek E 59  (solvent remover).
• Metal-Chek VP 30  (visible) +  Metal-Chek D72  (dry developer) +  Metal-Chek R 501  (solvent remover).

Conclusion

Choosing the right penetrant is not just a matter of preference — it’s  a guarantee of reliable results and compliance with technical standards .
Metal-Chek offers solutions for different sensitivity levels, methods, and types, always accompanied by technical certification and specialized support.

Contact the Metal-Chek technical team.

Follow us on Instagram:  @metalchek

Read also:

The Main Methods of Industrial Inspection and How to Choose the Ideal One

How to Choose the Ideal Penetrant Testing Process for Your Application?

Do you know what makes a penetrating liquid effective?

Industrial leaks are not just an operational headache. They can compromise a plant’s safety, productivity, and environmental compliance. Therefore, early leak detection is an essential practice for any modern industry, especially in contexts like Industry 4.0, where continuous monitoring and predictive maintenance are key to efficiency.

In this article, we will explore one of the main methods for detecting industrial leaks, focusing on non-destructive techniques based on the use of fluorescent additives and UV flashlights . The goal is to provide a comprehensive, technical, and accessible overview for professionals working in industrial maintenance , inspection , and sectors where operational reliability is non-negotiable.

Why is accurate leak detection vital?

Before we delve into the method, it’s worth reiterating: leaks can cause significant damage. We’re talking about:

• Loss of industrial fluids (oil, gas, water, compressed air, refrigerant, among others);
• Increased operating costs;
• Risks of fire or contamination;
• Damage to equipment and structures;
• Production interruptions;
• Legal and environmental non-conformities.

In a scenario where predictive maintenance is increasingly integrated into industrial strategies, the use of non-destructive testing (END) to identify and correct leaks has become a competitive differentiator.

The technology of fluorescent additives

Detection with fluorescent dyes is one of the safest, simplest, and most effective techniques for identifying leaks. The fluorescent additive works effectively in any closed circulatory system where liquids are used for lubrication, hydraulics, cooling control, and fuel systems.

The method involves adding a fluorescent additive — usually a colored liquid miscible with the system fluid (such as oil, water, fuel, or coolant) — which concentrates at the leak points. When exposed to ultraviolet (UV) light, this additive emits intense fluorescence, making even the smallest leaks visible.

How the method works:

1. Fluorescent dye is added to the system to be inspected (pipes, tanks, heat exchangers, radiators, hydraulic systems, etc.).
2. After a period of operation, the system is inspected with a UV flashlight .
3. Leaks are visually identified as bright spots, usually in shades of green or yellow.

Advantages:

• Non-destructive method;
• Affordable cost;
• Quick and visual detection;
• Excellent for small leaks;
• Compatible with various types of fluids.

Typical applications:

• Industrial and automotive refrigeration systems;
• Oil pipelines;
• Plumbing installations;
• Reservoirs;
• Air conditioning equipment (HVAC/R).
• Fuel lines;

The role of UV flashlights

UV flashlights are indispensable tools in this process. Their main function is to emit ultraviolet radiation, in the 365nm range, to excite the fluorescent molecules of the additive, making the leak visible to the naked eye.

Characteristics of UV flashlights:

• Laptops;
• Battery powered;
• IP certification;
• Specific power and wavelength for greater visual contrast;
• Long range;

Good practices in leak inspection

• Use certified additives that are compatible with the system fluid;
• Follow the manufacturer’s instructions regarding concentration and circulation time;
• Use UV flashlights with the appropriate wavelength;
• Document the identified leak points with photos and technical reports.

Safety and environment

The choice of method should always consider environmental and health impacts. High-quality fluorescent additives have NSF and OEM Grade certification, but their disposal must comply with local environmental regulations. The use of UV flashlights must also follow safety standards, avoiding prolonged direct exposure to radiation.

Conclusion: technology combined with intelligent maintenance

Leak detection using fluorescent additives and UV flashlights represents an efficient, affordable, and visually powerful solution for maintaining the integrity of industrial systems.

If your company operates in the industrial and commercial sectors , industrial maintenance , inspection, and welding , incorporating these practices can represent significant cost savings, in addition to ensuring compliance, safety, and performance.

Want to know which fluorescent additives and UV luminaires are ideal for your type of application? Talk to the Metal -Chek technical team — a national specialist in solutions for Non-Destructive Testing .

Contact us: (11) 3515-5287

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Every effective inspection begins with observation — not just what the eyes see, but what a technical and experienced eye is able to interpret. Visual Inspection (VI) is the initial step in identifying discontinuities , defects, wear, and anomalies that can compromise the integrity and performance of equipment.

More than just a superficial check, VT acts as an initial filter in quality control, directly contributing to cost reduction , risk prevention , and increased operational efficiency .

Furthermore, visual inspection serves as the gateway to more advanced non-destructive testing techniques, such as penetrant testing, magnetic particle testing, and ultrasound. In other words, when a visual indicator is detected, it’s the right time to deepen the analysis with complementary and more sensitive methods.

Although it seems simple, visual inspection requires much more than just “looking”:

• Technical training
• Knowledge of acceptance criteria
• Adequate lighting
• Support tools and instrumentation
• Evidence documentation

Visual Inspection in the Industry 4.0 Era

Those who think that Visual Inspection (VI) has lost importance with the advancement of automation are mistaken. On the contrary — it has evolved and integrated with new technological resources, expanding its reach, precision, and speed.

Today, VT is an active part of Industry 4.0 and can be combined with state-of-the-art digital solutions:

• Artificial intelligence for image recognition.
• Drones for inspections at heights or in hazardous areas.
• 4K cameras with thermal sensors
• Predictive analytics connected to digital dashboards

Most common applications of visual inspection.

Visual Inspection (VI) is widely used in various industrial sectors as a quick and effective assessment tool. Its main objective is to identify visible irregularities that may compromise the structural integrity, functionality, or safety of components and equipment.

The following table summarizes the main applications and what is sought to be identified in each case:

Equipment and Resources Used in Visual Inspection

Although many visual inspections are done with the naked eye, the use of auxiliary equipment significantly enhances the accuracy and reliability of the test. Some resources used include:

 Adequate natural or artificial light: Ensures adequate visibility. Poor lighting can compromise the detection of discontinuities.

Magnifying glasses and magnifying lenses: They amplify small details, allowing the identification of surface cracks, porosity, inclusions, or lack of fusion in welds.

Borescopes and industrial endoscopes: Optical instruments used for inspecting hard-to-reach areas, such as pipes, internal welds of pressure vessels, and aeronautical components.

Rulers, gauges and jigs: Tools for measuring dimensions, weld angles, weld bead profiles and alignments.

High-resolution cameras: They facilitate photographic documentation and historical comparison during periodic inspections.

Digital inspection and recording software: With the advancement of Industry 4.0, integrating visual inspections with digital systems allows for recording occurrences, generating reports, and maintaining traceability in accordance with regulatory requirements.

Tip:
In low-light environments, the use of adequate artificial light is not optional — it’s mandatory.

Best practices in performing visual inspections.

To ensure the effectiveness of visual inspection and the reliability of results, it is essential to adopt well-defined operational practices. Standardizing execution through written procedures and operational checklists helps minimize human error and ensure consistency in assessments. A simplified model is presented below that can be adapted to the needs of each sector:

BEFORE INSPECTION:

• Check that the surface is clean (free of contaminants such as paint, oil, grease, rust, dust, or debris).
• Check the ambient lighting (it should be sufficiently intense and evenly distributed, allowing for an accurate assessment of the surface. It is important to avoid reflections, shadows, or glare, especially on polished materials or those with irregular geometry. In locations with little natural light, the use of adjustable and directional artificial light sources is recommended to ensure good visibility).
• Assess the inspector’s physical and visual condition (e.g., fatigue, use of glasses).
• Assess the need for additional equipment and resources.

DURING THE INSPECTION:

• Observe surface continuity: deformations, cracks, oxidation.
• Check weld beads: profile, spatter, lack of fusion.
• Use magnifying glasses on areas with suspicion or small details.
• Photographing and documenting irregularities
• Assess the need for additional tests (liquid penetrant, magnetic particles, etc.).

AFTER INSPECTION:

• Record keeping and traceability (maintaining a history of inspections, photos, reports, inspection maps, and checklists with acceptance criteria. These records ensure traceability, effective audits, and support decision-making).
• Storing records digitally ensures traceability and facilitates audits.

Integration of Visual Inspection with Other END Methods

Visual Inspection (VI) is the starting point for most Non-Destructive Testing (END). While it can identify various surface flaws, it does not always provide sufficient information for a complete assessment of the component’s integrity. Therefore, it is essential to integrate it with complementary methods, especially when there are visual suspicions that require technical confirmation.

The table below shows how VT connects to the main END methods and the benefits of this combination:

Normative References

Visual inspection is governed by several technical standards that ensure standardized procedures, reliable results, and compliance with legal and industrial requirements. Below, we highlight some applicable technical standards:

• ISO 17637 – Visual Inspection of Welds in Metallic Materials: establishes requirements for performing visual inspection of welds, including acceptance criteria and recommended techniques.
• NBR 14842 – Visual Inspection of Welds: national procedures and requirements that guide the practice of visual inspection of welds.
• ASME Section V, Article 9 – Requirements for Visual Inspection: a standard widely used in the pressure equipment and boiler making industry.
• Petrobras Technical Standards (Examples: N-1596, N-1598, N-2370) – Specific guidelines for visual inspections in the oil and gas sector.

The First Line of Defense for Quality

Visual inspection is much more than just a keen eye—it’s an essential technical barrier against failures that compromise safety, productivity, and regulatory compliance.

Implementing a well-structured visual inspection program is the first step towards operational excellence. Furthermore, when combined with Metal-Chek methods such as Liquid Penetrant, Magnetic Particle, and Leak Detection , visual inspection transforms into an ecosystem of industrial reliability .

Next Steps for Your Company

To strengthen your visual inspection program and increase the reliability of your processes, consider:

✅ Assess the maturity of your visual inspection program.

✅ Empower your team with training based on recognized standards.

✅ Standardize checklists and procedures with specialized technical support.

✅ Invest in quality accessories and equipment to complement the visual stage.

If your company wants to increase process reliability and ensure technical compliance, Metal-Chek is your ideal partner.

Speak with our technical team and discover how we can help transform your inspection routines into competitive advantages. 

Follow us on Instagram:  @metalchek

Contact us at: (11) 3515-5287

If you want to guarantee accuracy, compliance, and operational safety in your Non-Destructive Testing (END), equipment calibration is not an optional step—it’s indispensable.
Companies that neglect this practice face serious risks:
❌ Inaccurate reports
❌ Undetected failures
❌ Non-conformities in audits
❌ Operational and reputational damage

➡️ When equipment is out of calibration, reliability disappears — along with operational safety.

What is Calibration and why is it Vital in END?

Calibration is a process of comparing two instruments (the measurand and the measured). This comparison involves calculating error and uncertainty, and these results are presented in a document called a calibration certificate.

• ✅ Relationship between measurement values ​​and uncertainties; 
• ✅ Technical standards are being met;

Standards such as ASME Section V, ASTM E1417, ASTM E1444, ASTM E3024, and ASTM E709 require that your equipment be calibrated for the results to have technical and legal validity.

Why is calibration a key differentiator?

1. Ensures Technical Precision

• False positives → good parts are discarded unnecessarily.
• False negatives → errors go unnoticed.

Both put security at risk, increase costs, and compromise the company’s reputation.

2. Avoid Penalties in Audits

Industries such as oil and gas, aeronautics, rail, and automotive are inflexible regarding non-compliant equipment.
Golden tip: Always demand certificates traceable to the RBC (Brazilian Calibration Network) or recognized international standards.

3. Reduces costs associated with rework.

Investing in calibration is cheaper than correcting errors caused by miscalibrated equipment.

Which equipment needs to be calibrated?

Penetrant Testing (PT)

• Radiometers/Photometers
• Thermometers
• Water pressure gauges
• Compressed air pressure gauges

Magnetic Particle (MP)

• Gaussmeters (Residual)
• Magnetic Field Meters
• Ammeters
• Timers
• Magnetizing equipment (Stationary Machines)
• Settling tubes

When should the equipment be calibrated?

The ideal calibration frequency is determined according to applicable standards.

How to Guarantee Traceability?

Compliance isn’t something you improvise. Follow these practices:

• ✔ Hire laboratories accredited by Inmetro (ABNT NBR ISO/IEC 17025);
• ✔ Archive and update calibration certificates;
• ✔ Use digital checklists with automatic due date alerts;

[PRACTICAL CHECKLIST] How to Organize Your Calibration Routine

Calibration means Safety, Reliability, and Quality.

In the world of Non-Destructive Testing, calibration is an act of technical responsibility and a commitment to safety .

Metal-Chek offers the best consumables and accessories to ensure your penetrant testing, magnetic particle testing, and leak detection are accurate, traceable, and reliable.

You may have the best partner laboratory — but if your products are not of high quality, the results will be compromised.

Ready to increase the reliability of your tests?

→ Contact our technical team right now.
We’ll help you select the best Metal-Chek products to make your tests safer and more effective.

Follow us on Instagram:  @metalchek

Contact us at: (11) 3515-5287