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In industrial processes where inspection reliability is essential, the choice of penetrant makes all the difference. Metal-Chek FP 91 was developed for water-washable fluorescent penetrant testing, offering clear indications, intense fluorescence, and easy removal – characteristics that directly contribute to more productive and safer inspections.

Classified as Type I, Method A, Level 2 , FP 91 is a medium-sensitivity , water-washable fluorescent penetrant , indicated for the detection of surface discontinuities in non-porous materials that require greater sensitivity in the test. Its inspection should be carried out with 365 nm UV-A light , according to the product’s technical instructions.

High sensitivity for more visible indications.

One of the main advantages of FP 91 is its ability to generate sharper indications with an intense fluorescent yellow-green color . In practice, this facilitates the visualization of discontinuities during inspection, especially in controlled environments with adequate lighting, even when using the developer-free technique.

This high detection capability is crucial in applications where small surface flaws can compromise the quality, safety, or performance of the inspected component.

Low background fluorescence: more contrast during inspection.

In addition to the intensity of the indications, the FP 91 exhibits low background fluorescence . This difference contributes to better contrast between the inspected area and any indications, reducing visual interference and facilitating a clearer reading by the inspector.

In fluorescent assays, this point is especially important, as a surface with excessive background can hinder the correct identification of discontinuities.

Washable with water and easy to remove.

FP 91 belongs to Method A , meaning it is a water-washable penetrant . This makes the process of removing excess more practical, as it can be done with a water spray or with clean, dry cloths that are then slightly moistened, according to the technical procedure.

The ease of removal helps optimize the inspection process, maintaining efficiency without compromising test quality. The description also provides guidance on how to avoid excessive washing, preserving the indication of potential defects.

Versatile application in different materials and processes.

The Metal-Chek FP 91 can be used in a wide variety of industrial applications, including materials testing:

• forged;
• laminates;
• fused;
• welds;
• manufacturing steps;
• Maintenance of assembled sets or components.

It can also be applied to ferrous and non-ferrous metals , non-porous ceramics, glass and various types of plastics, provided that the surface is within the temperature range indicated for the test, between 10 °C and 52 °C .

Low material consumption

FP 91 also stands out for its low material consumption , related to less drag during the process and excellent wetting. This factor can contribute to greater product utilization, especially in industrial routines with a high frequency of inspections.

Aerosol version FP 91 HI: practical application.

In addition to larger volume packaging, FP 91 is also available in an aerosol version with hydrocarbon propellant, FP 91 HI . This option is suitable for spray applications, offering practicality for spot inspections, maintenance, and situations where the use of portable packaging facilitates fieldwork.

The aerosol version retains the product’s main characteristics: intense fluorescence, easy removal with water, low background fluorescence, and clear indication of surface discontinuities.

Compliance with recognized standards and specifications.

Another important distinguishing feature of the FP 91 is its compliance with specifications widely used in the industrial market. The product meets requirements such as:

AMS 2644, ISO 3452-2, ASTM E-1417, ASTM E-165, ASME Section V Article 6, PETROBRAS N-2370 and N-1596.

This set of specifications reinforces the suitability of the FP 91 for applications in industrial environments that require technical control, standardization, and traceability of inspection processes.

How does FP 91 contribute to more efficient inspections?

By combining high fluorescent intensity, low background fluorescence, ease of removal, and good durability of indications, FP 91 contributes to a more efficient and reliable assay.

Among the main advantages of the product, the following stand out:

Greater clarity of indications , facilitating the identification of surface discontinuities;

Better visual contrast , due to low background fluorescence;

It is easy to operate because it is washable with water;

Versatile application , in different materials and industrial stages;

Low consumption , contributing to better product utilization;

Aerosol option , ideal for practical and localized applications;

Compliance with technical standards is important for qualified industrial processes.

Metal-Chek FP 91 is an efficient solution for fluorescent penetrant testing on non-porous materials requiring higher sensitivity. Its high revelation capacity, combined with ease of removal and low background fluorescence, makes it an excellent choice for industrial inspections demanding clarity, productivity, and reliability.

For best results, use should follow the applicable inspection procedure, with a properly cleaned surface, adequate penetration time, controlled removal of excess, uniform application of the developer, and inspection under appropriate light intensity.

Excellence in products for those seeking reliable results.

Metal-Chek provides complete solutions for Non-Destructive Testing: penetrant liquids, removers, developers, lighting fixtures and accessories, developed according to the main ASTM, ISO, ASME, NM and PETROBRAS standards , guaranteeing quality, safety and technical compliance in every inspection.

Speak with our  technical consultants  and find the ideal solution for your process.

Visit our  blog  and check out other technical content.

Discover our  complete product line .

Follow Metal-Chek on  Instagram ,  YouTube , Facebook  , and  LinkedIn.

The reliability of a liquid penetrant test is directly related to the sensitivity of the inspection system , that is, its ability to detect discontinuities of different dimensions.

To guarantee this performance, international standards establish the use of standardized reference blocks , used for sensitivity verification and quality control of the test.

Among these standards, ISO 3452-3 Type I stands out .

What is the ISO 3452-3 Type I standard?

ISO 3452-3 defines requirements for reference blocks used in liquid penetrant testing.

The Type I  standard consists of a metal plate with controlled artificial cracks , used to evaluate the performance of the penetrating system.

This pattern allows you to verify:

• the sensitivity of the assay
• the ability to reveal the indications
• the performance of the system composed of penetrant, remover and developer

Applications of the JIS standard

The ISO 3452-3 Type I standard is primarily used in two situations:

1) Materials acceptance test

Allows you to check the performance of new batches of:

• penetrants
• removers
• developers

This control ensures that the materials meet the expected level of sensitivity.

2) Verification of the test’s sensitivity

Used to confirm that the inspection system maintains adequate performance throughout its use.

JIS Standard Types

The patterns are available with different levels of depth:

• 10 µm
• 20 µm
• 30 µm
• 50 µm

The selection of the standard must be aligned with the level of sensitivity required by the application or as defined in a qualified procedure approved by a Level III inspector.

Relationship to the type of penetrant

The choice of pattern should take into account the type of penetrant used:

• Fluorescent penetrants (Type I)
→ higher sensitivity, typically evaluated with 10 µm or 20 µm standards
• Visible penetrants (Type II)
→ lower sensitivity, typically evaluated with 30 µm or 50 µm standards

This relationship allows for a correct evaluation of the performance of penetrant materials.

Importance of sensitivity control

Verifying sensitivity is essential to ensure the reliability of the test.

The absence of this control can result in:

• Failure to detect relevant discontinuities
• Inconsistency in results
• Loss of process reliability

The use of reference standards allows for the validation of system performance and maintains the repeatability of inspections.

The use of the ISO 3452-3 Type I standard is an essential practice for verifying performance in Liquid Penetrant (LP) testing .

The correct application of these standards contributes to the reliability of the process, meeting regulatory requirements and ensuring the quality of the inspections performed.

Excellence in products for those seeking reliable results.

Metal -Chek provides complete solutions for Non-Destructive Testing: penetrant liquids, removers, developers, lighting fixtures and accessories, developed according to the main ASTM, ISO, ASME, NM and PETROBRAS standards , guaranteeing quality, safety and technical compliance in every inspection.

Speak with our  technical consultants  and find the ideal solution for your process.

Visit our  blog  and check out other technical content.

Discover our  complete product line .

Follow Metal-Chek on  Instagram ,  YouTube , Facebook  , and  LinkedIn.

In critical industrial applications, especially those involving materials such as austenitic stainless steels, nickel-based alloys, and titanium , liquid penetrant testing requires not only sensitivity but also rigorous contaminant control .

The presence of elements such as sulfur, chlorine, and fluorine can compromise the integrity of the inspected material.

In this context, ASME BPVC Section V – Article 6, Appendix II establishes specific requirements for controlling these contaminants in the materials used in the test.

ASME V Requirements Art. 6 – Appendix II

Appendix II defines criteria for controlling contaminants in materials used in liquid penetrant testing, especially in sensitive materials.

Normal:

• For nickel-based alloys, the sulfur content must be controlled.
• For austenitic, duplex, and titanium stainless steels, chlorine and fluorine must be controlled.
• The maximum permitted limit for these contaminants is 0.1% by weight.

Furthermore, the standard establishes that:

• Penetrant materials must be analyzed by batch.
• Results must be documented and certificates of analysis issued.
• Certificates must contain batch identification and test results.

Importance of contaminant control

Controlling these elements is essential to avoid undesirable effects during and after the inspection.

Among the main risks associated with the presence of contaminants are:

• Stress corrosion;
• Alteration of material properties
• Surface contamination
• Non-compliance with regulatory requirements

These factors can compromise both the integrity of the component and the validity of the inspection performed.

Critical applications

Contaminant control is particularly relevant in sectors where structural integrity is critical, such as:

• Oil and gas industry
• Aeronautical sector
• Nuclear industry
• Boilers and pressure vessels

Certification and traceability

The standard requires that the materials used in the test have certification with batch traceability.

This documentation should include:

• Results of chemical analyses
• Product batch identification
• Proof of compliance with established limits

Proper selection of consumables

The choice of materials used in liquid penetrant testing should consider not only performance but also compliance with regulatory requirements.

This includes:

• penetrants
• removers
• developers

Using products with contaminant control and proper certification contributes to:

• Preserve the integrity of the inspected material
• Meet regulatory requirements
• Ensure consistency in results

Metal-Chek supplies consumables for liquid penetrant testing developed according to international standards, with contaminant control and batch traceability.

Final considerations

Meeting the requirements of ASME V Art. 6 Appendix II is fundamental in applications involving materials that require contaminant control.

Contaminant control should be considered an integral part of the inspection process, contributing to the safety, reliability, and technical compliance of the tests performed.

Excellence in products for those seeking reliable results.

Metal -Chek provides complete solutions for Non-Destructive Testing: penetrant liquids, magnetic particles, removers, developers, lighting fixtures and accessories, developed according to the main ASTM, ISO, ASME, NM and PETROBRAS standards , guaranteeing quality, safety and technical compliance in every inspection.

Speak with our  technical consultants  and find the ideal solution for your process.

Visit our  blog  and check out other technical content.

Discover our  complete product line .

Follow Metal-Chek on  Instagram ,  Facebook  , and  LinkedIn.

Every day, thousands of industrial structures, equipment, and components operate under severe conditions of pressure, temperature, and mechanical stress.

During manufacturing or throughout the lifespan of these materials, discontinuities can arise and, if not identified in time, can evolve into critical failures, directly impacting safety, operation, and industrial costs.

It is in this scenario that the Non-Destructive Testing (END) Inspector assumes an essential role.

Celebrated on March 27th, Non-Destructive Testing Inspector Day recognizes the importance of this professional who works on the front lines of failure prevention and industrial reliability.

What are Non-Destructive Tests (END)?

Non-Destructive Testing (END) methods are inspection methods used to evaluate materials, components, and structures without causing damage to the parts being analyzed.

These techniques allow for the identification of surface and subsurface discontinuities that can compromise structural integrity, directly contributing to the operational safety and reliability of industrial processes.

They are widely used in activities such as:

• Manufacturing of industrial components
• Weld inspection
• Preventive and predictive maintenance
• Quality control
• Structural integrity assessment

By enabling the early detection of discontinuities, END prevents unexpected failures, reduces operating costs, and increases the safety of operations.

The role of the END Inspector in industrial reliability

The END inspector is the professional responsible for performing, evaluating, and recording the results of inspections carried out using these methods.

Their role requires technical knowledge, mastery of applicable standards, and an understanding of inspection procedures.

Among their main responsibilities are:

• Evaluate the condition of materials and components
• Identify relevant discontinuities
• Interpret indications obtained during inspection
• Record results with technical accuracy
• Ensure compliance with standards and specifications

More than just performing tests, the inspector is responsible for ensuring the reliability of the results, a crucial factor for industrial safety.

Main Non-Destructive Testing methods used in industry

Several methods comprise Non-Destructive Testing. Among the most widely used are Liquid Penetrant Testing (LP) and Magnetic Particle Testing (MP).

Penetrant Testing (PT)

Liquid penetrant testing is used to identify surface discontinuities in non-porous materials.

The method consists of applying a highly penetrating liquid to the surface of the part. After an appropriate interval, the excess is removed and a developer is applied, allowing the indications to be visualized.

It is widely used in the inspection of:

• welding
• machined parts
• cast components
• metallic and non-metallic surfaces

Magnetic Particle Testing (MPT)

Magnetic particle testing is applied to ferromagnetic materials and allows the identification of surface or near-surface discontinuities.

During the test, the part is magnetized and particles are applied. In the presence of discontinuities, magnetic flux leakage occurs, forming visible indications.

It is used in the inspection of:

• welds
• shafts
• gears
• structural components
• parts subjected to mechanical stress

A fast, efficient method that is widely used in the industry.

Qualification and technical responsibility in END testing

Non-destructive testing (END) is not limited to the execution of the method; it also involves the correct interpretation of the observed indications.

Therefore, inspections must follow specific technical standards and procedures defined for each application.

The acceptance criteria, parameters, and procedures are established according to applicable standards and internal procedures of each company, under the responsibility of professionals qualified in the method.

The reliability of the results depends directly on three factors:

• Qualification of professionals
• Correct application of methods
• Proper use of materials and equipment

The role of Non-Destructive Testing in industrial maintenance

Non-destructive testing plays a strategic role in preventive and predictive maintenance, allowing the monitoring of component condition throughout their service life.

With this, it is possible to:

• Plan interventions in advance
• Avoid unexpected failures
• Reduce operating costs
• Increase equipment reliability

Applications of Non-Destructive Testing in major industrial sectors

Non-destructive testing is fundamental in various industrial sectors, especially where structural integrity is critical.

Among the main sectors are:

• Oil and gas industry
• Aeronautical sector
• Automotive industry
• Power generation
• Metal construction
• Industrial maintenance

In these environments, inspection directly contributes to ensuring the integrity of equipment, structures, and operational systems.

The importance of Non-Destructive Testing for industrial safety

Non-destructive testing is an essential part of modern industry, contributing to process reliability and operational safety.

By identifying discontinuities before they develop into critical failures, these methods ensure greater control over the integrity of equipment and structures.

On this Non-Destructive Testing Inspector Day, we reinforce the importance of the professionals who work on the front lines of inspection, ensuring that technical standards and quality criteria are met in every evaluation performed.

Excellence in products for those seeking reliable results

Metal-Chek provides complete solutions for Non-Destructive Testing: penetrant liquids, removers, developers, lighting fixtures and accessories, developed according to the main ASTM, ISO, ASME, NM and PETROBRAS standards , guaranteeing quality, safety and technical compliance in every inspection.

Speak with our  technical consultants  and find the ideal solution for your process.

Visit our  blog  and check out other technical content.

Discover our  complete product line .

Follow Metal-Chek on  Instagram ,  Facebook  , and  LinkedIn.

Aviation is one of the most stringent industrial sectors when it comes to operational safety. Aircraft are designed to operate under severe conditions of load, vibration, pressure variations, and continuous cycles of structural fatigue over thousands of flight hours.

To ensure that all components maintain their structural integrity over time, the aeronautical industry relies heavily on Non-Destructive Testing (END) .

More than just a verification step, ENDs (Non-Destructive Tests) are part of aviation safety culture. From the manufacturing of structures and components to maintenance programs throughout the aircraft’s lifespan, thousands of inspections are carried out to identify potential discontinuities before they evolve into critical failures.

Every safe flight depends on a series of technical inspections that ensure the structural reliability of the aircraft.

Non-Destructive Testing in the Aeronautical Industry

Non-destructive testing methods are used to evaluate the integrity of materials and components without compromising their future use.

In the aeronautical industry, different methods are applied as required by the aircraft manufacturer’s manual. Among the methods used are:
ultrasound
, radiography
, eddy currents
, liquid penetrant testing
, and magnetic particles.

Each method has a specific function within the inspection programs applied in the manufacturing and maintenance of aircraft.

Among these methods, fluorescent penetrant testing and fluorescent magnetic particle testing are widely used for the detection of discontinuities.

Technical rigor and materials control in aviation

The aeronautical sector adopts extremely rigorous criteria for the products used in inspection processes.

For example, the penetrating materials used in these processes must be qualified in the QPL — Qualified Products List .

Only listed materials may be used in certain aircraft inspection processes, ensuring standardization, traceability, and reliability in the results obtained .

Fluorescent penetrant liquid in aircraft inspection

Fluorescent liquid penetrant testing is widely used in the aeronautical industry to identify extremely fine surface discontinuities.

The method is based on the phenomenon of capillarity , allowing the penetrant to penetrate cracks or discontinuities open to the surface. After removing the excess and applying the developer, the retained penetrant returns to the surface, forming indications observed under ultraviolet illumination.

For aeronautical applications, the penetrants, removers, emulsifiers, and developers used must be properly qualified according to the applicable QPL list .

Metal-Chek offers the Sherwin Dubl-Chek line in Brazil , consisting of penetrant testing systems developed to meet the technical requirements of the aeronautical sector.

Fluorescent magnetic particles in ferromagnetic components

Magnetic particle testing is used to inspect components made from ferromagnetic materials.

The method involves magnetizing the component. When there is a surface discontinuity or a discontinuity near the surface, a distortion occurs in the magnetic field, forming a leakage field that attracts the magnetic particles applied to the part.

In the aeronautical industry, the test is typically performed using fluorescent magnetic particles in an oil-based liquid suspension , which provides greater sensitivity in the formation of indications.

In the context of the Metal-Chek line, fluorescent magnetic particles can be used in the aeronautical sector when applied in oil-based suspension , using the Supermagna OMC 10 MMS vehicle .

This combination allows for the proper formation of the suspension for application of the method, in accordance with the technical requirements adopted in aeronautical inspections.

Inspections throughout the aircraft’s lifespan

Non-destructive testing inspections are not limited to aircraft manufacturing.
These methods are part of ongoing maintenance and structural monitoring programs. Throughout the aircraft’s lifespan, components are periodically inspected to identify potential discontinuities caused by:
• structural fatigue
• repetitive load cycles
• vibration
• thermal variations
• severe operating conditions

This continuous monitoring allows for the identification of potentially critical conditions before they evolve into structural failures.

Air safety built into every inspection

Modern aviation safety is the result of a combination of advanced engineering, rigorous procedures, and reliable inspections .

Non-destructive testing is an essential part of this system, allowing the structural integrity of components to be evaluated without compromising their use.

Each inspection performed represents another level of assurance in the integrity of the aircraft, directly contributing to the safety of passengers, crews, and air operations worldwide.

Excellence in products for those seeking reliable results

Metal-Chek provides complete solutions for Non-Destructive Testing , with products developed according to the main ASTM, ISO, ASME, NM and PETROBRAS standards .

Among its solutions are systems for liquid penetrant testing , magnetic particles , and various consumables used in industrial inspections, contributing to consistent results, operational safety, and technical reliability.

Speak with our  technical consultants  and find the ideal solution for your process.

Visit our  blog  and check out other technical content.

Discover our  complete product line .

Follow Metal-Chek on  Instagram ,  Facebook  , and  LinkedIn.

In any industrial process, proper surface cleaning is not a detail, it is essential for a reliable result.

In Liquid Penetrant Testing (LP), a poorly prepared surface compromises the sensitivity of the method and can directly impact the interpretation of the readings. Outside of END, residues such as paints, varnishes, oils, and other contaminants also interfere with the quality of assemblies, finishes, and maintenance.

It is in this context that the TMC 10 Metal-Chek stands out: a technical remover developed for inspection, with sufficient versatility to meet industrial cleaning demands that require a high standard of performance.

What is TMC 10?

TMC 10 is a ready-to-use, non-halogenated, solvent-based remover formulated to offer:

• • fast action;
• • efficient removal of contaminants;
• • Evaporation without leaving residue;
• • Compatible with ferrous and non-ferrous metals, stainless steel, titanium, nickel alloys, non-porous ceramics, glass, and plastics.

Its control of contaminants (chlorides, fluorides and sulfur) meets the technical requirements applicable to Non-Destructive Testing, ensuring safety and compliance when used according to approved procedures.

Technical application in Non-Destructive Testing

In the context of END, TMC 10 can be used for:

• • Pre-cleaning of the surface before applying the penetrant;
• • Controlled removal of excess penetrant;
• • Removal of developers and contrast inks;
• • Final cleaning after inspection.

The application must always respect the qualified technical procedure, especially with solvent-removable penetrants, where controlled removal is essential to preserve the product retained in the discontinuities.

Its quick drying time and lack of residue help maintain the sensitivity of the method and the clarity of the instructions.

Far beyond END: industrial versatility

Although developed for technical inspection applications, the TMC 10 also meets other professional cleaning needs.

Its formulation allows for the efficient removal of:

• • paints and varnishes;
• • oils and greases;
• • Various industrial waste;
• • Contaminants on metal and plastic surfaces.

This versatility makes it suitable for:

Metallurgical industry

Cleaning metal parts, tools, and equipment before subsequent processes.

Painting workshops

Removal of paints and varnishes, preparing surfaces for a new finish.

Industrial maintenance

Cleaning machinery and components, contributing to the proper functioning and preservation of equipment. Always respecting applicable technical and safety recommendations.

Efficiency that impacts different sectors

A technical product with versatile applications generates positive effects throughout the company.

Production

Properly cleaned surfaces promote better adhesion, finish, and process stability.

Maintenance

Effective cleaning helps preserve and prepare components for technical interventions.

Quality

In END applications, the correct removal of contaminants is crucial for the reliability of the inspection.

Purchasing and management

The possibility of technical and industrial use contributes to inventory rationalization and standardization of inputs.

Why choose TMC 10?

The TMC 10 brings together features that make a difference in practice:

• ✔ Effective cleaning power
• ✔ Fast action
• ✔ Versatile application
• ✔ Residue-free drying
• ✔ Compatible with various materials
• ✔ Compliance with applicable technical standards

More than just a thinner or solvent, this is a solution developed to meet the needs of industrial environments that demand precision, efficiency, and reliability.

Technical cleaning is not a secondary step — it is an essential part of the industrial process.

Whether in Non-Destructive Testing or in maintenance and finishing applications, proper contaminant control directly influences the quality of the final result.

The Metal-Chek TMC 10 combines technical performance and industrial versatility, offering a reliable solution for those seeking efficiency and compliance in their operations.

Excellence in products for those seeking reliable results.

Metal-Chek provides complete solutions for Non-Destructive Testing, with products developed according to the main ASTM, ISO, ASME, NM and PETROBRAS standards, guaranteeing quality, safety and technical compliance in every inspection.

Speak with our technical consultants and find the ideal solution for your process.

Visit our blog and check out other technical content.

Discover our complete product line .

Follow Metal-Chek on Instagram , Facebook , and LinkedIn.

In an industrial setting, Quality Control is responsible for ensuring that products and processes meet established technical, regulatory, and contractual requirements.

Non-Destructive Testing (END) is an integral part of this Quality Control system. It consists of technical tools used to verify the integrity of materials and components without compromising their future use.

However, in many industrial environments, there is a disconnect between operations and the Quality or END departments.

On one side, those who execute.
On the other, those who inspect.

When this relationship is misunderstood, the perception arises that inspection exists only to point out flaws or interrupt the process. This view generates internal noise and weakens the quality culture.

Operation and END are not competitors. They operate at different stages of the same objective: ensuring the technical conformity and reliability of the final product .

The role of the operation in process integrity

Execution is the foundation of any industrial result.

It is the operational team that applies procedures, controls parameters, performs welding, assembly, and adjustments that determine the component’s performance.

Quality begins in the production process. When execution is consistent and aligned with technical requirements, inspection tends to confirm this conformity.

The operation, therefore, is not merely an executor; it is an active part of the quality control system.

The role of END in technical verification

Non-destructive testing serves to verify whether a product meets integrity criteria.

END does not create discontinuities.
It evaluates what is already present in the material or what is inherent to the manufacturing process.

When a relevant indication is identified, the objective is technical: to prevent an unsuitable condition from progressing in the process or reaching the customer.

Internal inspection reduces major risks, avoids external impacts, and preserves the integrity of the production system.

When conflict arises

Disagreements between operation and quality often arise when inspection is perceived as an obstacle to the pace of production.

However, a nonconformity identified internally represents an opportunity for controlled correction. Conversely, a failure detected externally can compromise contracts, schedules, reputation, and operational safety.

END acts as a validation step within the production flow, not as a barrier, but as a mechanism for technical verification.

When operations and END work as partners

Mature industrial environments exhibit clear characteristics:

• The operational team understands the acceptance criteria applicable to the process;
• The inspector understands the variables and limitations of the production process;
• There is objective technical communication;
• Adjustments are treated as process improvements, not as personal conflicts.

When integration exists:

✔ Rework decreases
✔ Process predictability increases
✔ Approval rate improves
✔ Trust between departments is strengthened

Inspection is now recognized as part of the quality workflow, and not as an impediment.

Quality culture: shared responsibility

Quality is not exclusive to the END sector.

It involves planning, execution, verification, and continuous improvement. When everyone understands their role within the system, the environment becomes more collaborative and technically consistent.

A strong quality culture reduces costs and improves performance indicators in a sustainable way.

Procedures and products as elements of stability

The partnership between operations and END also depends on a solid technical foundation:

• clear and well-defined procedures;
• objective acceptance criteria;
• Standardization of inspection methods;
• Reliable and consistent inspection products.

When parameters are clearly defined and the products used deliver consistent, specification-compliant performance, the process becomes more stable and technically reliable. Consistency in results strengthens trust between departments.

Operation and Non-Destructive Testing operate at different stages of the process, but share the same purpose: to ensure that the delivered product conforms to integrity requirements.

Overcoming the idea that the quality sector is merely a “pointer of errors” is essential to consolidating more mature, cooperative, and efficient industrial environments.

When execution and verification work in an integrated way, the result is a more stable, safe, and reliable production system.

Excellence in products for those seeking reliable results.

Metal-Chek provides complete solutions for Non-Destructive Testing, with products developed according to the main ASTM, ISO, ASME, NM and PETROBRAS standards, contributing to consistent and technically reliable inspections.

– Read more technical content about END on our blog
– Follow Metal-Chek on Instagram: @metalchek and on LinkedIn

In Liquid Penetrant (LP) testing, each step directly influences the effectiveness of the test. After proper surface preparation and adherence to the correct penetration time, the removal of excess penetrant liquid plays a critical role in the inspection process.

Improper removal can mask relevant discontinuities, generate false indications, or hinder the correct interpretation of results. Therefore, this step must be performed with the same technical rigor as the other phases of the test, always in accordance with the qualified and approved technical procedure.

This article discusses the importance of removing excess penetrant fluid, the main errors associated with this step, and its direct impact on the reliability of the liquid penetrant test.

The role of excess removal in the LP assay

The principle of the Liquid Penetrant test is based on capillarity , which allows the penetrant to penetrate discontinuities open to the surface.

After the penetration time, the excess liquid present on the surface must be removed, leaving only the penetrant retained within the discontinuities. This condition is essential for the developer to act correctly, promoting the reverse capillary effect of the penetrant and the formation of visible or fluorescent indications.

Improper removal compromises this balance and directly affects the formation and clarity of the indications.

What characterizes proper removal of excess?

Proper removal of excess penetrant fluid must meet the following criteria:

• to remove the penetrant from the surface without removing it from inside the discontinuities;
• to preserve the sensitivity of the method;
• to enable reliable visual interpretation.

These criteria are not universal and depend on factors such as:

applicable technical procedure.

type of penetrant (visible or fluorescent);

specified removal method;

surface condition;

Methods for removing excess penetrant fluid

Methods for removing excess penetrant may vary depending on the type of penetrant and the application.

Among the most commonly used methods are:

• removal with solvent  (remover);
• removal with water (spray jet);

The choice of method should take into account its compatibility with the penetrant used.

Main mistakes in removing excess penetrant

Excess removal is one of the steps where the most frequent errors occur in the liquid penetrant testing method. Among the main errors are:

Excessive removal

Excessive application of solvent or mechanical action from an intense water jet can remove the penetrant retained in the discontinuities, resulting in:

• loss of relevant indicators;
• reduction in assay sensitivity;

Insufficient removal

Incomplete removal of excess residue leaves it on the surface, promoting:

• difficulty of interpretation;
• emergence of false or irrelevant indications.

Impact of improper removal on the interpretation of indications

The visual interpretation of the indications depends directly on the quality of the excess removal.

When this step is not performed correctly, the following may occur:

• blurred or fuzzy indications;
• difficulty in distinguishing relevant from irrelevant indications;
• Increased risk of improper rejections or undetected failures.

These effects directly impact the reliability of the inspection and technical decision-making.

Metal-Chek solutions for removing excess penetrant

Metal-Chek offers a complete line of removers developed specifically for Penetrant Testing , ensuring efficient and controlled removal of excess product.

These solutions are designed for:

• to preserve the penetrant retained in the discontinuities;
• Avoid blotchy or fluorescent backgrounds;
• ensure compatibility with different LP methods;
• to meet the requirements of the main applicable technical standards.

The choice of the appropriate remover should always take into account the technical procedure and inspection conditions.

Final considerations

Removing excess penetrant fluid is not a secondary step in the test—it is a determining factor in its effectiveness .

When performed correctly, according to a qualified and approved technical procedure, this step ensures:

• proper training of the indications;
• reliable visual interpretation;
• Reducing errors and rework;
• Greater safety during inspection.

In liquid penetrant testing, precision and control at each stage are fundamental to ensuring consistent and technically reliable results.

Excellence in products for those seeking reliable results

Metal -Chek provides complete solutions for Non-Destructive Testing: penetrant liquids, removers, developers and accessories, developed according to the main ASTM, ISO, ASME, NM and PETROBRAS standards , guaranteeing quality, safety and technical compliance in every inspection.

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