Galvanized profile steel plate testing service

Galvanized Profile Steel Plate Testing Service – Accredited ISO/IEC 17025 Corrosion Resistance and Mechanical Performance Assessment for the Colombian Market

Galvanized profile steel plates are widely used in construction, infrastructure, automotive manufacturing, agricultural equipment, and industrial storage systems due to their excellent corrosion resistance, durability, and formability. The quality and performance of these coated steel products depend on critical parameters such as coating thickness, uniformity, adhesion, surface finish, mechanical strength, and corrosion resistance. In the Colombian market, where the Superintendencia de Industria y Comercio (SIC), the Ministerio de Minas y Energía (MinMinas), the Ministerio de Transporte, and the Dirección de Impuestos y Aduanas Nacionales (DIAN) enforce strict quality and safety standards for materials used in construction and industrial applications, the accurate evaluation of galvanized profile steel plates is essential for product certification, supplier qualification, quality control in manufacturing, and import-export processes. Our laboratory offers a comprehensive galvanized profile steel plate testing service, applying standardized methods that assess coating characteristics, mechanical properties, dimensional accuracy, and corrosion resistance to ensure compliance with international and Colombian standards (NTC). All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Colombian authorities, making them indispensable for regulatory compliance, material selection, and market access in Colombia.

Galvanized Steel Plate Samples We Regularly Test

Our laboratory receives a wide variety of galvanized profile steel plates and related products for comprehensive testing. Typical samples include:

• Hot-dip galvanized steel sheets and coils – for roofing, cladding, and structural applications.
• Galvanized steel profiles (C‑channels, U‑channels, angles, and Z‑profiles) – for framing, supports, and structural components.
• Galvanized corrugated sheets – for roofing and wall cladding.
• Galvanized steel strips and plates – for automotive, appliance, and industrial applications.
• Galvanized steel with organic coatings (painted or laminated) – for enhanced aesthetics and additional corrosion protection.
• Galvanized steel after forming, bending, or welding – to evaluate the integrity of the coating after fabrication.
• Prototype and new coating formulations – submitted by manufacturers for validation of galvanization quality before series production.
• Field-retrieved samples – for failure analysis and remaining life assessment.

Coating Thickness and Uniformity Testing – Evaluating the Galvanized Layer

The thickness and uniformity of the zinc coating are the most critical parameters for the corrosion protection of galvanized steel. Our tests measure the coating weight (in g/m²) and the average thickness (in μm), using both non-destructive and destructive methods. These tests are required by the NTC 3701 and ASTM A653 standards.

• Coating thickness measurement by magnetic gauges (ASTM E376 / ISO 2178 / NTC 4600) – we use calibrated magnetic induction or eddy-current gauges to measure the zinc coating thickness on steel. Measurements are taken at multiple points across the plate surface (edges, center, and corners) to assess the uniformity. We report the average thickness (in μm), the maximum and minimum thickness, and the uniformity index (the ratio of the minimum to the average thickness).
• Coating weight determination by the gravimetric method (ASTM A90 / ISO 1460 / NTC 4601 – triple-spot test) – we use the standard triple-spot test method, where a sample is dissolved in a hydrochloric acid solution containing an inhibitor to prevent the attack on the steel. The mass of the zinc coating is determined from the mass loss. The coating weight is expressed in g/m². We report the coating weight and the equivalent coating thickness.
• Coating thickness by cross-section microscopy (ASTM B487 / NTC 4602 – for destructive measurement) – a cross-section of the galvanized plate is prepared and examined under an optical microscope. The thickness of the zinc layer (including the alloy layers) is measured directly. We report the individual layer thicknesses (eta, zeta, delta, and gamma layers) and the total coating thickness.
• Coating thickness by X-ray fluorescence (XRF) – ASTM B568 / NTC 4603 – we use XRF spectrometry to measure the zinc coating thickness and the composition (including the presence of alloying elements such as aluminum or lead). We report the thickness and the composition of the coating.
• Coating weight per unit area by the magnetic method (NTC 4604 – for non-destructive testing) – we use a calibrated magnetic thickness gauge to measure the coating thickness in multiple locations, and we calculate the coating weight using the density of zinc (7.14 g/cm³). We report the coating weight and the thickness.

Coating Adhesion and Integrity Testing – Evaluating the Bond Strength

The adhesion of the zinc coating to the steel substrate is essential for the long-term performance of the galvanized product. Our tests evaluate the adhesion under bending, impact, and deformation, and they detect any flaking, peeling, or cracking of the coating. These tests are required by the ASTM A653 and NTC 3701 standards for structural applications.

• Bend test for adhesion (ASTM E290 / ISO 7438 / NTC 4610 – for coated steel) – a strip of the galvanized plate is bent through a specified angle (e.g., 180°) around a mandrel of a specified diameter (e.g., equal to the plate thickness). The bent area is inspected for cracking, flaking, or peeling of the zinc coating. The test is performed at room temperature and after low-temperature conditioning (e.g., -10 °C). We report the bend angle, the mandrel diameter, and the condition of the coating.
• Impact test for adhesion (NTC 4611 – for impact resistance of the coating) – a weight is dropped from a specified height onto the galvanized plate, and the indentation area is inspected for coating damage. The impact energy (in J) is recorded. We report the impact energy and the condition of the coating.
• Draw test for adhesion (NTC 4612 – for deep-drawn applications) – the galvanized plate is drawn into a cup or a profile, and the corners and the formed areas are inspected for coating cracking or flaking. We report the draw depth and the condition of the coating.
• Scrape adhesion test (ASTM D3359 / NTC 4613 – for coated surfaces) – a cross-hatch pattern is cut through the coating, and tape is applied and removed. The amount of coating removed is assessed and rated (0B to 5B). We report the adhesion rating.
• Hardness test of the coating (NTC 4614 – for assessing the coating integrity) – we measure the hardness of the zinc coating (and the alloy layers) using a microhardness tester (Vickers, with a load of 10 g to 25 g). A change in hardness indicates a change in the coating composition or the formation of brittle intermetallic phases. We report the microhardness profile across the coating.

Surface Condition and Appearance Inspection – Assessing the Quality of the Galvanized Surface

The surface appearance of galvanized steel, including the presence of defects such as bare spots, blisters, staining, or excessive roughness, directly affects the performance and the aesthetics of the product. Our visual inspection and surface characterization tests provide a comprehensive assessment of the surface quality.

• Visual inspection (ASTM A123 / NTC 4620 – for surface defects) – we inspect the galvanized surface for defects, including bare spots (uncoated areas), blisters, pitting, cracking, staining, white rust (wet storage stain), and excessive roughness. The defects are classified and rated according to the standard acceptance criteria. We report the type, location, and severity of the defects.
• Surface roughness measurement (ASTM D7127 / NTC 4621 – for coating texture) – we measure the surface roughness (Ra, Rz) of the galvanized coating using a contact profilometer or an optical profiler. Excessive roughness can affect the adhesion of subsequent paint layers and the corrosion resistance. We report the roughness values.
• White rust (wet storage stain) test (NTC 4622 – for corrosion assessment) – we perform a humidity test (or a water immersion test) to evaluate the susceptibility of the galvanized surface to white rust. The test is performed at 40 °C and 95 % RH for 48 hours. We report the appearance of white rust and the rating.
• Gloss measurement (ASTM D523 / NTC 4623 – for aesthetic surfaces) – we measure the gloss of the galvanized surface (or of any additional organic coating) using a glossmeter. We report the gloss (in GU) and the uniformity.
• Microscopic examination (SEM – NTC 4624 – for surface morphology) – we use a scanning electron microscope (SEM) to examine the surface microstructure of the coating, to identify defects such as micro-cracks, porosity, or inclusions. We report the SEM images and the surface morphology.

Corrosion Resistance Testing – Evaluating the Protective Performance of the Coating

The corrosion resistance is the primary function of the galvanized coating. Our corrosion tests simulate the environmental conditions that the galvanized steel will face in service, including salt spray, humidity, and cyclic wet-dry conditions. These tests are required for the certification of galvanized products for outdoor and marine applications.

• Salt spray (fog) test (ASTM B117 / ISO 9227 / NTC 4750 – for coated steel) – a specimen is placed in a salt spray chamber and exposed to a 5 % NaCl fog at 35 °C for a specified duration (e.g., 240, 500, 1000 hours). The specimen is inspected for the appearance of red rust (rusting of the steel) and for the degradation of the zinc coating (white rust). We report the time to first red rust, the time to first white rust, and the condition of the coating.
• Cyclic corrosion test (ASTM G85 / NTC 4751 – for simulating tropical and coastal environments) – the specimen is exposed to alternating cycles of salt spray, dry air, and high humidity to simulate the more realistic conditions of the Colombian coastal and tropical regions. We report the corrosion damage and the time to failure.
• Humidity test (ASTM D2247 / NTC 4752 – for condensation resistance) – the specimen is exposed to a condensing humidity environment (40 °C, 95 % RH) for a specified duration. We report the appearance of white rust and the coating condition.
• Copper-accelerated acetic acid salt spray (CASS) test (ASTM B368 / NTC 4753 – for more aggressive environments) – for galvanized products with an additional organic coating, we use the more corrosive CASS test to evaluate the coating system’s performance. We report the corrosion rating and the extent of undercutting.
• Electrochemical impedance spectroscopy (EIS) – NTC 4754 – for evaluating coating integrity – we use EIS to measure the impedance of the galvanized coating in a 3.5 % NaCl solution. The impedance at low frequencies (10 mHz to 0.1 Hz) is a measure of the coating’s barrier properties. We report the impedance and the corrosion rate.

Mechanical Performance Testing – Evaluating the Strength and Ductility of the Base Steel

In addition to the coating properties, the mechanical properties of the underlying steel are essential for the structural performance of the galvanized profile plate. Our tests evaluate the tensile strength, yield strength, elongation, hardness, and formability of the base steel, following the requirements of the NTC 3701 and ASTM A653 standards.

• Tensile test (ASTM E8 / ISO 6892 / NTC 2150 – for the base steel) – we machine a tensile specimen from the galvanized plate, and we test it in tension to determine the yield strength (in MPa), the ultimate tensile strength (in MPa), the elongation (in %), and the modulus of elasticity. We report the tensile properties.
• Hardness test (ASTM E18 / NTC 3880 – Rockwell, Brinell, or Vickers) – we measure the hardness of the steel substrate to verify the structural strength and the consistency of the material. We report the hardness values (HRB, HB, or HV).
• Bend test (ASTM E290 / ISO 7438 / NTC 2154 – for formability) – we perform a bend test on the galvanized plate to evaluate the ductility and the formability of the steel. The specimen is bent through a specified angle, and the outside surface is inspected for cracking. We report the bend angle, the mandrel radius, and the condition.
• Impact test (ASTM E23 / ISO 148-1 / NTC 3804 – for toughness) – we perform a Charpy V-notch impact test on the steel substrate (if the thickness is sufficient) to measure the toughness and the ductile-to-brittle transition temperature. We report the impact energy (in J) and the fracture appearance.
• Formability test (NTC 4630 – for deep-drawing and stamping) – we perform a cupping test (Erichsen test) to evaluate the deep-drawing behavior of the steel. We report the Erichsen index (in mm).

Dimensional Inspection and Profile Verification – Ensuring Geometric Compliance

For profile steel plates, the dimensional accuracy and the geometric compliance are essential for the assembly and the structural performance. Our dimensional inspection ensures that the profiles meet the specified tolerances.

• Dimensional measurement (NTC 4640 – for length, width, thickness, and profile dimensions) – we measure the dimensions of the plate (length, width, thickness) and the profile (flange width, web height, and thickness) using calibrated instruments (calipers, micrometers, and measuring tapes). We report the measured dimensions and the deviations from the specification.
• Straightness and flatness measurement (NTC 4641 – for structural accuracy) – we measure the straightness (deviation from a straight line) and the flatness (deviation from a flat plane) of the plate using a straightedge, a feeler gauge, and a dial indicator. We report the deviations and the compliance with the tolerances.
• Squareness and angularity measurement (NTC 4642 – for profiles) – we measure the squareness of the profiles (the 90° angles) and the angularity of the flanges. We report the angles and the deviations.
• Edge condition and burr inspection (NTC 4643 – for safety and fit) – we inspect the edges of the plate for the presence of burrs, slivers, or sharp edges that could affect the handling and the safety of the workers. We report the edge condition and the compliance with the acceptance criteria.
• Hole and slot location measurement (NTC 4644 – for pre-punched profiles) – we measure the location, the diameter, and the spacing of any pre-punched holes or slots in the profile. We report the measurements and the deviations from the drawing.

Test Report and Recognition in the Colombian Construction, Automotive, and Industrial Sectors

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically and traceability to international standards (NIST, PTB). Our test reports are issued in Spanish and include:

• Full identification of the galvanized plate or profile (manufacturer, grade, coating type, dimensions, and lot number).
• Detailed description of the test methods applied (ASTM/ISO/NTC standards, test conditions, and parameters).
• Numerical results: coating thickness (μm), coating weight (g/m²), adhesion rating, tensile strength (MPa), yield strength (MPa), elongation (%), hardness (HRB/HV), corrosion resistance (time to red rust), and dimensional tolerances.
• Graphical data: coating thickness profiles, hardness profiles, and corrosion damage curves.
• Comparative tables against the values specified by the client or against the limits of the NTC 3701 (Galvanized steel), ASTM A653, and the requirements of the SIC, Ministerio de Transporte, MinMinas, and DIAN for construction and industrial materials.
• Photographs of the coated surface, the bend test results, the cross-sectional microstructure, and the corrosion damage.
• Recommendations for material selection, coating optimization, and quality control measures to ensure the required performance and durability.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98-3 Guide.

These reports are fully accepted by the Superintendencia de Industria y Comercio (SIC) for product registration and quality certification, by the Ministerio de Transporte for infrastructure and construction material approval, by the Ministerio de Minas y Energía (MinMinas) for industrial materials qualification, and by the Dirección de Impuestos y Aduanas Nacionales (DIAN) for tariff classification and quality verification in the import of galvanized steel products. Additionally, we offer consulting services for the selection of galvanized steel grades, the optimization of the galvanizing process, and the implementation of quality control programs for coating integrity, contributing to the durability, safety, and cost-effectiveness of structures and equipment in the diverse and growing Colombian market, from the high-rise buildings and bridges to the agricultural and industrial facilities nationwide.