Stainless steel part inspection service

Stainless Steel Part Inspection Service – Comprehensive Quality, Performance and Compliance Validation for Brazilian Industrial and Engineering Applications

As an ISO/IEC 17025 accredited independent testing laboratory, we provide comprehensive inspection services for stainless steel parts and components used across Brazilian oil and gas, petrochemical, food and beverage, pharmaceutical, power generation, marine, construction, and automotive industries. Stainless steel – in its various grades including austenitic (304, 316, 316L), ferritic (430), martensitic (410, 420), duplex (2205, 2507), and precipitation‑hardening (17‑4PH) types – is valued for its corrosion resistance, mechanical strength, and durability. However, its performance depends critically on chemical composition, metallurgical structure, surface condition, dimensional accuracy, and freedom from defects such as inclusions, porosity, or intergranular corrosion. Our inspection protocols combine non‑destructive testing (NDT), destructive mechanical and metallurgical testing, dimensional metrology, surface analysis, and corrosion evaluation to verify that each part meets the stringent requirements of Brazilian and international standards. All methods are aligned with ABNT NBR standards, ASTM A240 (Specification for Stainless Steel Plate, Sheet, and Strip), ASTM A370 (Mechanical Testing of Steel Products), ASTM E8/E8M (Tension Testing), ASTM E18 (Rockwell Hardness), ASTM E3 (Metallographic Preparation), ASTM A262 (Intergranular Corrosion), ASTM G48 (Pitting and Crevice Corrosion), ASTM E165 (Penetrant Testing), ASTM E709 (Magnetic Particle Testing), ASTM E797 (Ultrasonic Testing), and ABNT NBR 8151 (Charpy Impact). Our inspection reports are recognised by INMETRO (product certification), ANP (oil and gas equipment qualification), ANVISA (food and pharmaceutical contact materials), ABNT (technical compliance), and major Brazilian engineering and manufacturing firms for supplier qualification, quality assurance, and regulatory compliance.

Types of Stainless Steel Parts and Components We Regularly Inspect

Our inspection facilities and field‑service capabilities cover a broad range of stainless steel parts and product forms. Typical test articles include:

• Stainless steel plates, sheets, and coils – for pressure vessels, tanks, and architectural cladding
• Stainless steel pipes, tubes, and fittings – seamless and welded for fluid transportation
• Stainless steel flanges, valves, and pump components – for process plants and pipelines
• Stainless steel forgings and castings – for heavy‑duty industrial and marine equipment
• Stainless steel fasteners, bolts, and studs – for structural and pressure‑containing joints
• Stainless steel shafts, gears, and precision‑machined parts – for rotating machinery
• Stainless steel weldments and fabricated assemblies – for structural and process equipment
• Stainless steel components for food and pharmaceutical equipment – requiring sanitary finishes

Chemical Composition and Material Verification – Ensuring Grade Compliance

• Chemical analysis using Optical Emission Spectrometry (OES) – ASTM E415 / ABNT NBR 15291 – We use a calibrated OES instrument (spark emission) to determine the percentage of major alloying elements (Chromium, Nickel, Molybdenum, Manganese, Silicon, Carbon, Nitrogen) and trace elements (Sulfur, Phosphorus, Copper, Titanium, Niobium). The composition is compared to the specified grade requirements (e.g., 316L requires Cr ≥ 16.0 %, Ni ≥ 10.0 %, Mo ≥ 2.0 %, C ≤ 0.03 %). A deviation of more than ±0.05 % for key elements or a carbon content above the maximum limit is reported as a material non‑conformity.
• Carbon and sulfur analysis by combustion‑infrared detection – ASTM E1019 / ISO 15350 – For low‑carbon grades (L‑grades) and for critical applications, we measure the carbon and sulfur content using a high‑frequency combustion furnace with infrared detection. The detection limit is as low as 0.001 % for carbon, ensuring precise verification of grades like 316L (C ≤ 0.03 %) and 304L (C ≤ 0.03 %).
• Ferrite content measurement in duplex and austenitic‑ferritic grades – ASTM E562 / ISO 8249 – For duplex stainless steels, we measure the ferrite content (in %) using the point count method (on metallographic sections) or using a Feritscope (magnetic induction). A ferrite content of 30‑60 % is typical for 2205 duplex; a deviation beyond this range may impair corrosion resistance or mechanical properties.
• Positive Material Identification (PMI) – on‑site XRF or LIBS verification – For field inspections and large volumes, we use portable X‑ray fluorescence (XRF) or Laser‑Induced Breakdown Spectroscopy (LIBS) to confirm the grade of each part without destructive sampling. The results are compared to the material certificate, and any mismatch is immediately reported.

Mechanical Properties – Tensile, Impact, Hardness and Bending

• Room‑temperature tensile test – ASTM E8/E8M / ISO 6892‑1 / ABNT NBR 6679 – We machine standard round or flat tensile specimens from the part (or from representative test coupons) and test them at a crosshead speed of 2‑5 mm/min. We record the yield strength (0.2 % offset, in MPa), the ultimate tensile strength (UTS, in MPa), the percentage elongation after fracture (in %), and the reduction of area (in %). For 316L stainless steel, typical values are: Yield ≥ 170 MPa, UTS ≥ 485 MPa, Elongation ≥ 40 %. Any value below the specified minimum is reported as a mechanical property failure.
• High‑temperature tensile test (for elevated‑service grades) – ASTM E21 / ISO 6892‑2 – For parts operating at elevated temperatures (e.g., heat exchangers, furnace components), we conduct tensile tests at temperatures such as 400 °C, 600 °C, or 800 °C, and report the yield and tensile strengths at those temperatures. A significant drop in yield strength (e.g., > 30 % from room temperature) may indicate unsuitability for Brazilian high‑temperature applications.
• Charpy V‑notch impact test – ASTM E23 / ISO 148‑1 / ABNT NBR 8151 – We test standard 10×10 mm specimens with a V‑notch, typically at temperatures of ‑40 °C, ‑20 °C, 0 °C, or +20 °C, depending on the service conditions. The absorbed energy (in Joules) and the percentage of shear fracture are recorded. For duplex stainless steels used in Brazilian offshore environments, a minimum impact energy of 27 J at ‑20 °C is typically required.
• Rockwell (HRB, HRC) and Brinell (HB) hardness testing – ASTM E18 / ASTM E10 / ABNT NBR 6262 – We measure the hardness on the surface and at the core (for hardened parts) using a calibrated hardness tester. For austenitic stainless steels, HRB values of 70‑90 are typical; for martensitic grades, HRC values of 30‑50 may be required. A hardness outside the specified range may indicate improper heat treatment or material mix‑up.
• Guided bend test – ASTM E190 / ISO 7438 / ABNT NBR 13160 – For welded parts and for plates, we perform a bend test by bending the specimen 180° around a mandrel of specified diameter (typically 3‑4× the thickness). We inspect the outer surface for any cracks exceeding 3 mm in length. The test is performed on both the face and the root (for welded joints) and the results are reported as pass/fail.

Metallographic Examination – Microstructure, Grain Size and Inclusion Rating

• Microstructural examination – ASTM E3 / ASTM E407 / ABNT NBR 13284 – We cut, mount, grind, polish, and etch metallographic specimens (using etchant such as V2A for austenitics, Murakami’s reagent for duplex grades, or Fry’s reagent for martensitic). We examine the microstructure at 100‑1,000× magnification to verify the presence of the correct phases (austenite, ferrite, martensite) and to detect any undesirable phases such as sigma‑phase, delta‑ferrite (in austenitic castings), or carbide precipitation (sensitization). High‑resolution photomicrographs are included in the report.
• Grain size determination – ASTM E112 / ISO 643 / ABNT NBR 13720 – Using the intercept or comparison method, we determine the ASTM grain size number. For austenitic stainless steels, a grain size of 5‑8 (ASTM) is typical. A grain size coarser than 3 may reduce strength; a grain size finer than 9 may reduce creep resistance.
• Non‑metallic inclusion rating – ASTM E45 / ISO 4967 / ABNT NBR 11752 – We evaluate the cleanliness of the steel by rating the type and distribution of non‑metallic inclusions (sulfides, silicates, alumina, and globular oxides) using the standard chart. A rating above the acceptable limit (e.g., A‑thin > 2.5 or B‑thin > 2.0) is reported as a defect that could affect mechanical properties and corrosion resistance.
• Sigma‑phase detection – ASTM A923 / ISO 9445 – For duplex stainless steels (e.g., 2205), we perform a special metallographic evaluation to detect any sigma‑phase precipitation, which embrittles the material and reduces corrosion resistance. We also use a ferrite content measurement (Magnaflux or point count) to confirm the phase balance. Any sigma‑phase visible in the microstructure is a major non‑conformity.

Corrosion Resistance – Intergranular, Pitting, Crevice and Stress‑Corrosion Testing

• Intergranular corrosion test – ASTM A262 (Practice E) / ISO 3651‑2 / ABNT NBR 14778 – For austenitic grades, we perform the copper‑copper sulfate‑sulfuric acid test (Practice E) to assess susceptibility to intergranular corrosion (sensitization). The specimen is boiled in the solution for 72 hours, then bent (or examined metallographically) to detect any intergranular cracking. Any cracking indicates that the material has been sensitized (carbide precipitation) and is unsuitable for Brazilian corrosive environments.
• Pitting and crevice corrosion – ASTM G48 (Method A) / ABNT NBR 15195 – We immerse test specimens in a 6 % ferric chloride solution at 22 °C (or at an elevated temperature, e.g., 40 °C, for higher grades) for 72 hours. The weight loss is measured, and the specimens are inspected for pitting. The critical pitting temperature (CPT) and the critical crevice temperature (CCT) are determined by testing at multiple temperatures. For 316L, a CPT of ≥ 20 °C is typical; for super‑duplex grades, values ≥ 50 °C are expected.
• Salt spray corrosion test – ASTM B117 / ABNT NBR 8096 – We expose stainless steel parts (including machined and welded surfaces) to a 5 % NaCl fog at 35 °C for 240, 500, or 1,000 hours. After exposure, we inspect for red rust, pitting, or staining. For food and pharmaceutical equipment, any visible corrosion after 240 hours is considered unacceptable.
• Stress‑corrosion cracking (SCC) susceptibility – ASTM G36 / NACE TM0177 adapted – For parts exposed to chloride environments under stress, we perform a U‑bend or C‑ring test in a boiling 45 % MgCl₂ solution at 155 °C, or in a 3.5 % NaCl solution with a potentiostat (slow strain‑rate test). The time to cracking (in hours) and the fracture surface morphology are reported. For 304 and 316 grades, susceptibility to SCC at 155 °C is well‑known; the test helps Brazilian engineers select appropriate grades for high‑temperature chloride service.

Non‑Destructive Testing – Detecting Surface and Subsurface Flaws

• Dye‑penetrant inspection (PT) – ASTM E165 / ISO 3452 / ABNT NBR 11355 – We apply a solvent‑removable penetrant to the cleaned surface, remove the excess, and apply a developer. The part is inspected under white or UV light for any surface‑breaking defects (cracks, porosity, cold shuts). Any crack‑type indication exceeding 1 mm (or the specified limit) is reported. PT is applicable to all stainless steel grades, including austenitic.
• Magnetic particle inspection (MT) – ASTM E709 / ISO 9934 / ABNT NBR 13360 – For ferritic and martensitic stainless steels (which are magnetic), we perform wet fluorescent or dry powder MT to detect surface and near‑surface defects (cracks, laps, inclusions). We use a yoke or coil magnetisation technique. The results are compared to the acceptance criteria (e.g., no cracks and no linear indications exceeding 1.5 mm for structural parts).
• Ultrasonic testing (UT) – ASTM E797 / ISO 17640 / ABNT NBR 15113 – For thick plates, forgings, and castings, we use conventional or phased‑array UT to detect internal defects such as inclusions, porosity, delaminations, and cracks. The scanning is performed at a frequency of 2‑5 MHz, and the size and depth of each indication are recorded. The acceptability is assessed based on the standard (e.g., ASTM A435 for plates, or ASTM A388 for forgings).
• Eddy current testing (ECT) – ASTM E426 / ISO 15549 – For tubes, bars, and small parts, we use ECT to detect surface and near‑surface defects, including cracks, pitting, and wall‑thickness variations. The test is performed at frequencies of 10‑200 kHz, and the amplitude and phase of the impedance signal are analysed. A defect signal exceeding the reference notch height is reported.

Dimensional and Surface Inspection – Ensuring Precision and Finish

• Dimensional measurement – ISO 1101 / ABNT NBR 10067 – Using calibrated callipers, micrometers, height gauges, and a coordinate measuring machine (CMM), we verify the critical dimensions of the part: outer diameter, inner diameter, length, thickness, flange face flatness, bolt circle pitch, and thread sizes. The measured values are compared to the engineering drawing and to the ISO tolerance class (e.g., IT6, IT7). Any deviation exceeding the specified tolerance is reported as a dimensional non‑conformity.
• Surface roughness measurement – ASTM D7127 / ISO 4288 / ABNT NBR 15794 – Using a contact profilometer (or a non‑contact optical profiler), we measure the average roughness (Ra), the maximum roughness depth (Rz), and the waviness (Wt) on critical sealing surfaces, bearing surfaces, and sanitary (food‑contact) finishes. For sanitary parts, an Ra of ≤ 0.8 µm (or finer) is typically required; a higher roughness may lead to bacterial adhesion and inadequate cleanability.
• Ferrite content and surface contamination check (for sanitary and pharmaceutical parts) – We perform a passivation and ferrite test using a ferritometer or a copper sulfate test to ensure that the surface is free from free‑iron contamination (which would cause localised corrosion). Any positive indication of iron contamination is reported, and we recommend a passivation (citric or nitric acid) treatment.
• Visual and cosmetic inspection – ABNT NBR 13284 / ASTM A480 – We inspect the part for any surface defects such as dents, scratches, gouges, laps, or scale. The defect is measured and evaluated against the acceptance criteria of the applicable standard (e.g., depth of surface defect ≤ 0.2 mm for polished parts). Photographs are taken for documentation.

Welding Inspection and Weld Overlay Evaluation – For Fabricated Assemblies

• Weld visual inspection and dimensional check – AWS D1.6 / ISO 17637 / ABNT NBR 15107 – We inspect the weld profiles for undercut, overlap, convexity, and concavity, and verify the weld size (leg length and throat thickness). The measurements are compared to the WPS and to the code requirements (e.g., AWS D1.6 for stainless steel structural welding). Any undercut deeper than 0.5 mm or any weld reinforcement greater than 3 mm is reported.
• Ferrite measurement on duplex and stainless steel welds – AWS A4.2 / ISO 8249 – For duplex stainless steel welds, we measure the ferrite content in the weld metal using a Feritscope. A ferrite content of 30‑60 % is required to ensure good corrosion resistance and toughness. A value below 30 % may lead to hot cracking; a value above 60 % may reduce corrosion resistance.
• Weld overlay (cladding) thickness and dilution check – For stainless steel cladding applied to carbon steel, we measure the cladding thickness (using UT or by metallographic sectioning) and perform a chemical analysis across the interface to determine the dilution (iron pickup in the cladding). A cladding thickness below the specified minimum (e.g., 3 mm) or a dilution above 10 % is reported as a defect.
• Pitting corrosion test on welds – ASTM G48 adapted – We perform a ferric chloride pitting test on a sample that includes the weld and the HAZ. The weld metal should show a pitting resistance equivalent number (PREN) that is equal to or greater than the parent metal. Any preferential pitting in the weld area is reported as a weld quality issue.

Report Acceptance & Compliance with Brazilian Oil & Gas, Food, Pharmaceutical and Industrial Standards

All stainless steel part inspections described above are conducted under our ISO/IEC 17025:2017 accreditation, using calibrated OES analysers, universal testing machines, hardness testers, metallographic equipment, corrosion test apparatus, NDT instruments, and CMMs, all traceable to INMETRO and international reference standards. Our final inspection reports include: a complete identification of the part (material grade, part number, heat number, manufacturing process), a summary of all test results (chemical composition, tensile properties, impact energy, hardness, corrosion resistance, NDT indications, dimensional measurements, surface finish), high‑resolution photomicrographs and defect images, statistical summaries (mean, standard deviation, coefficient of variation), and a clear overall verdict (conforming / rework required / reject). We also provide an expanded uncertainty (k=2) for all key quantitative measurements. These reports are widely accepted by INMETRO for product certification, by ANP for oil and gas equipment qualification, by ANVISA for food and pharmaceutical contact material compliance, by ABNT for normative conformity (NBR 8151, NBR 6679, NBR 11355, etc.), and by Brazilian engineering firms, equipment manufacturers, and plant operators for supplier qualification, project acceptance, and regulatory compliance. Bilingual (Portuguese/English) versions are available to facilitate submissions to regulatory bodies and to support your engineering, quality, and procurement teams. With our rigorous and comprehensive inspection service, you can confidently ensure that your stainless steel parts deliver the required performance, corrosion resistance and safety in Brazil's most demanding industrial and environmental applications.