Creep testing service

Creep Testing Service – Accredited High‑Temperature and Long‑Term Deformation Assessment for Metals, Polymers, and Composites

For Bangladeshi power plant operators, oil & gas contractors, structural engineers, and material suppliers, the ability of components to resist gradual deformation under sustained stress at elevated temperatures is fundamental to safety, asset integrity, and maintenance planning. Our ISO/IEC 17025 accredited laboratory offers a comprehensive creep testing service that accurately measures time‑dependent strain, rupture life, and creep rates across a wide range of materials – from superalloys and stainless steels to engineering plastics and polymer composites. With decades of experience in mechanical testing and failure analysis, we support your procurement, life‑extension, and quality assurance programmes, and our reports are accepted by Bangladesh’s energy, infrastructure, and manufacturing regulatory authorities as well as international project certifiers.

Product Samples We Regularly Test

We accept a wide variety of bulk materials, machined test pieces, and component sections that are subject to sustained loading at service temperatures. Our creep testing machines accommodate round, flat, and specialised geometries. Common samples include:

• Boiler tubes and superheater pipes – ferritic, austenitic, and nickel‑based alloys.
• Turbine blading and rotor steel – for steam and gas turbines in power generation.
• High‑temperature fasteners – bolts, studs, and nuts for flanged connections.
• Structural steels and weldments – used in pressure vessels, storage tanks, and furnace supports.
• Polymer and plastic components – pipes, seals, gaskets, and insulating materials.
• Composite and fibre‑reinforced materials – for aerospace, automotive, and chemical plant applications.
• Boiler header and casting sections – from existing plant for remnant life assessment.
• Welded and HAZ (heat‑affected zone) test coupons – to evaluate creep performance of weldments.

Constant Load and Constant Stress Creep Testing

The most fundamental creep measurement is carried out under constant load or constant stress. Our creep testing service follows rigorous international procedures to provide reliable long‑term deformation data:

• Constant‑load creep test (ISO 204, ASTM E139) – A specimen is heated to a set temperature (±1°C accuracy) and a fixed tensile load is applied, producing an initial stress. We continuously measure elongation using high‑resolution extensometers or LVDTs (linear variable differential transformers) over thousands of hours, recording the three creep stages (primary, secondary, tertiary). Rupture time and elongation at fracture are reported.
• Constant‑stress creep test (ISO 204 Annex A, ASTM E292) – Using a cam or lever mechanism, the applied load is reduced as the specimen elongates, maintaining a constant true stress. This is essential for materials with significant strain‑hardening and provides more fundamental creep data for constitutive modelling.
• Low‑stress creep and stress‑rupture (ASTM E292, DIN 50118) – For long‑life applications (e.g., power plant steam piping at 540°C), we apply stresses below 100 MPa and run tests for up to 10,000 hours or more. We report time‑to‑rupture and minimum creep rate.
• Creep testing in air, vacuum, or controlled atmosphere (ASTM E139, ISO 204) – To avoid oxidation effects, we can perform tests in inert gas (argon, nitrogen) or vacuum. This is crucial for reactive alloys such as titanium or zirconium.
• Multi‑specimen creep frames – up to 10 specimens simultaneously – Our laboratory operates multiple lever‑arm creep machines, enabling efficient testing of several stress/temperature combinations in parallel, reducing overall test duration for material qualification.

Elevated Temperature Creep for Metals and Superalloys

Metal components in power plants, refineries, and chemical facilities degrade through creep – we specialise in high‑temperature testing up to 1,200°C:

• Creep‑rupture testing of 1Cr‑0.5Mo, 2.25Cr‑1Mo, 9Cr‑1Mo (Grade 91) steels (ASTM E139, ISO 204) – These materials are widely used in Bangladesh’s power and fertilizer sectors. We test at temperatures from 450°C to 650°C and stresses from 30 MPa to 300 MPa, generating Larson‑Miller parameter curves for life prediction.
• Austenitic stainless steel (304H, 316H, 347H) creep testing (ASTM E139, ASME Section II) – For high‑temperature headers and reheaters, we measure creep ductility and rupture strength, comparing results against the ASME allowable stress tables.
• Nickel‑base superalloys (Inconel 718, 625, 800H, 617) – creep at 700°C‑1000°C (ASTM E139, ISO 204) – For gas turbine components, we determine the stress to cause 1% creep strain in 1,000 hours, and the stress‑rupture life at multiple temperatures.
• Weld metal and HAZ creep testing (ASTM E139 with transverse specimens) – We machine specimens with the weld metal in the centre or with the HAZ within the gauge length to assess the weakest zone, providing data for weld procedure qualification.
• Notched creep and stress‑rupture (ASTM E292, EN 10222) – Using a circumferentially notched specimen, we evaluate the notch sensitivity of the material under creep conditions, which is critical for complex geometries.

Creep Testing for Polymers and Plastics

Many engineering plastics and composite materials used in pipe systems, insulation, and structural applications exhibit significant creep even at room temperature. Our service covers long‑term viscoelastic behaviour:

• Tensile creep of plastics (ISO 899‑1, ASTM D2990) – We apply a constant tensile force to dumbbell‑shaped specimens at controlled temperature (23°C, 40°C, or 60°C) and measure strain as a function of time, typically up to 1,000 hours. The creep modulus and creep rupture time are reported.
• Flexural creep of plastics (ISO 899‑2, ASTM D2990) – For beams, pipes, and structural profiles, we apply a bending load and measure mid‑span deflection over time, calculating flexural creep compliance.
• Compression creep of elastomers and foams (ISO 801, ASTM D395) – We compress cylindrical specimens at a fixed percentage strain and monitor the force relaxation over time, providing data for seals and gaskets used in flanged joints.
• Creep at elevated temperatures for thermoplastics (PP, PE, PA, POM – ISO 899‑1, ASTM D2990) – We perform tests at 40°C, 60°C, and 80°C to simulate hot‑water pipes and industrial equipment, generating time‑temperature superposition master curves.
• Creep rupture of plastic pipes (ISO 1167, ASTM D1598) – For pressurised pipe sections, we apply a hydrostatic pressure and record time‑to‑failure at different temperatures, providing the basis for the design stress (HDB) and pressure ratings.

High‑Precision Strain Measurement and Data Acquisition

Accurate strain measurement over long test durations is crucial. Our laboratory employs state‑of‑the‑art instrumentation:

• High‑temperature extensometers – contact and non‑contact (ISO 9513, ASTM E83) – We use quartz‑rod or ceramic‑rod extensometers attached to the specimen gauge length, with resolution of ±0.0005 mm. For very small strains, we also employ laser interferometric or optical video extensometers that do not touch the hot specimen.
• LVDT displacement transducers on pull rods – For long‑duration tests, we monitor the displacement of the load train with external LVDTs, providing a continuous record of extension to rupture.
• Thermocouples (type K, S, R, or B) – three or more attached to gauge length (ASTM E220, ISO 204) – We ensure temperature uniformity within ±2°C over the gauge length, with redundant thermocouples for safety.
• Automatic data logging at user‑defined intervals – Our systems record strain, load, temperature, and time at intervals from 1 second to 1 hour, adapting to the creep rate. The entire time‑strain dataset is stored for post‑test analysis.
• Digital imaging and creep strain mapping (DIC – digital image correlation) – For critical specimens, we apply a speckle pattern and track strain fields using high‑resolution cameras throughout the test, enabling detection of localized necking or barrelling.

Creep Data Analysis and Life Prediction

Our service goes beyond reporting raw test results – we deliver engineering‑ready parameters that help you predict service life:

• Larson‑Miller parameter (LMP) and Orr‑Sherby‑Dorn (OSD) analysis (ASTM E139, API 579) – We fit time‑to‑rupture data at multiple temperatures to the LMP equation (LMP = T(C + log t_r)), deriving the material constant C and providing a master curve for life prediction.
• Minimum creep rate determination (ISO 204, ASTM E139) – We calculate the steady‑state creep rate (ε̇_min) from the secondary stage, which is used in design codes for strain limits.
• Creep strain at rupture and rupture elongation – We report the total strain at fracture and the reduction of area, indicating ductility – an essential parameter for assessing flaw tolerance.
• Stress exponent (n) and activation energy (Q) calculation – Using multi‑stress and multi‑temperature data, we determine the Norton‑Bailey creep law constants (ε̇ = A σⁿ exp(‑Q/RT)), enabling your engineers to extrapolate to different stress/temperature conditions.
• Remnant life assessment for in‑service components (API 579 / ASME FFS‑1, BS 7910) – For samples cut from operating plant (e.g., boiler tubes that have already served 100,000 hours), we perform accelerated creep testing at higher stresses and temperatures, then use the LMP approach to estimate the remaining creep life at the original service conditions.

Post‑Test Inspection and Failure Analysis

Understanding the fracture morphology provides vital clues about creep damage mechanisms. We offer comprehensive post‑test examination:

• Macroscopic and stereomicroscopic examination of fractured surfaces – We document the fracture appearance, noting the presence of necking, cup‑and‑cone, or flat fracture, which indicates ductile or brittle creep behaviour.
• Scanning electron microscopy (SEM – ASTM E986) of creep voids and microcracks – We examine the fracture surface and longitudinal sections for creep cavitation (intergranular voids), indicating grain‑boundary sliding damage.
• Metallographic cross‑section – grain size, precipitates, and microstructural degradation (ASTM E112, E407) – We prepare polished and etched sections to measure grain size, carbide coarsening, and the formation of sigma‑phase or other deleterious phases.
• Microhardness measurement across the gauge length (ISO 6507, ASTM E384) – We map hardness variations to detect strain localisation and softening due to thermal exposure.
• Residual life correlation – comparison with virgin (unexposed) samples – By comparing the creep rate of a service‑exposed sample with a new sample, we assess the degree of microstructural damage and predict the remaining safe operating life.

Environmental and Atmosphere Controls for Creep Testing

Creep behaviour can be influenced by oxidation, decarburisation, or hydrogen attack. Our test options include controlled environments:

• Air atmosphere (standard) – with oxidation effects included (ISO 204, ASTM E139) – For most industrial applications, tests are conducted in air, and we record oxide scale thickness after test.
• Inert gas (argon, nitrogen) – for oxidation‑sensitive alloys (ASTM E139, custom) – We provide a constant flow of high‑purity gas through the furnace to minimise surface oxidation, obtaining intrinsic creep data.
• Vacuum (10⁻⁵ mbar) – for ultra‑clean materials and space applications – We have specialised vacuum creep furnaces that operate up to 1,100°C in vacuum.
• Steam atmosphere – for boiler tube creep (custom, similar to ASTM E139 with steam line) – We can introduce superheated steam into the furnace environment to simulate actual power plant conditions, giving more realistic oxidation and creep interaction.
• Hydrogen and sour gas environment – for refinery applications – For alloys in hydrogen service, we perform creep tests in a pressurised hydrogen autoclave, assessing the risk of hydrogen attack.

Standards Compliance and Calibration

Our entire creep test program operates within a strict quality framework:

• Calibration of load cells, extensometers, and thermocouples – traceable to national standards (ISO 7500‑1, ASTM E74, ISO 204) – All sensors are calibrated at regular intervals with certified reference equipment, ensuring measurement uncertainty < 1% for stress and ±0.5°C for temperature.
• Furnace temperature uniformity mapping (ASTM E220, ISO 204) – We perform periodic 3‑D temperature surveys to confirm that the hot zone meets the specified ±2°C at each test temperature.
• Verification with reference materials (e.g., NIST SRM 2195, 2196) – We occasionally run validation tests using certified creep‑resistant reference alloys to confirm the system’s accuracy and reproducibility.
• Software validation for data acquisition and LMP analysis – Our in‑house software is validated against benchmark datasets from NIST and other international laboratories.

Report Accreditation and Compliance for Bangladesh

All creep test methods described above are performed under our ISO/IEC 17025:2017 accredited quality system, ensuring traceable measurements, validated procedures, and technically competent engineers. Our test reports are recognised by the Bangladesh Standards and Testing Institution (BSTI) for material certification and import clearance, and they meet the technical documentation requirements of the Petrobangla (Bangladesh Oil, Gas & Mineral Corporation) for pipeline and pressure equipment, the Bangladesh Power Development Board (PDB) for turbine and boiler components, and the Bangladesh Chemical Industries Corporation (BCIC) for high‑temperature reactor vessels. We also align our reporting with international design codes (ASME Boiler & Pressure Vessel Code, API 579, EN 13445) that are commonly referenced in Bangladeshi infrastructure projects. Each report provides a complete record of test conditions, temperature‑time curves, strain‑time data, calculated creep parameters (minimum creep rate, rupture life, LMP curve), fracture photographs, and a professional interpretation of the material’s fitness for service – giving you the confidence to approve new designs, extend the life of existing assets, and maintain safety standards.

Why Choose Our Creep Testing Service

We understand that creep data is often needed on a tight project schedule but requires long test durations. Our lab offers flexible test management – we can start tests promptly, provide interim reports at specified hours (e.g., 1,000, 5,000, 10,000 hours), and continue until rupture. We work closely with your engineering team to select appropriate stress levels, test temperatures, and extrapolation methods that match your design life. Whether you are a domestic manufacturer qualifying new tube material, an international contractor supplying equipment for a gas turbine project, or a plant operator assessing the remaining life of a 30‑year‑old steam header, our creep testing service delivers accurate, actionable, and internationally defensible data. Contact us to discuss your materials, service conditions, and required parameters – we will design a test plan that fits your timeline and helps you ensure long‑term reliability of your high‑temperature assets.