Overview
ISO 7500-2:2006 - "Metallic materials - Verification of static uniaxial testing machines - Part 2: Tension creep testing machines - Verification of the applied force" defines procedures for verifying the applied force of tension creep testing machines used for uniaxial creep testing in accordance with ISO 204. The standard covers a general machine inspection plus a formal verification of force for machines that apply load by dead weights, lever systems or direct spring loading. Machines that use an integral force‑measuring system are verified under ISO 7500-1.
Key topics and requirements
- Scope and machine types: Applies to dead‑weight machines, lever‑type creep testing machines and direct‑spring‑loading machines; excludes machines with load cells (see ISO 7500-1).
- Normative references: ISO 204 (creep testing method) and ISO 376 (calibration of force‑proving instruments).
- General inspection: Ensure machine is in good working order before force verification (see Annex A in standard).
- Force verification method: Uses tension force‑proving instruments compliant with ISO 376; instrument class must be equal or better than the machine class being verified.
- Masses and calibration: Use known masses (accuracy ±0.1 %, re‑verified at least every 5 years) or dedicated machine masses.
- Discrimination threshold: Determine the smallest detectable force increment (d) at 20 %, 60 % and 100 % of the force range (and at the lower limit when applicable).
- Lower limit of verification: Defined relative to the discrimination threshold and machine class (specified in the standard).
- Test procedure essentials:
- Align and self‑align loading train and proving device.
- Balance levers (overslung/underslung specifics included).
- Temperature compensation and stabilization; apply temperature corrections per ISO 376.
- Conditioning: exercise machine three times between zero and maximum force and reset to zero.
- Apply at least five approximately equispaced forces from 20 % (or lower limit) upward; repeat series three times, rotating the proving device about 120° between series.
- For spring‑loaded systems, calibrate the spring in a spring‑force calibration device using identical interfaces.
- Assessment and reporting: Calculate relative accuracy error and repeatability, assign machine class, and produce a verification report. Verification intervals are specified.
Applications and users
- Test laboratories performing uniaxial creep tests on metallic materials.
- Quality managers and materials engineers ensuring traceable force application for long‑term creep studies.
- Calibration laboratories and equipment manufacturers that supply or certify creep testing machines.
- R&D groups in metallurgy, aerospace, power generation and component life‑prediction where accurate creep load control is critical.
Related standards
- ISO 7500-1 - Tension/compression testing machines: verification and calibration of force‑measuring systems
- ISO 204 - Uniaxial creep testing in tension - Method of test
- ISO 376 - Calibration of force‑proving instruments
Keywords: ISO 7500-2:2006, tension creep testing machines, verification of applied force, discrimination threshold, force‑proving instruments, dead‑weight machines, lever‑type machines, spring‑loading machines, ISO 376, ISO 204.
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