Overview
EN ISO 7500-2:2006 - "Metallic materials - Verification of static uniaxial testing machines - Part 2: Tension creep testing machines - Verification of the applied force" specifies how to verify the force applied by uniaxial tension creep testing machines used in accordance with ISO 204. The standard defines a two-part verification: a general inspection of the testing machine and a verification of the applied force, applicable to dead-weight, lever-type and direct-spring-loading creep machines. Machines that use a force‑measuring system (load cell + conditioning + indicator) are verified under ISO 7500-1.
Key topics and technical requirements
- Scope: Verification for uniaxial creep testing in tension (per ISO 204).
- Types of machines covered: dead-weight machines, lever-type machines (overslung/underslung and jockey-weight variants), and spring‑loaded machines.
- Verification elements:
- General inspection (see Annex A) to ensure the machine is in good working order before force verification.
- Force verification using tension force‑proving instruments in accordance with ISO 376; the proving instrument class must be equal or superior to the class sought for the creep machine.
- Masses: Use known masses with accuracy ≤ ±0.1 % (verified at least every five years) or dedicated machine masses.
- Discrimination threshold (d): Smallest detectable increment of force. It must be determined at 20 %, 60 % and 100 % of the force range (and at the lower limit if testing below 0.2 F). Relative discrimination a = (d / F) × 100.
- Lower limit of verification (F_V): Determined by class; Table 2 gives F_V = 400·d (Class 0.5), 200·d (Class 1), 100·d (Class 2), where d is the discrimination threshold at 20 % of range.
- Test procedures: Alignment, balancing of levers or loading train, stepwise loading using calibrated masses, and assessment of applied force and repeatability.
- Documentation: Verification report and defined intervals between verifications.
Applications and users
EN ISO 7500-2:2006 is used by:
- Materials testing laboratories performing creep tests on metallic materials.
- Calibration laboratories and quality managers who certify testing machines.
- Manufacturers of creep testing machines for design validation and conformity checks.
- Metallurgists and R&D teams needing reliable, traceable force application in long‑term creep studies.
Practical benefits include improved traceability, reproducibility of creep data, and compliance with international testing requirements.
Related standards
- ISO 7500-1 - Verification and calibration of force‑measuring systems (for machines with load cells).
- ISO 204 - Method of test for uniaxial creep testing in tension.
- ISO 376 - Calibration of force‑proving instruments.
Keywords: EN ISO 7500-2:2006, tension creep testing machines verification, verification of applied force, creep testing, uniaxial testing machines, force-proving instrument, calibration, dead-weight machines, lever-type machines.
