Overview
ISO 5022:1979 - "Shaped refractory products - Sampling and acceptance testing" provides standardized directives for sampling shaped refractory products and for obtaining, from the smallest practical sample, the most precise assessment possible of a consignment’s quality. The standard specifies statistical terminology, sampling procedures for both non‑destructive and destructive tests, and rules for acceptance testing based on conformity with agreed specifications. It does not determine suitability for a specific application or allow meaningful comparisons of different product qualities for end‑use selection.
Key topics and requirements
- Scope and applicability: Applies to products manufactured from refractory materials; parties must agree on parameters before applying the methods.
- Statistical terminology: Definitions for population, sample, mean, standard deviation, confidence interval, and operating characteristic (OC) curve.
- Batching rules: Guidance on subdividing consignments into batches (e.g., by tonnage, manufacturing period, shape/size) to ensure homogenous sampling.
- Sampling methods: Procedures for single sampling and sequential sampling; separate instructions for sampling for non‑destructive tests and sampling for destructive tests.
- Inspection modes: Distinction between inspection by attributes (presence/absence of defects) and inspection by variables (measured quantitative characteristics).
- Acceptance criteria & risks: Use of Acceptable Quality Level (AQL) and Limiting Quality (LQ); discussion of producer’s risk (α) and consumer’s risk (β) and the relation to OC curves. (Typical reference cases in the standard use producer’s risk near 5% and consumer’s risk near 10%.)
- Reporting and annexes: Required content for sampling reports and informative annexes covering calculation of means/standard deviations, comparison of sample means, equations, and bibliography.
Practical applications and users
ISO 5022:1979 is used for consistent acceptance testing of shaped refractory consignments where statistical sampling is required. Typical uses include:
- Manufacturer quality control for bricks, shapes and formed refractories
- Incoming inspection and acceptance testing by purchasers (steelworks, foundries, glass and cement plants)
- Third‑party testing laboratories and inspection agencies implementing sampling plans
- Contracting and procurement teams specifying AQL, batching rules and reporting requirements
Practical benefits: standardized sampling reduces dispute risk, clarifies producer/consumer responsibilities (AQL, LQ, α/β), and provides reproducible acceptance decisions while minimizing sample sizes.
Related information
- Parties must mutually agree on sampling parameters and accept that ISO 5022:1979 does not assess application suitability.
- Annexes include calculation aids and OC curve references to implement sampling plans in practice.
Keywords: ISO 5022:1979, shaped refractory products, sampling, acceptance testing, AQL, LQ, producer’s risk, consumer’s risk, inspection by attributes, inspection by variables.