ISO 28598-2:2017

Overview

ISO 28598-2:2017 - "Acceptance sampling procedures based on the allocation of priorities principle (APP) - Part 2" defines coordinated single sampling plans for acceptance sampling by attributes. It provides attributes-based sampling procedures and a catalogue of single sampling plans indexed by Normative Quality Limits (NQLs) for successive independent inspections of the same lot by the supplier, customer and/or a third party. The standard applies to isolated lots or continuing series and to finished products, components, operations, processes, data and records where quality is expressed as percent nonconforming or nonconformities per 100 items.

Key topics and technical requirements

• Allocation of Priorities Principle (APP): framework for coordinating independent inspections (supplier, customer, third party) so each party can select plans while controlling risks.
• Single sampling plans by attributes: a catalogue of permissible single-sample plans indexed by NQLs; tables and rules for selecting plans are provided.
• Successive independent inspections: procedures for inspection sequences on the same lot to reduce sampling variability and conflicting outcomes.
• Scope of application: finished goods, discrete items, components, operations, processes and records; applicable for isolated lots and continuing series.
• Lot quality and NQLs: procedures assume a defined Normative Quality Limit expressed as percent nonconforming or nonconformities per 100 items.
• Risk coordination: guidance on assigning and limiting supplier/customer/third‑party risks and on coordinating permissible sampling plans and trust levels.
• Supporting materials: normative tables of sampling plans, selection rules, examples and theoretical justification (annexes include tables and application examples).

Practical applications and users

Who uses ISO 28598-2:2017:

• Quality managers and engineers in manufacturing and supply chains
• Suppliers conducting final inspection or product certification
• Customers performing incoming inspection, surveillance or acceptance sampling
• Third‑party inspectors, certification bodies and contract auditors
• Procurement and supply chain teams defining lot acceptance criteria in contracts

Practical benefits:

• Enables consistent, coordinated acceptance sampling across multiple inspecting parties
• Reduces sample size where supplier capability or certification information supports it
• Minimizes conflicting pass/fail results through harmonized plan selection
• Provides ready-to-use tables and rules to implement attribute-based sampling tied to contractual NQLs

Related standards

• ISO 28598-1 - Guidelines for the APP approach
• ISO 2859 series - Sampling procedures for inspection by attributes (Parts 1–3)
• ISO 28591 - Sequential sampling plans for inspection by attributes
• ISO 9000 - Quality management fundamentals and vocabulary

Keywords: ISO 28598-2:2017, acceptance sampling, allocation of priorities principle, APP, single sampling plans, attributes sampling, NQL, supplier inspection, customer inspection, third party inspection, lot quality.