Inspection

Inspection is the process of examining a material, product, system, or process to determine conformance with specified requirements and to identify defects or deviations. It may be conducted, documented, and used to decide whether to accept, repair, or reject an item. Unlike testing, which characterizes properties, inspection focuses on conformity to criteria and may include measurement, observation, and documentation.

Inspections vary by objective, timing, and method. Common types include visual inspection, dimensional inspection, functional or performance inspection, and regulatory or safety inspections. They can be performed on incoming materials, in-process components, finished products, or at pre-shipment and field sites. Methods may be manual, automated, or a combination, and can involve nondestructive testing.

A typical inspection process includes planning and standardization, selecting sampling methods, performing measurements or observations, comparing results with predefined acceptance criteria, and recording the outcome. When a deviation is found, decisions follow whether to accept with concession, rework, or reject. Documentation supports traceability and continual improvement.

Common tools include checklists, gauges, micrometers, calipers, coordinate measuring machines, and nondestructive examination techniques such as dye penetrant, magnetic particle, radiographic, and ultrasonic testing. Software inspections and code reviews are common in information technology and engineering, focusing on design and code quality rather than physical conformance.

Inspection programs are guided by quality management standards, industry codes, and regulatory requirements. ISO 9001 expects documented inspection and testing as part of quality management. Industry-specific standards, such as ASME or ISO 14644, provide criteria for equipment, environments, and procedures.

Effective inspection improves safety, reliability, and customer satisfaction, while reducing waste and liability. Limitations include human error, measurement uncertainty, sampling risk, equipment calibration, and the need for qualified inspectors. Ongoing training and validated procedures help mitigate these challenges.