ISO 9001:2008 requires documentation concerning six procedures when calibrating equipment of any kind: control of documents, control of records and control of nonconforming product, as well as internal audit, corrective action and preventive action. ISO 9001:2015 requires no procedure documentation, but requires that the scope of a business's quality system, its quality policy and quality objectives remain documented and maintained.
ISO 9001 certification is typically granted according to four criteria. The first of these is whether customers need the company in question to use properly calibrated equipment to satisfy their needs. The second factor is whether proper calibration is required by individual product specifications and what the specific tolerances are. The third factor is what the consequences of improper calibration are and whether improperly calibrated equipment represents a danger to the public. The fourth criterion is the cost of repair and calibration compared with the cost of equipment replacement.
When equipment fails to calibrate correctly, all of the nonconforming product's measurements made since its last calibration should be brought into question. Calibration errors of critical measurements may lead to corrective action such as product recall, while less severe errors may simply require re-measurement to take place after the nonconforming equipment is properly calibrated.