This document provides quality requirements for heat treatment in air or controlled atmospheres carried out in workshops and on site in connection with welding and forming. It applies mainly to ferritic steels, but can be used for other materials, as appropriate. This International Standard provides guidance for manufacturers that perform heat treatment or produce heat treated products or components. This document can also be used as a basis for assessing the manufacturer in respect to its heat treatment capability. The fulfilment of a requirement can be waived where justification can be provided that a specific requirement is not applicable to a specific process. This document is intended to be a flexible framework to provide: specific requirements for heat treatment by manufacturer in order to have a quality system in accordance with ISO 9001; specific requirements for heat treatment in specifications which require the manufacturer to have a quality system other than ISO 9001; specific guidance for a manufacturer developing a quality control system for heat treatment; specific guidance for post weld heat treatment for manufacturers adopting ISO 3834-2 or ISO 3834-3; detailed requirements for specifications, regulations or product standards that require control of heat treatment activities.