recognized by a Member State. Once a welder passes a test (or a series of tests), their employer or third party involved will certify their ability to pass the test, and the limitations or extent they are qualified to weld, as a written document (welder qualification test record, or WQTR). Normally this document is valid for a limited period (usually for two years), after which the welder must be retested. However some Qualifications are only valid for a single project, while others are unlimited as long as welders do not go beyond a specified length of time without performing that specific type of welding (this period is typically 6 months). Welders must maintain a log to demonstrate they have maintained their Qualifications. Welding inspector certification In addition to welders and welding machine operators, there are also schemes to independently certify welding inspectors and related specialities. The duties of the welding inspector are described in ISO 14731; however the requirement for inspector certification are not standardized, so there are differences in requirement between the various schemes. Some notable schemes established by personnel certification bodies are those of the American Welding Society, of the British Institute of Non-Destructive Testing (PCN), of The Welding Institute (CSWIP) and of the Canadian Welding Bureau (CSA W178.2). The American Welding Society offers the following programs: Certified Associate Welding Inspector Certified Welding Inspector Senior Certified Welding Inspector Certified Radiographic Interpreter The British Institute of Non-Destructive Testing offers three levels of certification: PCN Level 1 PCN Level 2 Weld Inspection PCN Level 3 Weld Inspection with radiographic interpretation The Welding Institute (TWI) in the United Kingdom offers the following certification scheme: CSWIP 3.0 (Level 1): Visual Welding Inspector CSWIP 3.1 (Level 2): Welding Inspector CSWIP 3.2 (Level 3): Senior Welding Inspector; with or without radiographic interpretation (3.2.1 or 3.2.2 respectively) The Canadian Welding Bureau offers the following programs: Level 1 Certified Welding Inspector Level 2 Certified Welding Inspector Level 3 Certified Welding Inspector The BINDT/PCN and TWI/CSWIP schemes are accredited by UKAS under ISO/IEC 17024. There are many other general schemes, as well as sector specific schemes. In 2008, the American Petroleum Institute introduced the API 577 Advanced Welding Inspection and Metallurgy programme of certification. Certification is issued following the successful completion of a multiple choice exam which is based on the recommended practice document API 577. Certification identifies the candidate as a 'Welding Inspection and Metallurgy Professional',