PVP2009-78143 PROCEDURAL ASSISTANCE WITH WORKING WITHIN ASME CODE CASE 2235-9

ABSTRACT The Time of Flight Diffraction Technique (TOFD) is becoming increasingly used as an alternative to Radiography within both the construction industry and the in service inspection of pressure vessels and pipe work. TOFD, like any other technique requires to be applied in a concise manner in order to achieve the theoretical targets of high probability of detection (POD), a low false call rate and proof of coverage. The introduction of ASME and European standards has brought some coherence to the application of TOFD for fabrication inspection. However, a difficulty lies in the determination of actual coverage by TOFD on different geometries. Although the ASME specifically requires documented evidence of the coverage achieved, common practice is that at best a table is included in the procedure indicating the setups for the different weld geometries involved. To produce a documented examination strategy showing component coverage is cumbersome without software aids. Even with software tools such as professional drawing packages, producing such scan plans is not a simple task if many different geometries are involved. Sonovation felt there was a need to assist industry in simplifying this requirement by producing a simple to use software program that will assist in visualizing the coverage achieved for any setup. This paper will describe the logic behind this software package and demonstrate how it can assist companies in not only preparing procedures in accordance with ASME Rules but acting as a validation tool then on to its use within organisations QA and Data Base systems. HISTORY Over the past 20 years Sonovation and many others have been working on the application of TOFD, which in the beginning was restricted mainly to verification and sizing of defects found with other NDT methods. This required skilled operators with a high degree of mathematical and scientific background to fully understand the application for specific challenges, mainly in In-Service Inspection. Many international projects have been carried out to improve the understanding of the advantages and limitations of TOFD. This led to the understanding that advantages of TOFD were not restricted to sizing alone, but could also be used for detection of defects. This has also opened the door to the application of TOFD as a quality control tool during manufacture. To be fully useable and accepted as a replacement for traditional NDT methods such as radiography, it was necessary to introduce: • A standardized way to apply TOFD. • Training and certification of operators. • Acceptance criteria. Over the years, the above requirements have been laid down in Europea