This project will develop ultrasonic NDE procedures, techniques and equipment for the volumetric examination of welded joints in polyethylene tanks of diameters up to 10 metres. In addition, the project will develop an inspection manipulator system that will be able to inspect welds in polyethylene tanks.
Thermoplastics are relatively new structural materials and they provide significant challenges for NDE. In particular, these materials are acoustically very opaque. For more demanding service applications, such as higher operating temperatures and pressures, there has been a lack of confidence in the long-term reliability of these materials and this has restricted the use of welded thermoplastic tank systems in these applications, despite their obvious benefits, including their inertness to most chemicals, corrosion resistance, ease of fabrication and cost. However, there is a renewed interest in the use of thermoplastic tanks for these more critical applications provided that applied inspection can be shown to give a high confidence level in the welded joint integrity and that of the adjacent parent material. Added to this is the need to develop a realistic defect acceptance standard for the range of structural welds found in thermoplastic tanks.