process feature | Pipe inspection & testing
detected), yellow (some anomalies detected) and red (significant anomalies identified) criteria. Overall, the technology achieved a 92% correlation
rate between the observed anomalies and joint quality. There were 22 joints of poor quality and six joints of good quality in the study. The technology successfully detected anomalies in all poor quality joints, and detected no anomalies in the fusion zone of four of the good quality joints. The NDT detected anomalies in two of the good quality joints. Two joints in the study that were intended to be
prepared as poor quality joints were determined to be of good quality through the NDT assessment and this was verified by destructive testing. Two joints that were intended to be good quality joints were determined to be of poor quality through the NDT assessment – which was also verified by destructive testing.
NDT inspection techniques were used on 26 gas pipe samples in a blind trial
assessment results to be returned to a minimally trained site operator via a red/green traffic light system, for use by utility companies and their contractors. As distribution integrity management programs have
evolved in North America, there has been increasing demand for commercially viable NDT systems for electrofusion fittings, says Impact. Similar demand exists in the UK, with studies suggesting that up to 20% of electrofusion fittings fail before their expected service life due to poor welding technique, weld contamination and machinery issues. Impact is currently offering an NDT quality inspec- tion service for critical pipeline installations throughout the UK, while Jana is working with North American gas companies to test and quality JanaDetect. More recently, the two companies have completed a blind trial of the technique to assess its detection capabilities. Multiple member companies from natural gas
research organisation NYSEARCH provided coupling and tapping tee electrofusion joints with unidentified defects for assessment. Twenty-six samples with 28 joints were prepared using different materials, sizes and manufacturers for the pipe and fittings. NDT assessments were conducted on each joint and spectral anomalies were identified by specific location. Each joint was assessed based on green (no anomalies
Corrosive testing At AMI’s Polymer Testing & Analysis conference earlier this year, Karin Jacobson of Swerea – a grouping of Swedish research institutes – told delegates about the importance of testing polymers in corrosive environ- ments. While pipes can undergo ageing due to the influence
of trace amounts of chemicals in drinking water, for example, she cited cases of pipes used to transfer aggressive fluids such as chlorine gas and strong acids. She cited the example of a corroded chlorinated PVC
(CPVC) pipe that had been exposed to chlorine – which showed a brittle outer layer and discoloured brown region underneath. The pipe was being taken out of service after more than eight years. The brittleness was caused by exposure to hot, wet
chlorine gas and brine solution. Dye staining helped to identify the depth of the
underlying discoloured region. When tested, its glass transition temperature was found to be lower than that in unaffected regions – and was probably cause by dehydrochlorination of the polymer, she said. Although higher impact grades of CPVC had similar
corrosion resistance to standard grades, the processing conditions of the CPVC did cause a difference – and could be 1.5 times more resistant, she said. A similar study looked at the effect of concentrated
Chillware, from SHS, builds up a ‘virtual cooling section’ of an extrusion line
20 PIPE & PROFILE EXTRUSION | October 2016
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