PROCESSING | STANDARDS AND TESTING


to UL Standard 651A for polyethylene electrical conduit pipe. The standard requires testing for performance


characteristics – including dimensions, crush and impact resistance, and moisture penetration – and evaluation of conduit materials. NSF offers certifica- tion to UL 651A to meet the increased demand for third-party certification of HDPE electrical conduit. The pipe is typically used in applications that require continuous lengths of flexible coil, moisture and corrosion resistance, or ductility at low temperatures. “As the plastic conduit market continues grow-


ing, so does the need of manufacturers to demon- strate product performance, safety and quality,” said Nasrin Kashefi, general manager of NSF’s plastics programme. “We are responding by offering certification to UL 651A.” Certification testing is carried out


Right: The Warp system from Inoex uses a radar sensor to measure pipe diameter and wall thickness


at NSF’s 20,000 sq ft Willow Run Laboratory in Ypsilanti, Michigan. As part of the certification process, NSF tests products and conducts facility audits. Here, certified manufacturers must main- tain in-plant quality control to ensure that conduit products comply with the standard on a continuous basis. Logan Bridges, executive vice


president at United Poly Systems, added: “We recognise the importance of the UL 651A listing in the HDPE industry, and are pleased to have pursued that certification with NSF.”


Radar precision The Warp system from Inoex uses radar sensor technology for precise contactless measurement of pipe diameter and wall thickness while it is being extruded. This helps users to collect process data – so that extrusion line performance can be optimised via closed-loop control – and store production data for future reference. The company has recently given the Warp system a new mechanical design, so that it has a smaller footprint and allows easier maintenance access, for instance. Inoex has also added a new system to the range.


The Warp 8/16 800 covers the diameter range from 160-900mm and comes with eight or 16 sensors. This makes it particularly attractive for 800mm lines, but it can also measure pipes with diameters up to 900mm. An innovative radar chip, specially designed lens geometry and powerful electronics are the


28 PIPE & PROFILE EXTRUSION | May 2021


core of this technology, says the company. Benefits of the system include: fast return on investment – typically less than 12 months; high productivity, as pipes can be made as close to minimum specifications as possible; and process optimisation to use less material per length.


Pipe assessment Scientists at Sheffield University in the UK have used ultrasound techniques to assess the ground conditions around buried plastic pipes. This, they said, will help to detect early signs of


failure in buried pipe – extending the use of infrastructure pipe in applications such as water transport.


An acrylic block of varying geometry was used to indent shapes in bedding media, to create regular and repeatable void shapes for laboratory experiments. Four common pipe bedding materials, two plastic pipe materials and three ultra- sound transducer frequen- cies were tested. Results showed that the


existence of voids can be detected from within the pipe. This potentially enables the approach to be applied for non-invasive field use as way to


evaluate pipeline operating conditions,


said the researchers, in a paper published in the journal Infrastructures. Two sets of ultrasonic experiment on the soil conditions were investigated: existence, shape, and dimension of the void; and water content in the soil. The ultrasound technique was able to detect water-filled voids and assess the soil support. Both are critical early indicators of failure, said the researchers. The technique requires water as the transmis- sion media so is suitable for use in water distribu- tion systems.


CLICK ON THE LINKS FOR MORE INFORMATION: � www.psilab.net � www.sciteq.com � www.plasticpipe.org � www.kwrwater.nl � www.electroscan.com � www.unitedpolysystems.com � www.nsf.org � www.inoex.de � www.sheffield.ac.uk


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