MACHINERY | PVC-O PIPE
Seismic resistance Ipex of Canada has extended its PVC-O pipe with a new version called Bionax SR – which has enhanced seismic resistance. The pipe is designed for water transmission and distribution and can withstand seismic shocks thanks to an extended bell – which allows the joint to telescope in and out during ground strains. The pipe has undergone extensive testing at the geotechnical lifelines facility at Cornell University in the USA. It is compatible with North American pipes and fittings (CIOD) and exceeds the Japa- nese seismic design standard by 70%, says the company. Thomas O’Rourke, professor of engineering at
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Molecor has begun offering a 50-year warranty on its PVC-O pipe
Restraining order Joint restraint devices that are used to carry out pressure testing on PVC-U pipe may need to be redesigned if they are to be used on PVC-O pipe. Property differences between the two materials
make this necessary, according to researchers in a paper presented at OzPipe. GM Quesada, a product development engineer at Costa Rica- based Simulation Driven Engineering, and KH Steinbruck of Steinbridge in the USA, carried out tests on five restraint devices, on both PVC-U and PVC-O pipe. The tests were carried out according to ASTM F1674 standard test method for joint restraint products for use with PVC pipe. This included: a sustained pressure test at 500psi for 1,000 hours; a minimum burst pressure test; and a cyclic surge pressure test. Because PVC-O pipe tends to be thinner – be- cause it has higher burst pressure and yield stress – it has a lower bending strength. “This plays against PVC-O joint restraints, since it is impossible to grip a pipe without applying a radial load – which in turn leads to bending,” said the authors. In general, PVC-O pipe is more sensitive to
‘collateral loads’ than PVC-U – and demands more rigorous design of joint restraints. “A better design will make careful installation less necessary,” they said. Factors such as engaging grips on as much of the pipe circumference as possible, keeping gripping elements parallel to the pipe surface, and spreading the gripping elements evenly all helped to improve performance. Overall, two types of restraint devices – called Sliding Grip Cap (SGC) and Internal C Grip (ICG) – worked well in all ASTM F1674 tests performed. “Properly designed devices will effectively restrain PVC-O pipes,” said the authors.
24 PIPE & PROFILE EXTRUSION | October 2020
Cornell University, said: “The pipe’s axial tension abilities is large enough to accommodate the great majority of liquefaction-induced lateral ground strains measured after four recent earthquakes in Christchurch, New Zealand.” Japan is also susceptible areas to earthquakes.
To counter this, it tends to rely on specifically designed ductile iron pipe. However, Ipex says that Bionax SR offers some advantages for the North American market – such as fewer joints, easier cutting and bevelling and a lack of corrosion. Manufacturing of the Bionax SR gasket system is both ID- and OD-controlled, says Ipex, so toler- ances are tighter than with conventional pipes. “Joints are always bottle-tight,” said the company. Bionax SR is available in diameters of 6-12in (15-30cm), with a pressure rating of 235. Last year, Aliaxis – the parent company of Ipex
–acquired US-based pipe manufacturer Silver-Line Plastics. The new company will be incorporated into Ipex. While Silver-Line does not produce PVC-O pipe, it does offer C-PVC – which will allow Ipex to expand its portfolio. Silver-Line also produces PE, PVC and PEX pipe. “Ipex will work closely with Silver-Line to ensure we capture the many exciting opportunities we have identified between our two companies,” said Alex Mestres, divisional CEO for Aliaxis Americas.
Relieving drought Molecor of Spain – which produces PVC-O pipes, as well as the machinery to make them – recently supplied a city in Bulgaria with pressure pipe to supply drinking water, following a severe drought. Pernik had suffered a serious drought since November 2019. A lack of rain – and the low water level in the Studena dam – threatened to leave 100,000 people without potable water. In addition, the existing water system was experienced huge leakage problems – with an
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