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Inspecting plastic pipes in Florence using PolyTest™ system

TWI used its patented PolyTest™ Phased Array UT plastic pipe inspection system to carry out non-destructive examinations of welds on pipelines carrying natural gas in Florence.

There an estimated 11.5 million kilometres of plastic pipe carrying essential gases and fluids installed globally. As plastic piping is increasingly used in applications that have traditionally favoured steel installations, there is a growing need for a reliable non-destructive testing method to ensure the integrity of pipeline welds.

PolyTest™is a new field inspection system for volumetric non-destructive testing of electrofusion and butt fusion joints in polyethylene (PE) pipes. It combines phased array ultrasonic testing technology with novel hardware solutions to meet the challenges presented by in-situ inspection of plastic pipe joints.

Modernising Florentine infrastructure

A major Italian energy provider is involved in a large-scale project to renew the aging infrastructure in the Tuscan city of Florence. With rail authorities insisting that any new PE gas lines installed beneath any rail infrastructure are fully inspected, TWI was contacted by PlastItalia, a leading producer of polyethylene fittings in Europe, to provide non-destructive testing services using the PolyTest system.

In-situ inspection 

TWI carried out two inspection visits, over the course of which its technicians inspected 28 electrofusion fittings in 315mm diameter PE gas lines.

During the first visit, in September 2015, TWI conducted inspections along the pavement of a busy street on the edge of the city. TWI inspected 20 EF fittings to confirm their integrity before the gas line was inserted inside a larger-diameter PE pipe installed beneath the adjacent railway lines.

Impressed by the effectiveness of the PolyTest inspection system, PlastItalia invited TWI to return to Florence in June 2016 to test a further eight EF fittings on an uninstalled gas line located on a road beneath a main rail station.

On each occasion, TWI inspected weld joints under site conditions, providing initial data analysis at the end of each day. This was supported with full detailed reporting, carried out by specialists in PE weld analysis at TWI’s UK headquarters.

To find out more about PolyTest and TWI’s plastic pipe inspection services, please email