Development of an Inline Water Mains Inspection Technology

Description

In the Netherlands the drinking water network comprises over 120,000 km of
infrastructure. Nearly 50% of the pipes is made of polyvinyl chloride (PVC) and just
about 30% is made of cementitious materials. The condition of the majority of these
assets remains unknown. Maintenance budget destination and decision-making on
replacement of assets is challenging without information on the condition of the
network. Inspecting the water network improves the management of assets and leads
to an efficient replacement plan of the faulty pipes. Therefore, an inspection
methodology is proposed which enables the detection and the measurement of
degradation in the water pipes.

The long term interaction of the pipes with the conveyed drinking water and
surrounding soil induces a layer of deterioration on both surfaces of cementitious
pipes. The ultrasonic signature of these layers can be determined with ultrasonic pulseecho
(PE) technique. Leaching of calcium is the main degradation mechanism of
cement-based pipes. For this reason, mortar specimens were partially submerged in
Ammonium Nitrate solution at different exposure times. Four degradation depths were
induced: 2.45, 3.2, 3.8 and 5.6 [mm]. Results show that by calculating the overall speed
of sound in the material it is possible to detect degradation as small as 2.45 [mm]. This
method has enabled higher sensitivity to thin degraded layers which was still a
limitation from previous research. Furthermore, the reflected amplitude from the
water-degraded mortar interface can be used for detecting early stage degradation as
well. Moreover, the generation of images from full scan of the specimens facilitates the
detection and localization of different degradation levels.

Period	3 Feb 2017
Event title	Maintenance Research Day 2017
Event type	Conference
Location	Utrecht, Netherlands