What does NDE need to achieve for cast iron pipe networks?

Rainer, Alexander; Capell, Tobias F.; Clay-Michael, N.; Demetriou, Michael A.; Evans, Timothy S.; Jesson, DA; Mulheron, M.; Scudder, L.P.; Smith, Paul A.

doi:10.1680/jinam.16.00020

Cited by 8 publications

(4 citation statements)

References 23 publications

(31 reference statements)

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“…The damage stages and median m obs values appear to be correlated, but the m obs value is so low, even in the sound state. Thus, improved nondestructive testing methods may be more beneficial for identifying the damage states of buried pipes [139].…”

Section: Gmentioning

confidence: 99%

A Simple Estimation Method of Weibull Modulus and Verification with Strength Data

Ono

2019

Applied Sciences

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This study examines methods for simplifying estimation of the Weibull modulus. This parameter is an important instrument in understanding the statistical behavior of the strength of materials, especially those of brittle solids. It is shown that a modification of Robinson’s approximate expression can provide good estimates of Weibull modulus values (m) in terms of average strength (<σ>) and standard deviation (S): m = 1.10 <σ>/S. This modified Robinson relation is verified on the basis of 267 Weibull analyses accompanied by <σ> and S measurements. Estimated m values matched normally obtained m values on average within 1%, and each pair of m values was within ± 20%, except for 11 cases. Applications are discussed, indicating that the above relation can offer a quantitative tool based on the Weibull theory to engineering practice. This survey suggests a rule of thumb: ductile metal alloys have Weibull moduli of 10 to 200.

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Section: Gmentioning

confidence: 99%

A Simple Estimation Method of Weibull Modulus and Verification with Strength Data

Ono

2019

Applied Sciences

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“…Previous work has shown that non-destructive evaluation, NDE is likely to be of limited use if taken as the only measure of assessment (Rainer et al, 2017). The anisotropic nature of grey cast iron due to the graphite flake distribution, orientation and size is one of the main Accepted manuscript doi: 10.1680/jinam.21.00019 8 hurdles in the development of a consistent and reliable NDE method.…”

Section: Introductionmentioning

confidence: 99%

Finite element analysis on grey cast iron assets: a case study on penstocks in the wastewater system

Khor

Farrow

Mulheron

et al. 2022

Infrastructure Asset Management

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Penstocks have been used in the water industry for flow control since the Victorian expansion and consolidation of clean and waste water networks. However, the Victorians were the first to use grey cast iron (GCI) castings to manufacture large scale penstocks. Most of these ageing assets are still in operation, however engineering assessments are necessary to determine a structure’s fitness-for-service. Even today, penstocks in the sewer system tend to be made from GCI, due to ease of manufacturing, resistance to corrosion and cost. One characteristic property of grey cast iron is the graphite flake structure in the material, contributing to its low toughness, inconsistency in material strength and brittle behaviour, despite exhibiting slight hardening properties. Finite element analysis (FEA), is a numerical method which allows the analysis of complex structures by splitting it into finite parts and solving them with a computer processor. Despite the versatility of FEA, appropriate considerations and assumptions are necessary due to the difficulty to obtain data from inspection and unique material behaviour of GCI. The article shows concerns for an analysis of GCI penstocks using FEA, which extends into the application of fracture mechanics approaches for defect assessments.

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“…Routine and yet effective condition assessment of these buried pipes can minimise the negative consequences of deterioration in the utility network. To further minimise the risk of damaging the utility network adopting non-destructive technologies (NDT) for assessment would be ideal as they have the potential for providing routine and effective assessment with minimum disruption (Roberge, 2007;Rainer et al, 2017). Geophysical techniques, such as Ground Penetrating Radar (GPR), have been utilised to locate and map cast iron pipes (Mooney et al, 2010;Pennock et al, 2010;Ayala-Cabrera et al, 2011) and assess their condition (Hao et al, 2012;Liu et al, 2012;Rogers et al, 2012;Liu and Kleiner, 2013) including determination of the corroded state of cast iron pipes.…”

Section: Introduction 76mentioning

confidence: 99%

Experimental Investigation into the Effects of Cast-Iron Pipe Corrosion on GPR Detection Performance in Clay Soils

Abed¹,

Torbaghan

Hojjati

et al. 2020

J. Pipeline Syst. Eng. Pract.

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Cast iron water distribution pipes are used widely in the UK and worldwide. Corrosion of these cast iron pipes often occurs due to an electrochemical process where the pipe is buried directly in a chemically aggressive ground (as is the case for some clays). The electrochemical process changes the pH environment and releases iron ions into the clay. This can cause chemical alteration of the clay minerals and 'corrosion products', such as iron oxide, hydroxide and aqueous salts, to form in the soil. These chemical interactions are complex and time dependent, and can potentially result in pipe failure, and thus the conditions under which they occur need to be understood. Ground Penetrating Radar (GPR) has been proposed for routinely detecting, assessing and monitoring buried cast iron pipes, and thus it is important to know how these chemical changes affect the electromagnetic properties of soil. A bespoke set of laboratory experiments was devised to simulate and accelerate cast iron corrosion (using electrokinetics) and ion migration processes in two types of clay, namely Kaolin Clay and Oxford Clay. Tests were conducted for periods of up to 3 months using both inert electrodes and a cast iron disc as the anode. The changes in the geotechnical properties (undrained shear strength, moisture content and Atterberg limits), the geophysical properties (permittivity) and the geochemical properties (iron content, pH and conductivity) were monitored. The results indicated that the Oxford Clay was much more aggressive in terms of the corrosion activity compared to the Kaolin Clay. The laboratory results were used in GPR simulations in relation to the detection of a buried cast iron pipe. The results showed that the chemically induced changes to the Kaolin Clay did not materially affect the performance of GPR to detect the cast iron pipe, whereas a pipe buried in Oxford Clay the (greatly accelerated) chemically-induced changes were sufficiently advanced after approximately 7-8 weeks to cause the GPR to be unable to detect the corroded pipe.

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What does NDE need to achieve for cast iron pipe networks?

Cited by 8 publications

References 23 publications

A Simple Estimation Method of Weibull Modulus and Verification with Strength Data

A Simple Estimation Method of Weibull Modulus and Verification with Strength Data

Finite element analysis on grey cast iron assets: a case study on penstocks in the wastewater system

Experimental Investigation into the Effects of Cast-Iron Pipe Corrosion on GPR Detection Performance in Clay Soils

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