Development of a Pipeline Surface Loading Screening Process

Warman, David; Chorney, Jules; Reed, M. D.; Hart, James D.

doi:10.1115/ipc2006-10464

Cited by 8 publications

(7 citation statements)

References 3 publications

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“…3 does not include the beneficial effects of lateral soil restraint. By combining the original Spangler formula and the Iowa formula, Warman et al (2009) proposed the modified Spangler equation as follows:…”

Section: R a F Tmentioning

confidence: 99%

Equation to predict maximum pipe stress incorporating internal and external loadings on buried pipes

et al. 2016

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Pipelines used for water and other services are very important lifelines in modern society. Commonly, these buried pipes are subjected to significant stresses due to external (traffic and earth) and internal (water pressure) loads. As many of these pipelines were laid sometime in the last century or earlier, in most cases their condition has deteriorated primarily by electrochemical and (or) microbiological corrosion. Corrosion activity (internal and external) can manifest in various forms, but in many cases will lead to reduced pipe thickness, which in turn leads to an increase in pipe stresses induced by the external and internal loads. Currently available analytical procedures to estimate pipe stresses are based on oversimplifications such as the two-dimensional (2-D) analysis based on Winkler springs, limiting their application to general pipe burial conditions. This paper describes the application of a three-dimensional (3-D) finite element method to analyse a buried pipe subjected to external and internal loads. Firstly, the finite element model is validated against the data from field tests conducted on the basis of a cast iron pipe that was laid in 1930 at Strathfield, Sydney, Australia. The results of these 3-D finite element analyses are then used to develop a closed-form expression to predict maximum stresses in pipes of different sizes buried in different soil types. Having obtained a good agreement between the proposed model outcomes and the 3-D finite element analysis results, the proposed model has been validated against the field test data under different internal and external loadings. The verified outcomes of the model reveal that it can be used to predict maximum stresses without conducting a full-scale finite element analysis, which often requires specific computational resources and computational skills. Furthermore, the proposed model can be used in probabilistic analyses, where a large number of calculations need to be carried out to account for the uncertainty of the input variables. The applications of the model are also discussed in relation to the assessment of pipe performance and remaining safe life.

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Section: R a F Tmentioning

confidence: 99%

Equation to predict maximum pipe stress incorporating internal and external loadings on buried pipes

et al. 2016

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“…The pressure from the live load results in both hoop stress and longitudinal stress in the buried pipe. The CEPA equation [10,11] can be used to determine the hoop stress from the live load as…”

Section: Stress From Live Loadmentioning

confidence: 99%

“…Warman et al [10,11] proposed a modified Spangler stress formula, which is also known as "CEPA equation". The CEPA equation combines the advantages of the original "Spangler stress formula" and the "Iowa formula", which enables it to consider the influence of both internal pressure and the support of the surrounding soil to the predicted hoop stress.…”

Section: Introductionmentioning

confidence: 99%

A New Approach to Determine the Stresses in Buried Pipes Under Surface Loading

Zhong¹,

Branam²,

Zand³

et al. 2016

Volume 2: Pipeline Safety Management Systems; Project Management, Design, Construction and Environmental Issues; Strain Based D

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All buried pipes experience loading from the weight of soil overburden. When pipelines cross railroads, roads, parking lots or construction sites, the pipes also experience live surface loading from vehicles on the ground, including heavy construction equipment in some scenarios. The surface loading results in through-wall bending in pipes, which generates both hoop stress and longitudinal stress. Current standards limit the stresses in buried pipes to maximum values in terms of hoop stress, longitudinal stress and combined biaxial stress. An early approach to estimating stresses and deformations in a pipe subjected to surface loads dates back to Spangler’s work in the 1940s. Many models have been developed since then. API RP 1102 provides guidance for the design of pipeline crossings of railroads and highways following the model developed by Cornell University for the Gas Research Institute (GRI). The Cornell model was developed only based on experiments on bored pipes crossing a railroad or a highway at a near-right angle. The live surface loading distribution is also limited to the wheel-layout typical of railroad cars and highway vehicles. Most other existing models only focus on the hoop stress in the pipe. In this paper, a new approach to determine the stresses in buried pipes under surface loading is introduced. The approach is suitable for assessing pipes beneath any type of vehicle or equipment at any relative position and at any angle to the pipe. First, the pressure on the pipe from surface loading is determined through the Boussinesq theory. Second, both hoop stress and longitudinal stress in the pipe are estimated. The hoop stress is estimated through the modified Spangler stress formula proposed by Warman and his co-workers (2006 and 2009). The longitudinal stress, due to local bending and global bending, is estimated by the theory of beam-on-elastic-foundation. The modulus of foundation can be determined through the soil-spring model developed by ASCE. The hoop stress, longitudinal stress and the resulting combined biaxial stress can then be compared against their respective limits from a pertinent standard to assess the integrity of the pipe and determine the proper remediation approach, if necessary. The performance of the proposed approach is compared in this study with the experimental results in the literature and the predictions from API RP 1102.

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“…Based on a single AASHTO H-20 truck [11] on unpaved road, F=16,000 lb and I c =1.5. An effective length of 3 feet is usually used in the field [12]. C t is computed using an equation listed in AWWA C150 [10] for pipe cover depths ranging from 2.5 feet to 32 feet.…”

Section: Circumferential Stressesmentioning

confidence: 99%

Numerical analysis of stresses for cured-in-place-pipe linings

Chuk¹,

Urgessa²,

Thippeswamy³

2011

WIT Transactions on the Built Environment

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Underground pipes, such as water supply pipes and sewer pipes, are subjected to reduced strength and cracking due to aging. In order to combat strength reductions, excavation technologies have been used widely that allow replacing existing pipes with new pipes. However, these methods require road closures, traffic regulation and repaving. Various non-excavation (trenchless) repairs have been used in the last twenty years. This paper presents numerical analysis methods of stresses for pipes rehabilitated with cured-in-place-pipe (CIPP) linings. A CIPP lining is the common name given to the installation of a resin impregnated tube into a deteriorated pipe and curing it in place to produce a new structural pipe within a pipe. Examples of different liner types and their effect on reducing pipe wall stresses are presented.

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Development of a Pipeline Surface Loading Screening Process

Cited by 8 publications

References 3 publications

Equation to predict maximum pipe stress incorporating internal and external loadings on buried pipes

Equation to predict maximum pipe stress incorporating internal and external loadings on buried pipes

A New Approach to Determine the Stresses in Buried Pipes Under Surface Loading

Numerical analysis of stresses for cured-in-place-pipe linings

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