Nearby Pipelines Research Articles

Inductive interference calculation on imperfect coated pipelines due to nearby faulted parallel transmission lines

The interference of power transmission lines to nearby pipelines and other metallic structures has been a research subject over the past 20 years. Especially during fault conditions, large currents and voltages are induced on the pipelines. Several methods have been proposed over the years and more recently one utilizing finite element calculations. The last method has the disadvantage that if it considers the pipeline to have a perfect coating, which is rarely the case as defects appear on the coating soon after the pipeline is buried in the ground. In this work a hybrid method employing finite element calculations along with Faraday's law and standard circuit analysis is discussed. The method is used in order to calculate the induced voltages and currents on a pipeline with defects, running in parallel to a faulted line and remote earth. Non-parallel exposures are converted to parallel ones and dealt with similarly. The defects are modeled as resistances, called leakage resistances. The fault is assumed to be a single earth-ground one and outside the exposure so that conductive interference is negligible. A sample case is analyzed and discussed. The results show that although the pipeline defects act in a way as to reduce the levels of induced voltages and currents, large currents can flow to earth through the defects that may damage the pipeline.

HOUSTON AREA FLOODS Shutdowns vex tight chemical markets

As if petrochemical markets didn't have problems enough, floods in the Houston area—and resultant shutdowns of plants, key pipelines, and the vital Houston Ship Channel—have put added pressure on already tight supplies of ethylene, propylene, and other basic chemicals and plastics. Heavy rain and flooding two weeks ago forced the closing of two Houston plants supplying basic chemicals and polymers (C&EN, Oct. 24, page 7). Snarled barge, train, and truck traffic have compounded the problems, as have rupture of five pipelines and ignition of fuels spilled from some of them. Unprecedented, forceful flooding of the San Jacinto River ruptured the nearby pipelines, spilling gasoline, crude oil, and propane. Workers controlled the fires that broke out, but did not extinguish them, allowing the fires to help remove petroleum products from the river. To prevent further ruptures, authorities shut down more than two dozen other pipelines carrying gasoline, natural gas, and such refined products as ...

Recent advances in the mitigation of AC voltages occurring in pipelines located close to electric transmission lines

In joint-use corridors where both pipelines and AC electric transmission lines are present, a portion of the energy contained in the electromagnetic field surrounding the electric transmission lines is captured by each pipeline, resulting in induced AC voltages which vary in magnitude throughout the length of each pipeline. During a fault on any of the transmission lines, energization of the earth by supporting structures near the fault can result in large voltages appearing locally between the earth and the steel wall of any nearby pipeline. Some form of mitigation is usually required to reduce these voltages to acceptable levels for the protection of personnel and of the pipeline itself. This paper presents a new mitigation design approach which not only reduces AC voltages effectively and economically, but also provides cathodic protection for the protected pipeline. Performance of this new mitigation method is illustrated with results from computer simulations, which show how important it is to have an accurate electrical model of the soil structure in any interference study. Results from large-scale mitigation design studies performed for ANR Pipeline Company and other gas transmission companies are presented. >

Analysis of Electrical Interference from Power Lines to Gas Pipelines Part I: Computation Methods

Analysis of electrical interference effects of transmission lines upon nearby pipelines has been a topic of growing interest due to the proliferation of rights-of-way which must be shared by transmission lines and pipelines. This paper describes the results of a recent joint EPRI/A.G.A. research project whose objectives were to develop an effective tool for simulating complex realistic right-ofway problems accurately and to investigate the effects of various system parameters. The ECCAPP computer program, which resulted from the EPRI/A.G.A. research program, combines a powerful input data preprocessor with a computation algorithm which accurately evaluates the effects of both conductive and inductive interference for arbitrarily positioned above-ground and buried conductors which could occur in typical rights-of-way. This paper discusses, in a detailed manner, the computation methods used by ECCAPP. A companion paper summarizes some of the results of an extensive parametric analysis which was conducted using ECCAPP and which illustrates some of the capabilities of the computer program and provides insight on how to control both conductive and inductive interference effects. Computer Program ECCAPP analyzes the effects of power transmission lines on neighbouring gas pipelines and determines the influence of mitigation measures, if any, on interference levels. A distinguishing feature of this computer program is its ability to analyze the combined effects of inductive (electromagnetic) and conductive (galvanic, through earth) coupling. These effects may develop simultaneously during power faults at transmission lines structures which are near gas pipelines, or during normal conditions.

Trenching By Explosives Nearby An ExistingPipeline: Charge Size Charts

Trenching by explosives in the vicinity of an existing pipeline can induce structural damage in the pipeline walls. Charge sizes defined on the basis of optimum trenching effectiveness must be verified on the basis of their impact on the existing nearby pipelines. An effective Structure Medium Interaction (SMI) approach, implemented in a 2-D code, is proposed to model the blast design scenarios. Stress and particle velocity decay is governed by exponential laws calibrated to fit experimental data by means of empirical parameters. Wave propagation filtering through the backfill around the pipeline is obtained by scaling stress and velocity on the basis of standard relationships governing the transmission phenomenon at the boundary. The methodology presented is aimed at producing design charts relating limiting charge to distance, medium, backfill and pipe characteristics. Design charts proposed can be readily used by practicing engineers to verify structural integrity of existing pipelines for the effects of nearby blasts.