Analysis for Wrinkling Behavior of Girth-Welded Line Pipe

The paper presents results for finite element analysis of full-sized girth-welded specimens of line pipe and compares these results with the behavior exhibited by test specimens subjected to constant axial force, internal pressure and monotonically increasing curvatures. Recommendations for the ‘best’ type of analytical finite element model are given. Comparisons between the behavior predicted analytically and the observed behavior of the experimental test specimens are made. The mechanism of wrinkling is explained and the evolution of the deformed configurations for different wrinkling modes is examined. It is concluded that the analytical tools now available are sufficiently reliable to predict the behavior of pipe in a manner that was not previously possible and that this should create a new era for the design and assessment of pipelines if the technology is properly exploited by industry.

Transit Time Ultrasonic Flow Meters for Natural Gas Measurement

The advantages of ultrasonic flow meters are well know — no line obstructions, large turndown ratio, bi-directionality, high accuracy — and ultrasonic meters are now widely used within the gas industry in a wide variety of applications. Ultrasonic meters are available in several different configurations ranging from high accuracy multipath spoolpiece meters to single path hot-tapped meters. While all of these meters operate on the same basic transit-time principle, there are significant differences in their operational aspects. This paper is intended to review the basic concepts of ultrasonic flow meters, to clarify the differences listed, and to explain how ultrasonic meters should be specified.

Interrelationship Between the Efficiency Characteristics and the Pressure Head Gradients Among Axial Flow Pumps

There is a correlation between the efficiency of the pump to the head produced. On the axial flow pump, whose efficiency characteristic is favorable, the pressure head gradient between the impeller inlet and the outlet sections, at an equivalent flow rate, may become larger than that for the less favorable axial flow pump. This fundamental interrelation may be held in the flow passage regardless to the flow rate whichever they are operated at design or off design flow rate. There may be a direct correlation between the efficiency of an axial flow pump and the ratio of the discharge valve cross section divided by the pipeline cross section. The smaller this ratio is the better the pressure head gradient is for the same flow rates. This ratio may be useful to estimate relative grade of heads, pressure head gradients, internal flow conditions, and efficiency characteristics among axial flow pumps.

Mechanics of Buried Chilled Gas Pipelines

This paper examines the factors influencing the modelling of soil-pipeline interaction for a pipeline which is used to transport chilled gas. The soil-pipeline interaction is induced by the generation of discontinuous frost heave at a boundary between soils with differing frost susceptibility. The three-dimensional modelling takes into consideration the time-dependent evolution of frost heave due to moisture migration, the creep and elastic behaviour of the frozen soil and flexural behaviour of the embedded pipeline. The results of the computational model are compared with experimental results obtained from the frost heave induced soil-pipeline interaction test performed at the full scale test facilities in Caen, France.

Problems of Restructurisation and Renewal of Old Gas Distribution Network in Wroclaw

Changing environment, growing demand for gas for heating, and shut down of old gas plant, cause necessity of restructurisation of the old gas distribution network in the city. Aging distribution network, replacement of manufactured gas by natural gas and rapid growth in number of leaks cause urgent necessity of replacement and rehabilitation of the old gas pipelines. Modern materials and technologies have enabled rehabilitation gas pipelines in the narrow busy streets of the city.

Recommissioning NPS 30 Pipeline

This paper will discuss all the steps taken to reclaim an 80 kilometre (50 Mile) NPS 30 (30″) pipeline loop, including the project planning, the labour requirements, the techniques utilized to complete the various stages of the project, some of the unique problems encountered, as well as, some options that were examined for hydrostatic test leak detection and water treatment. This project was a component of the Trans Mountain, Cdn $30 million, Stage II capacity expansion. This component of Stage II resulted in an increase of 3,000 m3/d (18,909 barrel/d) to the overall pipeline capacity achieving a 36,300 m3/d sustainable pipeline pumping capacity1 (230,000 barrel/d).

A Material Model for Pipeline Steels

Experience has shown that the pipe steel used in the Trans-Alaska Pipeline System has complex properties that must be taken into account in making safety assessments of the pipe. To obtain a better understanding of the steel behavior, a detailed test program has recently been undertaken. The test results have been used to develop a nonlinear model of the steel for use in stress and deformation analysis of the pipeline. This paper first outlines the model, and shows that it captures important aspects of the steel behavior, including progressive yielding and anisotropy. The paper then shows how the values of the model parameters can be calculated from experimental stress-strain data, and how the model can be used for the analysis of pressurized pipelines, accounting for interaction between hoop and longitudinal stress. The theory is based on von Mises yield and the Mroz plasticity model.

Pipeline Design Software and the Simulation of Liquid Propane/Butane - Light Oils Pipeline Operations

A comprehensive and integrated suite of computer software routines has been developed to simulate the flow of liquids in pipelines. The fluid properties module accommodates Newtonian and non-Newtonian liquids or mixtures including corrections for changes in properties with temperature and pressure. The hydraulic model calculates pressure drop in single or looped pipelines based on the diameter, route (length) and profile data provided. For multi-product pipelines the hydraulics module estimates energy loss for any sequence of batches given the size and fluid properties of each batch, and the velocity in the pipeline. When the characteristics of existing or proposed pipeline pumps are included, location and size of pumps can be optimized. The effect of heat loss on pressure drop is predicted by invoking the module which calculates the fluid temperature profile based on operating conditions, fluid properties, pipe and insulation conductivity and soil heat transfer data. Modules, created to simulate heater or cooler operations, can be incorporated to compensate for changes in temperature. Input data and calculated results can be presented in a format customized by the user. The simulation software has been successfully applied to multi-product, fuel oil, and non-Newtonian emulsion pipelines. The simulation and operation of a refinery products pipeline for the transportation of propane, butane, gasoline, jet and diesel batches will be discussed. The impact of high vapour pressure batches (i.e., propane and butane) on the operation of the pipeline and on the upstream and downstream facilities will be examined in detail.

Experiences With Simulation of Reciprocating Compressor Valve Dynamics

Experience with compressor valve modelling has shown that reciprocating compressor performance can sometimes be improved by subtle changes in valve design. Modelling has led to a better understanding of the physical behaviour of valves and of the compression process. Three compressor valve studies presented here demonstrate the benefits of valve modelling. Case 1 challenges the commonly held assumption that reducing the lift of a compressor valve will reduce the efficiency of the compressor. The capacity of this compressor is increased by reducing the valve lift. A plot of BHP/MMSCFD versus valve lift shows an inflection point that assists the analyst in optimizing the design. Case 1 also presents a method of calculating the economic effect of improvements in valve performance. Case 2 demonstrates the effect of inadequate flow area through the valve. Pressure in the clearance volume cannot decrease fast enough if flow areas are inadequate; the result is late valve closure, and therefore decreased valve life. Case 3 shows the importance of considering the design of the cylinder casting in addition to that of the valves. Here, insufficient cylinder flow area constricted gas flow. Since these cases were simulated, the analyst had the opportunity to evaluate the proposed solution over the entire range of operating conditions. He was able to select a valve which solved the immediate problem and be confident that it would perform adequately throughout the specified range of conditions.

Numerical Investigation of Jamming of Solid Particles in a Straight Pipe

The flow of fluids containing solid particles is numerically simulated in order to determine the critical parameters of the system leading to a jam. Two parameters are varied: the volumetric density of solid particles and the velocity of fluid flow. The energy dissipation in the system is due to dry friction losses and collisions. The results presented are based on the mathematical models of granular materials treated as multibody systems with variable topology. The fluid flow is considered to be potential. It is shown that jamming strongly depends on the volumetric density of particles and fluid velocity. The results of numerical experiments are in qualitative agreement with physical experiments of flow of spherical particles in a pipe.