Piping problems review

Improper or insufficient maintenance can lead to serious personnel or process accidents. A significant number of accidents don t involve complicated reactors, distillation columns, or large rotating equipment just plain old piping. 

Lorenzo, D. K., A Manager s Guide to Reducing Human Errors—Improving Human Per-fornumcc in the Chemical Industry, Chemical Manufacturers Association, Washington, D.C., July IWl). p, 17. 

Trevor A., What Went Wrong Case Histories of Process Plant Disasters, 3d ed. Houston Gulf Publishing Co., 1994, p. 217 plus a private communication with Trevor Kletz. 

Trevor A., Dispelling Chemical Engineering Myths, 3d ed. Washington, D.C. Taylor Si Franci.s, 1996, pp. 32-35. 

Trevor A., Critical Aspects of Safety and Loss Prevention. London Butterworth, 1990. pp. 160-61. 

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Electrochemical On-Line Corrosion Monitoring On-line corrosion monitoring is used to evaluate the status of equipment and piping in chemical process industries (CPI) plants. These monitoring methods are based on electrochemical techniques. To use on-line monitoring effectively, the engineer needs to understand the underlying electrochemical test methods to be employed. This section covers many of these test methods and their applications as well as a review of potential problems encountered with such test instruments and how to overcome or avoid these difficulties. 

In part II of the present report the nature and molecular characteristics of asphaltene and wax deposits from petroleum crudes are discussed. The field experiences with asphaltene and wax deposition and their related problems are discussed in part III. In order to predict the phenomena of asphaltene deposition one has to consider the use of the molecular thermodynamics of fluid phase equilibria and the theory of colloidal suspensions. In part IV of this report predictive approaches of the behavior of reservoir fluids and asphaltene depositions are reviewed from a fundamental point of view. This includes correlation and prediction of the effects of temperature, pressure, composition and flow characteristics of the miscible gas and crude on (i) Onset of asphaltene deposition (ii) Mechanism of asphaltene flocculation. The in situ precipitation and flocculation of asphaltene is expected to be quite different from the controlled laboratory experiments. This is primarily due to the multiphase flow through the reservoir porous media, streaming potential effects in pipes and conduits, and the interactions of the precipitates and the other in situ material presnet. In part V of the present report the conclusions are stated and the requirements for the development of successful predictive models for the asphaltene deposition and flocculation are discussed. 

Having introduced f, the objective is now to find a convenient analogy with which we may calculate any/factor. But first, how is this factor to be applied Why not just use the simple term hL and be done In answer, the hL factor, if reviewed in Fig. 6.1, is actually a part of the hydraulic grade line factor 144 Pi/p. Thus, the correct thing to do here is to put it in this factor. In all equation relationships of fluid flow problem solving, this is done. This simply says that/represents the flow of fluid losses due to friction inside pipe in all equations used. 

A review of the method of an incomplete group of repeating variables used for identifying pi terms reveals that the specific pi terms obtained depend on the somewhat arbitrary selection of this incomplete group. For example, in the problem of studying the heat transfer from a wall to a fluid flowing in the pipe, we have selected d, p, p, and X as repeating variables. This has led to the formulation of the problem in terms of pi terms ... 

Basically, start with a more flexible system, develop a design that works to your satisfaction, then review the connections to see where potential leak problems can be eliminated with pipe bending or welding, or other means. This is important if your goal is a safer, low maintenance system. 

This chapter illustrated how to use FEMLAB to solve the Navier-Stokes equations in a variety of situations. Some of these problems are classic, such as entry flow into a pipe and transient start-up of pipe flow. Most examples were for laminar flow in two dimensions, but one model was turbulent flow into a pipe, and another model was for a complicated three-dimensional geometry. To review, the chapter covered the following specific features ... 

Long-term trending of maintenance data is very useful to enable an understanding of equipment reliability issues. Plant simulations will not identify some of the critical concerns such as corrosion, erosion, liquid and gas maldistribution, and potential slug formation in piping. A detailed review of historical equipment inspection and problem/repair history is required to understand various maintenance, metallurgy and reliability issues. 

Some deep-well sites have not been without problems. Layers of rock and soil above the disposal sites became contaminated. There are questions about the reliability of geological sites to seal adequately the waste from movement and the potential failme of piping leading to the deposit site. Many sites have not fully resolved effects of potential earthquakes, failures in overpressured sites and other problems. An EPA study reviewed the risks of deep-well injection disposal." ... 

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