New at PipingDesign.com: 15 July 2000

[Chemical Processing Magazine has recently updated their archives section. As a result, some articles were offline for some time. Some of the articles below are newly-linked at PipingDesign.com, others were listed but inactive]

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Piping Flexibility Basics
Chemical Processing Magazine

<<One of the major requirements in piping design is to provide adequate
flexibility for absorbing the thermal expansion of the pipe. With the downsizing of engineering staffs and the availability of computer programs to calculate pipe stress analyses, there is a need to review the principles. This article discusses three basic areas of piping flexibility: forces and stresses created by thermal expansion, problems associated with too much flexibility and the significance of field-proven layouts.>>

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Designing Process Piping Systems
Chemical Processing Magazine

<<The design and specification of a fiberglass-reinforced plastic (FRP)
piping support system should not be a complicated proposition. Adhering to the manufacturer's design recommendations, a general understanding of the product's strengths and limitations and the application of sound piping practices helps ensure a successful installation. This article looks at some general guidelines for designing with FRP pipe.>>

Catching Up with Fluid Flow
Chemical Processing on the Web

Piping and the Energy Balance
Chemical Processing on the Web

<<The most important equation used to model flow in piping systems is the
energy balance, which has differing forms and can be expressed in different units. Most technical people are familiar with the Bernoulli equation form of the energy balance. The equation's drawback is that it's valid only for an ideal fluid-that is, a fluid that does not experience any frictional losses because of viscosity and interaction with pipe walls. It's advisable to apply a complete energy balance, incorporating all the relevant terms when analyzing or designing piping systems.>>

Finding the Best Buy in Piping
Chemical Processing on the Web

<<The piping system with the lowest installed price isn't necessarily the
best value, because the piping, valves, fittings and supports may cost too much to maintain. Life-cycle costing (LLC) can determine the "real cost of ownership." Rigorous life-cycle costing involves time-value of money and probability-based considerations because no one can predict the interest rate with certainty. But those methods may take too long for quick estimates in a plant. For plants let's look at a simplified approach that can yield fast, reasonable results.>>

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Computational Fluid Dynamics Analysis Solves Pump Noise Problem Chemical Processing Magazine

<<Pumping applications involving cooling water have been especially
difficult to solve because of the presence of dissolved air inherent in a cooling tower sump. Water that contains large amounts of dissolved air changes the apparent required net positive suction head (NPSH). In such applications, traditional correction techniques failed because the entire system was not analyzed and the source of the noise generation could not be pinpointed. This article explains the steps taken to solve this type of problem for Dow Chemical's plant in Freeport, TX, through computational fluid dynamics (CFD) and recounts the results.>>

Mechanics and Sizing of Positive Displacement Pumps Chemical Processing Magazine

<<In most engineering classrooms, soon-to-be-engineers learn that the
industrial world runs on centrifugal pumps. To a large extent that's true, but centrifugal pumps do have their limitations. One shortcoming is limited viscosity range. As fluid viscosity increases, the efficiency of centrifugal pumps diminishes rapidly. Inefficiently transferring viscous fluids dictates using a different type of pump in applications such as pumping resins, sludges and pulp. Positive displacement (PD) pumps are used to do this. PD pumps are barely mentioned (if that) in most undergraduate engineering programs, which can be a real problem to a new engineer who is not aware of the differences between PD and centrifugal pumps. PD pumps can be divided into two major classes: reciprocating and rotary. Reciprocating pumps typically use a piston or diaphragm to displace a certain volume of fluid per stroke of the piston or flex of the diaphragm, respectively. Rotary pumps incorporate some type of gear, rotor or screw mechanism to push the fluid.>>

Centrifugal Pump Installation
The Mc Nally Institute Received on Sat Jul 15 22:13:00 2000