Piping substitutions

L. C. Ambler, PVC Pipe as a Pipe Substitute forTraditionalPiping Products, Certain Teed Corp., Nov. 30, 1988. 

Regrettably, a refinery worker was injured by sulfuric acid because a 4-inch (10 cm) piping substitute gasket failed. The acrylic fibers in the nonasbestos gasket material were attacked by the acid. The asbestos fibers had resisted the chemical attack. 

For small diameter carbon steel pipes, substitution in equation 5.12 gives di, optimum = 0.830G° /A° ° p ... 

Now, contrary to popular opinions, this method need not be conducted in a sealed pipe bomb. Secondary amination by substitution is as much a reaction of opportunity as it is of brute force and heat. In fact, heating can tend to cause the reformation of safrole and isosafrole. So the simplest way to do this would be to use 500mL of ammonium hydroxide or alcoholic ammonia or, for those wishing to make MDMA or meth, 40% aqueous methylamine or alcoholic methylamine (to tell you the truth, methylamine is preferable in this method because it is more reactive that ammonia so yield will increase). This 500mL is placed in a flask and into it is poured a solution of 35g bromosafrole (30g phenylisopropyl-bromide) mixed with 50mL methanol. The flask is stoppered and stirred at room temperature for anywhere from 3 to 7 days. The chemist could also reflux the same mixture for 6-12 hours or she could throw the whole mix into a sealed pipe bomb (see How to Make section) and cook it for 5 hours in a 120-130°C oil bath. 

METHOD 2 [89]--1M MDA or benzedrine and 1M benzaldehyde is dissolved in 95% ethanol (Everclear), stirred, the solvent removed by distillation then the oil vacuum distilled to give 95% yellow oil which is a Schiff base intermediate. 1M of this intermediate, plus 1M iodomethane, is sealed in a pipe bomb that s dumped in boiling water for 5 hours giving an orangy-red heavy oil. The oil is taken up in methanol, 1/8 its volume of dH20 is added and the solution refluxed for 30 minutes. Next, an equal volume of water is added and the whole solution boiled openly until no more odor of benzaldehyde is detected (smells like almond extract). The solution is acidified with acetic acid, washed with ether (discard ether), the MDMA or meth freebase liberated with NaOH and extracted with ether to afford a yield of 90% for meth and 65% for MDMA. That s not a bad conversion but what s with having to use benzaldehyde (a List chemical) Strike wonders if another aldehyde can substitute. 

Rigid vinyl foams ia constmction markets have grown substantially due to improved techniques to manufacture articles with controlled densities and smooth outer surfaces. Wood mol ding substitute for door frames and other wood products is an area that has grown. Rigid vinyl foams are also used ia the manufacture of pipes and wines as resia extenders and ia sidings and wiadows as the replacement of wood or wood substitutes. 

Noncircular Channels Calciilation of fric tional pressure drop in noncircular channels depends on whether the flow is laminar or tumu-lent, and on whether the channel is full or open. For turbulent flow in ducts running full, the hydraulic diameter shoiild be substituted for D in the friction factor and Reynolds number definitions, Eqs. (6-32) and (6-33). The hydraiilic diameter is defined as four times the channel cross-sectional area divided by the wetted perimeter. For example, the hydraiilic diameter for a circiilar pipe is = D, for an annulus of inner diameter d and outer diameter D, = D — d, for a rectangiilar duct of sides 7, h, Dij = ah/[2(a + h)].T ie hydraulic radius Rii is defined as one-fourth of the hydraiilic diameter. 

The viscous or frictional loss term in the mechanical energy balance for most cases is obtained experimentally. For many common fittings found in piping systems, such as expansions, contrac tions, elbows and valves, data are available to estimate the losses. Substitution into the energy balance then allows calculation of pressure drop. A common error is to assume that pressure drop and frictional losses are equivalent. Equation (6-16) shows that in addition to fric tional losses, other factors such as shaft work and velocity or elevation change influence pressure drop. 

Also in the long term, the equipment loses its eflicieney, and replacement parts are substituted in a maintenance function. Also, the plant goes through production expansions and contractions new equipment is added into the pipes. In short, the system and its elevations and pressures, its resistances and velocities, are very dynamic. The BEP of the pump is static. 

Where outlet pressure losses exceed 10%, bellows valves are often considered. However, substitution of a bellows valve for a conventional valve may not necessarily solve the chatter problem since debits associated with bellows valves reduce the rated capacity of this type valve. Hence, the valve has a tendency to become oversized depending on the amount of back pressure encountered. For this reason, revision of outlet piping to reduce the back pressure within the 10% limit is strongly preferred to the alternative of installing a bellows valve. 

Often the facility is designed with equipment and piping that can handle the complete range of operating conditions, and with control valves selected so that their internals ( trim ) can be substituted as operaiing... 

There has been a rapid growth of the demand for plastics from less than 20 billion pounds in 1970 to nearly 50 billion pounds consumed in the United States in 1986, mostly due to the substitution of traditional raw materials. All over the world, plastics have replaced metals, glass, ceramics, wood papers, and natural fibers in a wide variety of industries including packaging, consumer products, automobiles, building and construction, electronics and electrical equipment, appliances, furniture, piping, and heavy industrial equipment [57-121]. Consumption patterns of PBAs in some countries are shown in Tabies 1 and 2. 

Although the following comments do not substitute for a complete analysis of each pipe system around a compressor, they serve to identify a few key points. 

Substituting Equations 4-59, 4-60, 4-56, and 4-55 into Equation 4-54 and solving for the tensile load capacity of drill pipe yields... 

Gas pipework in a user s premises serves the function of transporting the gas from the meter to the point of use in a safe way and without incurring an avoidable pressure loss. For low-pressure installations, the permitted pressure loss is only 1 mbar from the meter to the plant manual isolating valve at maximum flow rate. The pipework must be sized adequately to allow for this. Boosters are sometimes used to overcome pressure losses, but the use of a booster should never be considered a satisfactory substitute for correct design of pipe sizes. Where gas is available at higher pressures it may be permissible to tolerate pressure losses of more than 1 mbar. 

It has been determined that, with burial depths greater than two thirds the radius of the pipe, this equation provides a means of determining the required pipe stiffness for critical buckling. To make the equation easier to use, it can be rewritten by substituting certain values and solving for the required stiffness for buckling. Suppose that this Luscher Hoeg equation says we will require a pipe stiffness of 0.123 x 106 lb-in2/lineal in. to... 

As a first approximation, R/pu2 may be taken as 0.002 in each pipe, and substituting this value in equations 4 and 5 then ... 

At the walls of the pipe, that is where s — r, the velocity ux must be zero in order to satisfy the condition of zero wall slip. Substituting the value ux = 0, when s — r. then ... 

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