Rigid pipe

Rigid Systems. Literature pertaining to the theoretical analysis of the three-plane rigid piping system is voluminous (30). This Hterature is expanding steadily and, as it is becoming more abstract, tends to obscure the basic problem which is the analysis of a three-dimensional statically iadeterminate stmcture. 

The numerator gives the wave velocity for perfec tly rigid pipe, and the denominator corrects for waU elasticity. This formula is for thin-walled pipes for thick-walled pipes, the factor D/b is replaced by... 

In the massive form poly(vinyl chloride) is a colourless rigid material with limited heat stability and with a tendency to adhere to metallic surfaces when heated. For these, and other, reasons it is necessary to compound the polymer with other ingredients to make useful plastics materials. By such means it is possible to produce a wide range of products, including rigid piping and soft elastic cellular materials. 

One reason for the success of PVC is its formulation versatility. Products range from rigid piping and window frames to soft flexible foams, with such diverse materials as vinyl leathercloth, flexible sheeting and playballs somewhere in between. 

Fig. 4.19(b) Pipe extrusion (1) rigid pipe (2) flexible pipe... 

TWo additional observations can be made. First, because a rigid pipe transmits almost all the load of the earth cover to the trench bed, someone will occasionally be heard to say that rigid pipe, such as concrete pipe, does not require side support. This is not true. Second, because of the difference in the ways rigid and flexible conduit distribute the load of their earth cover, flexible piping materials are often said to require less bedding bearing strength, because they impose less of a load... 

What characteristics of high density polyethylene make it suitable for the manufacture of rigid pipe What limitations would there be in the use of this pipe ... 

Do not secure pipes too rigidly. Pipes must be free to expand so that they will not damage other parts of the system. 

In view of the foregoing, a very close approximation for valve opening may be achieved by assuming an incompressible liquid in a rigid pipe. Such an assumption for instantaneous closure would indicate an infinite pressure rise, but no such result is possible for an instantaneous opening. Therefore in this simplified case we can employ the energy equation, but with a term added for the acceleration head. 

Organic based systems are being developed as lead replacement for rigid pipe, pipe fittings, profile and cable (135,136,143), suppliers include Crompton. 

All rubbers, glasses, and plastics are polymers. You are probably familiar with natural polymers like cellulose (the building block of plant fibers) and synthetic polymers like polyethylene (plastic milk cartons), polyisoprene (automobile tires), polyethylene terephthalate (soft drink bottles), polymethyl methacrylate (Plexiglas ), polyvinylidene chloride (transparent plastic wrap), polytetrafluoroethylene (Teflon ), and various polyesters (fabrics). Polyvinyl chloride, the polymer shown earlier, is used to make rigid pipes, house siding, and protective coverings for automobile seals and dashboards, among many other applications. 

Lead stabilizers are primarily used in wire and cable and in rigid pipe applications. 

H H / C=C / H Cl Vinyl chloride Poly(vin / H h 1 1 -C-C— II H ClA yl chloride) orPVC vinyl seats in automobiles, vinyl siding for houses, rigid pipes, food wrap, vegetable oil bottles, blister packaging, rain coats, shower curtains, and flooring... 

Someone slows down and is hit by a faster-moving car from behind. The first crash produces a pile of stopped, wrecked cars. This pile then enlarges in the upstream direction jas more and more cars pile into the stopped wreckage.) The rate of propagation of the boundary between stopped and moving fluid (assuming rigid pipe walls) is the local speed of sound. That is not proved here, but may seem clearer after we have discussed the speed of sound in Chap. 8. From Chap. 8 we lean borrow the fact that for water the speed of sound is about c = 5000 ft/s j(1520 m/s), so that the stopped layer of water will reach the reservoir in r =L/c = (3000 m)/(1520 m/s), or about 2 s after the valve is closed. 

About 90% of the PVC produced is used in the form of homopolymers, the other 10% as copolymers and terpolymers. The largest application of homopolymers PVC compounds, particularly unplasticized grades, is for rigid pipes and fittings, most commonly as suspension homopolymers of high bulk density compounded as powder blends. 

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