Service reinforcement

Vol. 589 M. Schwind, Dynamic Pricing and Automated Resource Allocation for Information Services Reinforcement Learning and Combinatorial Auctions. XII, 293 pages, 2007. 

The modern Russian MIA flaw detectors use pulse version of the method [1-3], which peirnits to produce very portable (0.7 - 1.5 kg) and simple instruments, convenient especially for in-service testing. The objects to be tested are multilayer structures of reinforced plastics, metals and other materials honeycomb panels, antenna fairings, propellers, helicopter rotors and so on. In mentioned instruments amplitude-frequency analog signal processing is used. 

Reinforced furan resias have been used for many years in process piping and in underground sewer or waste-disposal systems. With a wide range in pH acceptability and good solvent resistance, furan piping has been a logical choice for many services. 

Dry chlorine has a great affinity for absorbing moisture, and wet chlorine is extremely corrosive, attacking most common materials except HasteUoy C, titanium, and tantalum. These metals are protected from attack by the acids formed by chlorine hydrolysis because of surface oxide films on the metal. Tantalum is the preferred constmction material for service with wet and dry chlorine. Wet chlorine gas is handled under pressure using fiberglass-reinforced plastics. Rubber-lined steel is suitable for wet chlorine gas handling up to 100°C. At low pressures and low temperatures PVC, chlorinated PVC, and reinforced polyester resins are also used. Polytetrafluoroethylene (PTFE), poly(vinyhdene fluoride) (PVDE), and... 

Hoses must be made for anhydrous ammonia service 2500 kPa (348 psig) working pressure and stamped for this service. In locations where hoses may be abraded, wke braid armored or reinforced hose types should be used. Hose ends should have boss or other acceptable ak kon ferruled couplings. 

Sophisticated stmctural analysis techniques make it possible to determine both the amount and exact orientation of reinforcement that the product wQl need to meet the critical stresses in actual service. Hybrid reinforcement systems containing different fiber compositions with different properties are being increasingly used. For example, hybrid carbon and glass fiber automotive drive shafts are in commercial use. 

Service temperature limitations must be considered in the use of composites, not only in the selection of polymer and process, but sometimes in the selection of the reinforcement as weU. Composites cannot generally perform as weU as metals or ceramics in very high temperature appHcations, but they can be made fire resistant to meet most constmction and transportation codes. 

A key feature implicitly included in the use of organic fibers for tire reinforcement is the abiHty to retain strength and modulus characteristics at elevated temperatures (80—120°C for most tires) sufficient to sustain service demands. Thus, a tire which may appear to be overdesigned at room temperature is, in many cases, reflecting the changes in properties experienced at operating temperatures. 

In addition to electrical uses, epoxy casting resins are utilized in the manufacture of tools, ie, contact and match molds, stretch blocks, vacuum-forrning tools, and foundry patterns, as weU as bench tops and kitchen sinks. Systems consist of a gel-coat formulation designed to form a thin coating over the pattern which provides a perfect reproduction of the pattern detail. This is backed by a heavily filled epoxy system which also incorporates fiber reinforcements to give the tool its strength. For moderate temperature service, a Hquid bisphenol A epoxy resin with an aHphatic amine is used. For higher temperature service, a modified system based on an epoxy phenol novolak and an aromatic diamine hardener may be used. 

Pinch The industrial equivalent of controlling flow bv pinching a soda straw is the pinch valve, Mves of this tvpe use fabric-reinforced elastomer sleeves that completely isolate the process fluid from the metal parts in the valve. The valve is actuated bv applying air pressure directly to the outside of the sleeve, causing it to contract or pinch. Another method is to pinch the sleeve with a linear actuator with a specially attached foot. Pinch valves are used extensively for corrosive material service and erosive sliirrv senice. This type of valve is used in applications with pressure drops up to 10 bar (145 psi),... 

Spiral baffles, which are sometimes installed for hquid services to improve heat transfer and prevent channeling, can be designed to serve as reinforcements. A spiral-wound channel welded to the vessel wall is an alternative to the spiral baffle which is more predictable in performance, since cross-baffle leakage is eliminated, and is reportedly lower in cost [Feichtinger, Chem. Eng., 67, 197 (Sept. 5, I960)]. 

A wide variety of thermoplastics have been used as the base for reinforced plastics. These include polypropylene, nylon, styrene-based materials, thermoplastic polyesters, acetal, polycarbonate, polysulphone, etc. The choice of a reinforced thermoplastic depends on a wide range of factors which includes the nature of the application, the service environment and costs. In many cases conventional thermoplastic processing techniques can be used to produce moulded articles (see Chapter 4). Some typical properties of fibre reinforced nylon are given in Table 3.2. 

H = History if a plant has used material successfully for many years, and the staff members know its strengths and limitations, how to weld it, etc., hesitate before making a change. For example, a fiberglass-reinforced plastic had given excellent service for many years when another composite from the same company, with the same name but a different number, was used instead, it failed overnight. 

For most fans, blades are riveted to the back plate or hub respectively. For centrifugals, the blades are usually welded to the shroud however, they can be welded to both shroud and backplate. For some designs and classes of service, an extra reinforcing ring is welded to the blades between the backplate and the shroud. This is particularly necessary for large heavy-duty units see Figure 12-120B. 

Face-seal materials can be chosen from filled, molded or reinforced resins with which water, hydraulic fluids, mineral oils or synthetic oils are all compatible. Their maximum temperature in service depends on the brittle point of the resin but, generally, the range is from —50°C to 100°C (122°F to 212°F). Abrasion resistance is generally good but, as far as possible, resins are not used in the presence of foreign solids. 

In the middle of the last century, the tensile properties of concrete were improved by the introduction of steel to reinforce the concrete. This practice has developed since then to such an extent that reinforced concrete is now one of the major structural materials used in construction. In general it has proved to be a good durable material with some of the structures erected at the turn of the century still providing satisfactory service in the late 1970s. 

---