Pipes and hoses

Mechanical perfoimance (tensile, flexural, impact, bursting pressure, and compressive strength), resistance to heat, thermal expansion coefficient, heat distortion temperature, maximum working temperature, burning class, UV stability, and working stress are the most important parameters characterizing performance requirements of pipes and hoses and are used as selection criteria. Fillers can help to fulfill these requirements, but are underutilized. Fillers seem mainly to be used to lower cost. 

Carbon black is very frequently used as an UV stabilizer. Pipes which are not normally exposed under their working conditions do need UV stabilization because 

For some apphcations a low thermal expansion coefficient is required and pipes are produced with glass fiber reinforcement which also increases the heat deflection temperature. 

Electrically conductive pipes are less well known. These pipes are used to prevent electrostatic hazards in oil tanker applications. The pipe for this purpose was developed using glass fiber for reinforcement and carbon fiber to obtain conductivity. There are also methods of production of such pipe where aluminized glass fiber is mixed with reinforcing glass fiber. 

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Several sections of this chapter discuss building materials (hoses and pipes, pavement, roofing, sealants, siding, and waterproofing). Here, we focus on wall materials and insulation in various extruded and molded profiles. Numerous polymers are used for these two applications. They include polystyrene, phenolic resin, polyvinylchloride, and polyurethanes for insulation purposes and polyvinylchloride, polyurethanes, and polyesters for wall systems and structural elements. The major methods of production include molding, extrusion, and pultrusion. 

Most molding machines use eleetric pumps to generate high pressure in a special oil. This hydraulic pressure is used to inject the plastic, to turn the screw, and to open and elose the mold. Any leak, especially in the high-pressure hoses and pipes, ean be hazardous. In addition, the oil can get hot enough to cause a bum. 

Applications Window frames, drain pipes, sewage and soil pipes, roofing sheets, cable and wire insulation, floor tiles, hose and pipes, stationary covers, fashion footwear, leathercloth. 

Excess flow-check valves are installed in hoses and piping systems that carry compressed gases. In the normal open position of this device, flow is permitted in either direction, as shown in Fig. 8-21(a). 

The delivery or header system usually consists of flexible hoses and rigid pipes. The design of this system must be coordinated with the plant layout, the material to be dispensed, and the instantaneous material delivery rate required. The two primary factors are material and delivery rate. Each material to be dispensed (adhesive or sealant) requires a unique and specific pumping pressure based on header size (hose and pipe inner diameter) and delivery rate. Calculations should be made to estimate system pressure drop for a proposed system configuration to determine if sufficient system pressure availability exists. Tests should also be conducted to verify system design. These calculations and tests should take into account... 

Other considerations for both heated and unheated delivery/header systems include modularity for system configuration or redesign, backup temperature sensors, hose and pipe sizing, ease of maintenance, and routing of hoses on the robot with regard to its movements during robot cycles and for robot maintenance. 

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