Pipe and tube extrusion

Tubes and pipes can be extruded from fluoro-plastics. These extrusions are usually applied in the transport of corrosive chemicals and, to a lesser extent, as linings. 

Variable Orientation Transparency Gloss Stiffness Impact Resistance 

The outside diameter of the pipe may be calibrated either by an internal air pressure of 1.3 to 2.0 bar, or by external calibration in a vacuum sizing tank (Fig. 6.17) operating at a pressure of 0.3 to 0.5 bar. For calibration by internal pressure, the diameter of the die ring is made approximately equal to the internal diameter of the finished pipe. For vacuum tank calibration, the die ring is made up to 25% larger and the haul-off is set for a wall thickness drawdown of up to 30%. 

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Figure 6.16 Typical spider-type tube die for pipe and tube extrusion.

Calibrator with ultrasonic gauging for pipe and tubing extrusion A=rubber seals B = stainless steel guides C brushes (to remove bubbles) D ultrasonic probes E water drain and water inlet. 

Pipe and Tubing. Extrusion of pipe and tubing accoimts for a very small fraction of LLDPE consumption. LLDPE offers higher burst strength, environmental stress crack resistance, and higher heat-distortion temperature than LDPE. Plastomer grades have been used to replace plasticized polyvinyl chloride in medical tubing applications (129). 

Fig. 5. Vacuum calibrator for pipe and tubing extrusion A, molten tube from die B, tank C, hinged cover with gasket D, sizing rings E, circulated and temperature-controlled water F, water level G, vacuum and H, inside of pipe open to atmospheric pressure (20).

Figure 7-47. Examples of calibration systems for pipe and tube extrusion lines.

Figure 8.15 Vacuum sizing tank used for pipe and tube extrusion.f ...

Copper and Copper Alloys Seamless copper, bronze, brass, copper-nickel-aUoy, and copper-silicon-aUoy pipe and tubing are produced by extrusion. Tubing is available in outside-diameter sizes from Vi6 to 16 in and in a range of wall thicknesses varying from 0.005 in for the smallest tubing to 0.75 in for the 16-in size. Tubing is usually specified by outside diameter and wall thickness. 

Extrusion. The main applications of this method include the production of film, sheet, pipe, and tubing. PB is usually extruded by using the same equipment (single- cu twin-screw extruders) as that used foi PP and HDPE, at melt and die temperatures of 170- 190°C. PMP is processed on extruders with a high length-to-diameter ratio at temperatures of 240-300°C. 

Several unique products are made by extrusion and the dies needed to make these products are classified as 1) sheet dies 2) flat-film and blown-film dies 3) pipe and tubing dies 4) profile extrusion dies and 5) co-extrusion dies. Furthermore, each product type has unique hardware downstream of the die to shape and cool the extruded melt. To aid the reader, detailed illustrations of the various die designs and the complementary downstream cooling and shaping hardware are shown. 

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