Foamed pipe

Chemson reports that its additive systems for foamed core pipe production have reached a stage at which they will permit recycled material to be incorporated, without any trade-off in terms of quality. The company suggests that, for a foamed core pipe plant with an output of about 350 kg per hour, the savings in materials costs could run to a six-digit amount during a year. 

Multi-layer technology for pipes has been on the market for about one and a half years and has been widely accepted for extrusion of large-diameter pipe for sewer ducts. Today, virtually no pipe of this type is produced without a core of foamed PVC between the inner and outer skins. The three-layer structure, in which the central core constitutes about 60% of the total material, reduces the weight of the pipe by about one-third, compared with conventional technology for production of a pipe of the same diameter. The blowing agent is nitrogen, directly metered into the machine as azodicarbonamide. 

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Rubber Transportation (e.g., conveyor belts, foamed pipes fior insulation) ... 

Before the storage of the flammable liquid (crude sulfate turpentine, CST), there were no flammable materials in the terminals enclosure. Local fire protection agencies specified a fixed foam-piping, fire-suppressing system as a condition to store flammable liquids. The terminal s management agreed to the terms of the protection package. 

Oxy. [OxyChem] PVC resins for blending, adhesives, flooring, coatings, records, color cones., automotive applies., inj. molded bottles and pipe fittings, calendered and extruded films, rigid foams, pipes, profiles, wire and cable, rotational castings. 

Applications blow molded bottles, calendered sheet, exterior trim, fence, film, foam, pipe, profile, rigid containers, siding, windows, wood-polymer composites... 

Phenolic foam pipe insulation has also been tested and approved by Factory Mutual for use as pipe... 

Region Cable Foam Pipes and fittings Window profiles ... 

Much of the recent development work on ATH is in the development of smaller particle size, less dust, and more translucency problems also present with antimony oxide. Surface coating with titanates and other materials has been tried successfully. In one case, a 40% ATH-filled low-density polyethylene for foamed pipe lines uses 0.5% isostearoyl titanate and in another, a Japanese company has developed a "self-extinguishing" polypropylene compound for household heater junction boxes that uses 30% ATH pretreated with 1% titanate in combination with halogen, to achieve a UL 94 V-1 rating [127]. 

ITDPE film ITDPE foam ITDPE pipes... 

Pipe and fittings remain a significant market for ABS, particularly in North America. ABS foam core technology allows ABS resin to compete effectively with PVC in the primary drain-waste and vent (DWV) pipe market. 

CeUular polymers are also used for pipe and vessel insulation. Spray and pour-in-place techniques of appHcation are particularly suitable, and polyurethane and epoxy foams are widely used. Ease of appHcation, fire properties, and low thermal conductivity have been responsible for the acceptance of ceUular mbber and ceUular poly(vinyl chloride) as insulation for smaller pipes. 

Spray. In spray-on appHcations the reactive iagredients are impingement mixed at the spray head. Thickness of the foam is controlled by the amount appHed per unit area and additional coats are used if greater than 2.5 cm (1.0 ia.) thickness is required. This method is commonly used for coating iadustrial roofs or iasulatiag tanks and pipes. 

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. 

Consistent with this model, foams exhibit plug flow when forced through a channel or pipe. In the center of the channel the foam flows as a soHd plug, with a constant velocity. AH the shear flow occurs near the waHs, where the yield stress has been exceeded and the foam behaves like a viscous Hquid. At the waH, foams can exhibit waH sHp such that bubbles adjacent to the waH have nonzero velocity. The amount of waH sHp present has a significant influence on the overaH flow rate obtained for a given pressure gradient. 

The newer open-ceU foams, based on polyimides (qv), polyben2imida2oles, polypyrones, polyureas, polyphenylquinoxalines, and phenoHc resins (qv), produce less smoke, are more fire resistant and can be used at higher temperatures. These materials are more expensive and used only for special appHcations including aircraft and marine vessels. Rigid poly(vinyl chloride) (PVC) foams are available in small quantities mainly for use in composite panels and piping appHcations (see Elame retardants Heat-RESISTANTPOLYA rs). 

Polyimide and Melamine. These are both low density, essentially open-ceU foams used as pipe insulations, particularly those involved with fluids operating at temperatures up to 530 K. Because these foams operate at higher temperatures and have improved flammabiHty characteristics compared to other foams, they are also used for some aircraft and marine appHcations. 

The pipe stiU furnace heats the feed to a predeterrnined temperature, usuaUy a temperature at which a predeterrnined portion of the feed changes into vapor. The vapor is held under pressure in the pipe in the furnace until it discharges as a foaming stream into the fractional distUlation tower. Here the nonvolatile or Hquid portion of the feed descends to the bottom of the tower to be pumped away as a bottom nonvolatile product, while the vapors pass up the tower to be fractionated into gas oU, kerosene, and naphtha. 

Silicone foam thus formed has an open ceU stmcture and is a relatively poor insulating material. Cell size can be controlled by the selection of fillers, which serve as bubble nucleating sites. The addition of quartz as a filler gready improves the flame retardancy of the foam char yields of >65% can be achieved. Because of its excellent dammabiUty characteristics, siUcone foam is used in building and constmction fire-stop systems and as pipe insulation in power plants. Typical physical properties of siUcone foam are Hsted in Table 10. 

The avadabihty of PMDI also led to the development of polyurethane-modified isocyanurate (PUIR) foams by 1967. The PUIR foams have superior thermal stabiUty and combustibiUty characteristics, which extend the use temperature of insulation foams well above 150°C. The PUIR foams are used in pipe, vessel, and solar panel insulation glass-fiber-reinforced PUIR roofing panels having superior dimensional stabiUty have also been developed. More recently, inexpensive polyester polyols based on residues obtained in the production of dimethyl terephthalate (DMT) have been used in the formulation of rigid polyurethane and PUIR foams. 

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