Abstract: The present invention provides methods and materials for coating relatively small quantities of particles including tablets, pellets or granules. The device effectively fluidizes the particles to be coated by controlled vibration of a perforated platform through which drying air is passed during intermittent spraying of the particles with a solution of organic or aqueous-based coating material. The method coats individual tablets having as low a mass as 50 mg and coats quantities ranging from less than about 50 mg to 10 g of tablets, pellets, or granules.

Abstract: A method of applying a synthetic resin layer to an outer surface of a metal part, comprising heating the metal part to a temperature higher than a melting point of a synthetic resin, embedding the heated metal part within a powdered mass of the synthetic resin, thereby melting a portion of the powdered mass surrounding the outer surface of the heated melt part, holding the heated metal part within the powdered mass for a time period sufficient to permit the molten portion of the powdered mass to be coated on the outer surface of the heated metal part as the synthetic resin layer, removing the metal part coated with the synthetic resin layer from the powdered mass, and maintaining the removed metal part at a temperature higher than the melting point and lower than a thermal decomposition point of the synthetic resin, to hold the deposited resin layer in a molten state for a suitable length of time, in order to allow the escape of possibly entrapped air from the resin layer.

Abstract: A vessel (1) contains a rotor disc (23) mounted for rotation around a vertical axis (17) and arranged to bound a processing space (31) disposed above it. The agglomeration and/or the coating of particles are accomplished by moving the particles by the rotation of the rotor disc (23) and by means of a gas, in particular air, passed upwardly through the processing space (31) and by spraying them with a liquid. The torque required for the rotation of the rotor disc (23) is continuously measured by means of a torque measuring member (75) disposed between the rotor disc (23) and the drive device (77) arranged to drive the same. The agglomeration and/or the coating operation is controlled on the basis of the time-dependent variation of the torque and/or of the first derivative of the same, and/or of a variable having relation to the torque and/or its derivative.

Abstract: A fluidized bed dryer/granulator (10) for coating pellets (P) used in the preparation of pharmaceutical materials, comprises a chamber (11) having a top wall (12) and a bowl (16) at the bottom thereof and an axial air inlet (19) for directing a flow of air axially therethrough, and at least one removable air inlet (20, 21) positioned in the chamber for directing a circumferential flow of air into the chamber to interact with the axial flow to produce an orbital or swirling motion, enhancing the rate of treatment of the material in the chamber.

Abstract: Undesirable conversion of a silicon source, such as silane, in the freeboard above a fluidized bed of silicon particles in a fluidized bed reactor, can be reduced by cooling the gas within the freeboard. Preferably, the reduction in temperature is achieved by introducing into the freeboard, a stream of relatively cool quench gas such as hydrogen, which also reduces the concentration of silane in the freeboard. As a result of these two factors, the invention improves the service factor of the fluidized bed apparatus, and reduces the amount of silane conversion to undesired by-products.

Abstract: Process and apparatus for fluidized bed mixing of fluids and gases in which the fluid is injected with a high angular velocity through a relatively narrow, preferably single, orifice (3). The angular velocity may be imparted by injecting the fluid at high velocity tangentially at the periphery of the squate chamber (4) so that angular momentum is gained as it spirals inwards towards orifice (3). Optionally, an open-topped hopper (5) for solids is suspended above orifice (3). The lower end of the hopper (5) terminates in a second orifice (7) located vertically above orifice (3). The solid particles are thereby swept radially outwards towards the wall of the chamber (1) in co-current admixture with the fluid.

Abstract: A method of forming a surface layer of carbide, nitride, carbonitride, or solid-solution on the surface of a material to be treated, which comprises disposing in a fluidized bed furnace a treating agent comprising a powder of a refractory material, and a powder of a metal for forming a carbide, nitride, carbonitride or solid-solution or a powder of an alloy thereof, introducing a fluidizing gas into the fluidized bed furnace to fluidize the treating agent and form a fluidized layer, disposing the material to be treated in the fluidized layer, and introducing a predetermined amount of halide into the fluidized layer, and an apparatus for forming the surface layer on the material to be treated, comprising a furnace body for forming the surface layer in the fluidized layer of the treating agent, a heating furnace for heating the fluidized layer, a halide supply pipe in communication with the outside of the furnace body, and a halide gas jetting pipe disposed within the furnace body, which is connected to the hal

Abstract: Disclosed is a method of casting a shape. A laser or electron gun is directed at a fusible powder in a fluidized bed. The beam melts the powder and the melted powder fuses and solidifies on a surface to form the shape. Also disclosed is apparatus for casting a shape. The apparatus includes a fluidized bed containing a fluidized powder, a surface within the bed on which the shape is cast, an electron beam or laser directed at the surface, which has an energy sufficient to fuse the powder, means for controlling the level of the powder in the fluidized bed relative to the surface, and means for controlling the horizontal position of the surface relative to the beam.

Abstract: A method of applying a synthetic resin layer to an outer surface of a metal part while the metal part is positioned within a powdered mass of a thermally fusible synthetic resin. The metal part within the powdered mass is induction-heated to a temperature between a melting point and a thermal decomposition point of the synthetic resin, to melt a portion of the powdered mass surrounding the outer surface of the heated metal part, and to deposit the molten portion of the powdered mass on the outer surface of the heated metal part, as the synthetic resin. The metal part is pushed down by a predetermined distance within the powdered mass, at least once at a point of time after the metal part has been positioned in the powdered mass, and before the induction-heating step has been completed.

Abstract: A method and apparatus for applying a synthetic resin layer to an outer surface of a metal part while the metal part is placed within a powdered mass of a thermally fusible synthetic resin. The metal part within the powdered mass is induction-heated to a temperature higher than a melting point and lower than a thermal decomposition point of the synthetic resin, in order to melt a portion of the powdered mass surrounding the heated metal part, and thereby permit the molten portion of the powdered mass to be deposited as the synthetic resin layer on the outer surface of the heated metal part. To facilitate the placement of the metal part in the powdered mass, air may be blown into the powdered mass to keep the mass in a fluid state.

Abstract: A method and apparatus for forming a layer of a carbide or nitride of, for example, titanium or vanadium on the surface of material to be treated in a fluidized bed furnace. A refractory powder for forming a fluidized bed, a vessel or vessels filed with powder of a treating agent, and the material to be treated are placed in the furnace. The treating agent includes powder of at least one carbide or nitride forming metal or alloy and powder of at least one compound selected from the group consisting of chlorides, fluorides, bromides, iodides and boro-fluorides of alkali and alkaline earth metals and/or at least one of an ammonium halide and a metal halide. A fluidizing gas is introduced into the furnace under heat to form a fluidized bed in which the surface of the material to be treated is treated. The vessel or vessels are placed in the furnace in a spaced-apart relation from the material to be treated, so that no powder of the treating agent may adhere to the surface of the material to be treated.

Abstract: An electrostatic toning system employed in applying toner to latent electrostatic images on the surface of a dielectric material. Toning is accomplished by fluidizing the toner in a gaseous stream, charging the toner in the fluidized bed, and conveying the charged toner to the dielectric surface by means of a toner receptive member in contact with the fluidized toner.

Abstract: Granules are processed with a liquid coating material in a vessel having a fluidizing bed on a horizontal or slightly inclined perforated plate and spouting beds, the fluidizing bed having a depth of 0.10 to 1.00 m in the static state and 0.30 to 1.50 m in the fluidizing state, the coating material being sprayed upwardly in a conical form with a spray angle of 30 to 80 degree from spray nozzles disposed in the spouting beds, a gas strean being fed at a spouting velocity of 5 to 50 m/sec. and a flow rate of 250 to 10,000 Nm.sup.3 /hour, each spouting bed unit being disposed in a density of 0.5 to 5 units/m.sup.2 on the fluidizing bed.

Abstract: Undesirable conversion of a silicon source, such as silane, in the freeboard above a fluidized bed of silicon particles in a fluidized bed reactor, can be reduced by cooling the gas within the freeboard. Preferably, the reduction in temperature is achieved by introducing into the freeboard, a stream of relatively cool quench gas such as hydrogen, which also reduces the concentration of silane in the freeboard. As a result of these two factors, the invention improves the service factor of the fluidized bed apparatus, and reduces the amount of silane conversion to undesired by-products.

Abstract: This invention relates to particle coaters and in particular to a method and apparatus for a circulating bed particle coater which is particularly adapted for coating small diameter particles.

Abstract: The interior of a rotary-disk apparatus is divided by a generally cylindrical wall into an inner processing zone and an outer processing zone. The inner processing zone can be connected to an disconnected from the outer processing zone by moving the wall into and out of sealing engagement with an underlying rotary disk. When the wall and the disk are not in sealing engagement with each other, a gap is formed which permits the transfer of granules from the inner processing zone to the outer processing zone as a result of the rotation of the disk.

Abstract: An improved squeegee roller particularly suited for use in an instant camera has a texture formed by stud-like bumps. A complex contour is provided to the roller by varying the heights of the bumps along the roller surface. In a method and apparatus for producing the roller a pulsed laser beam is used to produce the bumps and the energy of each pulse is varied according to a predetermined program to adjust the height of a bump formed.

Abstract: Fluid-assisted granulating and coating apparatus having a circular planar material circulation plate assembly rotatably mounted coaxilly within a cylindrical work area of an upright vessel, the plate assembly including a plurality of concentric circular slots opening radially outwardly into the work area for directing a suspension fluid radially outwardly thereinto for enhanced material circulation in a circularly spiraling fashion without undesirable concentration or stagnation of charge material within the work area and without undesirable material loss through or clogging of the fluid flow slots. This remarkable effectiveness of the apparatus enables its operation under either fluidized or non-fluidized conditions to provide significant flexibility in controlling the characteristics of granules produced.

Abstract: A method and apparatus for powder surface treatment by turning the powder into a fluidized layer while passing gas made, at least partially, of a reactive gas, through the powder, to improve dispersion stability of powder pigments.Since the powder is turned into the fluidized layer by gas made, at least partially, of reactive gas, powder particles are put in close and uniform contact with the reactive gas, ensuring full surface treatment of the powder.

Abstract: Fluidized bed apparatus for use in applying a coating, having a relatively lesser density, to particles, having relatively greater densities by causing passage of a gaseous atmosphere through a bed of the particles. The apparatus includes an enclosure holding a bed of the particles and means for causing flowing of the gaseous atmosphere carrying a material for forming the coating through the bed of particles to be fluidized. The apparatus further includes means for adding seed particles to the bed and weir tube means removing coated particles from the bed when the contents of the bed achieves a predetermined level. Finally, the apparatus includes discharge means receiving the coated particles from the tube means and conveying them to a collection location remote from the enclosure.

Abstract: Method and apparatus for continuously coating discrete particles in a turning fluidized bed formed in a cylindrical coating vessel with a rotary disk at the bottom thereof by blowing hot air into the vessel through air blow holes located between the circumference of the disk and cylindrical side wall of the vessel while spraying a coating material into contact with the particles in the turning fluidized bed, characterized by introducing a particulate raw material and a coating material into the turning fluidized bed at constant feed rates; and discharging coated particles at the same rate as the feed rate of the particulate raw material through a particle discharge port located at such a height as to guarantee an average residence time corresponding to a desired coating rate under given operating conditions including the feed rate of the raw material, the rotational speed of the disk and the feed rate of hot air.

Abstract: A device for use in fluidized bed techniques, particularly for coating tablets or the like, which comprises a container for use as a processing zone for the material to be processed, a sensor device or the like for monitoring the upper end area of the processing zone, and apparatus for moving the material through the processing zone.

Abstract: A fluidized bed apparatus and method are disclosed for coating, granulating and/or drying particles. The particles are circulated within a chamber by means of circumferential air flow. A first gas stream moves upwardly through the chamber. A second gas stream enters the chamber through openings in the side wall of the chamber. The openings extend generally horizontally and tangential to the side wall so that the second gas is directed circumferentially in the chamber for three-dimensional rotation and circulation of the particles.

Abstract: A method and apparatus for microencapsulating an electroluminescent phosphor with an extremely thin coating. The process involves vaporizing a poly-para-xylylene, pyrolyzing the resulting vapors to form reactive monomeric radicals, and then passing such vaporous radicals to a vacuum deposition zone where they contact tumbling particles of an electroluminescent phosphor under vacuum conditions. As the particles are being coated, they are sifted by means of a screen. The reactive monomeric radicals deposit on the tumbling particles, are adsorbed by the particles, and polymerized into a very thin coating on the surfaces of the particles.

Abstract: Methods of and apparatus for coating the glass envelope and predetermined portions of the end caps of a fluorescent lamp with a coating of polymeric material including securing the end caps against displacement, subsequently, preheating the glass envelope and the predetermined portion of the end caps to a first predetermined temperature above the melting point of the polymeric material for a predetermined amount of time; subsequently, masking the electrical connecting pins and all of the end caps except the predetermined portion thereof; subsequently, exposing the glass envelope and the predetermined portion of the end caps to a fluidized bed of powder of the polymeric material for a predetermined amount of time to apply a coating of the powder to the glass envelope and to the predetermined portion of the end caps; subsequently, reheating the glass envelope and the predetermined portion of the end caps to a predetermined temperature above the melting point of the polymeric material and for a predetermined amo

Abstract: A fluidized bed furnace for coating fuel particles for nuclear reactors, ticularly high temperature reactors, can be emptied without cooling down the reaction tube by substituting an inert gas for the coating gas and then lowering the inner tube through which this gas is fed so as to clear a passage in the surrounding outer gas feed tube through which the kernels may fall down to a diverting device in the intermediate space between the inner and outer tubes that guides the kernels to a discharge tube. The reaction tube is emptied by lowering the feed gas pressure by cutting off the carrier gas flow and regulating the escape of the inert gas through an overflow pipe. After the reactor is emptied, the flow of carrier gas can be restored and the overflow pipe shut, so that the reactor can be refilled, after which the flow of coating gas is restored and another coating operation can begin without delay.

Abstract: A massive article is coated by chemical vapor deposition in a chamber having a horizontal cross-sectional configuration generally matched to the horizontal cross-sectional configuration of the article. For an article which is relatively thin between a pair of opposed faces so that the article is subject to breakage by the force of surging particles of a fluidized particle bed, breakage is reduced in a coating chamber having vertical sidewalls that generally parallel the faces of the article and relatively narrow endwalls. The article is centered in the chamber with its faces parallel to the sidewalls leaving a region between the faces that accommodates an adequate flow of carrier gas and coating vapor without requiring a large charge of particles that would create undue surging force against the article.

Abstract: Method and apparatus for filling a cable core unit with powder in a fluidized bed in which the unit is vibrated laterally by introducing energy pulsations into the bed, the pulses being transmitted as successive waves through the powder particles to transfer the energy to the unit and set up the vibration. In preferred constructions, the pulsations are set up by a reciprocating piston means disposed beneath the upper surface of the powder. There may be two or more piston means spaced in the feed path direction for the unit or a single piston extending.

Abstract: A process and apparatus for filling multi-conductor cables, particularly a telecommunication cable with several insulated wires surrounded by a covering and a sheath, with a mixture of powders which expand with the absorption of moisture. The conductors are fed in spaced relation into the entrance of a casing having an interior, frusto-conical wall which decreases in diameter from its entrance to its exit. The exit is small in diameter compared to the entrance so that the conductors converge as they pass from the entrance to the exit. Intermediate the entrance and the exit, the conductors are subjected to the powders which are caused to follow a helicoidal course by a screw which directs them toward the exit. Due to the shape of the casing wall, the powders are forced toward the conductors.

Abstract: For certain related dimensions of features of a nozzle feeding a fluidized bed reactor from below, it has been found that a central flow of a coating gas is squeezed down in diameter in passing through a constriction at the nozzle end by the action of the surrounding dilution gas flow, without the setting up of turbulence such as might have been expected, which would cause deposits from the decomposition of the coating gas at the constriction. The spacing between the mouth of the central tube that feeds the coating gas and the constriction at the end of the nozzle should be in the range of 20 to 70 mm, the diameter of the constriction aperture should be in the range from 3 to 10 mm and the diameter of the central channel should be greater than the constriction aperture diameter but not more than 3.5 times the latter diameter. For coating particles having a density of about 10 g/m.sup.3 and a diameter of about 200 .mu.m , the constriction aperture diameter should not exceed 7 mm.

Abstract: A method of manufacturing a recombinant lead acid battery includes placing two or more cell packs in a battery container and then loading the container into a frame mounted on a rotary capstan. The container is transferred to a moulding station and the plate straps and intercell connectors are moulded around the plate lugs. The container is then transferred to a coating station and the intercell connectors are dipped while still hot into a fluidized bed of epoxy resin particles. The particles adhere to the intercell connectors and are cured by their heat thereby forming an impervious layer around them. This layer acts as an electrolyte creepage barrier and prevents the surface of the intercell connectors acting as an electrolyte path for intercell ionic leakage.

Abstract: A fluidized bed furnace employed for depositing pyrolytic carbon or silicon carbide on nuclear fuel particles is supplied with an inert dilution gas and a decomposable coating gas. These are supplied by means of a gas injector having at least three pipes 4 for coating gas extending within a surrounding duct for a stream of dilution gas 6. This leads to a partition 2 at the base of the bed, having at least three apertures 3 for through passage of the gases.

Abstract: A fluidizable bed structure with a rigid support for carrying a bed of fluidizable powder, the support being at least two inches deep and having its porosity formed by interstices which reduce in total area from the lower surface of the support to its upper or support surface. A fluidizable bed structure is also described having a support which has an electrode contacting it with the depth of the support from its upper surface to the electrode sufficient to prevent arcing from the electrode to the upper surface.

Abstract: A fluidization unit comprising a fluidizer (2) and a chamber (1) for containing a granular, powdery or like substance (3) to be fluidized. The chamber has at least one air-tight wall and the fluidizer comprises an assembly of an air-tight base sheet member (5), a porous sheet member (4), and a peripheral sealing member (6), holding the sheet members apart in a fixed relationship. In operation, said fluidizer is placed in the chamber with its air-tight base member resting against an air-tight wall of the chamber. A preferred application is in the handling of powders for electrostatic enamelling.

Abstract: An electrode for a fluidizable bed coating apparatus comprising a plurality of electrically conductive tubes and a tube carrier. The tubes extend from the carrier and have free ends at which there is a concentration in intensity of an electric field when the tubes are connected into an electric circuit, and the tubes channel fluidizing gas through them and through the concentrations in intensity of the electric field.

Abstract: A method of coating ceramic nuclear fuel particles containing a major amount of an actinide ceramic in which the particles are placed in a fluidized bed maintained at ca. 800.degree. to ca. 900.degree. C., and niobium pentachloride vapor and carbon tetrachloride vapor are led into the bed, whereby niobium metal is deposited on the particles and carbon is deposited interstitially within the niobium. Coating apparatus used in the method is also disclosed.

Abstract: A method and apparatus are disclosed by which electrical conductor cable can be produced utilizing electrostatic coating means, which method and apparatus are highly convenient, uncomplicated and economical to carry out. An outstanding and unique feature of the cable produced in accordance herewith resides in the presence of a web portion of reduced cross-section connecting the individual conductors, by which manual severence of one from another is facilitated. Most desirably, the apparatus and method provide means for producing individual insulating coatings on each of the conductors, which means ideally utilizes an electrostatic cloud coating technique.

Abstract: In a granulator of the jet layer type, all the liquid jetting openings are located in a passage for a gas jetted from the gas jetting opening and each liquid jetting opening is located at a position higher than the gas jetting opening by a vertical distance smaller than the inner diameter of the gas jetting opening. The granulator may have an additional device such as an excess size-having particle-collecting means, a five particle treating means, a rectifying pipe member, a fuffer member and a hindrance and breakage member.

Abstract: A method is provided for fluidizing and vaporizing particulate solid coating reactants by first establishing a fluidized bed of dispersed particulate solid coating reactants and thereafter drawing a volume of fluidizing gas and suspended particulate solid coating reactant to a vaporizer while mixing an additional volume of gas therewith and then vaporizing the dispersed particulate solid coating reactant in the reactant-gas mixture. The reactant-gas mixture is then directed into contact with a substrate to be coated in order to deposit a film thereon.

Abstract: A fluidized bed has an aperture plate which is inclined to the horizontal, to cause excessively large or dense particles to migrate to a collection point from which they may be removed from the particulate mass. Disruption of fluid flow through the aperture plate due to settled out particles is thus avoided. Preferably the aperture plate is made of a material which has the same permeability as the fluidized mass, thus inherently providing flow regulation necessary for even fluidization above the slope plate. To make investment casting molds, a gravity "rainsander" device is coupled with a fluidized bed. When slurry used in the mold making process drips from a pattern it falls into the fluidized bed thereby converting the errant drops into particulate balls which are conveniently removed.

Abstract: An apparatus for granulating and/or coating particles in a spouted bed having a cylindrically shaped enclosure surrounding and extending upward from a downwardly converging frustoconical structure connected to a gas flow conduit. A downwardly inclined flange extends from the walls of the cylindrical portion to overlap the top of the frustoconical part defining an annularly extending gap therebetween for allowing finished granules to exit therethrough.

Abstract: A device for introducing a gaseous flow stream in an apparatus for granulating and coating particles in a spouted bed including a flow directing structure located between the spouted bed containing portion of the device and the gaseous flowstream feeding portion. The flow directing structure directs the gaseous flow stream in the upward direction for preventing contact and agglomeration of particles in the vicinity of walls of the device.

Abstract: A granule producing apparatus comprises: a container; an exhaust means provided to the top of the container; a space in the upper interior of the container for separating solid material from gases; a space for a fluid bed in the lower interior of the container; a porous floor immediately below the fluid bed space for defining the lower limit of the fluid bed; an air chamber beneath the porous floor for supplying air streams to form the fluid bed; a means for supplying jet stream of air, provided below the fluid bed air stream supply chamber; a plurality of parallelly arranged funnels, said each funnel consisting of an inverse truncated cone and a cylindrical pipe connected to the lower end of the cone, said upwardly enlarged cone opens into the interior of the container with its upper end merging with the porous floor, said each cylindrical pipe having its lower end connected to the jet stream supply means; a means disposed within the upper portion of the cylindrical pipe of each funnel for spraying liquid un

Abstract: A fluidized bed apparatus comprises a container 18 and a bottom screen 16. The screen 16 comprises a perforated plate 28 having a plurality of large openings therein above each of which is secured a perforated cone 34. Fluid blown through a duct 12 passes through the perforations in the plate 28 and the perforations in the cones 34 into material 10 which is thereby fluidized. Circulation of the material 10 is rendered more uniform and the risk of damage lessened.

Abstract: A nozzle injection unit for an oil fired fluid combustor has a pair of co-axial tubes sealed together at one end. The outer tube has an inlet and lateral outlets near the sealed end and is connected to an air supply. The inner tube is connected to a fuel oil supply and has a number of circumferential lateral outlets communicating with the outer tube. The oil emerging from the inner tube is carried by the air flow in the outer tube into the fluidized bed where it is ignited and consumed.

Abstract: A method for polymer coating of chain link fence is disclosed. The thermoplastic polymer is applied in a fluidized bed after the fence is woven. The fence is compressed in the fluidized bed to allow coating of all portions of the chain link.

Abstract: An apparatus is disclosed for fluidizing and vaporizing particulate solid coating reactants by first establishing a fluidized bed of dispersed particulate solid coating reactants and thereafter drawing a volume of fluidizing gas and suspended particulate solid coating reactant to a vaporizer while mixing an additional volume of gas therewith and then vaporizing the dispersed particulate solid coating reactant in the reactant-gas mixture. The reactant-gas mixture is then directed into contact with a hot substrate to be coated in order to deposit a film thereon.

Abstract: The conductors of a cable core unit are powder filled by passing the core unit through a fluidized bed of powder with the conductors substantially closed together. The filled cable core unit can be wrapped with tape after exit from the fluidized bed. Cable cores may be filled also by passing them through a fluidized bed. The core units of the cores may be closed together or separated, but the conductors of each unit are closed together.

Abstract: For powder filling of cables, in a fluidized powder bed, it has been proposed to pass the cable core through the bed in a substantially closed condition. There is a limit to the number of conductors a core can have for effective filling. In the present invention the cable core is opened up into a number of core units by passing through an opening member. The opening member is freely ridable on the cable core and has a hole for each unit. The opener is held against a support member and an air bearing formed between the two members. Air is also usually fed to the holes in the opener member through which the core units pass to prevent flow of powder out from the bed. The opening member can be positioned in the fluidized bed or outside immediately prior to passage of the cable core through the bed. The units are each in a substantially closed condition in the bed and the units close to a single core also in the bed.

Abstract: A method of powder coating the inside of tubular goods, such as oil field pipe and the like, by connecting one end of the pipe to a means for producing a flow of compressible gases therethrough. The other end of the pipe is open to atmospheric pressure. A valve means is connected upstream of the pipe between the inlet end thereof and a container for holding a single charge of plastic powder. The charge of powdered plastic is isolated upstream of the pipe inlet. The charge is of sufficient size to coat the entire inside peripheral wall surface of the pipe with a substantial uniform coating of plastic.