METHOD AND APPARATUS FOR REMOVING BITUMINOUS MATERIALS FROM TUBES OR PIPES

Abstract: The present invention relates to a method for removing bituminous materials from tubes or pipes being coated on the outer surface and/or the inner surface with a layer of bitumen, and to an apparatus for carrying out said method. The tubes or pipes are submerged in vertical or substantially vertical position in a bath of bitumen (2) which has been heated to a temperature in the range of from 100 DEG C to 250 DEG C and are slowly removed from said bath (2) in the same or substantially the same position after 5 to 15 minutes. The apparatus consists of a container (1) which is filled with bitumen, can be heated to a temperature between 100 DEG C and 250 DEG C and has such a form and such dimensions that at said temperature said pipe can be positioned therein vertically or substantially vertically. Further, means (6) are provided to heat the contents of the container (1) to said temperature and to maintain said temperature, means (18) are provided to bring said pipe into the container (1) at said temperature and to remove the pipe from the container (1) after 5 to 15 minutes, and means (11) are provided to remove superfluous bitumen from the container (1).

Description: Method and apparatus for removing bituminous materials from tubes or pipes. The present invention relates to a method for removing bituminous materials from tubes or pipes being coated on the outer surface and/or the inner surface with a layer of bitumen, and to an apparatus for carrying out said method. In this specification, with bitumen is meant the dark coloured, semi-solid to solid, meltable mixture of high molecular hydrocarbons being obtained as residue in the process of the thermal treatment of petroleum (destination, cracking and so on) and the fraction of natural asphalt soluble in carbondisulfide, as well as tar, pitch and bituminous substances predominantly consisting of bitumen, tar and/or pitch. Metal tubes or pipes, e.g. ade of iron or steel, which are used for e.g. above-ground and underground pipe lines, usually for the transport of water or gas, and normally have a length of some meters to even 20 meters and a diameter which may be even 2 meters, are often coated with a layer of bitumen on the outer surface and/or the inner surface for protection against corrosion or other damage. Coating can be performed right after production of the pipes. Pipe lines for the transport of water or gas may be constructed immediately after the coating of the pipes or the pipes may be stored for later use without running any risk of corrosion or other damage. The layer of bitumen is applied to the pipe at increased temperature such that the bitumen becomes soft cr even fluid and can be processed convenien ly. Often the layer of bitumen is applied to the pipes with the aid of filamentous material or fabric, e.g. jute or a synthetic fibrous material, especially on the outer surface of the pipes, by submerging the fibrous material or the fabric in the liquid bitumen and wrapping said material or fabric around the pipes. When the metal of the tubes or pipes coated with bitumen is to be worked or discarded tubes or pipes coated with bitumen are to be made into scrap, the bitumen has to be removed first. Up to now the removal of the layer of bitumen from such tubes or pipes is far from simple. For pipes with an outer coating of bitumen the removal is performed for example by conveying hot air, combustion gases or a mixture therof, which has been obtained by means of a burning unit for gas or oil, through the pipe so that the bitumen softens, after which the bitumen is removed manually with knives or scrapers. This is a laborious and time- consuming work. Because of danger for fire the temperature cannot be raised too much. Moreover, heating may liberate noxious gases and vapours which may be dangerous for the persons removing the bitumen and on performing the job in the open may be harmful for the environment and on performing the job in a closed chamber may require special ven ilation means. Also it has been attempted to remove the layer of bitumen from the outer surface of a pipe by pulling the pipe by great force through the opening of a thick steel plate having a diameter equalizing the outer diameter of the pipe itself, and said opening possibly being provided with a sharp edge so that in this way the layer of bitumen is scraped from the pipe. Also this method is difficult to perform, while the apparatus is subject of heavy wear. For the removal of bitumen from the inner surface of upipes no practically .performable method is known. An object cf the present invention is a new method for the removal of bitumen from a tube or pipe covered on the outer surface and/or inner surface with a layer of bitumen. 5 further object of the present invention is a new apparatus for carrying out said method. On carrying out said method with said apparatus the method allows the bitumen with any fibrous material or fabric contained therein to be effectively removed from the pipe in a fast and safe fashion and moreover allows the recovery of the bitumen in a convenient form for the usual purposes. The method is characterized by the fact that the pipe coated with bitumen is submerged in vertical or substantially vertical position in a bath of bitumen which has been heated to a temperature in the range of from 100 °C to 250 °C and is slowly removed from said bath in the same position after 5 to 15 minutes, usualy 10 minutes. Bitumen softens in the temperature range of from 30 °.C to 70 °C and is fairly liquid in the temperature range of from 70 °C to 100 °C, but the viscosity is still too high for efficasiously carrying out the method according to the invention. Above 100 °C bitumen is fully liquid. Heating above 250 °C is not necessary and even undesired, as various noxious vapours and gases are escaping from the bitumen which have to be collected and/or removed. The bath of bitumen is kept preferably at a temperature in the range of from 160 °C to 200 °C, e.g. at a temperature of about 180 °C. At that temperature the viscosity is sufficiently low and the pipe coated with bitumen and submerged in the bath attains fast (within a few minutes) the temperature required for making the coating of bitumen fully liquid. The bitumen of the coating is then mixed very fast with the bitumen present in the bath and on removal of the pipe in vertical or substantialy vertical position the bitumen will flow down from the pipe like water so that the pipe leaves the bath without the inner and/cr outer coating of bitumen. The fibrous materials, fabrics and/cr other materials which are contained in the bituminous coating, and/or adherent materials (sand, small stones, pebbles and such kind of materials) are also taken up by the liquid bitumen and sink to the bottom of the bath. The contaminations collected on the bottom can be removed therefrom at intervals in a way and with means explained below when the apparatus according to the invention is described in detail. Thus, in this way also separation between the bitumen and said materials is effected. The apparatus according to the invention with which the method according to the invention can be carried out, consists of a container which is filled with bitumen, can be heated to a temperature between 100 °C and 250 °C and has such a form and such dimensions that at said temperature said pipe can be positioned therein vertically or substantially vertically. Further, means are provided to heat the contents of the container to said temperature and to maintain said temperature, means are provided to bring said pipe into the container at said temperature and to remove the pipe from the container after 5 to 15 minutes, means are provided to remove said contaminations at the bottom and means are provided to remove superfluous bitumen from the container. The invention is explained below by way of the FIGURES in the accompanying drawings showing examples of embodiments of an apparatus according to the invention. The examples of embodiments described below are not intended to restrict the invention in any way. FIG. 1 is a cross-sectional view take along the central vertical line of an apparatus according to the present invention; FIG. 2A and 2B are cross-sectional views of a schematicaliy ' designated sluice system for removal of materials from the apparatus shown in FIG. 1; FIG. 3 is a cross-sec ional view taken aior.g the central vertical line of another embodiment of an apparatus according to the invention; FIG. 4 is a fragmentary cross-sectional view of a detail of the apparatus according to FIG. 3 on an enlarged scale; FIG. 5, 6 and 7 are cross-sectional views of the 5 apparatus according to FIG. 3 taken along the lines V-V, VI-VI and VII-VII, respectively. The apparatus according to FIG. 1 comprises a container 1 with bitumen 2 which is placed in a wider container 3 which is provided with an insulation mantle 4 on 0 the exterior. The upper edges of the containers are on substantially the same level. Container 1 is made of steel plate having a thickness of 10 - 20 mm, e.g. 15 mm., has a circular cross-section and is rounded off at the bottom. Also a flat bottom is feasible. Container 3 is also a 5 cylinder made of steel plate of proper thickness, e.g. 25 mm. The containers may both have a form and cross-section different from those in the drawings, however the forms shown and the circular cross-section are preferred. ■ The diameter and the height of container 1 should be ϋ adapted, of course, to the diameter of the pipes to be treated. An internal diameter of 1,5 - 2,0 , e.g. 1,6 , and a height of 10 - 20 m, e.g. 15 , will do for the treatment of most of the pipes in current use. Container 1 is positioned in cylinder 3 in such a 5 way that at the bottom of the cylinder 3 a. space 5 remains available serving as a stoke-hole for heating the bitumen 2 in container 1. By means cf a burner 6 positioned at the bottom of cylinder 3 outside the stoke-hole 5 at the side therof and fed with gas or oil the container 1 can be heated 0 and maintained at said temperature. The diameter of cylinder 3 is adapted to that of the cylindrical container 1. With an external diameter of 1,6 m ' for container 1 and r. internal diameter of 2,0 for cylinder 3 an annular space 7 of about 20 cm is formed 5 ' between container 1 and cylinder 3. Hot combustion gases from the stoke-hole 5 are vented through this space 7. By means of metal guide strips or vanes 8 positioned in the interspace 7 in the spiral form around container 1 from the bottom to the top the path of the combustion gases to the outlet at the top of the apparatus is made longer so that the heat present in the gases is utilized in the most optimal way for bringing and maintaining the bitumen at the temperature required. The metal strips 8 are made, for example, of steel plate having a thichness of 5 mm and a width of 15 cm. The distance between the windings of the spiral of strips is e.g. 1,5 m- Also the height of cylinder 3 is adapted to that of the cylindrical container 1. The height of cylinder 3 above the bottom of the stoke-hole 5 is , for example, 16 m so that with a height of container 1 of 15 m the height of the stoke-hole is about 1 m. In the construction of the apparatus according to FIG. 1 a cylinder 3 of greater height is used, e.g. 18 m. This cylinder 3 is anchored, in a block or plate of armed concrete 9 a length of 2 m for providing a firm construction. The part of cylinder 3 extending from the block 9 of concrete is coated on the outside with an insulation mantle 4 consisting of e.g. a layer of sand having a thickness of about 40 cm and being enclosed in the space formed between the outside of the cylinder 3 and the inside of an outer cylinder surrounding the cylinder 3, said outer cylinder having a diameter of 2,8 m and being made of steel having a thichness of 3 mm. Instead of sand a different insulation material may be used, e.g. glass wool or a heat resisting foam material. Th bottom of the stoke-hcle 5 is covered with a layer of fire proof bricks 10 to inhibit loss of heat through the block 9 of concrete and also to protect the blc ? of concrete against toe high temperatures. The container 1 is filled with bitumen until about 2 meters below the upper edge thereof, so that in this case pipes with a maximum length of 13 m can be treated. On treatment of the pipes the volume of the bitumen increases. The level of the liquid bitumen 2 is kept constant at about 2 meters below the upper edge of container 1 by means of an overflow system 11 comprising a dischargeduct 11 (internal diameter 10 cm), one end of which being connected with an opening in the side wall of container 1 at a height of about 2 meters below the upper edge therof and the other end of which being provided with a valve 12, said dischargeduct running within the interspace 7 from said height down and extending below through the wall of cylinder 3 and the insulation mantle 4 to the valve 12 outside the apparatus. In this way the dischargeduct is maintained at the temperature within the apparatus and the bitumen which is present in said dischargeduct remains in the liquid state ensuring an unhindered discharge. Superfluous bitumen is removed from container 1 through this overflow system 11. The bitumen collected via valve 12 can be stored in drums, if desired, and/or be utilized as such for the usual purposes. At the high temperature to which the bitumen is heated, vapours and gases, among others polyσyclic aromatic hydrocarbons, may escape from the bitumen and such gaseous materials should be captured. For that purpose container 1 s closed with a removable lid 13 and a duct 14 (internal diameter 20 cm) is connected with the space above the bitumen through an opening in the side wall of the container 1, said duct 14 first extending horizontally through the side wall of container 3 and then turning off downwardly and being connected with.suction means or ventilator 15 which sucks away the gases and vapours mixed with air from above the bitumen. The mixture is supplied, supplemented with air if required, to the burner 6 and is burnt in admixture with the fuel supplied to the burner. When pipes coated with bitumen "filled" ■ with fibrous materials or fabrics are treated, then said fibrous materials or fabrics will sink to the bottom of the container 1 after the liquefaction of the coating of bitumen in the hot bath. Also. adherent contaminations (sand, small 5 stones, pebbels and such kind of materials) mix with the liquid bitumen and sink to the bottom of the container 1. In the embodiment of an apparatus according to the invention shown in FIG. 1 a removable grid 16 is installed at some distance above the bottom of container 1, said grid 0 collecting the fibrous materials and/or fabrics and other coarse materials. The grid 16 has a circular form and a slightly smaller diameter than container 1. The grid 16 rests on a number of supports 17 being secured to the side wall near the bottom of container 1. The grid 16 may be a 5 steel plate with perforations or may consist of a number of parallel bars at some distance from one another said bars being secured for example in a metal ring, or may consist of a pair of crossing bars connected to one another at' the points of intersection. The grid is preferably provided with an upward rim or side wall which is preferably perforated, so that in fact a perforated cylindrical trough is formed. A number of steel cables or chains 18 (at least 3) are secured to the grid or the perforated trough, said cables or chains allowing the grid or trough 16 to be hoisted from the 5 container 1 through the liquid bitumen. This is performed regularly between the successive treatments of pipes in order to remove the materials collected on the grid or in the trough, after which the grid or trough is replaced in the bath of bitumen by means of the steel cables or chains L ' 18 until it rests on the supports 17 again. Sand and other fine materials will pass the grid and will collect at the bottom. The lowest point of container 1 has an opening leading to a duct 19 (internal diameter e.g. 7,5 cm). The contaminations (sand, small stones and such ' • ' kind of materials) collected at the bottom of container 1 can be removed through this duct 19 and a valve 20. The removal of the contaminations can also be carried out by means of a sluice system schematically shown in FIG. 2A and 2B. The opening in the bottom of container 1 is communicating with an opening in the side wall of a horizontal tube 21. Tube 21 is provided with a coaxial, close-fitting tube 22 therein, tube 22 being closed at both ends and being glidable to and fro in tube 21 by means of a rod 23. Tube 22 is provided with two openings in the side wall lying opposite to each other (suitably in a shifted fashion), the upper opening corresponding with the opening in the side wall of tube 21 communicating with container 1 and the lower opening corresponding with an opening below in tube 21 communicating with the outletduct 19 such that when the upper opening connects tube 22 with container 1, the lower opening is closed and the reverse. Tube 22 is moved in tube 21 such that tube 22 communicates with container 1 (the lower opening in tube 22 and thus the entrance to duct 19 being closed) and tube 22 is filled with contaminations from container 1 (see FIG. 2A) . Then tube 22 is moved in tube 21 by means of the rod 23 such that tube 22 communicates with the outletduct 19 (the upper opening in tube 22 and thus the opening in the bottom of container 1 being closed) so that tube 22 can be empted in duct 19 (see FIG. 2B) . By moving tube 22 to and fro in tube 21 as required the contaminations (sand, small stones and such kind of materials) can be removed portionwise from container 1. Use of this sluice system makes valve 20 superfluous. For inserting the pipes to be treated in container I in vertical position and removing them from container 1 in the same position a hoisting apparatus is needed allowing the pipes to be hoisted so high that they can be brought in a vertical pos ion above the lid 13. Any suitable heis inς apparatus can be used, e.g. a portal crane or a hoisting apparatus with telescopic pipes. It should be appreciated that the distance between the highest attainable point of the hoisting apparatus and the lid 13 corresponds with at least the greatest length of the pipes to be treated in container 1. Thus, in the embodiment disclosed said point 5 should be about 30 . For inserting the pipes to be treated in container 1 and removing them from container 1 the lid 13 should be removed each time. The lid 13 can also be constructed in the form of a "diaphragm", i.e. the lid is composed of 4 or more o segments, each being secured at the upper edge of container 1 by means of hinges in such a way that the segments can be turned in upward direction as well as in downward direction. Moreover, the hinge of each segment is provided with a spring system keeping the segment in horizontal position so 5 that the container is kept closed. A pipe to be treated is brought above the "diaphragm" lid 13 in vertical position by means of the hoisting apparatus. When the pipe is lowered onto the lid 13, the weight thereof forces the hinged segments to turn downward and the pipe.can be lowered in the ϋ bath 2 of bitumen. The spring system closes the segments again after passage of the pipe so that the container 1 remains closed during the treatment of the pipe. When the pipe is hoisted from the container again, the hinged segments are turning upward and after passage of the pipe 5 the spring system closes the segments again. In the "diaphragm" lid in closed position a small central opening is left free which is sufficient large to allow the cable with which the pipe is hoisted into and out of the bath remaining secured to the pipe during the treatment in the c bath. At the start-up of the apparatus the bitumen in the container 1 will be solid. When the burner 6 is ignited, the bitumen at the bottom of the container I wii become liquid first. The bitumen at the bottom will expand and this can 5 lead to a dangerous local increase of pressure. To avoid this situation a duct 24 (internal diameter of 10 cm, wall thickness of 1 cm) is mounted in the interspace 7 along container 1 running from an opening in the side-wall of container 1 close to the bottom therof and upward in said 5 interspace to an opening in the side-wall of container 1 above the top level of the bitumen. As duct 24 is lying in the interspace 7 through which the hot combustion gases are flowing upwardly, the bitumen in said duct will become fluid in a very short time. During the heating of the container a 0 surplus of bitumen at the . ottom of container 1 can be discharged through duct 2 ~ .o the space above the bath of bitumen 2, so that the inc..-.rase of pressure at the bottom of container 1 during heating can be avoided. For safety reasons a pressure reducing valve 32 (see 5 FIG. 7) may be provided for at the bottom of the container 1 said valve coming into operation for discharging bitumen in the case of an unforeseen overpressure. After the heating of the bitumen to the required temperature the bitumen can be kept at said temperatuer by '0 means of a thermostat controlling the burner. The thermometer for measuring the temperature of the bath of bitumen 2 is suitably installed close to the bottom of container 1 (in FIG. 7 designated with reference numeral 33). 5 With the method according to the present invention pipes coated with bitumen can be decoated in a safe and fast way and in a manner fully acceptable from the point of view of environmental pollution control. After removal from the bath of bitumen the pipe(s ' ) may still be coated at most with a very thin film of bitumen which may be removed completely, if desired, by submerging the pipe(s) when still warm in a bath of an organic solvent being a good solvent for bitumen, e.g. carbondisuifide. After removal from the bath of bitumen 2 the pipeis) 35 can be cooled in the open air. However, if desired, the pipe(s) may be cooled faster by submerging in a tank with water. It should be noted that several pipes having different diameters can be decoated simultaneously by submerging a bundle of pipes being slided coaxially into each other in the bath of bitumen. In this way two, three, four or even more pipes can be decoated simultaneously, provided the diameters therof differ sufficiently to slide the pipes coaxially into each other. After the pipes have been slided into each other, they can be fixed with repect to each other whereafter the bundle of pipes is hoisted in the container 1 and after say 10 minutes removed from the container 1. In fact, the fixation of the pipes with respect to each other simply means that the pipes during the treatment in the bath and the hoisting into and out of the bath should be prevented from sliding out of each other. This may be simply accomplished by sliding the pipes into each other in horizontal position, bringing a firm cable through the inmost of the pipes and providing one end of the cable with a bar or plate of metal having a length which is greater than the diameter of the largest pipe. The other end of the cable running through the bundle of pipes is secured to the hoisting means and on hoisting up the bundle of pipes said bar or plate of metal being positioned across the bundle of pipes at one end thereof and the weight of the pipes on the bar or plate prevent that the pipes slide out of each other during the hoisting into the bath, the treatment in the bath and the removal from the bath. With the method according to the present invention a bundle of pipes slided into each other can also be treated effectively due to the good flowability of the bitumen at the temperature of treatment. Moreover, the space between the pipes slided into each other increases in fact due to the liquefaction of the coating of bitumen making the flowing away of the bitumen from between the pipes easier when hoisting the pipes out of the bath. In the embodiment of the apparatus described above the gases and vapours escaping from the bitumen are sucked off and tranported to the burner. In the variant of of a sucking system described below said gases and vapours are not transported to the burner in order to avoid any risk of detrimentally affecting the operation of the burner. Said variant of a sucking system is illustrated in FIG. 3 - 7 showing another apparatus according to the invention. Parts of the apparatus according to FIG. 3 - 7 corresponding with parts of the apparatus according to FIG. 1 are designated with the same reference numerals. As shown in FIG. 3 two annular chambers 25 and 26 made of metal are provided for in the upper part of the interspace 7 around container 1. Also the stoke-hole 5 is provided with an annular chamber 27 of metal. Chamber 25 is in communication with the space in the container 1 above the bitumen by means of horizontal slits 28 being present in the wall of the container 1 and running from chamber 25 in inclined downward direction through the wall of container 1 (see FIG. 4 with an enlarged detail of FIG. 3). The slits have a width of e.g. 3 mm and a horizontal length of e.g. 10 cm, the distance between the slits around container 1 being e.g. 2 cm. " Through duct 29 chamber 25 is also connected with the blow side of a blower 30, while the suck side of the blower is connected with chamber 27 around the stoke-hole 5. The annular chamber 26 is connected with the chamber 27 through duct 31, as indicated in FIG. 3. Preferably three ducts 31 (internal diameter e.g. 10 cm) are applied at mutual distances of 120® around chamber 26 (see FIG. 5 - 7). The annular chamber 26 is communicating further with the space above the bitumen in container 1 through a number cf openings in the side wail of container 1. The air circulation system thus formed operates as follows: Eiower 30 propels hot air from chamber 27 through duct 29 to chamber 25 and then by force through the slits 23 in the space of container 1 above the bitumen in an inclined downward direction. Blower 30 provides a subpressure in chamber.27 so that air is sucked from chamber 26 through 5 duct(s) 31 and in this way through the openings in the wall of the container 1 from said container just above the surface of the bitumen. This air entraineε the gases and vapours escaping from the heated bitumen through chamber 26 and duct(s) 31 to chamber 27. This is promoted by means of 0 the inclined downwardly directed stream of air coming from the slits 28. The combustible vapours and gases escaping from the bitumen and entrained to chamber 27 come into contact with the very hot surface of the wall of cylindrical container- 3 in chamber 27, so that said vapours and gases 5 are heated above their ignition . temperature and are burnt in chamber 27. The combustion gases are tranported through blower 30, duct 29, chamber 25 and slits 28 to the space above the bitumen in container 1. Superfluous combustion gases and air, hardly containing.any noxious substances, are 0 escaping through openings in the lid 13 to the open air. When the chambers 25 and 26 would block completely the annular passage through interspace 7, an outlet for the combustion gases from the stoke-hole 5 should be made below chamber 26 through the walls of the containers .1 and 3 and 5 the insulation mantle 4. The hot air in the air circulation system blown through the slits 28 in inclined downward direction has further advantages therein that during the hoisting of the pipe out of the bath this air is blown by force against the - outer surface of the pipe entirely around the pipe so that the liquid bitumen even more effectively flows down from the pipe, i.e. is blow off the pipe. In the cross sections in FIG. 5 - 7 there is shown that in the embodiment of the apparatus according to FIG. 3 ~ ~ duct 31 is present in triplicate, which also holds for ducts 11 and 24. Further, 3 chains or cables 18 are present. With the method and the apparatus according to the invention also cables coated with bitumen and having for example a core of copper can be decoated by hanging these cables in the bath of liquid bitumen for some time. In this way the copper can be reclaimed fast as well as the bitumen. This method offers big advantages in comparison with conventional burning off. Also metal parts coated with bitumen, e.g. parts of motor vehicles, can be decoated with the method and the apparatus according to the invention. The method according to the invention can be carried out in the apparatus in a semi-continuous way by using above the apparatus a kind of "merry-go-round"-hoistsystem by which a number of pipes are hanged. The "merry-go-round"- . hoistsytem can be programmed such that a pipe to be treated is hoisted down in the bath, hanged in the bath for a predetermined time en then hoisted out of the bath. This pipe is then automatically transported until above a bath containing water and hoisted in the bath for cooling down. Simultaneously a next pipe to be treated is hoisted above the container 1 and then in the bath. During the removal of this next pipe from container 1 after the predetermined time the cooled pipe is removed from the water bath simultaneously. The "merry-go-round"-system is set in motion again for tranporting the pipes further, wherafter a next pipe is treated and the preceding pipe is cooled, and so on. The residence time of a pipe in the bath of bitumen is sufficient long to replace a new pipe to be treated for a decoated and cooled pipe in the "merry-go-round"-system. The semi-continuous method is interrupted at a suitable moment for the removal, the cleaning and the replacement of the • grid or -trough 16. Within the scope of the invention various modifications can be made in the apparatus which are obvious for a person skilled in the art after reading the foregoing specification .

Claims: Cl a ims . 1. Method for removing bituminous materials from tubes or pipes being coated on the outer surface and/or the inner surface with a layer of bitumen characterized in that the tube or pipe coated with bitumen is submerged in vertical or substantially vertical position in a bath of bitumen which has been heated to a temperature in the range of from 100 °C to 250 °C and is slowly removed from said bath in the same or substantially the same position after 5 ■to 15 minutes. 2. Method according to claim 1, characterized in that the bath of bitumen has a temperature in the range of from 160 °C to 200 °C 3- Method according to claim 2, characterized in that the bath of bitumen has a temperature of about 180 °C. 4. Method according to claim 1 - 3, characterized in that for the treatment of several pipes having different diameters these pipes are slided into each other and treated in that way by said method. 5. Apparatus for carrying out the method according to claims 1 - 4, consisting of a container (1) which is filled with bitumen (2), can be heated to a temperature between 100 ?C and 250 °C and has such a form and such dimensions that at said temperature said pipe can be positioned therein vertically or substantially vertically, whereby means are provided to heat the contents cf the container ■ (1) to said temperature and to maintain said temperature, means are provided to _brinς said pipe into the container (1) at said temperature and to remove the pipe from the container (1) after 5 to 15 minutes and means are provided to remove superfluous bitumen from the container (1). 6. Apparatus according to claim 5, characterized in that the container (1) with bitumen (2) is placed in a wider container (3) which is provided with an insulation mantle (4) on the exterior, said container (1) being positioned in container (3) in such a way that at the bottom of the container (3) a space (5) remains available serving as a stoke-hole (5) for heating the container (1) with bitumen, that the means to heat container (1) with its contents to said temperature and to maintain said temperature consists of a burner (6) fed with gas or oil and burning into the stoke-hole (5) and that the interspace (7) between the containers (1,3) serves as dischargeduct for the combustion gases whereby by means of metal guide strips or vanes (8) positioned in the interspace (7) the path of the combustion gases to the outlet at the top of the apparatus is extended. 7. Apparatus according to claim 5 - 6, characterized in that the means to remove superfluous bitumen from the container (1) and to keep the level of the liquid bitumen (3) in the container (1) constant consists of an overflow system comprising at least one dischargeduct (11), one end of which being connected with an opening in the side wall of container (1) with bitumen (2) at a height corresponding to said level and the other end of which being provided with a valve (12), said dischargeduct running within the interspace (7) from said height down and extending bel w through the wall of container (3) and the insulation mantle 'X. ) , whereby superfluous bitumen is discharged from the container X ) through the valve (12). 8. Apparatus according tc claim 5 - 7, characterized in that a duct .14) is connected with the space above the bitumen through an opening in the side wall of the container (1), said duct (14) extending through the side wall of container (3) and the insulating mantle (4) and being connected with suction means or ventilator (15) which sucks away from above the bitumen air mixed with any gases and vapours which are originating from the bitumen, and supplies this mixture to the burner (6) where it is mixed with the fuel. 9. Apparatus according to claim 5 - 8, characterized in that a removable grid or a perforated cylindrical trough (16) is installed near the bottom of container (I) with bitumen (2), said grid or trough collecting the fibrous materials and/or fabrics and/or other coarse contaminations which are present in " the bitumen to be removed from a pipe and by which grid or trough with the aid of chains or cables secured to the grid or the trough, said materials and/or fabrics and/or said contaminations are removed from the bath of bitumen. 10. Apparatus according to claim 5 - 9, characterized in that at the lowest point of container (1) a duct (19) with valve (20) is present through which duct contaminations (sand, small stones and such kind of materials) collected at the bottom of container (1) can be removed. 11. Apparatus according to claim 5 - 9, characterized in that below the lowest point of container (1) a sluice system (21,22,23) is present consisting of a tube (21) closed at both ends, said tube (21) being provided with a coaxial, close-fitting tube (22) therein, tube (22) also being closed at both ends and being giidable to and fro in tube (21) by means of a rod (23), whereby tube (21) is provided with two openings in the side wall lying opposite to each other, if desired in a shifted fashion, one opening communicating with container (1) at the lowest point thereof and the other communicating with the outletduct (19) and the side wall of tube (22) being provided with openings corresponding therewith such that these cannot correspond therewith simultaneously so that by gliding to and fro the tube (22) by means of the rod (23) the contaminations (sand, small stones and such kind of materials) collected at the bottom of container (1) are removed portionwise from container (1) . 12. Apparatus according to claim 1 - 11, characterized in that for preventing unwanted pressure increases at the bottom of the container (1), for example during the start up heating, at least one duct (24) is 5 mounted in the interspace (7) connecting a location inside container (1) near the bottom thereof with the space above the bitumen in the container (1). 13. Apparatus according to claim 1 -7 or 9 - 12, 0 characterized in that above the level of the bitumen in the container (1) two annular chambers (25) and (26) are provided for around container (1) in the interspace (7) lying above each other, each being connected through at least one opening with the space above the bitumen in 5 container (1) and through at least one duct (29 and 31, respectively) with ' an annular chamber (27) provided for around the stoke-hole (5), thus forming an air circulation system, and in duct (29) a blower (30) is provided for propelling hot air from chamber (27) to chamber (25) and ^ blowing it through the opening(s) between chamber (25) and the space in container (1) above the bitumen into container (1) and from said space through the cpening(s) between the space in container (1) above the bitumen and chamber (26) through chamber (26) and duct (31) back to chamber (27) and 5 thereby entraining the gases and vapours escaping from the liquid bitumen from the space above the bitumen to chamber (27) where they are burnt through contact with the very hot surface of the wall of stoke-hole (5). 14. Apparatus according to claim 13, characterized in that between the upper chamber (25) and the space in container (1) above the bitumen openings are provided for in the wall of container (1) in the form of inclined downwardly directed slits (28)

Inventors: HENDRIKUS JOHANNES SWANENBERG, HENDRIKUS, JOHANNES, SWANENBERG
Applicants: SWANENBERG BEHEER BV, SWANENBERG BEHEER B.V.
Application year: 1993
Main classification: B08B7
IPC codes: B08B7, B08B9