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WO1993000212A1 - A method of coating a plastic pipe and a plastic pipe coated by the method - Google Patents

A method of coating a plastic pipe and a plastic pipe coated by the method Download PDF

Info

Publication number
WO1993000212A1
WO1993000212A1 PCT/FI1992/000201 FI9200201W WO9300212A1 WO 1993000212 A1 WO1993000212 A1 WO 1993000212A1 FI 9200201 W FI9200201 W FI 9200201W WO 9300212 A1 WO9300212 A1 WO 9300212A1
Authority
WO
WIPO (PCT)
Prior art keywords
pipe
protective coating
plastic
coating
surface layer
Prior art date
Application number
PCT/FI1992/000201
Other languages
French (fr)
Inventor
Jyri Järvenkylä
Mikael Andersson
Anders Vestergaard
Original Assignee
Uponor N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Uponor N.V. filed Critical Uponor N.V.
Priority to DE4291982A priority Critical patent/DE4291982B4/en
Publication of WO1993000212A1 publication Critical patent/WO1993000212A1/en
Priority to GB9303660A priority patent/GB2263524B/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H59/00—Adjusting or controlling tension in filamentary material, e.g. for preventing snarling; Applications of tension indicators
    • B65H59/10—Adjusting or controlling tension in filamentary material, e.g. for preventing snarling; Applications of tension indicators by devices acting on running material and not associated with supply or take-up devices
    • B65H59/36—Floating elements compensating for irregularities in supply or take-up of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
    • B29C63/02—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material
    • B29C63/04—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material by folding, winding, bending or the like
    • B29C63/06—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material by folding, winding, bending or the like around tubular articles
    • B29C63/065—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material by folding, winding, bending or the like around tubular articles continuously
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
    • B29C63/0056—Provisional sheathings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
    • B29C63/02—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material
    • B29C63/04—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material by folding, winding, bending or the like
    • B29C63/08—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material by folding, winding, bending or the like by winding helically
    • B29C63/10—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material by folding, winding, bending or the like by winding helically around tubular articles
    • B29C63/105—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor using sheet or web-like material by folding, winding, bending or the like by winding helically around tubular articles continuously
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H51/00—Forwarding filamentary material
    • B65H51/20—Devices for temporarily storing filamentary material during forwarding, e.g. for buffer storage
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L57/00—Protection of pipes or objects of similar shape against external or internal damage or wear
    • F16L57/06—Protection of pipes or objects of similar shape against external or internal damage or wear against wear
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/15—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor incorporating preformed parts or layers, e.g. extrusion moulding around inserts
    • B29C48/151—Coating hollow articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B29C48/19—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their edges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B29K2023/0608—PE, i.e. polyethylene characterised by its density
    • B29K2023/0633—LDPE, i.e. low density polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2023/00—Tubular articles
    • B29L2023/22—Tubes or pipes, i.e. rigid

Definitions

  • a method of the present invention for coating a plastic pipe and a plastic pipe coated by the method aim at avoiding the above-mentioned problems in such a way that the electric welding of pipes ready for installation can be carried out by the welder without any laborious preparation steps.
  • the method of the invention is thus charac ⁇ terized in that the surface layer is made of plastic upon the pipe to form a protective coating by a suit- able coating technique, and that the protective coat ⁇ ing is made easily detachable at least at the ends of the pipe.
  • the welding can be carried out more easily, and safety at work is increased when using the method of the invention.
  • Safety at work and the quality of the work are also affected by the fact that the pipes simply cannot be welded without removing the coating within the joint area on account of the outer diameter of the pipes which is greater than normally. Consequently, joint ⁇ ing with mechanical joints and/or welding is always carried out with clean pipe ends, which ensures successful welding and appropriate performance of the working machines.
  • the pipe of the invention is characterized in that the surface layer forms a protective coating on the pipe in such a way that the protective coating is easily detachable at least within the area of the pipe ends. .
  • the protective coating provided in the pipe according .to the invention also prevents UV radiation from reaching the surface layer of the pipe itself, where it would cause decomposition reactions.
  • plastic pipes are UV stabilized according to the re- quirements of each particular case by through-dyeing them with expensive colour agents often containing poisonous heavy metals. In a pipe provided with a protective coating this is not necessary but the UV protection and requisite dyeing are effected only in the protective coating with considerably lower costs and reduced environmental effects.
  • FIG 1 shows one embodiment of the method of the invention
  • Figure 2 shows another embodiment of the method of the invention
  • Figure 3 shows a pipe of the invention in a welding situation and partly in section.
  • a plastic pipe 2 is coated by means of co-extrusion with a surface layer according to the method of the invention.
  • the surface layer is extruded from molten plastic material 1 upon the pipe 2 of nominal size so as to form a protective coating 3.
  • Co-extrusion nozzles 5, such as so-called cro ⁇ shead nozzles, are obvious to one skilled in the art, and so the co-extrusion will not be described in any greater detail herein.
  • the protective coating is made easily detachable over its entire length or at least at the pipe ends.
  • the surface layer 3 or protective coating of the pipe 4 formed according to the invention can be made e.g of linear LDPE or recycled waste plastic.
  • linear LDPE low density polyethylene
  • waste plastic is advantageous in that it is very cheap and especially suitable for the use according to the invention, which is highly tolerant e.g to variation in the quality of the plastic material.
  • the protective coating is made of a plastic material which is poorly weldable or cannot be welded at all. In this way, the worker will notice at the welding stage at the latest if the protective coating should not have been removed. It is also to be considered on selecting the material that if the protective coating formed by the surface layer of the pipe is made of a plastic differing chemically from the pipe material, the adhesion between the pipe and the protective layer will probably not be as good as when using similar materials.
  • the adhesion properties between the pipe and the protective coating can be advantageously affected by adding a considerable amount of fillers to the protective coating, or by forming the protective coating on the pipe at a rel ⁇ atively low temperature.
  • This can be contributed to with a suitable shaping of the tool so that e.g. a so-called cold seam is formed at the crosshead, opposite to the material feed point, and on the other side of the pipe, at which the coating tears easily.
  • Both methods aim at making the surface of the pro ⁇ tective coating to be formed relatively hard, that is, reduce its . tendency to adhere, and making it relatively hard in structure, so that it is easy to detach from the pipe e.g. by knocking.
  • Suitable fillers include chalk and talc.
  • FIG. 2 Another embodiment of the method of the invention is shown, that is, coating of a plastic pipe 6 with a surface layer 7 to form a protective coating by spirally winding with a tangential nozzle 8.
  • This coating method also enables "mechanical" detachment of the protective coating, that is, the surface of the pipe is revealed by re ⁇ moving the spirally wound protective coating by tear- ing from the end of the coating (cf. Figure 3) .
  • a suitable spiral tear seam can be achieved e.g. by rotating the tool 5 shown in Figure 1.
  • Such an intentionally formed seam can further be formed into a "cold seam", thus further improving the tearing properties, by cooling the co-extrusion tool 5 locally by a water circula ⁇ tion, for example.
  • the co-extru ⁇ ion tool 5 can also be cooled locally in such a way that a longitudinal tear seam is formed in the surface layer 3. It is also possible to provide the protective coating with a longitudinal tear cord or with a thinner strip, whereby an easily tearable seam is obtained in the axial direction.
  • a peel-off effect can be produced in the protective coating, which is charac ⁇ terized by that the strength ' properties of the layer are different in the radial and axial direction.
  • an agent preventing adhesion is introduced between the pipe and the surface layer forming the protective coating at the coating stage.
  • agents promoting weldability and/or crosslinking are also possible.
  • One suitable agent for improving welding properties is dicumyl peroxide.
  • Crosslinking agents supplement the cross- linking reactions of the pipe material in the attachment surface and lubricates the surface, which is of advantage also in view of reducing the adhesion of the protective coating.
  • Crosslinking agents may be the same generally known radicals as used in the matrix material of the pipe.
  • the above-mentioned agents can be introduced between the pipe and the protective coating e.g. through a separate nozzle 9 in the form of a thin plastic film 10 containing such agents, as shown in Figure 2.
  • this type of layer can also be formed by co-extrusion.
  • Figure 3 shows schematically the structure of a pipe 11 according to the invention.
  • the surface layer that is, a protective coating 12 is formed upon a pipe 13 of nominal size in such a way that it is easily detachable.
  • the protective coating made of linear LDPE or recycled waste plastic, for example, is extruded on the pipe by co-extrusion or wound by a tangential nozzle.
  • a sufficient amount of fillers is added to the protective coating to achieve a rigid structure, and colouring and UV stabilizing agents are also added, whereby no such agents are needed in the pipe to be protected.
  • the pipe itself is of undyed plastic which has not been UV stabilized while the protective coating contains the identifying colour agents and UV stabilizing agents.
  • this plastic film may also contain other desired agents to be introduced between the surfaces, such as agents promoting weldability and cross ⁇ linking.
  • the protective coating 12 is peeled off at the ends 15 of the pipes to be welded together (cf. Figure 3) ; the pipe ends are positioned against each other; and the welding, such as electric welding (electrofusion socketing) , is carried out in a known manner. Thereafter the pipe laying is continued as usual as the protective coating on the surface of the pipe does not affect the installation in any way.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)
  • Laminated Bodies (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Abstract

The invention relates to a method of coating a plastic pipe with a surface layer and a plastic pipe coated with a surface layer. The surface layer (12) is formed of plastic upon a pipe (13) into a protective coating by a suitable coating technique in such a way that the protective coating is easily detachable at least at the pipe ends.

Description

A method of coating a plastic pipe and a plastic pipe coated by the method
In the handling, installation and connection of plastic pipes, the pipe surface is extremely liable to damage. In modern plastic pipe installation techniques, for example, a tunnel is bored in the ground for the pipe, and the pipe is then pushed through the tunnel e.g. into an excavation where the following joint is to be made.
It is clear that the pipe becomes scratched and dirty when handled in this way. This is disadvanta¬ geous firstly as the pipe material may be notch sensitive, in which case scratches cause greater damages in the pipe during subsequent handling. Secondly, dirt on the pipes prevents successful welding. Today, PE pipes in particular are jointed together by electric welding (electrofusion socket¬ ing) , and almost the only reason for unsuccessful welding by this technique is that the surface of the pipe is dirty or oxidized. Therefore the pipe ends always have to be cleaned with sand paper, for example, before jointing. In practice, the cleaning result is often uneven (the underside of the pipe is treated less carefully) and the quality depends on the professional skill of the worker.
A method of the present invention for coating a plastic pipe and a plastic pipe coated by the method aim at avoiding the above-mentioned problems in such a way that the electric welding of pipes ready for installation can be carried out by the welder without any laborious preparation steps.
The method of the invention is thus charac¬ terized in that the surface layer is made of plastic upon the pipe to form a protective coating by a suit- able coating technique, and that the protective coat¬ ing is made easily detachable at least at the ends of the pipe.
In addition to the obvious advantages asso- ciated with the protection of the pipe, the welding can be carried out more easily, and safety at work is increased when using the method of the invention. Safety at work and the quality of the work are also affected by the fact that the pipes simply cannot be welded without removing the coating within the joint area on account of the outer diameter of the pipes which is greater than normally. Consequently, joint¬ ing with mechanical joints and/or welding is always carried out with clean pipe ends, which ensures successful welding and appropriate performance of the working machines.
Other preferred embodiments of the method of the invention are characterized by what is disclosed in the accompanying claims. The pipe of the invention is characterized in that the surface layer forms a protective coating on the pipe in such a way that the protective coating is easily detachable at least within the area of the pipe ends. . The protective coating provided in the pipe according .to the invention also prevents UV radiation from reaching the surface layer of the pipe itself, where it would cause decomposition reactions. Today, plastic pipes are UV stabilized according to the re- quirements of each particular case by through-dyeing them with expensive colour agents often containing poisonous heavy metals. In a pipe provided with a protective coating this is not necessary but the UV protection and requisite dyeing are effected only in the protective coating with considerably lower costs and reduced environmental effects.
Other preferred embodiments of the pipe of the invention are characterized by what is disclosed in the accompanying claims. In the following the invention will be described in greater detail by means of examples with reference to the attached drawings, in which
Figure 1 shows one embodiment of the method of the invention; Figure 2 shows another embodiment of the method of the invention; and
Figure 3 shows a pipe of the invention in a welding situation and partly in section.
In Figure 1, a plastic pipe 2 is coated by means of co-extrusion with a surface layer according to the method of the invention. The surface layer is extruded from molten plastic material 1 upon the pipe 2 of nominal size so as to form a protective coating 3. Co-extrusion nozzles 5, such as so-called croεshead nozzles, are obvious to one skilled in the art, and so the co-extrusion will not be described in any greater detail herein. Using means according to the basic method or other means to be described below, the protective coating is made easily detachable over its entire length or at least at the pipe ends. It is essential that the protective coat¬ ing can be detached when required with simple means without the use of edge tools or other similar means causing scratches so as to keep the surfaces to be welded as intact as possible. One well-known way of removing the surface layer is to utilize the so- called peel-off effect, which is created when the strength properties of the coating are different in the radial and axial direction. The surface layer 3 or protective coating of the pipe 4 formed according to the invention can be made e.g of linear LDPE or recycled waste plastic. An advantage of linear LDPE is that, considering its price, it has a high scratch resistance and burst strength, whereas waste plastic is advantageous in that it is very cheap and especially suitable for the use according to the invention, which is highly tolerant e.g to variation in the quality of the plastic material. It is really an advantage that the protective coating is made of a plastic material which is poorly weldable or cannot be welded at all. In this way, the worker will notice at the welding stage at the latest if the protective coating should not have been removed. It is also to be considered on selecting the material that if the protective coating formed by the surface layer of the pipe is made of a plastic differing chemically from the pipe material, the adhesion between the pipe and the protective layer will probably not be as good as when using similar materials. In addition, the adhesion properties between the pipe and the protective coating can be advantageously affected by adding a considerable amount of fillers to the protective coating, or by forming the protective coating on the pipe at a rel¬ atively low temperature. This can be contributed to with a suitable shaping of the tool so that e.g. a so-called cold seam is formed at the crosshead, opposite to the material feed point, and on the other side of the pipe, at which the coating tears easily. Both methods aim at making the surface of the pro¬ tective coating to be formed relatively hard, that is, reduce its . tendency to adhere, and making it relatively hard in structure, so that it is easy to detach from the pipe e.g. by knocking. Suitable fillers include chalk and talc.
With reference to Figure 2, another embodiment of the method of the invention is shown, that is, coating of a plastic pipe 6 with a surface layer 7 to form a protective coating by spirally winding with a tangential nozzle 8. This coating method also enables "mechanical" detachment of the protective coating, that is, the surface of the pipe is revealed by re¬ moving the spirally wound protective coating by tear- ing from the end of the coating (cf. Figure 3) .
In the case of co-extrusion, a suitable spiral tear seam can be achieved e.g. by rotating the tool 5 shown in Figure 1. Such an intentionally formed seam can further be formed into a "cold seam", thus further improving the tearing properties, by cooling the co-extrusion tool 5 locally by a water circula¬ tion, for example. The co-extruεion tool 5 can also be cooled locally in such a way that a longitudinal tear seam is formed in the surface layer 3. It is also possible to provide the protective coating with a longitudinal tear cord or with a thinner strip, whereby an easily tearable seam is obtained in the axial direction.
In these ways, a peel-off effect can be produced in the protective coating, which is charac¬ terized by that the strength 'properties of the layer are different in the radial and axial direction.
In one preferred embodiment of the method of the invention, an agent preventing adhesion is introduced between the pipe and the surface layer forming the protective coating at the coating stage. At the same time, taking into account the use for which the pipe to be formed is intended, it is also possible to introduce agents promoting weldability and/or crosslinking between the pipe and the surface layer forming the protective coating. One suitable agent for improving welding properties is dicumyl peroxide. Crosslinking agents supplement the cross- linking reactions of the pipe material in the attachment surface and lubricates the surface, which is of advantage also in view of reducing the adhesion of the protective coating. Crosslinking agents may be the same generally known radicals as used in the matrix material of the pipe. The above-mentioned agents can be introduced between the pipe and the protective coating e.g. through a separate nozzle 9 in the form of a thin plastic film 10 containing such agents, as shown in Figure 2. Of course, this type of layer can also be formed by co-extrusion.
Figure 3 shows schematically the structure of a pipe 11 according to the invention. The surface layer, that is, a protective coating 12 is formed upon a pipe 13 of nominal size in such a way that it is easily detachable.
The protective coating made of linear LDPE or recycled waste plastic, for example, is extruded on the pipe by co-extrusion or wound by a tangential nozzle. A sufficient amount of fillers is added to the protective coating to achieve a rigid structure, and colouring and UV stabilizing agents are also added, whereby no such agents are needed in the pipe to be protected. Accordingly, in one preferred embodiment of the invention, the pipe itself is of undyed plastic which has not been UV stabilized while the protective coating contains the identifying colour agents and UV stabilizing agents.
If the adhesion between the pipe and the protective coating cannot be adjusted to a desired level in any other way during the production process, it is possible in one embodiment of the invention to insert a thin plastic film preventing adhesion between 14 the pipe and the surface layer forming the protective coating. In addition to agents preventing adhesion, this plastic film may also contain other desired agents to be introduced between the surfaces, such as agents promoting weldability and cross¬ linking.
When using the pipe according to the invention the protective coating 12 is peeled off at the ends 15 of the pipes to be welded together (cf. Figure 3) ; the pipe ends are positioned against each other; and the welding, such as electric welding (electrofusion socketing) , is carried out in a known manner. Thereafter the pipe laying is continued as usual as the protective coating on the surface of the pipe does not affect the installation in any way.
It is obvious to one skilled in the art that the different embodiments of the invention are not restricted to the examples described above, but they may vary within the scope of the accompanying claims.

Claims

Claims:
1. Method of coating a plastic pipe with a sur¬ face layer, c h a r a c t e r i z e d in that the surface layer (3; 7; 12) is made of plastic on the pipe (2; 6; 13) to form a protective coating by a suitable coating technique, and that the protective coating is made easily detachable at least at the ends of the pipe.
2. Method according to claim 1, c h a r a c ¬ t e r i z e d in that the surface layer (3) is formed upon a pipe (2) of nominal size as a pro¬ tective coating by co-extrusion.
3. Method according to claim 2, c h a r a c - t e r i z e d in that the co-extrusion tool (5) is rotated so as to form a spiral seam in the surface layer (3) .
4. Method according to claim 2, c h a r a c ¬ t e r i z e d in that the co-extrusion tool (5) is cooled locally so that a longitudinal seam is formed in the surface layer (3) .
5. Method according to claim 1, c h a r a c ¬ t e r i z e d in that the surface layer (7) is formed on a pipe (6) of nominal size as a protective coating by a tangential nozzle (8) by spirally winding.
6. Method according to any of claims 1 to 5, c h a r a c t e r i z e d in that the protective coating (3; 7; 12) formed by the surface layer of the pipe (2; 6; 13) is made of linear LDPE.
7. Method according to any of claims l to 5, c h a r a c t e r i z e d in that the protective coating (3; 7; 12) formed by the surface layer of the pipe (2; 6; 13) is made of recycled waste plastic.
8. Method according to claims l to 7, c h a r - a c t e r i z e d in that the protective coating (3; 7; 12) formed by the surface layer of the pipe (2; 6; 13) is made of a plastic differing chemically from the material of the pipe.
9. Method according to any of claims 1 to 8, c h a r a c t e r i z e d in that a substantial amount of fillers is added to the protective coating (3; 7; 12) of the pipe (2; 6; 13).
10. Method according to any of claims 1 to 9, c h a r a c t e r i z e d in that the protective coating (3; 7; 12) is formed on the pipe (2; 6; 13) at a relatively low temperature to reduce its adhesion to the surface of the pipe.
11. Method according to any of claims 1 to 10, c h a r a c t e r i z e d in that an agent prevent¬ ing adhesion is introduced between (14) the pipe (2; 6; 13) and the protective coating (3; 7; 12) at the coating stage.
12. Method according to any of claims 1 to 11, c h a r a c t e r i z e d in that an agent promoting weldability is introduced between (14) the pipe (2; 6; 13) and the protective coating (3; 7; 12) at the coating stage.
13. Method according to any of claims 1 to 12, c h a r a c t e r i z e d in that an agent promoting crosslinking of the pipe material is introduced between (14) the pipe (2; 6; 13) and the protective coating (3; 7; 12) at the coating stage.
1 . Method according to any of claims 9 to 13, c h a r a c t e r i z e d in that the agents to be introduced between
(14) the pipe (2; 6; 13) and the protective coating (3; 7; 12) are introduced between the pipe and the protective coating at the coating stage through a separate nozzle (9) in the form of a thin plastic film (10) containing these agents.
15. Plastic pipe coated with a surface layer c h a r a c t e r i z e d in that the surface laye (3; 7; 12) forms a protective coating on the pipe (2 6; 13) in such a way that the protective coating i easily detachable at least within the area of th pipe ends.
16. Plastic pipe according to claim 15 c h a r a c t e r i z e d in that the surface laye (3; 7; 12) is formed on a pipe (2; 6; 13) of nomina size as a protective coating.
17. Plastic pipe according to claim 15 or 16 c h a r a c t e r i z e d in that the protectiv coating formed by the surface layer (3; 7; 12) is o linear LDPE.
18. Plastic pipe according to claim 15 or 16, c h a r a c t e r i z e d in that the protectiv layer formed by the surface layer (3; 7; 12) of th pipe is of recycled waste plastic.
19. Plastic pipe according to any of claims 1 to 18, c h a r a c t e r i z e d in that th protective coating formed by the surface layer (3; 7; 12) of he pipe is of a plastic differing chemicall from the material of the pipe.
20. Plastic pipe according to any of claims 15 to 19, c h a r a c t e r i z e d in that a substantial amount of fillers is added to the protective coating (3; 7; 12) of the pipe.
21. Plastic pipe according to any of claims 15 to 20, c h a r a c t e r i z e d in that an agent preventing adhesion is introduced between (14) the pipe (2; 6; 13) and the protective coating (3; 7; 12) .
22. Plastic pipe according to any of claims 15 to 21, c h a r a c t e r i z e d in that an agent promoting the weldability of the pipe is introduced between (14) the pipe (2; 6; 13) and the protective coating (3; 7; 12) .
23. Plastic pipe according to any of claims 15 to 22, c h a r a c t e r i z e d in that an agent promoting the crosslinking of the pipe material is introduced between the pipe (2; 6; 13) and the protective coating (3; 7; 12).
24. Plastic pipe according to any of claims 21 to 23, c h a r a c t e r i z e d in that a thin plastic film (10) containing the desired agents to be introduced between the pipe (2; 6; 13) and the protective coating (3; 7; 12) is inserted between (14) the pipe and the coating.
25. Plastic pipe according to any of claims 15 to 24, c h a r a c t e r i z e d in that the pipe
(2; 6; 13) is of undyed plastic which has not been UV stabilized while the protective coating (3; 7; 12) contains the identifying colour agents and UV stabilizing agents of the pipe.
26. Plastic pipe according to any of claims 15 to 25, c h a r a c t e r i z e d in that the strength properties of the protective coating (3; 7; 12) are different in the radial and axial direction.
PCT/FI1992/000201 1991-06-28 1992-06-26 A method of coating a plastic pipe and a plastic pipe coated by the method WO1993000212A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE4291982A DE4291982B4 (en) 1991-06-28 1992-06-26 A method of coating a plastic pipe and plastic pipe coated by the method
GB9303660A GB2263524B (en) 1991-06-28 1993-02-23 A method of coating a plastic pipe and a plastic pipe coated by the method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI913162A FI99158C (en) 1991-06-28 1991-06-28 Method for protecting the surface of a plastic pipe for connection by electric welding and an electrically weldable plastic pipe
FI913162 1991-06-28

Publications (1)

Publication Number Publication Date
WO1993000212A1 true WO1993000212A1 (en) 1993-01-07

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PCT/FI1992/000201 WO1993000212A1 (en) 1991-06-28 1992-06-26 A method of coating a plastic pipe and a plastic pipe coated by the method

Country Status (5)

Country Link
AU (1) AU2019292A (en)
DE (2) DE4291982T1 (en)
FI (1) FI99158C (en)
GB (1) GB2263524B (en)
WO (1) WO1993000212A1 (en)

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WO1994022661A1 (en) * 1993-04-01 1994-10-13 British Gas Plc Joining bodies of thermoplastic material
US5943474A (en) * 1997-07-09 1999-08-24 Branson Ultrasonics Corporation Welding method and apparatus
US5949959A (en) * 1997-07-09 1999-09-07 Branson Ultrasonics Corporation Welding method and apparatus
US6205160B1 (en) 1998-09-24 2001-03-20 Branson Ultrasonics Corporation Laser diode array
FR2811739A1 (en) * 2000-07-11 2002-01-18 Geci Stainless steel pipe e.g. for transporting pharmaceutical or food products has anti-condensation covering of cold-extruded silicone rubber
WO2004016421A1 (en) 2002-08-19 2004-02-26 Uponor Innovation Ab Plastics pipe
WO2004016976A1 (en) * 2002-08-19 2004-02-26 Uponor Innovation Ab Plastics pipe
WO2004016420A1 (en) * 2002-08-19 2004-02-26 Uponor Innovation Ab Plastics pipe
EP1593896A1 (en) 1995-01-18 2005-11-09 Uponor Limited Plastic pipes
US6968762B1 (en) 1999-05-25 2005-11-29 Caldervale Technology Limited Pipe preparing tool V
EP1914462A2 (en) 2006-10-19 2008-04-23 Egeplast Werner Strumann GmbH & Co. KG Multi-layer plastic pipe
US8398908B2 (en) 2004-12-23 2013-03-19 Radius Systems Limited Plastics pipe
EP2716439A1 (en) 2012-10-04 2014-04-09 egeplast international GmbH Object with multilayer exterior
WO2024016023A1 (en) * 2022-07-12 2024-01-18 Brownlow George Method of coating a pipe

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GB2349934A (en) * 1999-05-10 2000-11-15 Glynwed Pipe Systems Ltd Pipes
RU2188927C1 (en) * 2001-12-06 2002-09-10 Устюгов Владимир Аркадьевич Antifriction coat for guide profile
RU2188926C1 (en) * 2001-12-06 2002-09-10 Устюгов Владимир Аркадьевич Guiding profile
EP3760903B1 (en) * 2019-07-04 2022-04-13 HakaGerodur AG Multilayered tube and methods of use and manufacture
EP4336079A3 (en) 2019-07-12 2024-06-05 Uponor Infra Oy Multilayered pipes, method of producing the same and method of welding two multilayered pipes

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Cited By (21)

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Publication number Priority date Publication date Assignee Title
WO1994022661A1 (en) * 1993-04-01 1994-10-13 British Gas Plc Joining bodies of thermoplastic material
US5888331A (en) * 1993-04-01 1999-03-30 Bg Plc Joining bodies of thermoplastic material
EP1818586A1 (en) 1995-01-18 2007-08-15 Uponor Limited Plastics pipe
EP1593896A1 (en) 1995-01-18 2005-11-09 Uponor Limited Plastic pipes
US6278562B1 (en) 1997-07-09 2001-08-21 Branson Ultrasonics Corporation Radiation filter used in welding apparatus
US5949959A (en) * 1997-07-09 1999-09-07 Branson Ultrasonics Corporation Welding method and apparatus
US5943474A (en) * 1997-07-09 1999-08-24 Branson Ultrasonics Corporation Welding method and apparatus
US6205160B1 (en) 1998-09-24 2001-03-20 Branson Ultrasonics Corporation Laser diode array
US6968762B1 (en) 1999-05-25 2005-11-29 Caldervale Technology Limited Pipe preparing tool V
FR2811739A1 (en) * 2000-07-11 2002-01-18 Geci Stainless steel pipe e.g. for transporting pharmaceutical or food products has anti-condensation covering of cold-extruded silicone rubber
AU2003269094B2 (en) * 2002-08-19 2008-09-18 Radius Systems Limited Plastics pipe
WO2004016421A1 (en) 2002-08-19 2004-02-26 Uponor Innovation Ab Plastics pipe
WO2004016976A1 (en) * 2002-08-19 2004-02-26 Uponor Innovation Ab Plastics pipe
WO2004016420A1 (en) * 2002-08-19 2004-02-26 Uponor Innovation Ab Plastics pipe
US8685508B2 (en) 2002-08-19 2014-04-01 Radius Systems Limited Plastics pipe
US8398908B2 (en) 2004-12-23 2013-03-19 Radius Systems Limited Plastics pipe
EP1914462A3 (en) * 2006-10-19 2011-02-23 egeplast Werner Strumann GmbH & Co. KG Multi-layer plastic pipe
DE102006049338A1 (en) * 2006-10-19 2008-04-24 Egeplast Werner Strumann Gmbh & Co. Kg Multilayer plastic pipe
EP1914462A2 (en) 2006-10-19 2008-04-23 Egeplast Werner Strumann GmbH & Co. KG Multi-layer plastic pipe
EP2716439A1 (en) 2012-10-04 2014-04-09 egeplast international GmbH Object with multilayer exterior
WO2024016023A1 (en) * 2022-07-12 2024-01-18 Brownlow George Method of coating a pipe

Also Published As

Publication number Publication date
GB2263524B (en) 1995-01-04
FI913162A0 (en) 1991-06-28
FI99158B (en) 1997-06-30
AU2019292A (en) 1993-01-25
GB2263524A (en) 1993-07-28
DE4291982B4 (en) 2005-05-25
DE4291982T1 (en) 1994-01-13
FI99158C (en) 1997-10-10
GB9303660D0 (en) 1993-04-28

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