CN111212997A

CN111212997A - Pipe having a coating on an inner surface and method of manufacturing a pipe

Info

Publication number: CN111212997A
Application number: CN201780082577.3A
Authority: CN
Inventors: 增田祥; 谢秀萍
Original assignee: AGC Asia Pacific Pte Ltd
Current assignee: AGC Asia Pacific Pte Ltd
Priority date: 2017-10-31
Filing date: 2017-10-31
Publication date: 2020-05-29
Anticipated expiration: 2037-10-31
Also published as: KR20200078417A; KR102470281B1; CN111212997B; TW202017671A; TWI727214B; WO2019088914A1

Abstract

A method of manufacturing a pipe and a pipe having a coating on an inner surface of the pipe are provided. The method can comprise the following steps: coating a lining material on the surface of the flat plate; bending opposite edge portions of the coated flat sheet to form a pair of elongated hooks; bending the coated flat plate and engaging the pair of elongated hooks to form a tube; heating a location of the engaged pair of elongated hooks; and pressing an outer surface of the tube and an opposite inner surface of the tube at the heated location of the engaged pair of elongated hooks.

Description

Pipe having a coating on an inner surface and method of manufacturing a pipe

Technical Field

The present invention relates to a pipe having a coating on an inner surface and a method of manufacturing the pipe.

Background

The inner surfaces of various types of conventional tubing used in the industry (such as water tubing, gas tubing, heat transfer tubing, etc.) need to be resistant to corrosion and chemical reactions between the tubing and the fluid flowing in the tubing. This may be achieved by coating the inner surface of the tube with a resin layer, such as a fluororesin layer.

Coated or lined fluororesins are often used in particular in chemical, pharmaceutical and semiconductor industries where exposure to highly corrosive chemicals is likely.

The fluororesin material may be in the form of a powder, and therefore it contains the resin itself or as a compound mixed with additives such as a colorant, an acid scavenger or a filler. The method of coating the fluororesin material to the inner surface of the pipe may be performed by applying an electrostatic powder coating on the inner surface of the pipe using an electrostatic powder spray gun, and then heating the pipe to melt the powder to form a coating layer. However, this method can only produce tubing with only one film at a time. If several layers of film are required, several separate coatings are required to achieve the target film thickness. This can slow down the tube manufacturing time. Furthermore, counter ionization (backionization) is a problem in this process because excessive accumulation of charge prevents further deposition of electrostatic powder on the surface of the pipe with the traditional coating.

Another method is the Roto-lining method, which involves introducing a granular fluororesin material on the inner surface of a substrate and heating the tube so that the granular fluororesin material melts and allows it to flow uniformly through a well-controlled spinning and heating process. Since the flow depends not only on the rotation of the substrate, but also on factors such as the uniformity of heating, the interaction between the fluororesin material and the substrate, and the like, it is inherently difficult to control the exact flow of the molten particulate fluororesin material. Generally, the rotating liner method is suitable for liners or coatings having a thickness greater than 1mm, and not for thinner liners or coatings having a thickness less than 1 mm.

In both of the foregoing methods, it is difficult to obtain an inner coating layer of uniform thickness without occurrence of lining defects because it is difficult to control the spraying of the electrostatic powder spray gun and the flow of the molten particulate fluororesin material.

In response to the aforementioned problems/difficulties, various technical developments have been made. For example, coating fluororesin powder on a flat metal plate before bending and welding has been used to obtain a tubular pipe having an inner surface coating. However, there are negative effects caused by the use of welding techniques. Parts subjected to welding may experience temperatures above the thermal decomposition temperature of the fluororesin liner material. It is necessary to modify the affected parts in which the fluororesin lining material has decomposed due to high temperature. In addition, decomposition of the fluororesin causes emission of harmful gases that pose a risk to the human body.

Another approach, as described in japanese patent application No. JP1992-352689, involves lining the interior surface of the sump with a single piece of fluororesin film, without any overlap of the fluororesin film. The terminal edges of the fluororesin films are adjacent to each other so that the edges form a butt joint. A sealing membrane is then placed over the butt joint to cover it. The butt joint is sealed using techniques that involve the application of heat and pressure on the sealing film (e.g., heat sealing or welding). However, this process requires additional heating and melting of the sealing film. These additional steps make it difficult to control the thickness uniformity of the coating and can reduce the efficiency of the process of coating the interior surface of the sump.

On the other hand, japanese patent No. 3954120 describes a method involving drawing a tubular lining hydrocarbon base material into a metal pipe and pressing the tubular lining onto the inner surface of the pipe by compressed air supplied into the lining material. This method is applicable to hydrocarbon resins (such as polyethylene and polypropylene), but is not applicable to other resins having higher yield strength (such as fluororesin). Unlike hydrocarbon resins, fluororesins require higher pressure before they plastically deform. Therefore, if this method is applied to coating a fluororesin, a significant pressure will be required in the process, which may affect the efficiency of the process or cause a safety risk.

Disclosure of Invention

According to an aspect of an example of the present disclosure, there is provided a method of manufacturing a pipe having a coating on an inner surface of the pipe. The method can comprise the following steps:

(i) coating a lining material on the surface of the flat plate;

(ii) bending opposite edge portions of the coated flat sheet to form a pair of elongated hooks (catch);

(iii) bending the coated flat plate and engaging the pair of elongated hooks to form a tube;

(iv) heating a location of the engaged pair of elongated hooks; and

(v) pressing an outer surface of the tube and an opposing inner surface of the tube at the heated location of the engaged pair of elongated hooks.

According to another aspect of an example of the present disclosure, there is provided a tube made by the method, the tube having at least two elongated hooks that engage with each other to form the tube.

Drawings

Embodiments of the present invention will become better understood and readily appreciated by those skilled in the art from the following written description, by way of example only, and with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a flat plate 110 and a liner material 104 for coating on a surface of the flat plate 110;

FIG. 2 is a perspective view (transparent) of a plate 110 with opposite edge portions 106 of the plate bent in opposite directions;

fig. 3 is a front view of the tube 100 that has been formed from the flat sheet of fig. 2.

Fig. 4 is a front view of the tube 100 showing how a pair of elongated hooks 108 engage each other.

Fig. 5 is a front view of the tube 100 showing the pair of elongated hooks 108 engaged with each other.

Fig. 6 is a front view of the tube 100 showing the use of the

compression rollers

102 and 103 at one location of the pair of elongated hooks 108.

Fig. 7 is a perspective view of the tube 100, showing the position of the pair of elongated hooks 108 on the tube 100 and the movement of the pressure roller along the position of the pair of elongated hooks 108.

Fig. 8 is a perspective view of the formed tube showing an example of how the position of the pressure roller can be fixed to the tube.

The figures are not drawn to scale and are intended for illustrative purposes only.

Detailed Description

Referring to fig. 1, 2 and 3, the present disclosure relates to a method for manufacturing a pipe 100 having a coating on an inner surface of the pipe 100. The method comprises the following steps:

(i) coating the liner material 104 on the surface of the plate 110;

(ii) bending the opposite edge portions 106 of the coated flat sheet 110 to form a pair of elongated hooks 108;

(iii) bending the coated plate 110 and engaging the pair of elongated hooks 108 to form the tube 100;

(iv) heating a location of the engaged pair of elongated hooks 108; and

the outer surface of the tube 100 and the opposite inner surface of the tube 100 are pressed at the heated location of the engaged pair of elongated hooks 108.

The tube 100 has a coating on the inner surface of the tube 100 and has at least two elongated hooks 108 that engage each other to form the tube 100. The at least two elongated hooks 108 of the tube 100 are adhered together by the coating after the application of heat and pressure.

Fig. 1 shows an example of a plate 110. The plate 110 includes two flat surfaces F_AAnd F_B. Two flat surfaces F_AAnd F_BAre the major outer surfaces of the plate 110 that are on opposite sides of each other. The plate 110 may have various width, length, and thickness dimensions to suit its intended use. In the example of fig. 1, the plate 110 is substantially rectangular in shape. The word "flat" herein means that the plate 110 may be precisely flat or may appear flat upon random visual inspection, although it may appear slightly uneven through the use of instrumentation, i.e., it may be slightly wavy or it may be slightly curved.

The plate 110 may have various shapes, and those skilled in the art will appreciate that the plate 110 is only one example used to describe the method for coating the inner surface of the tube 100, and that other possible forms of structures and frame components suitable for manufacturing the tube 100 may also be used.

In this example, the plate 110 is made of metal (e.g., steel, aluminum, or copper). However, it should be understood that the plate 110 may be made of different combinations of materials depending on the fluid or object that is intended to be transported through the tube 100. The different material combinations may include metal alloys, metal composite alloys, or any material combination in which at least one component is a metal, such that the material combination results in a malleable and bendable material. In addition, the plate 110 may also be made of other types of composite materials including plastics.

The liner material 104 to be adhered to the plate 110 as shown in fig. 1 may comprise an adhesive surface to adhere to any surface of the plate 110 suitable for implementing the tube 100. Specifically, in the present example, the surface of the flat plate 110 to be adhered to the lining material 104 is F_AMajor outer surface, and F_AThe major outer surface will then become the inner surface of the pipe element 100. The liner material 104 may be made of an adhesive material that can adhere to the surface of the plate 110. In the case where the liner material 104 is made of an adhesive material, it is possible that the adhesive property of the liner material 104 to be adhered to the surface of the flat plate 110 is activated when the liner material 104 is heated to a certain temperature. It should be understood by those skilled in the art that the method of applying the liner material 104 to the surface of the flat plate 110 is not limited to those described above, but will include any reasonable method generally known and used in the coating industry for the pipe 100.

In this example, the liner material 104 is a fluororesin film. Examples of fluoropolymers that can be used to form the fluororesin film include Ethylene Tetrafluoroethylene (ETFE) and Perfluoroalkoxyalkane (PFA). Fluorocopolymers as described in patent publication US7112640B2 are also examples of suitable polymers that can be used to form fluororesin films. In other configurations, the liner material 104 may include more than one layer of fluororesin film. The fluororesin film layer in direct contact with the surface of the flat plate 110 may be configured to have adhesive properties for attaching to the surface of the flat plate 110. A tacky material containing a carboxyl functional group is an example of a material having a tacky property suitable for use as a fluororesin film. The purpose of coating the surface of the plate 110 (i.e., the inner surface of the pipe 100) is, for example, to help improve the flow of fluids or to reduce corrosion of the pipe 100. Accordingly, any liner material 104 suitable for accomplishing this purpose may be used.

The thickness of the lining material 104 in the tube 100 may be between 100 μm and 500 μm depending on the application of the tube 10 to be implemented. The liner material 104 may comprise more than one layer of overlapping material. Thus, the thickness of the lining material 104 in the tube 100 may be set according to the degree of overlapping material to be implemented. Such a thickness range of the lining material 104 between 100 μm and 500 μm is suitable for the metal pipe 100 used in industry for transporting metal corrosive fluids. Unlike the existing rotary lining method, the thickness of the lining material 104 is not limited to 1mm or more.

after the lining material 104 is applied to the surface of the panel 110, the edge portion 106 of the panel 110 and the opposing edge portion 106 of the panel 110 (hereinafter collectively referred to as "opposing edge portions 106") are bent as shown in FIG. 2. FIG. 2 is intentionally drawn to be transparent so that the opposing edge portions 106 that are bent can be clearly seen, FIG. 2 is also intentionally drawn so that the opposing edge portions 106 are not to scale but are larger than in actual practice the "edge portion 106" of the panel 110 refers to the area of the panel 110 that is on or along the perimeter or edge of the panel 110. each opposing edge portion 106 is bent to form an oblique angle α relative to the adjacent portion 107 of the panel 110. each opposing edge portion 106 can be bent suitably at a similar angle or at a different angle to meet the purpose of forming the pair of elongated hooks 108 that can attach or engage each other when the pair of elongated hooks 108 are brought together. in this example, each opposing edge portion 106 is bent to the same angle relative to the portion of the panel 110 adjacent to each edge portion 106 but in the opposite direction, wherein one of the opposing edge portions 106 is bent relative to the main surface F of the panel 110_ABent at an angle in a first direction, and the other opposite edge portion 106 opposite to the other main flat surface F of the flat plate 110_BBent at the same angle but bent in a second direction opposite the first direction. The opposing edge portions 106 of the plate 110 may each be in their opposing directions relative to the respective major flat portions of the plate 110 prior to bendingFlat surface F_AAnd F_Bbent at an angle α between 135 deg. and 170 deg..

In this example, the opposing edge portions 106 are each substantially rectangular in shape. The opposing edge portions 106 may be bent such that they have a similar width W or a different width W, suitable for forming the pair of elongated hooks 108. Each opposing edge portion 106 may be curved to have a width between 10mm to 20 mm. In this example, the length of the opposing edge portions 106 will form the length of the tube 100. In this example, the opposing edge portions 106 will eventually form the pair of elongated hooks 108. Thus, the terms "opposing edge portions 106" and "elongated hook 108" are used interchangeably in this disclosure.

After bending the opposite edge portions 106 of the coated flat plate 110 to form the pair of elongated hooks 108, the next step in the method for coating the inner surface of the tube 100 is to then bend the flat plate 110 into the shape of the tube 100 so that each individual member of the pair of elongated hooks 108 will be in close proximity to each other as shown in fig. 3. Fig. 3 shows a side view of the tube 100 in a configuration before the elongated hooks 108 engage each other. The term "immediately adjacent" may refer to the elongated hook 108 being positioned along and/or near the circumference of the tubular 100 just prior to the complete formation of the tubular 100 by bending the flat plate 110. The elongated hooks 108 may be brought closer together so that they are separated from each other by a small gap or opening 120. Those skilled in the art will appreciate that the meaning of "immediately adjacent" is provided merely by reference, as it is understood that the tube 100 need not be circular in shape, but that other shapes of the tube 100 are possible.

As shown in fig. 3, the purpose of bending the flat plate 110 up to the point of having the elongated hooks 108 separated by a small gap or opening 120 is to provide sufficient space to adjust and align each individual member of the pair of elongated hooks 108 to enable the pair of elongated hooks 108 to engage with each other to form the tube 100, at the current step in the method. Each individual member of the pair of elongated hooks 108 is referred to generally as each opposing edge portion 106. Fig. 4 shows a step after the step shown by fig. 3, namely bending the flat plate 110 to engage the elongated hook 108. The flat plate 110 is bent so that one of the pair of elongated hooks 108 is positioned over the other of the pair of elongated hooks 108 so that they can engage and hook. When the respective edge portions 106 overlap, the pair of elongated hook portions 108 engage and hook onto each other. After engagement and hooking, the pair of elongated hooks 108 are pressed or flattened into surface contact with each other so that the tube 100 forms its intended conduit shape as shown in fig. 5 for transporting fluids or objects therein, and does not separate such that the tube 100 will leak or fail to serve as a conduit for transporting fluids or objects therein.

It should be appreciated that the pair of elongated hooks 108 may be made with the liner material 104 applied thereto, or in another configuration, made without the liner material 104 applied thereto. This may be accomplished by sizing the liner material 104 to cover or uncover the area where the elongated hooks 108 are to be formed when the liner material 104 is applied to the flat panel 110. In this example, the pair of elongated hooks 108 have the lining material 104 applied thereto and the lining material 104 is sandwiched between the pair of elongated hooks 108 when they are in contact with each other. Having the liner material 104 sandwiched between the pair of elongated hooks 108 advantageously helps the elongated hooks form a stronger joint when heat is applied to soften the liner material 104. The softened liner material 104 sandwiched between the pair of elongated hooks 108 helps to adhere the metal layers of the pair of elongated hooks 108 together. In other words, the pair of elongated hooks 108 are adhered by the coating or lining material 104 of the tube.

In this example, as shown in fig. 5, the tube 100 formed by engaging the pair of elongated hooks 108 is substantially tubular or cylindrical in shape and has a hollow core adapted to transport objects, such as fluids, within the tube 100. The cross-section of the tube 100 is annular and it is substantially circular. However, it should be understood that other shapes of the tube 100 are possible that can be manufactured via the methods described herein or similar methods. For example, the tube 100 may have a substantially quadrangular or polygonal cross-section.

After bending the coated flat plate 110 and engaging the pair of elongated hooks 108 to form the tube 100, the subsequent step is to apply heat and pressure to a location of the engaged pair of elongated hooks 108 (which may also be considered a joint of the tube 100). In this example, the location of the engaged pair of elongated hooks 108 may also be referred to as the location of the respective edge portions 106 that overlap and are in surface contact with each other. Heat is applied to soften but not completely melt the liner material 104 on the pair of elongated hooks. The softened liner material 104 facilitates adhesion to the metal surface of the elongated hook 108 and to the adjacent portion 107 of the tube 100 that will be in contact with the surface of the edge portion 106. Pressure is applied in opposite directions to each other at the elongated hooks 108, one force being applied on the inner surface of the tube 100 at the location of the elongated hooks 108 and the other force being applied on the outer surface of the tube 100 opposite the inner surface of the tube 100 at the location of the elongated hooks 108. Heat and pressure may be applied separately or simultaneously at the location of the engaged pair of elongated hooks 108. If the heat and pressure are applied separately, they may be applied at short intervals from each other to sufficiently soften the liner material 104 to facilitate adhesion to the metal surface of the elongated hooks 108 while the liner material 104 is still sufficiently soft.

In this example, the positions of the engaged pair of elongated hooks 108 are simultaneously pressed and heated to engage the surfaces of the respective edge portions 106 that are bent to overlap each other. The heat applied to this location reduces the viscosity of the liner material 104 to facilitate adhesion to the surface of the overlapping respective edge portions 106 and to the adjacent portion 107 of the tube 100 in surface contact with the surface of the respective edge portions 106.

The heating at the location of the engaged pair of elongated hooks 108 should not completely melt the liner material 104 or the tube 100. Otherwise, there may be an undesirable variation in the coating thickness of the lining material 104, at least around the location of heating in the inner surface of the tube 100. Applying heat to the engaged pair of elongated hooks 108 for a short period of time (e.g., less than 1 minute, which is suitable for this example) helps prevent the liner material 104 from completely melting. Further, in this example, the location of the engaged pair of elongated hooks 108 is heated to a temperature between 60 ℃ below the melting point of the lining material 104 and 20 ℃ above the melting point of the lining material 104. This is the desired temperature range for softening the liner material 104. The heating temperature at the location of the engaged pair of elongated hooks 108 is much lower than the welding temperature of the metal used to make conventional tubing without the pair of elongated hooks 108. Thus, unlike some conventional techniques for joining and manufacturing pipes involving metal welding, this example has the following advantages: the liner material 104 will not be heated to a metal welding temperature that would decompose the liner material 104.

Pressure may be applied to the location of the engaged pair of elongated hooks 108 as described below. In the present example, as shown in fig. 6 and 7, two press rolls 102 and 103 are provided and they are made to move in tandem to provide pressure at the location of the engaged pair of elongated hooks 108 of fig. 5. Nip rolls 102 and/or 103 may be heated such that heat and pressure may be applied simultaneously. In this example, the heat and pressure are applied at approximately the same time, as the pressure is applied immediately after the liner material 104 softens and has adhesive properties. Having two

press rollers

102 and 103 provides a counter force that exerts a fastening or pinching pressure on the outer surface of the tube 100 at the heated location of the engaged pair of elongated hooks 108 and on the opposite inner surface of the tube 100 at the heated location of the engaged pair of elongated hooks 108. The pressing roller 103 presses against the inner surface of the pipe 100 at the heated position of the engaged pair of elongated hooks 108, and the pressing roller 102 presses the outer surface of the pipe 100 at the heated position of the engaged pair of elongated hooks 108, which is opposite to the inner surface of the pipe 100 at the heated position of the engaged pair of elongated hooks 108. The applied pressure not only facilitates adhesion of the lining material 104 to the metal surfaces at the engaged pair of elongated hooks 108, the pressure also presses the metal at the engaged pair of elongated hooks 108 into shape to form a strong joint. It should be understood that the number of press rolls may not necessarily be limited to two, but may be more than two.

In this example, the pressure roller 102 is disposed such that its axis of rotation 111 is orthogonal to the longitudinal axis 109 along the length of the tube 100, as shown in fig. 7. In this example, the pressure roller 103 is also disposed within the tube 100 in the same manner such that its axis of rotation 111 is orthogonal to the longitudinal axis 109 along the length of the tube 100. For convenience, only the axis of rotation of one of the nip

rollers

102 and 103 is shown, and the same reference numeral 111 is given to both axes of rotation. Further, in the present example, the rotation axes of

press rollers

102 and 103 are parallel to each other. However, it should be appreciated that

press rollers

102 and 103 may be arranged in any manner so long as

press rollers

102 and 103 are capable of sufficiently and efficiently applying pressure and/or heat to the location of the engaged pair of elongated hooks 108. The objective is to roll nip

rollers

102 and 103 over the curved opposite edge portions 106 that are curved to form the engaged pair of elongated hooks 108.

Each

press roll

102 and 103 is substantially cylindrical. Each

pressure roller

102 and 103 is rotatable about its axis of rotation 111. In another configuration, it is possible that only nip roller 102 is rotatable and nip roller 103 is not rotatable. In another configuration, it is also possible that only pressure roller 103 is rotatable and pressure roller 102 is not rotatable. It is also possible in one arrangement that both nip

rollers

102 and 103 are replaced by a pair of non-rotating pressure applying elements. In this case, they will press on the elongated hook 108 and slide along the opposite surface of the elongated hook 108 during the pressing and/or heating process. The pressure applying element may be made with a smooth surface to reduce friction as it slides along the surface of the elongated hook 108.

The press roll 103 may be coated or manufactured with a non-stick material to prevent the heated pressed liner material 104 from adhering to the press roll 103. Examples of the non-stick material include fluoropolymers such as Polytetrafluoroethylene (PTFE) and the like. The application of heat to the location of the engaged pair of elongated hooks 108 may be accomplished by, for example, induction heating of the pressure rollers 102 and/or 103, and/or the tubular member 100.

The heating at the position of the pair of engaged elongated hooks 108 may be performed simultaneously with pressing the position of the pair of engaged elongated hooks 108 by heating the pressing roller 103 and/or 102. Alternatively, in the case where the tube member 100 is made of a thermally conductive material (such as metal), the tube member 100 may be alternatively heated to adhere the surfaces of the overlapped respective edge portions 106, which are coated with the lining material 104, and the adjacent portions 107 of the tube member 100, which are in surface contact with the surfaces of the respective edge portions 106, to each other. In another arrangement, both the rollers 103 and/or 102 and the pipe 100 may be heated. In yet another arrangement, the outer surface of the tube 100 and the opposite inner surface of the tube 100 at the location of the engaged pair of elongated hooks 108 may be pressed to adhere the surfaces of the overlapping respective edge portions 106 and the adjacent portions 107 of the tube 100 in surface contact with the surfaces of the respective edge portions 106 to each other, followed by heating at the same location of the engaged pair of elongated hooks 108 to ensure adhesion at the location of the engaged pair of elongated hooks 108.

There are several methods for performing pressing of the outer surface of the tube 100 and the opposing inner surface of the tube 100 at the heated location of the engaged pair of elongated hooks 108. One example of performing the pressing of the outer surface of the tube 100 and the opposing inner surface of the tube 100 at the heated location of the engaged pair of elongated hooks 108 is: when the position of the engaged pair of elongated hooks 108 is pressed by the

pressing rollers

102 and 103, the

pressing rollers

102 and 103 are kept fixed and the pipe 100 is continuously moved in a direction along the length of the pipe 100. Alternatively, in another example,

rollers

102 and 103 may be continuously moved in a direction along the length of pipe 100 over the entire length of elongated hook 108 while the inner surface of pipe 100 along the length of elongated hook 108 and the opposite outer surface of pipe 100 along the length of elongated hook are pressed and pipe 100 remains stationary. In all of these examples, another press roll 102 will move in tandem with press roll 103.

Fig. 8 shows a perspective view of the formed tube 100 of fig. 7 and further shows how the position of the press rolls 102 and 103 of fig. 7 can be fixed inside the tube 100. A support apparatus 800 is shown in fig. 8. The supporting apparatus 800 includes a pressing roller 103, a roller support 805, an extendable shaft 804, a roller support 806, another roller 807, and a supporting shaft 802. A press roller 103 to be positioned inside the pipe member 100 is fixed to one end of the roller support 805. Specifically, the platen roller 103 is rotatably mounted to the support 805 so that the platen roller 103 can be rotated. The other end of the support 805 is attached to one end of the extendable shaft 804. The other end of the extendable shaft 804 is attached to a roller 807 through a roller support 806. The pressure roller 103 and the roller 807 are located at opposite ends of the support apparatus 800 and are both arranged to exert pressure on the inner surface of the tube 100. The extendable shaft 804 may be mechanically adjusted such that the length of the support apparatus 800 from the point where the pressure roller 103 applies pressure on the inner surface of the tubular 100 at the location of the elongated hook 108 to the point where the counter roller 807 contacts the lining material 104 applied over the inner surface of the tubular 100 or the inner surface of the tubular 100 matches the diameter of the tubular 100. The press roller 102 is mounted on the outside of the pipe 100 in such a manner that it contacts the outer surface of the pipe 100 at the position of the elongated hook 108 pressed by the press roller 103, and moves in series with the press roller 103.

The extendable shaft 804 may include a biasing mechanism, such as a spring, to exert a force on the pressure roller 103 and the roller 807 at opposite ends from each other. The pressure roller 103 and the roller 807 in turn exert pressure on the inner surface of the pipe 100 at the position of the engaged pair of elongated hooks 108 and on the other side of the inner surface of the pipe 100 opposite to the position of the engaged pair of elongated hooks 108, respectively.

The support shaft 802 extends orthogonally in the direction of the length of the tube 100 from a position at the extendable shaft 804. The length of the support shaft 802 is adjustable.

The support shaft 802 may extend a length greater than the length of the pipe 100 to a fixed position at the outside or outer side of the pipe 100 to fix the position of the support apparatus 800. In case the pipe 100 is moved during the pressure application and the press roller 103 is kept fixed, the support apparatus 800 needs to be fixed in place.

In another configuration where the tubular 100 remains in the same position and the

rollers

102 and 103 move through the tubular 100, the support shaft 802 may be attached to an actuator (not shown in fig. 8) to roll the support apparatus 800 to a different position along the tubular 100.

The support 805 and/or the extendable shaft 804 may be configured as a heating device for heating the pressure roller 103, which in turn heats the position of the elongated hook 108. Alternatively, nip roll 102 may be one that is heated instead. In another configuration, both nip

rollers

102 and 103 may be heated together by a heating device.

In the specification and claims, unless the context clearly dictates otherwise, the term "comprising" has the non-exclusive meaning of the word meaning in the sense of "including at least" and not "consisting only of …". The same applies to corresponding grammatical variations of other forms of the word, such as "including", "containing", etc.

While the invention has been described in connection with a number of embodiments and implementations, the invention is not so limited but covers various obvious modifications and equivalent arrangements, which fall within the terms of the appended claims. Although features of the invention are expressed in certain combinations among the claims, it is contemplated that these features can be arranged in any combination and order.

Claims

1. A method of manufacturing a pipe having a coating on an inner surface of the pipe, the method comprising:

(a) coating a lining material on the surface of the flat plate;

(b) bending opposite edge portions of the coated flat sheet to form a pair of elongated hooks;

(c) bending the coated flat plate and engaging the pair of elongated hooks to form a tube;

(d) heating a location of the engaged pair of elongated hooks; and

(e) pressing an outer surface of the tube and an opposing inner surface of the tube at the heated location of the engaged pair of elongated hooks.

2. The method of claim 1, wherein the liner material is a fluororesin film.

3. A method according to claim 1 or 2, wherein the opposite edge portions are bent in opposite directions.

4. A method according to any one of claims 1 to 3, wherein the opposite edge portions are each curved to have a width of between 10mm and 20 mm.

5. The method of any one of claims 1 to 4, wherein the opposing edge portions are each bent at an angle of between 135 ° and 170 ° to form the pair of elongated hooks.

6. The method according to claim 2, wherein the fluororesin film is a tacky fluororesin having at least one tacky group such as a carboxyl functionality.

7. The method according to claim 2, wherein the thickness of the fluororesin film is between 100 μ ι η and 500 μ ι η.

8. The method according to any one of claims 1 to 7, wherein the heating is performed at a temperature between 60 ℃ below the melting point of the lining material and 20 ℃ above the melting point of the lining material.

9. The method of any of claims 1-8, wherein pressing the tubular at the heated location of the engaged pair of elongated hooks is performed using at least two press rolls, wherein one press roll presses an outer surface of the tubular at the heated location of the engaged pair of elongated hooks and the other press roll presses an opposite inner surface of the tubular at the heated location of the engaged pair of elongated hooks.

10. The method according to claim 9, wherein the heating at the location of the engaged pair of elongated hooks is performed by heating at least one of the pressure rollers.

11. The method of claim 9 or 10, wherein the pressure roller that presses the outer surface of the tubular at the heated location of the engaged pair of elongated hooks and presses the opposite inner surface of the tubular at the heated location of the engaged pair of elongated hooks is moved in a direction along the length of the tubular.

12. The method according to any one of claims 9 to 11, wherein the pressure roller pressing against the inner surface of the tube at the heated position of the engaged pair of elongated hooks is connected to a first end of a support device located inside the tube, a second end of the support device opposite the first end of the support device comprising a roller for contacting lining material coated on the inner surface of the tube or the inner surface of the tube.

13. The method of any of claims 1-10, further comprising moving the tube in a direction along a length of the tube while the heated locations of the engaged pair of elongated hooks are being pressed.

14. A tube made by the method of any of claims 1-12, the tube having a coating on an inner surface of the tube and at least two elongated hooks that engage with each other to form the tube.

15. The tube of claim 14, wherein the at least two elongated hooks are adhered together by the coating.