JPH0113226Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) This invention is a ring used in the preheating process of steel pipes when the surfaces or joints of large-diameter pipelines are coated with heat-shrinkable synthetic resin tape for anticorrosion, mainly outdoors. Regarding burners. (Prior art) Conventionally, pipeline pipes used for transporting crude oil, natural gas, etc. are usually coated with various anti-corrosion protection coatings, and among them, extruded polyethylene coating (factory coating) is the most commonly used. It is widely used due to its excellent properties. However, the coated pipe is usually welded at both ends at the pipeline facility site, but since the area near the welded part of the pipe is exposed, heat shrink tape or the like is used to seal it after welding. Currently, exposed welded parts are coated with anti-corrosion protection. To apply the anti-corrosion protection coating to the welded part of the pipeline, first, the area near the welded part of the pipeline is preheated uniformly with the flame of a hand burner, and then heat-shrinkable tape or sleeve is placed around the entire circumference of the welded part. Furthermore, a method has been used in which the heat-shrinkable material is uniformly heated and shrunk from the entire circumference by a burner flame, and is brought into close contact with the welded part of the pipeline to provide an anti-corrosion protective coating. On the other hand, in recent years, instead of extrusion coating in factories, similar synthetic resin materials have been used to coat pipes over their entire length at pipeline facility sites. As such a material, a so-called heat-shrinkable tape is used, which is a heat-shrinkable synthetic resin sheet with an adhesive layer provided on one side. This material is usually adhesively coated onto the pipe surface by hand or mechanical wrapping, but in order for heat-shrinkable tape to fully demonstrate its anticorrosive properties, it is necessary to bond the pipe with the tape's adhesive layer. It is necessary to preheat it to a temperature suitable for the agent. Such preheating can be performed by preheating the pipe surface with a hand burner or the like. However, if the coated steel pipe is a large-diameter steel pipe with a diameter of 1 meter or more, or if the steel pipe is coated under harsh weather conditions (low temperature,
If the coating is carried out in a windy environment (for example, outdoors), it is difficult to uniformly preheat the area to be coated by heating the area to be coated using a small heating means such as the above-mentioned hand burner. Further, the heated portion of the portion to be coated may cool down within a short time after being heated, and it is extremely difficult to achieve uniform preheating over the entire portion to be coated. Therefore, conventionally, a plurality of burners with injection ports facing inward in the radial direction of the ring are arranged circumferentially on a ring-shaped support member, and are movably attached to a steel pipe via support legs. A ring burner is used to heat the outer circumference of the steel pipe. When preheating steel pipes, a ring burner is rotated in the circumferential direction of the steel pipe and gradually moved in the axial direction of the steel pipe, and the area to be coated is uniformly coated with flames simultaneously injected from the injection ports of multiple burners. It is heating up to . When rotating the ring burner, due to factors such as the gas supply hose attached to the ring burner, it is not possible to rotate the ring burner continuously in one direction. Next, it is moved in the direction of the tube axis while rotating in the opposite direction. That is, by reciprocating the steel pipe in the circumferential direction, it is gradually moved in the pipe axial direction. (Problem to be solved by the invention) However, in the case of such a conventional example, the direction of movement is variable, so when moving the ring burner in the circumferential direction of the steel pipe, the direction of movement is not constant; Therefore, there is a problem in that the position of the flame injected onto the steel pipe is irregular, making it difficult to uniformly heat the steel pipe. In addition, when reversing the ring burner, the ring burner is moved in the circumferential direction of the pipe, then the direction of movement is changed, and the ring burner is moved a certain distance in the direction of the pipe axis, and then rotated in the opposite direction. There was a problem in that it had to be moved while being operated, which was time-consuming and inefficient. The present invention was devised to solve the problems of the prior art, and its purpose is to:
It is an object of the present invention to provide a ring burner for heating steel pipes that is easy to handle and can uniformly heat steel pipes. (Means for solving the problem) Therefore, in order to achieve the above object, the present invention provides a caster that contacts the outer periphery of the steel pipe on the support leg of the support member, and also has a regulation that restricts the moving direction of the caster. It consists of a set of means. (Example) The present invention will be explained below based on the illustrated example. 1 to 3, reference numeral 1 indicates a ring-shaped support member, and the support member 1 is attached to a steel pipe 2 via a support leg 3 having casters 9, which will be described later, so as to surround the steel pipe 2. The support member 1 is attached so that the ring plane thereof is perpendicular to the tube axis of the steel tube 2, and is movable on the steel tube 2 via the support legs 3. The support member 1 consists of a semicircular upper support member 1a and a lower support member 1b, each of which is formed from a hollow steel pipe and connected by bolts through blind flanges 4 provided at both ends. ing. On the inner peripheral side of the support member 1, a plurality of burners 5, . . . are arranged radially at equal intervals in the circumferential direction of the support member 1. Each burner 5 extends inward in the radial direction of the ring of the support member 1, and the injection port 5a is directed toward the steel pipe 2 side. ) to prevent the flame of burner 5 from hitting the worker during work. Further, by tilting the burner 5 in this manner, the flame flows over the surface of the steel pipe 2, and the flame is projected over as wide a surface as possible. Furthermore, the support leg 3 has a bracket 7 on which two adjustment nuts 6, 6 are attached, and a bracket 7 on which two adjustment nuts 6, 6 are attached.
It consists of threaded rods 8, 8 that are screwed together, and casters 9, 9 that are attached to the ends of the threaded rods 8, 8 so as to be rotatable about the screw shaft. The bracket 7 extends inward in the radial direction of the ring from the inner circumferential surface of the support member 1 along the ring plane of the support member 1, and has a tip end with a cross section T extending forward and backward of the ring plane of the support member 1.
The adjustment nuts 6, 6 described above are provided on the front side overhanging part 7a and the rear side overhanging part 7b, respectively, and the threaded rods 8, 8 are screwed together, and the two supporting members 1 are connected to each other. It is designed to be stably supported by casters 9, 9. The caster 9 is rotatably attached to the end of the threaded rod 8 via a support shaft 9c provided on a holding member 9b that holds the wheel 9a. Wheel 9 relative to the axis of support shaft 9c
The axle 9d of a is offset. Threaded rod 8
A bolt attachment member 10 having an L-shaped cross section is fixed to the end of the bolt, and a side wall 10a extending in the direction of the screw axis of the threaded rod 8 is arranged on the side of the caster 9a. On the side wall 10a of this bolt attachment member 10,
Angle adjustment bolts 11, 11 are provided as regulating means for regulating the moving direction of the caster 9 at intervals perpendicular to the threaded axis of the threaded rod 8. The angle adjustment bolts 11, 11 are mounted on opposite sides of the support shaft 9c of the caster 9 (see FIG. 3C). That is, when the ring burner is rotated in the circumferential direction (direction A in the figure) as shown in FIG.
The moving direction of the ring burner is a direction tilted by an angle α with respect to the A direction (B direction in the figure), and the ring burner is a steel pipe 2.
move in the tube axis direction (direction C in the figure). Furthermore, when the ring burner is rotated in the opposite direction (direction A' in the figure), the caster 9 rotates around the support shaft 9c and comes into contact with the angle adjustment bolt 11 on the opposite side, so that the caster 9 rotates in the direction A'. The ring burner is moved in a direction tilted by an angle α with respect to the direction (B' direction in the figure), and the ring burner is also moved in the same direction as in the case of FIG. 4A. In FIG. 1, reference numerals 12 and 12 indicate valves, which are connected via flexible hoses 12a to gas cylinders 13 and 13 containing fuel gas, respectively, and the fuel gas is supplied from the valve 12 to the support member 1.
The fuel is supplied to each burner 5 through the inside of the burner 5. Next, the operation of this embodiment will be explained. First, the upper support member 1a and the lower support member 1b are set on a portion of the steel pipe 2 to be preheated, and connected through the flange portions 4, . At this time, each burner 5 on the circumference
The distance between the injection port 5a and the surface of the steel pipe 2 is adjusted using the threaded rod 8 so that the distance is equal on the circumference. Next, the valves 12, 12 are opened and the burner is ignited to start heating the steel pipe. When you hold the ring burner in your hand and apply force in the circumferential direction of the steel pipe 2, the caster 9
A moment is applied around the support shaft 9c, and the caster 9 attempts to orient itself in the circumferential direction of the pipe, but the rotation of the caster 9 is restricted by the angle adjustment bolt 11, and the caster 9 is oriented at an angle relative to the circumferential direction of the pipe. It is directed in the direction of α. By continuing to rotate, the ring burner advances diagonally and gradually moves in the direction of the tube axis. Further, when the ring burner is reversed and rotated in the opposite direction of the pipe circumference, the caster 9 rotates around the support shaft 9c, and the angle adjustment bolt 1 on the opposite side rotates.
1, the ring burner is also moved diagonally, and the ring burner is moved in the tube axis direction. By moving the ring burner back and forth in the circumferential direction of the pipe in this way, the ring burner advances while always maintaining a constant angle α with respect to the circumferential direction of the pipe by the caster 9, and the outer circumferential surface of the steel pipe 2 is kept uniform by the flame of the burner 5. It will be heated accordingly. A steel pipe heating experiment was conducted using the ring burner of this example, and the results are shown below. Steel pipe 2 is a 24 ^B steel pipe with a thickness of 9.5 mm and a length of
As shown in Fig. 5, the temperature on the surface of the steel pipe 2 was measured at six locations (C, D, E, F, G, H) in the pipe axis direction, and the distance L between each was set at 6000 mm. It was set to 500mm. Furthermore, at the _F position, as shown in _FIG .
Measurement positions were set at F ₃ and F ₄ ). Also, the feeding direction X of the ring burner is from C position to D, E, F, G,
It is designed to move in the order of H. The angle α between the feeding direction of the caster 9 of the ring burner and the circumferential direction of the steel pipe 2 is 19°, and the feeding speed S of the ring burner steel pipe 2 in the pipe axial direction is S ₁ (0.5 m/min.), S ₂
(1.0 m/min.) and S ₃ (1.5 m/min.). The ring burner is
The steel pipe 2 was heated by reciprocating 90 degrees left and right in the circumferential direction of the steel pipe 2. The experimental results are shown in FIG. 7, and according to the figure, a temperature gradient is created from the C position at the beginning of heating up to about 1.5 m from the F-2 position, and thereafter it is stable. Therefore, in order to wind the tape from the position at the beginning of heating, it is sufficient to lower the feeding speed S at the beginning of heating, and then heat the tape at a constant speed S when the temperature stabilizes. Regarding the temperature distribution in the circumferential direction of the tube, as shown in Table 1, the temperature was higher at the upper point F-1, but when the moving speed S was S ₁ (0.5 m/min.), The temperature difference Δt between F-1 and before heating is about
Since the temperature is about 15°C higher, there is usually no problem with tape wrapping. However, when working in a field such as a desert area, the temperature difference between the upper and lower parts of the pipe becomes large, so in this case, the valve 12 of the upper support member 1a may be throttled to weaken the flame. In addition, the feed speeds marked with * in Table 1 are F- for S ₁ and S ₃ .
The temperature measured in No. 3 is lower, but this is because cooling water remained after cooling the steel pipe.

[Table] (Effects of the invention) The present invention consists of the above structure and operation.
When heating a steel pipe, simply by rotating the ring burner in the circumferential direction of the steel pipe, the movement direction of the caster is automatically set in a fixed direction by the regulating means, so the ring burner is fed stably and the steel pipe is heated evenly. The effect of being able to do this is obtained. Also, when reversing the ring burner, simply by rotating the ring burner in the opposite direction, the caster automatically corrects its posture in the opposite direction and the direction of movement of the ring burner remains constant, making operation extremely easy and increasing work efficiency. This has the effect of improving.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a ring burner for heating steel pipes according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the - line of the apparatus shown in Fig. 1, and Fig. 3 A, B, and C are the apparatus shown in Fig. 1. Front view, side view and bottom view of the caster,
4A and 4B are bottom views showing the operating state of the caster in FIG. The figure is a sectional view taken along the line -- in FIG. 5, and FIG. 7 is a diagram showing the temperature difference between the positions of the steel pipe in the axial direction before and after heating. Explanation of symbols, 1...Supporting member, 2...Steel pipe, 3
...Support leg, 5...Burner, 6...Adjustment nut,
8... Threaded rod, 9... Caster, 9a... Wheel,
9b... Support member, 9c... Support shaft, 10... Bolt attachment member, 11... Angle adjustment bolt (regulating means).

Claims (1)

[Scope of utility model registration request] A steel pipe heating ring in which a support member having a plurality of burners arranged circumferentially with injection ports facing radially inward is movably attached to a steel pipe via support legs, and the burners heat the outer periphery of the steel pipe. A ring burner for heating a steel pipe, characterized in that the support leg is provided with a caster that contacts the outer periphery of the steel pipe, and a regulating means for regulating the moving direction of the caster.