JP2010005658A - Structural member for slip-on type weld pipe-fitting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a sufficient weld heat input even if the weld heat input is lowered by dispersion. <P>SOLUTION: The structural member for a slip-on type weld pipe-fitting includes an insertion hole in which a pipe is inserted and fillet welding is performed. On the periphery in the side of the inside diameter of the insertion opening, a minute projection to be melted by a weld heat input in fillet welding is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a structural material for a plug-in welded pipe joint that can reduce the occurrence of poor penetration by providing a minute projection at the tip.

  Plug-welded pipe joints such as socket weld joints have been used in many joints since work setup is easy. In ordinary butt welding of pipes, it is necessary to produce a back wave, and high technology and skill are required as welding techniques. On the other hand, socket welded joints are not required to have the skills and skills.

  FIG. 3 is a diagram showing an axial cross-section of a socket welded joint in which good penetration has been performed. The pipe 2 is inserted into the socket 1, and there is no welding defect (poor penetration) between the end face of the socket 1 and the surface of the pipe 2, and a fillet weld A is formed.

  Socket welded joints are generally used for small-diameter pipes with an inner diameter of about 11.0 mm to 90.0 mm, but it is judged that there is no need for the welding operator to produce a back wave like butt welding. For welding technology management, if the welding heat input is too large for a small-diameter pipe, there is a thermal effect on the inner surface of the pipe and material deterioration. Done.

  FIG. 4 is a diagram showing an axial cross section of a socket weld joint in which a weld defect (poor penetration) occurs. The fillet weld B is welded between the end face of the socket 1 and the surface of the pipe 2, but a defect C is generated. Since the parts to be welded, that is, the socket 1 and the pipe 2 have a large heat capacity, defects such as poor penetration as shown in FIG. 4 occur unless welding heat input that matches the heat capacity is applied.

  In general, a surface inspection such as a liquid penetrant inspection is performed as a method for inspecting a socket welded joint. However, this inspection method cannot detect defects inside the weld such as a penetration failure. Such a defect can be detected by using a radiation transmission test. However, because radiation is used, it is necessary to set up a management area, etc. In consideration of the difficulty and cost of preparation, it is generally adopted as a simple joint. It is difficult to adopt for existing socket welded joints. In the pressure resistance test, a slight penetration failure may pass the inspection.

  If there is such a penetration failure, the planned strength is not ensured, and there is a possibility of leakage during use, so it is necessary to suppress the occurrence of the penetration failure.

  As described above, socket welded joints are often used for small diameter pipes. For this reason, the installation location of the pipe is often a narrow portion or is installed in a location close to the wall or floor of the room, and the welding operation is often performed in a location where the welding posture is bad. For this reason, variations in welding heat input are likely to occur. If the heat input is insufficient (becomes too low) due to variations in welding heat input, the possibility of the above-mentioned poor penetration increases. Therefore, sufficient penetration is possible even for slight heat input variations. It is necessary to design a joint that provides

  The present invention has been made to solve such a conventional problem, and it is possible to obtain a sufficient penetration even when the welding heat input varies. Is to provide.

  The present invention material is a structural material for insertion welded pipe joints in which piping is inserted into the insertion port and fillet welded, and is welded around the inner diameter side of the end surface of the insertion port during fillet welding. It is characterized by having a microprojection that is easily melted by heat.

  According to the structural material for plug-welded pipe fittings of the present invention, by providing small protrusions on the end face to which the structural material is welded, even if the welding heat input varies and the small protrusions are sufficiently melted, As a result, it is possible to provide a joint in which the occurrence of defective penetration that is a problem is reduced.

  Hereinafter, a structure material for a plug-welded pipe joint according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, a socket welded joint will be described as an example, but the present invention can also be applied to a general insertion welded joint.

  FIG. 1 is a view showing the shape of a structure material for a plug-welded pipe joint according to a first embodiment of the present invention.

  In the socket weld joint 100 having a structure in which the pipe 102 is inserted into the insertion port 101 b of the socket 101, a minute protrusion 101 a is formed around the inner diameter side of the end surface of the insertion port 101 b of the socket 101.

  A socket (insertion welded pipe joint structure material) 101 according to the present embodiment includes a minute protrusion 101a that is a portion having a small heat capacity locally at a portion to be welded of the socket weld joint 100, and has a heat input during welding. Even if the welding heat input becomes small due to variation, the minute protrusion 101a itself is sufficiently melted by the welding heat input during fillet welding to suppress the occurrence of defects, thereby reducing the possibility of poor penetration. Thus, a good weld joint can be obtained.

Here, the microprojection portion 101a of the present embodiment has a right isosceles triangular shape having a height w1 and a width w2 of about 2.5 mm or less, and a cross-sectional area of a cross section in the central axis direction of the insertion port 101b of about 4 mm ² or less. It preferably has a cross-sectional shape.

  FIG. 5 is a diagram illustrating an example of a welding procedure of a general socket-welded joint. As shown in FIG. 5 (a) and FIG. 5 (b), the socket weld joint method is basically two-layer three-pass or two-layer two-pass, and when the so-called leg length or throat thickness of the socket 1 is large. In other words (when the w2 direction in FIG. 1 is large), it is normal to increase the number of layers and the number of passes.

  As shown in FIG. 5 (c), in order to finish the welding of the joint in one layer and one pass, when welding is performed with a large welding heat input, the heat influence on the inner surface of the pipe 2 is large, leading to deterioration of the material. In addition, if there is an internal defect here, it tends to lead to leakage as it is, so welding is often performed with at least two layers.

Therefore, the dimension of the minute protrusion 101a may be a dimension that allows sufficient penetration even if the dimension of the minute projection 101a varies in the direction of less welding heat input during the first pass of the first layer welding. That is, when the leg length or throat thickness of the socket 1 is large, it is only necessary to increase the number of layers and the number of passes, and the protrusion dimensions of the minute protrusions 101a are such that the height w1 and the width w2 are about 2.5 mm or less. There is little need to increase the cross-sectional area from about 4 mm ² or less.

  However, in the case of an insertion welded joint other than the socket welded joint, or when a welding method with a large heat input such as automatic TIG welding or MIG welding is applied, the size of the minute protrusion 101a may be increased. However, when the size of the small protrusion 101a is increased, the heat capacity of the protrusion itself increases, so that the meaning of providing the protrusion of the present embodiment that melts even with a small heat input is reduced.

  In the case of this embodiment, it is preferable that the cross section of the microprojection 101a is a right-angled isosceles triangle, but may be a shape of another triangle that is not a right-angled isosceles triangle because of workability and weldability. .

  FIG. 2 is a diagram showing the shape of a structure material for a plug-in welded pipe joint according to a second embodiment of the present invention.

  In the socket weld joint 200 having a structure in which the pipe 202 is inserted into the insertion port 201b of the socket 201, a minute projection 201a is formed around the inner diameter side of the end surface of the insertion port 201b of the socket 201.

The socket 201 of the present embodiment has a portion having a small heat capacity locally to the place to be welded of the socket weld joint 200, that is, a height w1 and a width w2 of about 2 mm or less, and a cross section in the central axis direction of the insertion port 201b. There is a square projection 201a with a cross-sectional area of about 4 mm ² or less, and even if the welding heat input becomes small due to variations in welding heat input during welding, the part melts sufficiently and may cause poor penetration This makes it possible to obtain a good welded joint.

  In the case of the present embodiment, the cross-sectional shape of the minute protrusion 201a is preferably a square, but may not be a square or a rectangle due to workability and weldability.

  As described above, according to the insertion welded pipe joint structural material of each embodiment of the present invention, by providing a minute projection at the tip of the socket insertion port, even a slight variation in welding heat input can be achieved. Thus, a good penetration joint can be obtained, and the possibility of occurrence of leakage of liquid or gas inside the pipe in use can be reduced. Moreover, although the triangle and the quadrangle were mentioned as an example of the cross-sectional shape of the minute protrusion, the cross-sectional shape is not limited to these, and any shape that can be processed may be used.

It is sectional drawing which shows the structure of the structural material for insertion welding type pipe joints of 1st Embodiment of this invention. It is sectional drawing which shows the structure of the structural material for insertion welding type pipe joints of 2nd Embodiment of this invention. It is a figure which shows the axial direction cross section of the example of the socket welded joint in which favorable penetration was performed. It is a figure which shows the axial direction cross section of the example of the socket welding joint in which the penetration defect has arisen. It is a figure which shows the example of the general welding procedure of a socket welded joint.

Explanation of symbols

100: Plug-weld type pipe joint 101 of the first embodiment of the present invention 101: Socket 101a: Minute protrusion 102: Pipe 200: Plug-weld type pipe joint 201 of the second embodiment of the present invention 201: Socket 201a: Minute protrusion Part 202: piping

Claims (5)

A construction material for a plug-in welded pipe fitting in which a pipe is inserted into the insertion port and fillet welded,
A structure material for a plug-welded pipe joint, comprising a minute protrusion that melts by welding heat input during fillet welding around the inner diameter side of the end face of the insertion port.   2. The structural material for a plug-in welded pipe joint according to claim 1, wherein the minute protrusion is melted by welding heat input in a first pass during fillet welding.   The cross-sectional shape of the microprojection part is a substantially right triangle, and the length of each orthogonal side is 2.5 mm or less, The structural material for an insertion welded joint according to claim 1 or 2.   The cross-sectional shape of the microprojection portion is a substantially square, and the length of one side is 2 mm or less. The structural material for an insertion welded joint according to claim 1 or 2. The cross-sectional area of the microprojection is 4 mm ² or less, the structural material for a plug-welded pipe joint according to any one of claims 1 to 4.

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