JPS5944951B2 - How to weld tubes and tube sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding method that requires a small number of manufacturing steps and is applicable to welding tubes and tube sheets of various thicknesses from thin to thick.

Conventionally, the method of fixing the tubes and tube sheets of multi-tube boilers and heat exchangers is as shown in Figure 1, by inserting the tubes 2 into tube holes provided in the tube sheet 1, and then attaching the tube ends to the tube sheet surface. The weld metal 3 and expanded tube 4 ensure strength and airtightness.

However, according to this fixing method, there is a slight gap 5 between the tubes 1 and 2, so depending on the fluid on the shell side, crevice corrosion a as shown in Fig. 2 or as shown in Fig. 3 may occur. The pipe 2 may be blocked in the direction of the arrow due to the accumulation of products such as b, and when high-temperature gas flows to the pipe 2 side, the welded part 3 and the inlet of the pipe 2 are heated to a high temperature, and the Thickness reduction c as shown in the figure
This may eventually lead to fluid leakage.

Therefore, the internal welding method shown in FIGS. 5 and 6 has been proposed as a measure to prevent the gap between the tube and the tube sheet.

The method shown in FIG. 5 involves cutting out the tube seat 1 from the tube sheet 1, butting the tube seat 1 and the tube 2 together, and performing butt welding 3 using an arc from a tungsten electrode 7 that is automatically rotated by a shaft 6. It is. However, this method has the disadvantage that machining the tube seat 1 is extremely expensive. In the method shown in FIG. 6, a part of the tube 2 (approximately 1 mm) is inserted into a tube hole provided in the tube plate 1, and welding 3 is performed using an arc from a tungsten electrode 7 that is automatically rotated by a shaft 6. It is.

However, even with this method, it is very difficult to set the amount of insertion of the pipe 2, and there are drawbacks such as uneven welding. The method shown in Figures 5 and 6 uses TIG welding without using filler metal, so the tube wall thickness is 4m77! In some cases, it is impossible to weld completely. The present invention provides a welding method that does not have the above-mentioned various drawbacks and can weld thin-walled pipes, such as those with a wall thickness of about 4 mm, with a small number of manufacturing steps.

That is, the method of the present invention includes: (1) Providing a specially shaped protrusion corresponding to the wall thickness of the tube at the bottom of the tube hole of the tube plate, further providing an annular groove at the bottom of the protrusion, and inserting a part of the tube into the annular groove. , perform TIG Uranami welding without using filler metal, and then use TIG welding with the above protrusion as filler metal. (hereinafter referred to as the first invention), (2) an annular groove is provided at the bottom of the tube hole of the tube, a part of the tube is inserted into the annular groove; The second feature is that TIG uranami welding is performed without using filler material, and then TIG welding is performed by inserting a ring-shaped filler material according to the wall thickness of the pipe (
(Hereinafter, this will be referred to as the second invention).
7! Even in the case of a thin-walled tube of L8 degree, it is not only possible to obtain a scarlet joint having a sufficient throat thickness, but also the temporary positioning of the tubes can be performed accurately and easily.

Note that the method of the present invention is not limited to butt welding of thin-walled tubes, but can be widely applied to temporary welding of tubes and tubes of thick-walled tubes, multi-tube boilers, various heat exchangers, etc.

Hereinafter, the method of the present invention will be explained in detail using the drawings.

7 and 8 are diagrams showing an embodiment of the first invention of the present invention.

First, in FIG. 7, a protrusion 11 corresponding to the wall thickness of the tube 2 is provided at the bottom of the tube hole of the temporary tube 1, and an annular groove 12 is provided at the bottom of the protrusion. For thin-walled pipes 1
Insert about 2mm.

In this case, the dimensions of each part are as follows, as an example.
If the wall thickness of the tube 2 is Tmm and the diameter is Dmm, then 11 in FIG.
-d+(1±0.5)M7! L, l2-1~2 dragon, 13
=d-(2-4)Mm,l4=t+(2-3)Mm,l
5=d+(4~6)7177! It is. Next, in FIG. 8A, the tungsten electrode 1 is automatically rotated by the shaft 13.
With an arc from 4, for example, while flowing Ar gas,
? Perform the first layer TIG Uranami Rakuten 15 without using filler material,
Thereafter, in FIG. 8B, the second layer of TlG is bonded using the protrusion 11 as a filler material, and the bonded portion 1 having a sufficient throat thickness is formed.
Get 6.

According to the first invention, since the tube 2 is inserted into the annular groove 12, the positions of the tube 2 and the temporary tube 1 can be easily and accurately set when they are independent, and the protrusion 11 Since this is provided as a filler material in the second layer TIG welding, it is possible to obtain a welded part with sufficient strength even in the case of a thin-walled pipe with a wall thickness of about 4 mm.

Moreover, since there is no need to feed filler material from the outside, the mechanism of the welding machine is simple, and it can be used for small tubes of 1 inch or less, and combinations of thick-walled tube plates and thick-walled tubes with a wall thickness of 200 mm or more. Various types of internal welding can be easily performed.

9 to 11 are diagrams showing an embodiment of the second invention of the present invention.

First, in FIG. 9, an annular groove 12 is provided at the bottom of the tube hole of the temporary tube 1, and a part of the tube, for example, in the case of a thin-walled tube, is inserted into the annular groove 12.
Insert about 2mm.

An example of the dimensions of each part in this case is as follows.

If the wall thickness Tm of the tube 2 is the diameter d, then in Fig. 9, 11=d
+(1±0.5)Mm, l2=1~2mm, 15=d-
(2-4) Mm. In Fig. 9, numeral 17 indicates a ring-shaped reinforcement material inserted after the first layer TIG connection, which will be described later, and the dimensions of the ring-shaped reinforcement material are as follows: In the case, in Fig. 11, 16=d-(2~4)Mm, l7
-2 to 4φ. Next, in FIG. 10A, the first layer TIG uranami welding 15 without using a filler material is performed using an arc from a tungsten electrode 14 that is automatically rotated by a shaft 13 while flowing, for example, Ar gas, and then, as shown in FIG. B
Then, insert the ring-shaped filler material 17 and perform TIG welding on the second and third layers to obtain a sufficient throat thickness. Contact part 1
Get 6.

According to the second invention, since the tube hole shape of the tube 1 is simple, the number of machining operations is small, and since the tube 2 is inserted into the annular groove 12, the positions of the tube 2 and the tube 1 when they are independent can be set. can be easily and accurately performed.

Furthermore, when connecting the second and third layers with TIG@, a ring shape according to the wall thickness of the tube 2 is used. In order to insert filler material 17, the wall thickness is 4m77!
Not only is it possible to obtain a joint with sufficient strength even with thin-walled pipes, but there is no need to install a bulking material feeding mechanism in the welding machine, so the mechanism of the welding machine is It is simple and can easily perform various internal welds, such as small diameter pipes of 1 inch or less, and combinations of thick-walled pipes and thick-walled pipes with a wall thickness of 200 mm or more.

[Brief explanation of the drawing]

Figures 1, 5, and 6 are explanatory diagrams showing the conventional method of connecting pipes and pipes, and Figures 2 to 4 are explanatory diagrams showing various defects that occur in the tube and tube sheet fixed by the method shown in Figure 1. 7 and 8 are explanatory diagrams showing one embodiment of the first invention of the present invention, and FIGS. 9 to 11 are explanatory diagrams showing one embodiment of the second invention of the present invention.

Claims (1)

[Claims] 1. A protrusion of a special shape corresponding to the wall thickness of the tube is provided at the bottom of the tube hole of the tube sheet, and an annular groove is provided at the bottom of the protrusion, and a part of the tube is inserted into the annular groove and melted. A method for welding a tube and a tube sheet, characterized by performing TIG uranami welding without using a filler material, and then performing TIG welding using the projection as a filler material. 2. An annular groove is provided at the bottom of the tube hole in the tube sheet, a part of the tube is inserted into the annular groove, TIG uranami welding is performed without using filler metal, and then a ring-shaped filler metal is added according to the wall thickness of the tube. A method of welding a tube and a tube sheet, which is characterized by inserting a tube and performing TIG welding.