JPS6149789A - Periphery welding method of clad steel pipe - Google Patents

Abstract

PURPOSE:To prevent a base metal component in a weld metal and in a clad steel pipe from being diluted, by joining a solid short pipe of the same component compound as a cladding material to the clad steel pipe by means of frictional welding, etc. CONSTITUTION:A solid short pipe 1 having the same component compound as a cladding material 10a is joined by frictional welding 2, and subsequently, groove work is performed for a pipe end part of the solid short pipe 1. Clad steel pipes 10, 10 prepared in said way are butted, and the periphery is welded by a welding material 4 of a co-metal with the short pipe 1. In this way, a carbon steel base metal 10b is not diluted in the weld metal 4, and the component of the solid short pipe 1 is scarcely varied, therefore, the corrosion resistance and other characteristics are not deteriorated.

Description

[Detailed Description of the Invention] The present invention relates to a method for circumferential welding of clad steel pipes, which provides a circumferential bath weld of clad steel pipes with excellent corrosion resistance, and is suitable for use in cases where the grooves are not aligned. Another object of the present invention is to provide a method by which a good joint can be obtained.

Industrial applications Welding technology for clad steel pipes.

1 pickle.

33 Recent Techniques 1'5: A method for circumferentially welding clad steel pipes is shown in Figure 4 [Stainless Steel Clad Square Pipe 10].

10 are butted together and hand welded or TIG welded, forming a groove 11 and a mouth as shown in Fig. 5, and welding 12't- to this, and from the inner layer 1wJ to multiple welds. A layer is formed extending from the stainless steel cladding material 10a to the carbon steel base material 10bK.

Problems to be Solved by the Invention However, in the conventional method as described above, it is difficult to limit the weld metal of the inner layer IPF to the thickness range of the stainless steel clad mating material 10a, and the clad mating material The carbon steel base material 10a is likely to be formed across the carbon steel base material 10b, and in such a case, the carbon steel base material 10a
Cr of the stainless clad material 10a is reduced by dilution on the b side.
, Ni, decreases the amount of alloying elements such as XMO, and the corrosion resistance of the part decreases. Furthermore, if the roundness of the steel pipes to be welded is slightly different, misalignment will occur in the butt grooves, as shown in FIG. In other words, the stainless steel clad material 10a of the clad steel pipe normally has a thickness of only 2 to 3 mm, and if a misalignment as shown in Fig. 6 occurs, the clad thickness at the circumferential welded joint becomes significantly smaller. Corrosion resistance inevitably deteriorates.

``Completion of the invention'' Means for solving all the problems The present invention was devised after repeated studies in view of the above-mentioned circumstances, and includes a cladding material for the cladding steel pipe at the end of the cladding steel pipe. This is a circumferential welding method for clad steel pipes, which is characterized by friction welding, diffusion welding, or flash butt welding of solid short pipes having the same component system, and then matching metal welding between the solid short pipes.

By joining a solid short pipe of the same composition as the mating material to a working clad steel pipe by friction welding, etc., we can accurately achieve joining between dissimilar metals by υ solid phase welding. Circumferential welding can be effectively carried out by welding the same metal between the weld metal and the clasp, ensuring sufficient characteristics due to the clad steel pipe joining material.

EXAMPLE A specific embodiment of the present invention will be described with reference to all the attached drawings as appropriate. As shown in FIG. 1, the entire inner surface is made of rad steel as shown in FIG. 2.3. f
f1O4- In addition, as shown in this 11th example, a solid short pipe 1 having the same composition as the mating material 10a is friction welded (Fr1ction Weld).
) 2, and then, as shown in FIG. 1(B), a bevel 3 is formed at the end of the solid short tube 1.

The clad steel pipe 10.10 prepared in the above manner is pushed gently as shown in Fig. 1 (C), and in this state, the short pipe 1
Weld 2 circumferences on-site to the same metal welding material 4 as shown in the same figure).

Fig. 1 (4) Stainless clad steel pipe 7, >
+ Connect the solid stainless steel short tube 1 to the knee 1 12°! □ The reason why the friction welding method was used to
Disappearance welding (solid phase welding = r ability, clad steel pipe 1
This method can be said to be the most suitable as it does not leave any problems when joining the carbon steel base material 1oO and the dissimilar metals 4 and 4 of the short pipe 1. This J-prize ball bath welding has a length of 100 to 20 mm as stainless clad steel pipe 1.
As shown in Figure 2, a long clad steel pipe l Q f is fixed and pressurized while rotating the short pipe 1 as a rotating body.Easy rotation operation. You can meet people appropriately based on your sexuality.

However, depending on the opening, diffusion bonding or flash butt welding may be used instead of bX Rj contact.

If the solid short pipes 1 and 1 are joined in this way, a groove 3 is formed between the solid short pipes 1 and 1, and the solid short pipes 1 and 1 are welded together with the same weld metal 4, it is possible to Even if there is a misalignment as shown in Fig. 6, no matter where the 131-layer weld metal curve is formed, there will be no carbon-copper content in the weld metal. Since there is almost no fluctuation, there is no deterioration of corrosion resistance or other properties, and clad steel/U
A favorable welding sound can be made.

Specific examples of connections made using the method of the present invention are as follows.0 Table 1 below shows the analysis results of the chemical composition of the mating material and base material of the duplex stainless clad steel pipe as the test steel pipe. As shown in , steel pipe size 30”
OD X 17.1 vs Roro.

Also, it has the same component composition as the laminated material in this Table 1,
Plate thickness 17. A two-phase solid steel sheet of l+ffm was prepared as 1, and it was joined by friction welding. That is, the conditions for this friction welding are as shown in Table 2 below.

Table 2 Furthermore, the thus obtained product was prepared by forming a welding groove 3 on the short tube 1 portion and attaching it to the short tube 1 and the same metal welding material as shown in Fig. 1 (2).
This welding could be carried out easily and accurately using a conventional method.

However, a corrosion test was conducted on the joint portion of the friction welded joint 2 as described above.

That is, the shape of the test piece is as shown in Figure 3, and it is a 4-point bending test piece with a thickness of 1.5 + 0.1 mm and a width of 10 mm, centered on two friction welded parts. The sample was taken from the inner surface of the steel pipe, and the corrosive solution for this sample was 0.02 atm, PH2S -0.9
It is a 5% Haα solution at 95° C. with a partial pressure of 8 atm PCO□. That is, it was immersed in this solution for two weeks, and the applied stress was 60% of SMYS (27.4 kg/pus2).
Actually, four test pieces were tested at the same time, but none of the results of the 1-high corrosion test using 4-point bending showed any cracks.

"Effects of the Invention" As explained above, the present invention has excellent properties such as corrosion resistance in mounting materials for circumferential welding of this type of clad steel pipe. It is possible to accurately form circumferential welds that ensure stable characteristics by smoothing out the dilution variation NJ of the components shown, and even if there is a misalignment, and ensuring stable characteristics. This is a highly effective invention.

[Brief explanation of the drawing]

The drawings show the technical details of the present invention, in which Fig. 1 is an explanatory diagram showing all steps of the method of the present invention, Fig. 2 is a side explanatory diagram of the friction welding method, and Fig. 3 is an explanatory diagram of the friction welding method. is an explanatory diagram of a test piece regarding a welding example of the present invention, fJ! Figure J4 is a slope view of butt circumferential welding by the conventional method, Figure 5 is a cross-sectional explanatory diagram of the groove shape and weld lamination of the welded part, and Figure 6 is a cross-sectional diagram of the welded part.
The figure is a sectional view showing an example of the misaligned state. However, in these drawings, 1 is a solid stainless steel short pipe, 2 is a friction weld, 3 is a groove, and 4 is a welded part hj'k.
, 10 is a clad steel pipe, 10a is its joining material, 10b
indicates the carbon copper base material gold. Patent applicant Kuchimoto Steel Tube Co., Ltd. Inventor Makai Taira
Hiroshi Nomura - Kita 1) Written by Yutaka
Kiyoteru Hiraga

Claims (1)

[Claims] A cladding characterized in that a solid short pipe having the same composition system as the cladding material of the clad steel pipe is friction welded, diffusion bonded or flash butt welded to the end of the clad steel pipe, and then metal welding is performed between the solid short pipes. Circumferential welding method for steel pipes.