JPS61245976A - Performance method for welding titanium outer lining copper alloy tube and copper alloy tube plate - Google Patents

Abstract

PURPOSE:To weld surely a Ti outer lining copper alloy tube to a copper alloy tube plate by removing the Ti outer lining layer of the end part of a Ti outer lining copper alloy tube (Ti clad tube) and by melting the end part of the inner copper alloy tube and copper alloy tube directly or via copper alloy member. CONSTITUTION:The Ti clad tube is inserted into the hole of a copper alloy tube plate 3 by removing only the width (d) of the end part of the outer lining Ti tube 1 of said Ti cladding tube. The end part of the copper alloy tube 2 of the inner tube which is cladded to the Ti tube 1 and the tube plate 3 are then welded directly in this state. In case of a comparatively thicker gap being caused between the tube 2 and tube plate 3 by the removal of the Ti tube 1, the copper metal made spacer S equivalent to the thickness of the Ti tube 1 is inserted into this gap. The tube 2, spacer S and tube plate 3 are then melted together and welded.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention relates to a method for attaching a titanium-clad copper alloy tube, that is, a clad tube having a titanium tube as an outer tube and a mixing tube as an inner tube, to a copper alloy tube sheet; In particular, it relates to methods of attachment by welding.

BACKGROUND OF THE INVENTION Titanium-clad copper alloy tubes have recently been used as members of heat exchangers used in corrosive environments, and have the following characteristics.

1) Excellent corrosion resistance due to the titanium tube on the outside.
Particularly resistant to the corrosive effects of ammonia in steam.

2) Since the pipe is made of copper alloy, contamination by living organisms in seawater can be prevented.

3) Since the pipe is a double pipe, its strength is improved, and it has excellent earthquake resistance and seawater leakage resistance.

4) Excellent heat conductivity because the inner tube is made of copper alloy.

However, despite having the above characteristics, it has been difficult to attach these tubes to the tubesheet. The conventional tube expansion method is not airtight or watertight, has low thermal conductivity, and lacks strength and reliability. In addition, the seal welding method is used when a brittle alloy layer is formed between titanium and copper and other additive elements, and when the heat capacities of titanium and copper alloys are significantly different, especially when making titanium into thin walls, during welding. Titanium and copper alloy do not melt uniformly, resulting in poor fusion and burn-through.

Problems to be Solved by the Invention The present invention is a method that solves the problems in the welding method described above and enables a titanium-clad copper alloy tube to be reliably welded to a copper alloy tube sheet.

Means for Solving the Problems The structure of the present invention for solving the above-mentioned problems in the conventional method is that when welding a titanium-clad copper alloy pipe to a tube sheet,
After removing the titanium outer layer at the end of this clad pipe and bringing the end of the copper alloy inner pipe into contact with the copper alloy tube sheet directly or through a copper alloy member, the outer welding layer is welded. This is a method of welding a clad copper alloy pipe and a tube sheet.

To specifically explain the above configuration with reference to the drawings, FIG. 1 shows a titanium tube 1 (titanium outer lining) and a clad copper alloy tube 2.
This is an example in which the titanium outer lining is removed by the width d of the end of the copper alloy tube 2, the tube is inserted into a hole in the tube sheet 3, and the end of the copper alloy tube 2 and the tube sheet 3 are welded together. When the thickness of the titanium outer sheath is thin, the copper alloy tube and the tube sheet can be directly welded even if there is a gap equivalent to the thickness of the outer sheath as in this example.

The example shown in Fig. 2 is mainly a case where the thickness of the titanium outer layer is thick, and the end of the copper alloy tube 3, which is the inner tube, is expanded to make the copper alloy tube 3.
This is an example in which the end portion of the tube sheet is pre-processed so that it comes into direct contact with the tube sheet, and then welded with the welding torch 4.

Figure 3 shows the copper alloy tube 2 by removing the titanium outer lining.
In this example, a spacer S made of a prepared alloy is inserted into the gap corresponding to the thickness of the titanium tube 1 and the copper alloy tube 2, the spacer S, and the tube sheet are welded together. be.

FIG. 4 shows that the inner diameter of the hole in the tube sheet 3 is approximately equal to the outer diameter of the copper alloy tube 2 so that a protrusion 7 corresponding to the thickness of the titanium tube 1 is formed inside the hole in the tube sheet 3. Made the same way, copper alloy tube 2
This is an example in which the end of the copper alloy tube 2 and the tube sheet 3 are welded so that they are in direct contact with each other.

The welding method for welding the copper alloy tube 2 and the tube sheet 3 may be any known method, or may be a method using a welding rod. The conditions for selecting the joining method shown in the drawings mainly depend on the wall thickness of the titanium tube 1.

As a guideline, if the wall thickness of the titanium tube is 0.3++a+ or less, welding can be performed by the method shown in FIG. 1, but the method shown in FIG. 2 is preferable. Moreover, if it exceeds 0.31all, the method shown in FIG. 2, FIG. 3, or FIG. 4 is appropriate.

Further, the width d excluding the titanium tube 1 needs to be 2a+a or more.

The present invention will be specifically explained below with reference to Examples.

Dimensions of Example Pipe Internal pipe (copper alloy pipe): Cu-1 with wall thickness of 0.7111111
0% Ni (C7060T) Outer tube (titanium tube): Titanium tube with wall thickness of 0.3 mm or 0.5 mm. Tube plate made of aluminum bronze with wall thickness of 30a + o + 22.5 mm.
with a hole in it.

Titanium tube removal width d=5ma+ Welding conditions AC-TIG arc welding: Welding current 100A to 130A
1 Welding speed iscpm Ar gas flow rate: 15A/1n Welding rod: Cu-9%AI (ERCuAI-A 2 equivalent) 2.4 The results of welding under the following conditions are shown in Table 1 below.

Table 1 * Effects of the invention in which the end of the outer tube is welded to the tube plate without removing the end of the outer tube As explained above, this invention provides the following effects.

1) Conventional welding methods can be used because copper alloys are welded together.

Although a welding rod may not be used (melt run), a suitable welding rod can be used if necessary.

2) Workability is good because copper alloys are welded together. Also,
Various defects such as poor fusion, cracking, and burn-through do not occur, and a fragile alloy layer with titanium does not form.

3) In particular, the methods shown in FIGS. 2 to 4 can prevent the occurrence of poor fusion.

From the above results, it can be said that a reliable and reliable welded joint was created.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a welded part showing an example of the method of the present invention. FIG. 2 is a sectional view of a welded part when the inner tube end is expanded. FIG. 4 is a cross-sectional view of a welded portion when a projection is provided on the tube sheet. 1...Titanium tube 2...Copper alloy tube 3...Tube sheet 4...Welding torch 5...Welding arc
6...Welded part 7...Protrusion d...Titanium tube removal width S...Copper alloy spacer

Claims (1)

[Claims] When welding a titanium-clad copper alloy tube (a clad tube with a titanium outer tube and a copper alloy tube as an inner tube) to a copper alloy tube sheet, the titanium outer layer at the end of the clad tube is removed. , a titanium-exposed copper alloy tube and a copper alloy tube, characterized in that the end of the copper alloy inner tube and the copper alloy tube sheet are welded directly or after they contact each other via a copper alloy member. Method of welding with a plate.