JPS59193771A - Welding method of stainless steel piping - Google Patents

Abstract

PURPOSE:To reduce a welding cost by disposing successively plural pieces of stainless steel pipes on the same axial lines, sealing gaseous nitrogen therein, and joining the successive junctures thereof by inert gas welding. CONSTITUTION:Stainless steel pipes 10, 12 are adjoined to each other on the same axial line, and the outside ends of both pipes 10, 12 are respectively closed. A feeding port 14 and a discharging port 16 for gaseous nitrogen are respectively provided to the closed ends of the pipes. A tungsten electrode 20 is positioned above the juncture of the pipes 10, 12, and the open end of a welding torch 18 is positioned to face the central part. The gaseous nitrogen is fed and filled through the port 14 into the pipes 10, 12, and gaseous argon 22 is discharged from the inside of the torch 18; at the same time, an arc is generated between the electrode 20 and the pipes 10, 12 and a filler metal 24 is inserted into the arc to perform welding. The oxidation of the inside surface of the weld zone is prevented and the welding cost is reduced by using gaseous nitrogen for the inert gas in the above-mentioned way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of welding stainless steel piping in which nitrogen gas is sealed inside the stainless steel piping to prevent oxidation of the inner surface of the piping.

Conventionally, when welding stainless steel pipes, the ends of the stainless steel pipes are connected together and placed on the same axis, and argon gas or helium gas is filled inside the stainless steel pipes, and then the ends of the stainless steel pipes are welded together. Inert gas welding prevents oxidation of the inner and outer surfaces of the stainless steel piping.

However, sealing inert gas such as argon gas or helium gas inside stainless steel piping uses a large amount of gas, which is expensive, and has the disadvantage that a large amount of inert gas is used, increasing welding costs. had.

The present invention eliminates the above-mentioned drawbacks of the conventional method and uses nitrogen gas for the scum sealed inside stainless steel piping, thereby making it possible to inexpensively prevent acid fusing on the inside of stainless steel piping, and reducing welding costs. The purpose of the present invention is to provide a method for welding stainless steel piping that can reduce the amount of damage caused by the welding process.

In the present invention, after the end surfaces of at least two stainless steel pipes are connected to each other, crab gas is sealed inside the pipes to prevent oxidation of the inner surface of the pipes, and the connected parts are welded with inert gas.

Embodiments of the invention shown in the five drawings will be described below.

In the drawings, reference numeral 10.12 denotes stainless steel tubes, and the axes of each stainless steel tube 10.12 are aligned and their end surfaces are adjacent to each other to communicate the interior.

Then, the outer ends of both stainless steel bars 10 and 12 are closed, and a nitrogen sludge inlet 14 is connected to one of the closed ends.
Further, a nitrogen gas discharge port 16 is provided at the other closed end.

On the other hand, the opening of the welding torch 18, in which the tungsten electrode 20 is located in the center, is opposed above the continuous portion of the two stainless steel tubes 10.12.

When performing welding, nitrogen gas is injected into the interiors of both stainless steel tubes 10 and 12 from the nitrogen gas inlet 14 to fill them. Next, argon gas 22, which is an inert gas, is discharged from the inside of the welding torche 8, an arc is generated between the tungsten electrode 20 and the stainless steel ixo, and the filler metal 24 is inserted into the stainless steel pipe 10.1.
2 and filler metal 24 are welded by bath melting.
It is used for welding.

In the above embodiment, the case where TIG welding is performed has been described, but it is needless to say that MIG bath welding may be performed without being limited to this.

Since the present invention uses nitrogen scum as the inert scum sealed inside the stainless steel pipe as described above, it is possible to prevent oxidation from occurring on the inner surface of the welded part.

This has excellent effects such as being able to reduce welding costs.

[Brief explanation of drawings]

The drawings are schematic diagrams showing embodiments of the invention. 10.1'2・Stainless steel pipe 14・・Yamoto scum θmi population 16・Nitrogen gas discharge port 1B・・Welding torch 20
...Tungsten electrode 22, argon gas 24...
Melted and kidnapped. 2

Claims (2)

[Claims] (1) The end surfaces of at least two stainless steel tubes are arranged in series on the same axis, and then nitrogen gas is filled in the stainless steel tubes, and the continuous portions of the stainless steel tubes are inert gas welded. A distinctive method of welding stainless steel piping. (2) The stainless steel pipe welding method according to claim 1, wherein the inert gas welding is TIG welding.