RU2284886C2 - Method for welding of titanium and alloys thereof - Google Patents

Abstract

FIELD: process used for welding in inert gas of angular or T-shaped connections of large-sized metal constructions from titanium or alloys thereof, in particular, tubular sections.

SUBSTANCE: method involves providing protection of reverse side of welded seam by feeding shielding gas through apertures preliminarily formed in one of members to be welded into channel preliminarily provided on inner surface of the same member. Shielding gas is thereby fed along the entire perimeter of seam to be welded. Pipeline flanges may be replaced without dismantling of the entire construction. Welded seams provided with the use of said method are free of cracks.

EFFECT: simplified method and improved quality of welded seams.

1 dwg

Description

The invention relates to the field of welding of titanium and its alloys.

When repairing large titanium metal structures (gas pipelines, pipe sections with active media, etc.), it becomes necessary to replace flanges in separate places of the pipeline without dismantling the entire structure. In these cases, the flange is cut off from the pipe along the weld with abrasive circles, and a new flange 2 is put on pipe 1 (Fig. 1) in place of the removed flange and welded to it with a one-side fillet weld INp - welding with a tungsten electrode in an inert gas with filler material (INP - welding in an inert gas And non-consumable N electrode with an additive - p: GOST 14771).

When a pipe section with defective flanges is removed, the pipe shortens. After the installation and welding of new flanges between them in the pipe system, an excess distance occurs, which is eliminated in the future when tightening the flanges due to the flexibility of the pipe system in other areas.

The limited flexibility of the system necessitates reducing the length of the section cut when replacing the flange, which makes it difficult, and often makes it impossible to approach the back of the seam for the implementation of protective blowing. It is also impossible to fill the entire system with inert gas. Welding the fillet weld without protecting the reverse side, as our experience shows, leads to cracks due to saturation of the weld with oxygen and nitrogen.

In electric arc welding of titanium and its alloys, inert gas (argon, helium and their mixtures) must be protected both on the front side of the seam and on the back side, as well as on areas adjacent to the seam that are heated during welding to temperatures above 600 ° C. For this purpose, various means are used: supplying a shielding gas to the main nozzle of the welding torch and an additional attachment to it, lining welding with supplying gas to the groove for the seam, filling the welded container, passing the protective gas through the inner cavity of the pipes, welding in chambers [1] p. 86, [2] p. 344, 438, [3] p. 52, [4] p. 305., application of an aluminum layer on the reverse side of the parts to be welded [5].

In all known methods of protecting the reverse side of a seam, either welding in a chamber filled with inert gas, or filling a container or pipe with inert gas, or blowing inert gas through special devices located on the back side of the seam, or spraying on the back side of the aluminum protective layer is used [5 ].

The aim of the proposed method is to protect the reverse side of the seam in the absence of access to it.

If it is impossible or technically and economically inexpedient to use the listed methods of protecting the reverse side of the weld when welding angular and tee joints of titanium, a method is proposed, characterized in that the said protection is carried out by supplying protective gas through openings made in one of the elements to be welded into the channel previously made on the inner surface of the same element, with the possibility of supplying gas around the entire perimeter of the weld. Protection can thus be achieved without access to the back of the seam. The technique for protecting the back of the seam is visible from the drawing.

Before installing flange 2 on the pipe 1 on the inner annular surface of the flange, a groove channel K is pumped into which argon is supplied through holes O drilled radially in flange 1. Once in the channel, argon washes the back of the weld along the entire perimeter and exits through the gaps, protecting the back of the joint and adjacent areas from atmospheric oxygen and nitrogen. Fittings 3 are screwed into the radial channels O on the outer surface of the flange 1, connected to the manifold 4, through which argon is supplied from the cylinder. After welding the flange, the collector is removed, the fittings are turned out of the holes, and the holes are welded by argon-arc welding with a tungsten electrode using an additive.

Similarly to the described, it is possible to protect the reverse side of the seam when welding other corner and tee joints.

The prototype of the proposed method can be a method of welding titanium and its alloys [5].

A common feature of the proposed method and method [5] is a sign of protection of the reverse side of the seam when performing corner and tee joints. Unlike the prototype, the inventive method allows protection without access to the back of the seam, which is necessary when using the method [5].

Literature

1. Shorshorov M.X. Welding of titanium and its alloys. / M.X. Shorshorov, G.V. Nazarov. - M .: Mashgiz, 1959. - 136 p.

2. Moroz L.S. Titanium and its alloys [T.1]. / L.S. Moroz [et al.]. - L .: Sudprom, 1960 .-- 516 p.

3. Itelson G.M. Titanium equipment. / G.M. Itelson. - M .; L .: Mashgiz, 1964 .-- 148 p.

4. Galitsky B.A. Titanium and its alloys in chemical engineering. / B.A. Galitsky [et al.] - M.: Mechanical Engineering, 1968. - 339 p.

5. Description of the invention. to A.S. SU 338321 A, IPC 7 V 23 K 9/02. The way to protect the back of the seam. Lysakov V.F., Kirilyuk V.F. - No. 1442829/25 - 27; declared 05/25/70; publ. 05/15/85. Bull. Number 18. - 2 p.: Ill.

Claims (1)

A method of welding titanium and its alloys, including the implementation of an angular or T-joint with protection of the reverse side of the weld, characterized in that the said protection is carried out by supplying a protective gas through openings made in one of the elements to be welded into the channel previously made on the inner surface of the same element with the ability to supply protective gas around the entire perimeter of the weld.