WO2021167498A1 - Method for laser welding of pipeline connections - Google Patents

Abstract

The invention relates to the field of welding. The invention can be used for external multi-pass automatic laser welding of fixed joints of pipeline connections. The invention makes it possible to produce flawless pipe-steel welded connections that are equal in strength to the base metal. The invention is achieved by narrow gap preparation of the edges to be welded, pre-heating and accompanying heating of the edges to be welded and use of a laser beam oscillation technique. The invention can be used in welding production in various industrial sectors.

Description

[Installed by ISA according to rule 37.2] LASER WELDING PIPE CONNECTIONS

The invention relates to the field of welding and, in particular, external automatic multi-pass orbital laser welding of non-rotatable circular butt joints of pipelines, including performing a root weld in deep penetration mode, a corrective pass ("hot" pass), filling, corrective and facing-corrective layers seam.

The currently existing technologies of mechanized orbital arc welding of non-rotating circular butt joints include the execution of a root weld, a corrective pass ("hot" pass), filling, corrective and facing-corrective seam layers [Pipeline Welding: Textbook. allowance / F.M. Mustafin, N.G.Blekherova, O. P. Kvyatkovsky and others. - M .: OOO "Nedra-Business Center", 2002. - 350 p.].

The disadvantages of mechanized orbital arc welding of non-swivel butt joints of pipes have been well studied [Experience in the development of modern domestic technologies and equipment for mechanized welding of main gas pipelines / V. A. Galkin [et al.] // Welding and diagnostics. 2011. No. 2. P.37-43].

The choice of certain welding processes during the construction of pipelines is primarily influenced by technical and economic factors, taking into account the guarantees of the quality of welded joints.

Laser welding technologies have certain technical and economic advantages over arc welding, in particular, laser welding can be carried out both in the mode of thermal conductivity (conduction) and in the mode of deep (channel) penetration [Katayama S. Handbook of laser welding. - M .: Tekhnosfera, 2015 .-- 704 p .; Grigoryants A.G., I.N. Shiganov, A.I. Misyurov Technological processes of laser processing: [Electronic resource] / AG Grigoryants, IN Shiganov, AI Misyurov; ed. A.G. Grigoryants. - M .: Publishing house of MSTU im. N. E. Bauman, 2006. - 664 p.].

The idea of using laser welding to make pipe girth welds is not new. Since about 2000, a number of papers have been published discussing the possibilities of using a gas CO2 laser [Gainand Y. et al .: Laser orbital welding applied to offshore pipe line construction. Pipeline technology Vol. II Elsevier Science 2000 p. 327-343.], As well as a solid-state Nd: YAG laser [Fujinaga S. et al. Development of an allposition YAG laser butt welding process with addition of filler wire // Welding Journal. 2005.19 p. 441-446] for the implementation of the orbital welding process. But it was technically impossible to implement the idea of the process of laser orbital welding of pipelines in those years.

Known patent RU 2 355 532 C2 "Orbital welding device for the construction of pipelines."

A significant advantage of the invention is that, with only a single welding cycle, it is possible to connect two pipe ends in the field in an autonomous mode.

One welding optical head is installed on the orbital trolley. A block for heating the wire is installed in front of the wire feeder (wire feeder). The device contains at least one MSG welding head installed indirectly or directly on the orbital trolley with all service systems.

The disadvantage of the orbital welding device for the construction of pipelines [patent RU 2 355 532 C2] is the use of one optical laser welding head.

Taking the joint welding time as a parameter that dictates the pace of construction of trunk pipelines, it should be noted that one welding optical head does not provide the required performance.

Another disadvantage of the orbital welding device for the construction of pipelines [patent RU 2 355 532 C2] is the need to perform a technological operation of demagnetizing the edges to be welded, since the device uses a welding head for MSG welding.

As you know, magnetization affects the process of forming a bead in automatic arc welding. With the appearance of magnetization of the welded edges, the height of the seam decreases, the depth of penetration increases, undercuts are formed along the edges of the seam, and the effect of spattering of the weld pool is enhanced.

Known patent application US 20110186615 A1 for a system based on gears for orbital welding of non-rotatable annular butt joints.

According to this patent, one (two or more) welding torches can be used for welding, moving around the circumference of the pipe using gearing.

The following welding technologies can be used for welding: metal electrode welding in a gas atmosphere (GMAW), welding with non-consumable tungsten electrode (GTAW), mechanized or automatic flux-cored arc welding (FCAW), laser beam welding.

At the same time, arc types of welding require a wide slot groove.

The geometry of the weld groove groove is not reported in this document.

One of the problems when welding high-strength pipe steels is the formation of cold cracks in the near-weld portion of the heat-affected zone. In order to exclude the formation of cracks, devices are used for preliminary or concomitant heating of the welded edges and thermal cycling of the welded joint using a device for scanning the laser beam.

Welding is carried out simultaneously with two optical welding heads located on movable carriages and moving along the pipe circumference with the help of gearing along the band.

One of the main criteria determining a high-quality welded joint made of high-strength pipe steels is to obtain the mechanical properties of the welded joint equal in strength with the base metal and the absence of defects.

The objective of the present invention is to provide a method for external multi-pass automatic laser welding of fixed circular butt joints from high-strength pipe steels to obtain high-quality welded joints with high economic efficiency.

The technical result that can be obtained with the implementation of the present invention is to obtain a defect-free welded joint of equal strength with the base metal, to reduce labor costs during mechanical cutting of welded edges, to significantly reduce the cost of consumable welding materials (welding wire, shielding gases) and to increase the rate of pipeline construction ...

The solution to the problem in this welding method is achieved as follows:

1. Narrow gap groove of the welded edges.

2. Preliminary and concurrent heating of the edges to be welded with automatic maintenance of the heating temperature during the welding process.

3. Application of the laser beam oscillation technique to control the thermal welding cycle and eliminate defect formation in the welded joint.

According to the claimed method, laser welding is performed in a narrow gap groove.

Narrow-gap groove allows to realize single-layer single-roll filling of the welded edges, which significantly reduces the technological cycle of the welding process.

Narrow gap groove of the welded edges excludes the use of arc welding methods due to the physical effect of magnetic "blowing" and significant geometric dimensions of the welding torches.

The use of a narrow-gap groove of the welded edges allows several times to reduce the volume of machining and consumable welding materials, to increase the welding speed, the pace of construction and the economic efficiency of pipeline construction.

One of the significant problems in welding high-strength pipe steels is the formation of hardening martensitic structures in the near-weld portion of the heat-affected zone. The formation of hardened structures leads to the appearance of cold cracks. In order to exclude the formation of cold cracks, preliminary and concomitant heating of the welded edges is carried out and the technique of oscillating the laser beam is used to control the welding thermal cycle. The oscillation of the laser beam is performed with a certain amplitude, frequency and configuration of the trajectory of the laser beam.

In addition, scanning the laser beam excludes the formation of defects in the seam: discontinuities, pores.

Figure 1

general view of an orbital device for laser welding of pipelines is presented.

Figure 2

the welding head of an orbital device for laser welding of pipelines is presented.

Way ( , 2) external multi-pass automatic laser welding of non-rotatable circular butt joints of pipelines consists in the fact that welding is performed using the technique of laser beam oscillation in a narrow-gap groove of butt-welded edges according to the scheme of one welding bead in the welding layer.

In this case, the edges to be welded are heated by an inductor, and the laser beam oscillates during the formation of the root, filling, facing and facing-correcting layers of the seam with a given amplitude, frequency and beam sweep configuration.

On marked: 1 - pipe, 2 - carriage, 3 - welding head.

On marked: 3 - welding head, 4 - gear teeth (band).

The method has been tested in orbital automatic laser welding of non-rotating circular butt joints of gas pipelines with a diameter of 1420 mm, on pipes 1 ( ) of strength class K60 with a wall thickness of 25.8 mm. [CONCLUSION No. 31323949-118-2017 of Gazprom VNIIGAZ LLC]. Protocol No. 31323949-118-028 - 2017 dated 07/05/2017 on a mobile orbital device for automatic one-sided laser welding of fixed circular butt joints of gas pipelines "manufactured by LLC NPK UTS Integration, which is included in the Register of welding equipment approved for use on facilities of PJSC Gazprom. Field of application - construction, reconstruction and overhaul of field and main gas pipelines. [MINUTES No. 31323949-118-028 - 2017 dated 05.07.2017 PJSC Gazprom].

Two fiber ytterbium lasers of the LS series were used for welding, each of which provided an output power of up to 10 kW.

Mechanical tests carried out, the results of non-destructive testing of welded joints and metallographic studies of welded joints showed that they meet the requirements of the normative and technical documentation [STO Gazprom 2-2.2-136-2007 “Instructions on welding technologies during the construction and repair of field and main gas pipelines. Part I ".].

The proposed method for external automatic one-sided multi-pass single-roll laser welding of non-rotating circular butt joints of pipelines has shown high technological reproducibility of the welding process, ensuring high quality of the welded joint and it can be used for welding in many industries.

The claimed invention meets the criterion of industrial applicability, since it can be manufactured using known technical means.

Welding of pipelines: Textbook. allowance / F.M. Mustafin, N.G.Blekherova, O. P. Kvyatkovsky and others. - M .: LLC "Nedra-Business Center", 2002. - 350 p.

Experience in the development of modern domestic technologies and equipment for mechanized welding of main gas pipelines / VA Galkin et al.] // Welding and diagnostics. 2011. No. 2. P.37-43.

Katayama S. Handbook of laser welding. - M .: Technosphere, 2015 .-- 704 p.

Grigoryants A.G., I.N. Shiganov, A.I. Misyurov Technological processes of laser processing: Electronic resource] / AG Grigoryants, IN Shiganov, AI Misyurov; ed. A.G. Grigoryants. - M .: Publishing house of MSTU im. N.E.Bauman, 2006 .-- 664 p.

Gainand Y. et al .: Laser orbital welding applied to offshore pipe line construction. Pipeline technology Vol. II Elsevier Science 2000 p. 327-343.

Fujinaga S. et al. Development of an allposition YAG laser butt welding process with addition of filler wire // Welding Journal. 2005.19 p. 441-446.

STO Gazprom 2-2.2-136-2007 “Instruction on welding technologies during construction and repair of field and main gas pipelines. Part I ".

Invention patent 2009 - RU 2355532.

Patent application 2011 - US 20110186615.

Claims (1)

The method of external multi-pass automatic laser welding of non-rotatable circular butt joints of pipelines, which consists in the fact that the welding is performed by means of the laser beam oscillation technique in a narrow groove of butt-welded edges according to the scheme of one welding bead in the welding layer, while the welded edges are heated by an inductor, and the laser beam oscillates in the process of forming the root, filling, facing and facing-corrective layers of the seam with a given amplitude, frequency and configuration of the beam sweep.

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