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Application And Development Of Automatic Welding Equipment For Long Distance Pipelines

Mar 21, 2019

The West-East Gas Pipeline Project is the first demonstration project in China that uses large-scale automatic welding technology and fully demonstrates the superiority of advanced technology. Through the baptism of this magnificent project across the century, automatic pipe welding technology has been accepted by most construction units, and will be more widely used in future pipeline projects to play a greater role. Since 1997, CNPC Engineering Technology Research Institute has been committed to the research of automatic pipe welding equipment and process technology. It has been developed and applied for nearly ten years. The APW series automatic pipe welding equipment has been developed for more than 70 pipeline projects. Set, of which, 56 sets were applied in the West-East Gas Pipeline Project. Has achieved good engineering application performance, and accumulated a wealth of on-site construction experience. In the recent years after the completion of the West-East Gas Pipeline Project, we have continued to focus on the in-depth study of this technology, and have achieved application results in pipeline welding intelligent technology and automatic sealing and bottom welding technology, and began to play. effect. It is a meaningful work to sort out and summarize the work in this area and promote the further development of automatic pipe welding technology. The following is a review and reflection on this aspect of work.

1. Characteristics and application of APW-II automatic welding machine

The development of APW-II pipeline all-position automatic welding machine is based on the state of China's pipeline technology, and makes full use of the latest technological achievements of today's scientific and technological development, and has developed a set of all-position automatic pipe welding equipment in line with China's national conditions. It is trying to fundamentally improve the productivity and quality of on-site pipeline welding in China and improve the working conditions of welders. The technical achievement is a set of pipeline automatic welding special equipment and its supporting technology applicable to China's on-site technical conditions and workers' technical and cultural qualities.

1.1 The main technical features of the equipment

APW-II type full-position automatic welding machine consists of welding machine head (including trolley walking system, welding gun swinging system, welding gun height adjustment system), welding track, control system and welding power supply.

Its main technical features are:

(1) All-position welding suitable for long-distance pipeline fixed connection of large and medium-diameter.

(2) The drive control system adopts DC servo drive control technology based on PWM speed regulation and closed-loop control system for displacement sensing detection. It has high positioning accuracy and strong anti-interference ability, achieving the reliability and durability required for field use. 

(3) Welding parameters such as current, voltage, welding gun swing speed, swing amplitude, and dwell time at both ends can be set before welding, and can also be adjusted in real time during the welding process. 

(4) In order to achieve precise control of the swing at high swing speed, this project adopts a cover-feed feedback swing control sensor circuit, which converts the displacement of the swing system into a controllable electrical signal through a specially designed sensor. At the same time, it has a memory function for location.

(5) The track adopts the form of open rigid circular track, which is light and light, convenient for loading and short auxiliary time. The track loading time is s0.5 minutes. (6) The technology is complete and there are matching welding technology.

Among them, the key technology combined with automatic control and manual intervention solves the problem that the processing error of the groove in the pipeline construction in China is large, the misalignment of the field group and the gap of the pair are not automatic welding. The pass rate of automatic welding can reach 98%. This is the most significant advantage of this equipment compared to other similar equipment at home and abroad. This feature is an important prerequisite for the automatic and automatic pipeline welding equipment to be engineered and put into practical use under the conditions of our country.

1.2 Application of APW-II Pipe All-position Automatic Welding Machine in Engineering 1.2.1 Application Overview

(1) Since May 2001, the APW-II pipeline all-position automatic welding machine has been used in 56 sets of oil construction units in Daqing, Liaohe, North China, Changqing and Dagang respectively, and the total number of West-East Gas Pipeline owners has been completed. The pipelines of the line and branch lines are welded for more than 100 kilometers, and the pass rate of welding is over 98%.

(2) As a specialized institution in the petroleum industry, while focusing on technology development, it pays more attention to transforming new technologies into means for construction companies to improve their efficiency. In preparation for the West-East Gas Transmission, we organized the training of automatic welding and welding, and trained more than 300 welders who are skilled in automatic welding operations. This is an essential basic work in the promotion of new technologies.

(3) The Academy of Engineering and the China Oil Pipeline Bureau jointly undertook research on the welding process technology of the West-East Gas Transmission Line Project. In view of the high standard and high quality technical requirements of the West-East Gas Transmission Project, based on the in-depth analysis of the weldability of the X70 pipeline steel of large diameter, thick wall and high strength grade, the APW-II pipeline full position automatic is adopted. Welding equipment, research on automatic welding technology and welding process qualification test, compiled welding procedure regulations, and provided important technical support for automatic welding equipment to truly enter the West-East Gas Transmission Project.

1.2.2 Engineering Application Examples

(1) In 2002, Liaohe Oil Construction Company II used 10 sets of APW-II full-face automatic welding equipment to form an automatic welding operation class. 20 welding I were trained and one-time was awarded by West-East Gas Pipeline Company. The work permit was issued. From July to January 2002, the construction of the 17th section of the West-East Gas Pipeline Project was completed. The cumulative welding completed 1252 welds, including φ1016x14.6 pipeline 915 crossing and φ1016x17.5 pipeline 337 crossing, with a cumulative length of 14.16 km. The pass rate of welding once reached 98.7%. It is one of the best units in the welding quality of the East Section of the West-East Gas Pipeline Project and has been highly appraised by the Engineering Director and the owner.

Following the successful application in the West-East Gas Pipeline Project in 2002, Liaohe Oil Construction Second Company used 14 sets of equipment to construct on the B section of the 10th section of the West-East Gas Pipeline in 2003, welding the West-East Gas Pipeline φ1016x14.6 The cumulative length is more than 20 kilometers, and the qualification rate of welding once reaches 98 8%.

(2) Changqing Oil Construction Company from June to November 2003, after the on-the-job training for welders, the APW-II pipeline full-position automatic welding equipment was used to carry out the construction of Section B of the West-East Gas Pipeline 13 section, welding φ1016x14 The pipe of .6 is 40.2 km, and the welding-time pass rate is over 98%.

(3) Dagang Oil was built in April 2005. It uses 12 APW-II pipeline all-position automatic welding equipment to form a flow operation unit. It automatically carries out the 8th section of the West-East link line of the West-East Gas Transmission Line. Welding operations to achieve the desired results.

2. Research and development of new technologies

2.1 Pipe welding intelligent technology

The development of flexible and intelligent technology represents the development direction of automatic pipe welding technology. Based on the success of the development and application of APW-II equipment, the Engineering Technology Research Institute carried out the development and research of a new generation of automatic welding equipment based on the actual situation of the field application and the increasing construction requirements. On the one hand, the existing technology is further improved and improved, and the intelligent function is added.

Subsequently, the APW-III digital intelligent long-distance pipeline all-position automatic welding machine was introduced, which is an upgraded product of the APW-II type welding machine. The characteristics of this type of welding machine are as follows:

(1) The industrial computer system is used to realize automatic control of the entire welding process through hardware design and software programming. The welding parameters of each section are stored in the computer and the parameters are automatically switched during the welding process. In order to make up for the deficiencies of the prior art, the manual intervention function is inserted in the process of full control of the computer, which is a practical function combined with the field conditions.

(2) An angle-encoded space position cover detection system is adopted, which can accurately determine the angular position cover of the welding trolley. Thereby, the welding trolley can be capped at any position, and the welding parameters at the position are arc-welded.

(3) The swinging system adopts stepping motor subdivision drive control, which further improves the accuracy of the swing control and system reliability.

(4) Developed a welding torch height sensing detection device, which can automatically adjust and control the wire dry elongation during the welding process under the control of the computer. The labor intensity of the welder is further reduced.

2.2 Economical and applicable domestically produced pipeline automatic sealing and bottom welding machine

"West-to-East Gas Transmission" application practice found that the welding of the root bead has become the bottleneck of the automatic welding technology to give full play to its technical advantages. In the construction unit without internal welder and PWT automatic welding equipment, STT semi-automatic root is generally used. The welding of the weld bead is far from being able to meet the needs of automatic welding flow. Therefore, accelerating the development of high-efficiency automatic sealing and bottom welding technology has become an urgent need of each unit.

The Engineering Technology Research Institute has developed a low-cost all-position automatic sealing machine with independent intellectual property rights and its supporting welding technology in combination with the actual situation of each construction unit, and has been shaped into an APW-RI type pipe full-position automatic sealing. Welding equipment.

2.2.1 Existing sealing method

At present, in the construction of long-distance pipelines, there are several methods for welding the back-sealing welds:

(1) Down-welding of cellulose electrode. This method is generally used for the root bead welding of manual welding. For automatic welding, the slag cleaning and grinding work of the root bead is very large, which obviously affects the automatic welding efficiency.

(2) STT semi-automatic welding. This is the method currently in common use. The advantage is that the operation is convenient, the weld bead is formed well, and the efficiency is high, but the speed of the back seal welding still cannot meet the requirements of automatic welding.

(3) Inner welder. The inner welder has a fast welding speed and good weld quality, which is an ideal method for sealing the bottom. However, the inner welder can only adapt to one pipe diameter, and the utilization rate of equipment reuse is low, so the relative cost of equipment configuration is high, and most construction units are unbearable.

(4) PWT automatic root welder. The device is flexible in use, has high welding efficiency, and has a wide adaptability to the pipe diameter. It is an ideal automatic bottom sealing equipment. However, the equipment is complicated, the groove shape is special, and the processing is difficult. It is necessary to mature the application in the on-site construction, and it still takes a certain period of time to accumulate technology and experience. In addition, the equipment is an Italian product, the price is high, the technical support is not perfect, and it is difficult to promote and apply it in most construction units in China. However, we believe that the technical form of this equipment should be the development direction of automatic sealing and bottom welding equipment.

2.2.2 Main features of APW-R-I type pipe full-position automatic sealing and bottom welding equipment:

(1) According to the process requirements of back-sealing welding, the special welding power source developed by the combined pulse droplet over-wave control method is used to improve the penetrating power of the arc by increasing the energy density of the arc. The device has a peak current of up to 600A and a short-circuit current of up to 750A. At the same time, through the precise control of the droplet transfer process, the welding spatter is effectively reduced, and the welding process is stable and the bead molding is good. The test confirmed that the special welding power source developed by the project has the arc penetration, the stability of the welding process and the adjustment of the welding parameters to meet the welding requirements of the all-position sealing bead.

(2) Using embedded industrial control system combined with multi-axis intelligent motion control card, and through the design of hardware interface circuit and power drive circuit, and the design of system software, realize the drive of the motor, the execution of welding action, and meet the sealing welding The required features and the reliability of the device.

(3) Adopting high-precision space angle sensing detection system, it can detect the division accuracy of the full-position interval according to the requirements of the back-sealing welding, realize the precise control of the welding process and ensure the quality of the weld bead.

(4) The system equipment and supporting technology completed in this project are applicable to double U-shaped composite groove, and fully applicable to domestic welding wire, 100% CO2 gas protection, in which the groove size is basically combined with the existing PWT recommendation. The groove is consistent, but through experimentation, the specific details have been improved, extending the scope of application of the prior art.

(5) APW-R-I type pipe full position automatic sealing and bottom welding equipment. The equipment adapts to the diameter of the pipe larger than φ600mm; it adapts to the gap of 0~0.5mm, the offset of 1+0.5mm, and the blunt edge of 1+0.5mmo

3. Existing problems and thinking

The West-East Gas Pipeline Project is the first large-scale application of automatic welding technology in China. The automatic welding equipment at home and abroad competes to show each other. Each has its own merits, fully demonstrating the characteristics of high-quality and high-efficiency of advanced technology and equipment, and has obtained the main, supervision and construction units. And the recognition and affirmation of all parties. It is a recognized development trend to use automation technology instead of labor to promote the advancement of equipment technology in various construction units. However, the application of automatic welding in the West-East Gas Pipeline Project is still a trial work. The project with a total length of more than 4,000 kilometers has only completed 800 kilometers of automatic welding. Among them, some problems have also been reflected. And the solution will surely further improve and improve the automatic welding technology, and truly improve the pipeline construction level in China to a new level. Here are some comments on some general issues, as follows:

(1) The composition of the construction team

Modern equipment requires high-quality personnel to master. Automatic pipe welding equipment is a high-tech technical equipment that combines the advanced results of multidisciplinary research. Its operators should have a certain foundation of scientific and cultural knowledge. The methods of use and operating habits are completely different from the use of traditional equipment. It does not require skilled skills for long-term training, but it requires a cultural background. It is recommended that the construction unit should consider its academic background when recruiting automatic welders.

(2) Maintenance of equipment

Pipeline automatic welding machine system equipment is a computer-controlled electronic and electrical products. The composition and function of the equipment are very different from the traditional mechanical and electrical equipment. The maintenance of the equipment is difficult for ordinary electricians. In order to ensure the normal operation of the project, the on-site needs to equip the electronic engineers with certain professional knowledge according to the configured number of equipment to carry out fault repair and daily maintenance to ensure the normal use of the equipment and produce the benefits.

(3) Technical support

Practice has proved that the long-distance pipeline automatic welding technology is a comprehensive technology. It is a multi-disciplinary, multi-disciplinary and multi-special technology combination. In order to maximize the benefits, some reasonable configuration is needed. And matching. From the manufacture of pipes to the matching of welding consumables; from beveling to field grouping; from pipelayers, beveling machines, counterparts to on-site generators, transportation equipment, etc.; from back cover welding to filling cover; from preheating , polishing to welding inspection, etc., all need a scientific combination, and this aspect also needs a systematic study. It also includes the perfection and scientificization of technical standards, the in-depth and comprehensive research of process technology, the scientific and reasonableness of each process, the understanding and mastery of the operators by technology.

(4) Organization and management

Modern equipment is used for modern engineering. Of course, modern organization management is required. The traditional construction team management mode obviously does not meet the normal performance of automatic welding technology. This requires the quality of management personnel, the construction of management system, and construction. Organizational forms and compensation incentives need to be changed and improved. This aspect also requires systematic and in-depth research.

(5) Sustainable development of technology

The advanced technology can only represent the technical level of a period, and the development of technology in various scientific fields will certainly promote the continuous advancement of automatic welding technology. The technical problems that are difficult to overcome now, with the advancement of technology, will certainly be solved in the near future. Therefore, while promoting the application of existing technologies, it is necessary to continue to adhere to the development and research of new technologies, which is also an inevitable law of the development of science and technology.

4, the conclusion

In short, the construction of long-distance pipelines is an important part of the project construction in the future. Through the West-East Gas Transmission Project, the superiority of the automatic welding technology was demonstrated, and its high efficiency and high quality were recognized by everyone and attracted attention from all aspects. It enhances our confidence and determination to further improve and enhance existing technologies. With the development and improvement of integrated technology, the application of automatic welding technology for long-distance pipelines will become increasingly popular. This is of great positive effect on improving the overall technical level of China's pipeline construction enterprises, achieving integration with world pipeline construction, and participating in the competition of the international pipeline construction market.