Research on manufacturing process and quality control of pressure welded pipe
In the context of continuous social and economic development, pressure welded pipe as an important structure of various types of engineering, its manufacturing process and manufacturing quality has become an important element affecting the operation of the later project. This paper is mainly on the pressure welded pipe manufacturing process and quality control of the relevant content to make certain analysis and research, in order to promote the better development and progress of related engineering production.
Pressure welded pipe belongs to the current industrial pipeline installation of important load-bearing equipment, this equipment has the important characteristics of pressure resistance, high temperature resistance and high stability, so that the pipeline in a complex environment can still be better to provide more pipeline energy.
Pressure welded pipe is not a large amount of work, but its manufacturing process has a certain technical difficulty, the technical requirements for welding is also relatively high, so only good quality control of all aspects of the project to better ensure the quality of the project carried out.
To implement the specific construction before the need to prepare a sound construction organization design, manufacturing plans and quality control measures and quality plans, the need to get the approval of the supervisor before becoming the steel pipe manufacturing construction operations in the importance of guidance documents. Before carrying out the formal construction work, also need to pay more attention to the technical delivery of the relevant staff, to ensure that all welders must be licensed to avoid all kinds of construction problems.
Preparation of steel materials
The steel plate material used in the implementation of the project needs to be selected according to its basic energy absorption and chemical composition, and generally needs to meet the relevant regulations in terms of size, shape and allowable deviation and thickness deviation. The incoming steel plates also need to be accepted by the supervisor to avoid problems.
Welding material preparation
When selecting welding consumables, it is necessary to pay attention to the parameters of welding consumables, and then order the welding consumables according to the construction schedule and arrangement. For the welding consumables, it is necessary to choose the steel whose quality meets the construction needs and the requirements of the relevant specifications, and the welding rods, welding wires and fluxes need to be baked and kept in accordance with the regulations of SL432-2008.
The scribing of the steel plate needs to meet the relevant provisions of the pressure pipe manufacturing and installation and acceptance specifications, and is generally marked on the steel plate in accordance with the release drawings, with attention to the up, down, left and right directions when marking. After the marking and numbering are completed, a combination of semi-automatic and CNC machine cutting is used to carry out the undercutting operation.
After the steel plate is scribed, the specific cutting work should be carried out according to the marked bevel angle and the position of the cutting line, and the two types of methods more commonly used in the cutting process are mechanical cutting and gas cutting. In the bend, vertebrae and other curved parts of the cut, to ensure a good shape of the cut, generally need to use the guide, through reasonable adjustment to form the required curve shape.
Rolling plate and trimming arc
In the process of steel pipe rolling, need to follow some provisions: the direction of the rolled plate generally need to maintain consistency with the direction of steel pipe rolling. And for the surface of the steel plate has been stripped of some oxide and stains, need to do a good job of cleaning it in a timely manner. Also note that metal objects should not be used for direct hammering of the steel plate.
After the steel pipe is rolled, you need to use the sample to check its curvature. Generally in the diameter of the steel pipe is greater than 6m, the sample plate chord length of 1.5m, the gap between the sample plate and the tile can not exceed 2.5mm, if the problem of local deviation, it is necessary to carry out the work of arc correction. Repair arc is generally in a single section of the tube longitudinal welding is completed after 24 hours and then in the coil can be walked back and forth, if the value of deviation is relatively small, you can also use the jacking way to calibrate the round.
The process of rounding needs to be carried out on the platform of the steel pipe factory, in the actual rounding process, you need to focus on the perimeter of the steel pipe and the gap between the weld seam, you need to ensure that the steel plate is wrong teeth and the flatness of the pipe mouth. After rounding, you need to ensure that the actual perimeter of the steel pipe and the design perimeter can not exceed the error.
The so-called rounding is a reasonable adjustment of the roundness of the steel pipe, in order to facilitate the subsequent assembly. Some of the common way to adjust the roundness is to use the metre-type movable support to do a good job of adjusting the roundness support, after adjusting the roundness operation need to ensure that the ellipticity of the steel pipe can not exceed 3D/1000.
Assembly of large sections
To achieve the shortening of the steel pipe installation period, it is necessary to do a comprehensive consideration of the overweight and transportation conditions, and to try to assemble the single section of steel pipe into a large section within the factory. For the process of large section assembly, the main thing is to assemble the first section of steel pipe vertically on a platform, and then lift another section of steel pipe, through this way to do docking, and then the stall will be welded, using the appropriate work to do a good job of adjusting the gap, from a certain point after the work is divided into two working surfaces to do a good job of pressing seams.
Pressure welded pipe welding needs to comply with the relevant regulations and specifications, because the longitudinal seam and ring seam of pressure welded pipe belong to one or two types of welding seam, in the process of welding work needs to be carried out by professional welders to implement the operation.
Priming layer welding
In the process of welding the bottom layer, to do a good job of preheating, in the bevel when the water droplets of iron, after swinging back and forth from left to right, down to extinguish the arc to generate the molten pool seat, in the process of the second arc to the top of the welding rod, the arc is fully aligned with the inner corner and then welded in the interior of the pipe wall.
Cover layer welding
The welding of the cover layer is similar to that of the filler layer, and the basic welding process is similar, but it is necessary to maintain uniformity when swinging the welding rod to avoid affecting the aesthetics of the weld. In addition, a 2mm weld height should be reserved in the welding process.
Capping layer welding
This is done after the welding of other parts is completed, and it is necessary to fuse the welding channels in the pressure pipe before welding to ensure that the width and height of the weld seam are consistent, so that the welded structure can be more beautiful and does not affect the flow of the pipe. In addition, the sealing layer welding also needs to pay more attention to some depressions, weld tumors and other problems, and do the corresponding treatment.
Quality control of pressure welded pipe
For the pressure pipe, the quality of its quality is directly related to the quality of raw materials, but also can not be separated from the continuous improvement of the pipe manufacturing process. In order to further ensure the quality of pressure welded pipe manufacturing, in the selection of the main and auxiliary materials are required to strengthen attention to the quality of the standard degree, and to do a good job of the relevant technical and regulatory review, according to the construction of the relevant requirements for the purchase of materials. To achieve a reduction in the installation process and construction costs, it is necessary to select the appropriate steel plate specifications in accordance with the length and width of the steel pipe and the condition of the equipment in the construction drawings to further ensure the manufacturing quality of the pressure pipe.
Optimize the welding process
In order to reduce the amount of welding deformation and deviation of the steel pipe shape and size during the welding process, the welding process can be optimized to do a good job of strengthening the quality by increasing the welding level. The specific welding process is in the inner welding seam is the use of gas welding priming layer, and then use submerged arc welding two layers of the way. The outer welding seam is mainly used in the way of carbon arc gas planing root cleaning and then cover welding a layer.
Optimization of assembly method
For the straight section, the steel pipe needs to be lifted to the roll welding cart after reasonable adjustment of the gap and wrong teeth, and then the overall size of the situation to do a good job of checking and processing, to be qualified after a welding; for the bend section, it is a special pipe section, the length and weight is too large will affect the difficulty of transport and lifting, so it needs to be divided into suitable short sections to do a good job of assembly.
The products involved in the process of making pressure pipes need to be assembled well in advance in advance in the factory, and the design requirements and the provisions of the bidding documents should be used as the basic guidelines to achieve the important inspection of the various quality indicators of the products. For the already long line of quality problems to do a good job of timely resolution, to further ensure that the quality of the final product can meet the relevant requirements. For the same batch of products, it is generally in accordance with the procedures stipulated in the contract to apply to the supervisor, who will then make the work of acceptance together with the relevant experts.
In conclusion, under the influence of the expanding scale of industrial construction in China, the industrial pipeline has an important role in promoting the regulation of industrial efficiency, the traditional industrial pipeline has been unable to meet the current development, in order to further ensure the quality of engineering construction, the manufacture and development of pressure welded pipe has become an important direction. Doing a good job on the quality control of pressure welded pipe has an important role in promoting the future development of industrial engineering.
Author: Guangjie Zhou
Source: China Steel Pipe Manufacturer – Yaang Pipe Industry (www.pipelinedubai.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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