Pipelines play a vital role in human health and are strategically important for all countries. Pipelines are built for the transportation of crude oil, refined oil, natural gas, biofuels, and other fuels, as well as for clean water, hot water, steam transportation, and irrigation. These liquids and gases are essential for human life, economic growth, industrial production, construction, infrastructure, agriculture, and energy security.
Today, there are approximately 4,000,000 km of pipelines in 120 countries, half of which are oil and gas pipelines. Due to the increasing energy consumption and energy policies aimed at securing energy resources, there is tremendous growth in oil and natural gas pipeline construction. Population growth, per capita water consumption, and increased demand for water, piling, and construction pipes due to urbanization are also significant. These large pipelines and many steel structures are constructed through longitudinal or spiral welded steel pipes.
The total construction time of a long pipeline project is primarily determined by the pipe supply time and the pipe laying time. The pipe supply time depends on the pipe factory’s production speed. The factory’s capacity and speed are directly related to the steel plate movement speed and welding speed. In large projects, to shorten the pipeline construction time, the total length capacity is distributed among two, three, or more pipe suppliers according to their locations. Thus, multiple pipe factories produce pipes and deliver them to the construction site for the pipe laying steps. High-quality and flawless pipe production is crucial, especially for oil and gas pipeline projects with strict quality requirements and tight project timelines. The quality of the pipe or pipeline results from the quality of raw materials, pipe production stages, such as bending, welding, cutting, beveling, coating, and pipe laying steps, as well as joint welding, testing, insulation, backfilling, and restoration of disturbed areas. The most critical steps that have a significant impact on overall quality are the factory welding sources and pipe joining welding sources.
Submerged arc welding is the primary welding process used for producing longitudinal or spiral welded pipes. In tandem submerged arc welding applications, depending on the pipe usage, steel type, pipe thickness, and diameter, both internal and external welding are performed with one or more wires. The welding properties and behavior of the flux in submerged arc welding are crucial for achieving high-quality, flawless welds at high production line speeds and high parameters. Mechanical properties, impact resistance, crack resistance, corrosion resistance, and gas impermeability are fundamental requirements for pipes and weld joints. The profiles of internal and external weld joints must have good mechanical properties, and the coating and paint thickness must be homogeneous, which are other important criteria.
Pipe joining welding is a challenging task due to field conditions. Pipelines often pass through rural areas where there may be no electricity, cold and windy conditions, and the ground may be sloped or wet. In such locations, joining, assembling, and positioning for welding can be very difficult. The welding work must be done flawlessly; otherwise, cutting, preparing, and reassembling faulty pipes results in significant time loss for the project. For this reason, experienced project managers and pipe welders pay close attention to the performance of welding consumables and welding machines/generators. High penetration, wetting of pipe sidewalls, good blending, smooth weld profiles without undercuts, low spatter, and easy position welding are crucial characteristics.
Rastahl’s customer-focused product development method plays a key role in providing reliable and high-quality products for the pipe manufacturing and pipeline industries. Submerged arc welding fluxes and wires are developed according to the production test results of the pipe factory and detailed quality expectations for various pipe production. Special pipe welding electrodes used in joining welding, such as cellulose electrodes, basic electrodes, high tensile steel electrodes, gas-shielded welding wires, and solid wires, are tested and developed with welding machines at various pipeline construction sites. In addition to the welding consumables and welding machines' performance, the packaging and protection class have been improved for harsh field conditions to withstand high or low temperatures, rain, wind, sand, soil, and mud. Furthermore, auxiliary products such as carbon electrodes, electrode drying ovens, cutting, and grinding stones are designed and manufactured to enable welders to prepare and weld joints quickly and flawlessly. Solar-matic auto-darkening welding helmets ensure clear visibility of the arc and molten weld pool, thus achieving the required weld quality. Additionally, to protect welders during difficult welding positions in pipeline welding, welding gloves, aprons, and other clothing are carefully produced.
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