Special Shot Blasting Machine for Steel Pipe Inner Walls

Steel pipes are widely used in various industries, such as oil and gas transportation, water supply and drainage, chemical engineering, and construction. The inner wall of steel pipes is often exposed to corrosive media (such as oil, gas, water, and chemicals) during use, which can lead to rust, corrosion, and scaling, affecting the service life of the pipes and the quality of the transported media. Therefore, effective surface treatment of the inner wall of steel pipes is essential. Special shot blasting machines for steel pipe inner walls are designed to address the unique challenges of inner wall treatment, providing efficient, thorough, and uniform derusting, descaling, and surface strengthening solutions. This article provides a detailed introduction to special shot blasting machines for steel pipe inner walls, covering their working principle, structural characteristics, technical parameters, application fields, advantages, operation methods, and maintenance precautions.

The working principle of a special shot blasting machine for steel pipe inner walls is similar to that of other shot blasting machines, which is based on the kinetic energy impact of projectiles. However, due to the narrow and long space of the steel pipe inner wall, the machine has a unique projectile delivery and recovery mechanism. The core component of the machine is the internal blast lance, which is inserted into the steel pipe. The blast lance is equipped with blast nozzles that can rotate 360 degrees, ensuring that the projectile stream can cover the entire inner wall of the steel pipe. When the machine is in operation, the blast wheel accelerates the projectiles, which are transported to the blast nozzles through the blast lance. The rotating nozzles spray the high-speed projectile stream onto the inner wall of the steel pipe, removing rust, oxide scales, oil stains, and other contaminants. At the same time, the impact of the projectiles forms a uniform rough surface on the inner wall, improving the adhesion of anti-corrosion coatings and enhancing the corrosion resistance of the steel pipe.

The structural characteristics of a special shot blasting machine for steel pipe inner walls are closely related to its function of treating the narrow inner space of steel pipes. The machine mainly consists of a frame, steel pipe clamping and rotating mechanism, internal blast lance system, abrasive supply and recycling system, dust removal system, and electrical control system. The frame provides support for the entire machine, ensuring its stability during operation. The steel pipe clamping and rotating mechanism is used to fix the steel pipe and drive it to rotate at a certain speed. This rotation, combined with the axial movement of the blast lance, ensures that the entire inner wall of the steel pipe is uniformly treated. The clamping mechanism is usually adjustable to adapt to steel pipes of different diameters and lengths.

The internal blast lance system is the core part of the machine, consisting of a blast lance, rotating nozzles, and a driving mechanism. The blast lance is made of high-strength steel pipes to withstand the high pressure of projectiles and the impact of debris. The rotating nozzles are designed to spray projectiles in a 360-degree direction, ensuring no dead corners in the inner wall treatment. The driving mechanism controls the axial movement of the blast lance, allowing it to move back and forth inside the steel pipe to treat the entire length of the inner wall. The abrasive supply and recycling system is responsible for delivering projectiles to the blast lance and collecting and reusing the projectiles after impact. Due to the limited space inside the steel pipe, the recycling system usually uses a suction device to collect the projectiles and debris from the inner wall, which are then transported to the separator for cleaning and sorting. Usable projectiles are reused, while debris and dust are discharged to the dust removal system.

The dust removal system is crucial for maintaining a clean working environment and protecting operators' health. It collects the dust and debris generated during the shot blasting process, which may contain harmful substances such as metal particles and abrasive dust. Common dust removal equipment includes bag-type dust collectors and electrostatic precipitators, which have high dust collection efficiency. The electrical control system controls the operation of the entire machine, including the rotation speed of the steel pipe, the axial movement speed of the blast lance, the supply of abrasive, and the operation of the dust removal system. Modern machines are often equipped with touch-screen control panels and PLC systems, enabling automatic operation and parameter adjustment, which improves production efficiency and reduces operational errors.

Key technical parameters of special shot blasting machines for steel pipe inner walls include the range of steel pipe diameters and lengths that can be processed, shot blasting efficiency, projectile speed, abrasive consumption, steel pipe rotation speed, blast lance movement speed, and power consumption. For example, a typical machine may be capable of processing steel pipes with diameters ranging from 150mm to 1500mm and lengths ranging from 3m to 12m. The shot blasting efficiency may be 500-1000 kg/h, and the steel pipe rotation speed may be adjustable between 5-30 rpm. These parameters are designed to meet the treatment needs of different types of steel pipes, and users can select the appropriate machine model according to their specific requirements.

Special shot blasting machines for steel pipe inner walls are widely used in industries that require high-quality inner wall treatment of steel pipes. One of the main application fields is the oil and gas industry. Oil and gas pipelines are often laid in harsh environments (such as deserts, oceans, and cold regions) and are exposed to corrosive media such as crude oil, natural gas, and seawater. The inner wall of these pipelines must be thoroughly derusted and anti-corrosion treated to prevent corrosion and leakage, ensuring the safe transportation of oil and gas. Another important application field is the water supply and drainage industry. Water supply pipes need to have a clean inner wall to avoid secondary pollution of water quality, while drainage pipes need to resist corrosion from sewage. Shot blasting treatment of the inner wall can effectively remove contaminants and improve the corrosion resistance of the pipes.

In addition, these machines are also used in the chemical industry (for processing pipes transporting chemical media), the power industry (for processing boiler pipes and heat exchanger pipes), and the construction industry (for processing steel pipes used in building structures). For example, in the chemical industry, steel pipes transporting corrosive chemicals (such as acids and alkalis) require a high-quality anti-corrosion layer on the inner wall. Shot blasting treatment ensures that the anti-corrosion coating adheres firmly to the inner wall, extending the service life of the pipes and preventing chemical leakage.

Compared with traditional inner wall treatment methods (such as manual derusting, chemical derusting, and high-pressure water jetting), special shot blasting machines for steel pipe inner walls have significant advantages. Firstly, they offer high treatment efficiency. The machine can process the inner wall of a steel pipe continuously and quickly, which is much more efficient than manual derusting. Secondly, the treatment effect is thorough and uniform. The rotating nozzles and moving blast lance ensure that every part of the inner wall is treated, avoiding residual rust and oxide scales. Thirdly, they improve the surface quality of the inner wall. The impact of projectiles forms a uniform rough surface, which enhances the adhesion of anti-corrosion coatings and improves the corrosion resistance of the steel pipe. Fourthly, they are environmentally friendly. Unlike chemical derusting, which uses harmful chemical agents that pollute the environment, shot blasting is a physical treatment method that does not produce harmful waste. The dust removal system and abrasive recycling system further reduce environmental pollution. Finally, they reduce labor intensity. Automatic operation eliminates the need for operators to enter the narrow inner space of steel pipes for manual treatment, improving the safety and comfort of the working environment.

The operation method of a special shot blasting machine for steel pipe inner walls involves several key steps: pre-preparation, clamping and positioning, parameter setting, shot blasting operation, and post-treatment. Before operation, operators need to inspect the machine's components (such as the blast lance, nozzles, clamping mechanism, and dust removal system) to ensure they are in good working condition. They also need to clean the inner wall of the steel pipe to remove large debris and oil stains. Next, the steel pipe is placed on the frame and clamped and positioned by the clamping mechanism. Operators then set the relevant parameters through the electrical control system, such as the steel pipe rotation speed, blast lance movement speed, and abrasive supply amount. After starting the machine, the blast lance is inserted into the steel pipe, and the rotating nozzles spray high-speed projectiles to treat the inner wall. During the operation, operators monitor the machine's operation status and the treatment effect of the inner wall. After the shot blasting is completed, the blast lance is withdrawn, and the steel pipe is unloaded. The inner wall of the steel pipe is then inspected. If the treatment effect meets the requirements, it can be transferred to the coating process. If not, the parameters are adjusted, and the shot blasting is repeated.

Maintenance of special shot blasting machines for steel pipe inner walls is crucial to ensure their normal operation and extend their service life. Daily maintenance tasks include cleaning the machine's surface and internal debris, checking the lubrication of moving parts (such as the blast lance driving mechanism and clamping mechanism bearings), and inspecting the wear of easily worn parts (such as nozzles and blast lance liners). Regular maintenance includes disassembling and inspecting the blast lance and nozzles, replacing worn parts, checking the tightness of the abrasive supply pipeline, and calibrating the machine's parameters. It is also important to maintain the dust removal system regularly, such as cleaning the dust collection bags and checking the air flow. In addition, operators need to follow the operating procedures strictly to avoid improper operation that may cause damage to the machine. For example, they should not overload the machine or use inappropriate abrasives. Maintenance records should be kept in detail to facilitate the tracking and analysis of the machine's working status.

In summary, special shot blasting machines for steel pipe inner walls are specialized equipment that plays a vital role in the surface treatment of steel pipe inner walls. Their unique structural design and working principle enable them to efficiently and thoroughly treat the narrow inner space of steel pipes, improving the surface quality and corrosion resistance of steel pipes. With the continuous development of industries such as oil and gas, water supply and drainage, and chemical engineering, the demand for high-quality steel pipe inner wall treatment will continue to grow, driving the further innovation and improvement of special shot blasting machines for steel pipe inner walls. Future machines are expected to be more intelligent, efficient, and energy-saving, better meeting the needs of different industries.