Scheme of H Beam Shot Blasting Pretreatment Line
1. Brief Profile
The H Beam Shot Blasting Pretreatment Line is a specialized continuous production system engineered to address the surface treatment needs of H-shaped steel—one of the most widely used structural components in construction, bridge building, and heavy machinery. Unlike standalone shot blasting machines, this line integrates multiple functional modules (feeding, shot blasting, dust collection, drying, and discharge) into a seamless workflow, designed specifically for the long length, large cross-section, and uniform surface quality requirements of H beams.
H beams typically have a “web-and-flange” structure (a central vertical web connecting two horizontal flanges), which creates hard-to-reach areas (e.g., the inner corners of flanges) that standard blasting struggles to cover. The pretreatment line solves this by using a combination of horizontal and vertical blast wheels, ensuring every surface—including flange inner walls and web edges—receives consistent cleaning. Its core goal is to remove rust, mill scale, oil, and other contaminants from H beams before subsequent processes (e.g., painting, galvanizing, or welding), which enhances coating adhesion, improves corrosion resistance, and extends the service life of the final steel structure.
The line is designed for high throughput to match mass production of H beams. A typical line can process H beams with lengths ranging from 6m to 30m and weights up to 5 tons per unit, operating continuously at speeds of 0.5–3 m/min. It also incorporates intelligent control systems to adapt to different H beam sizes (e.g., flange widths of 100–600mm, web heights of 150–900mm) without manual reconfiguration, reducing downtime between batches.
Environmental compliance is a key design focus. The line’s closed-loop structure and high-efficiency dust collection system capture over 99.9% of blasting dust, meeting global emission standards (e.g., EU EN 15038, US EPA NESHAP). Additionally, the shot recovery and recycling system minimizes steel shot waste, cutting operational costs by 20–30% compared to open-blast systems.
In summary, this pretreatment line is not just a surface cleaning tool but a critical upstream process for H beam manufacturing. It ensures consistent quality, high efficiency, and eco-friendliness, making it indispensable for industries that rely on high-performance H beam structures—from skyscraper frames to long-span bridges.
2. Application
The H Beam Shot Blasting Pretreatment Line is widely adopted across industries that use H beams as core structural components, as it ensures the steel meets strict surface quality standards for subsequent processing and long-term performance. Its ability to handle large volumes of H beams with consistent results makes it a staple in construction, heavy industry, and infrastructure projects. Below are its key application areas:
2.1 Construction and Building Industry
In high-rise building and industrial plant construction, H beams form the “skeleton” of structures (e.g., column supports, floor beams, roof trusses). These H beams must undergo pretreatment to remove mill scale (a byproduct of steel rolling) and rust, which can weaken the bond between the beam and anti-corrosion coatings. The pretreatment line processes H beams in batches, ensuring each beam’s surface reaches Sa 2.5–Sa 3 cleanliness (per ISO 8501-1)—the standard required for high-adhesion paint systems. For example, in a skyscraper project using H beams with 300mm flange widths and 500mm web heights, the line processes 20–30 beams per hour, preparing them for epoxy primer application that protects against indoor humidity and outdoor weathering.
2.2 Bridge and Infrastructure Construction
Long-span bridges (highway, railway, or pedestrian) rely on H beams for their load-bearing capacity and durability. These beams are exposed to harsh environments—saltwater (coastal bridges), freeze-thaw cycles (cold regions), and heavy traffic vibrations—making pretreatment critical. The line’s ability to clean H beams up to 30m long (common in bridge segments) and 5 tons in weight ensures consistent rust removal, even on the inner flange corners where moisture accumulates. For a coastal bridge project, the line processes H beams with 400mm flange widths, removing salt residues and rust before hot-dip galvanizing—a process that requires a clean surface to form a uniform zinc coating.
2.3 Heavy Machinery and Equipment Manufacturing
Heavy machinery (excavators, cranes, mining trucks) uses H beams in their frames and booms, where strength and corrosion resistance are essential. The pretreatment line prepares H beams for welding and coating, ensuring no contaminants interfere with weld integrity or coating adhesion. For example, a crane manufacturer processing H beams with 250mm flange widths and 400mm web heights uses the line to remove oil (from machining) and light rust, creating a rough surface profile that improves the bond between the beam and wear-resistant paint—extending the crane’s service life in dusty construction sites.
2.4 Steel Structure Fabrication Plants
Steel fabricators that supply H beams to various industries rely on the pretreatment line as a core production step. These plants handle diverse H beam sizes (e.g., 100mm narrow flanges for small structures to 600mm wide flanges for industrial cranes) and require quick changeovers. The line’s adjustable blast wheels and conveyor speed allow fabricators to switch between beam sizes in 5–10 minutes, maintaining high throughput. For a fabricator supplying both building and bridge clients, the line processes 50–80 H beams daily, ensuring each meets the client’s specific cleanliness requirements (Sa 2.5 for buildings, Sa 3 for bridges).
3. Features
The H Beam Shot Blasting Pretreatment Line is distinguished by features tailored to the unique challenges of H beam processing—long length, complex cross-section, and high-volume production. These features ensure efficient, uniform cleaning while optimizing operational cost and environmental performance:
3.1 H Beam-Specific Blast Wheel Configuration
To clean the H beam’s web, flanges, and inner corners, the line uses a “multi-angle blast wheel array” with 6–12 blast wheels positioned strategically:
Horizontal Wheels: 4–6 wheels mounted above and below the conveyor, targeting the top and bottom surfaces of the H beam’s flanges. These wheels use large steel shots (1.2–2.0mm) and high velocity (80–100 m/s) to remove thick mill scale and rust.
Vertical Wheels: 2–4 wheels mounted on the sides of the blasting chamber, angled at 30°–45° to direct shots into the inner corners of the flanges (a common blind spot in standard machines). These wheels use smaller shots (0.8–1.2mm) to avoid damaging the web while ensuring full coverage.
All wheels are adjustable via PLC—when processing H beams with wider flanges (e.g., 600mm), the vertical wheels automatically move outward to maintain optimal distance, ensuring consistent cleaning across all beam sizes.
3.2 Continuous Roller Conveyor System for Long H Beams
The line’s conveyor system is designed to handle H beams up to 30m long and 5 tons heavy, with features that prevent bending or shifting during transport:
Heavy-Duty Rollers: Rollers are made from high-carbon steel (45#) with heat-treated surfaces (HRC 50–55) to resist wear from long H beams. They are spaced 300–500mm apart to support the beam’s weight evenly, preventing sagging.
Variable Speed Control: Conveyor speed adjusts from 0.5–3 m/min via a variable-frequency motor. Slower speeds (0.5–1 m/min) are used for heavily rusted beams, while faster speeds (2–3 m/min) handle newly rolled beams with light mill scale—balancing quality and throughput.
Side Guides: Adjustable side guides along the conveyor keep the H beam centered, ensuring it aligns with the blast wheels and avoids collisions with the chamber walls. This is critical for beams with irregular flange widths, preventing uneven cleaning.
3.3 High-Efficiency Dust and Shot Management
The line’s closed-loop design minimizes waste and environmental impact:
Dual-Stage Dust Collection: A cyclone separator first removes large dust particles (e.g., rust fragments), then a HEPA filter captures fine particles (down to 0.3μm) with 99.97% efficiency. This ensures emissions comply with global standards and protects operators from respiratory hazards.
Shot Recovery and Recycling: A magnetic separator and air classifier separate reusable steel shots from debris, returning 95% of shots to the blast wheels. The system also includes a shot level sensor that alerts operators to refill only when necessary, reducing shot waste by 30% compared to manual systems.
3.4 Intelligent PLC Control with H Beam Presets
The line’s control system simplifies operation and ensures consistency:
H Beam Presets: The PLC stores 10–20 preprogrammed settings for common H beam sizes (e.g., “200×100mm flange/web,” “500×300mm flange/web”). Operators select a preset, and the system automatically adjusts blast wheel angle, conveyor speed, and shot flow rate—eliminating manual calibration.
Real-Time Monitoring: Sensors track surface cleanliness (via vision cameras), shot quality, and conveyor alignment. If a beam has incomplete cleaning (e.g., missed inner flange corners), the system alerts operators and suggests adjustments (e.g., increasing vertical wheel intensity).
4. Main parts
The H Beam Shot Blasting Pretreatment Line consists of interconnected modules, each designed to handle a specific step in H beam pretreatment. These parts work in tandem to ensure continuous, efficient, and uniform processing of H beams, with designs optimized for the steel’s long length and complex cross-section:
4.1 Feeding and Alignment Module
This module prepares H beams for blasting by ensuring they enter the chamber straight and centered:
Infeed Conveyor: A heavy-duty roller conveyor (same design as the main conveyor) transports H beams from the storage area to the blasting chamber. It has a length of 5–10m to accommodate long beams and reduce stress on the main line.
Centering Guides: Two adjustable steel guides (height 1–2m) on either side of the infeed conveyor. These guides use hydraulic cylinders to adjust their distance (100–800mm) based on the H beam’s flange width, ensuring the beam is centered before entering the blasting chamber.
Position Sensors: Laser sensors detect the H beam’s position and send data to the PLC. If the beam is misaligned, the PLC adjusts the guides in real time, preventing collisions with the blast wheels.
4.2 Shot Blasting Chamber
The chamber is the core of the line, where H beams undergo surface cleaning:
Chamber Structure: A steel enclosure (length 4–8m, width 1.5–3m, height 2–4m) lined with wear-resistant manganese steel plates (Mn13) to withstand shot impact. The chamber’s walls are sloped to direct shots and debris toward the recovery system.
Blast Wheel Array: 6–12 blast wheels (diameter 300–600mm) mounted in horizontal and vertical positions. Horizontal wheels (4–6) target flange tops/bottoms, while vertical wheels (2–4) target web sides and flange inner corners. Each wheel is driven by a 15–37kW motor, with adjustable speed (1500–3000 rpm) to control shot velocity.
Sealing System: Rubber curtains at the chamber’s entrance and exit prevent shot leakage and dust escape. The curtains are reinforced with steel plates to resist wear from H beams, and they are replaceable for easy maintenance.
4.3 Shot Recovery and Recycling Module
This module ensures efficient reuse of steel shots:
Screw Conveyors: 2–4 screw conveyors (length 4–8m, diameter 200–300mm) at the bottom of the blasting chamber, transporting shots and debris to the magnetic separator. The screws are made from wear-resistant steel to handle abrasive materials.
Magnetic Separator: A rotating magnetic drum (diameter 300–500mm) that separates steel shots from non-magnetic debris (rust, scale). The drum’s magnetic core attracts shots, which are scraped off into a collection chute, while debris falls into a waste bin.
Air Classifier: A vertical air column that removes fine dust and small debris from the recovered shots. Adjusting airflow (5–10 m/s) ensures only shots of the correct size (0.8–2.0mm) are sent to the shot hopper for reuse.
4.4 Dust Collection Module
This module captures blasting dust to meet environmental standards:
Cyclone Separator: A large cyclone (diameter 800–1200mm, height 2–3m) that uses centrifugal force to remove large dust particles (≥10μm) from the air. These particles fall into a sealed bin for disposal.
HEPA Filter Unit: A bank of 10–20 HEPA filters (each with 99.97% efficiency for 0.3μm particles) that clean the remaining air. The unit includes a pulse-jet cleaning system—compressed air (0.5–0.7MPa) periodically blows dust off the filters, ensuring consistent airflow.
Exhaust Fan: A 15–45kW fan that pulls air through the chamber and dust collection system, maintaining negative pressure to prevent dust leakage. The fan’s speed is adjustable to match the line’s throughput.
4.5 Discharge and Inspection Module
This module completes the pretreatment process and checks beam quality:
Outfeed Conveyor: A roller conveyor (length 5–10m) that transports cleaned H beams to the next process (painting, galvanizing). It includes a cooling section (if the line has a drying module) to lower the beam’s temperature to ambient levels.
Vision Inspection System: A camera array that captures images of the H beam’s surface and compares them to a “clean” reference (Sa 2.5/Sa 3). If the beam fails inspection, the system alerts operators and diverts the beam to a rework station.
Labeling Unit: An optional unit that prints and applies a label to the H beam, recording pretreatment parameters (date, time, cleanliness level) for traceability—critical for industries like aerospace or bridge construction with strict quality records.
5. Basic Parameter
The basic parameters of the H Beam Shot Blasting Pretreatment Line are tailored to the size, weight, and production volume of H beams, ensuring the line meets the needs of different industries (construction, bridge building, machinery). These parameters are adjustable to accommodate diverse H beam specifications while maintaining efficiency and quality:
5.1 H Beam Handling Capacity
This parameter defines the line’s ability to process different H beam sizes and weights:
Maximum H Beam Length: 6–30m. Short-length lines (6–12m) are for small H beams (e.g., building floor beams), while long-length lines (20–30m) handle bridge segments or large machinery frames.
Maximum H Beam Weight: 1–5 tons. Light-duty lines (1–2 tons) process small H beams (flange width ≤200mm), while heavy-duty lines (3–5 tons) handle large beams (flange width ≥400mm, web height ≥600mm).
H Beam Cross-Section Range:
Flange Width: 100–600mm (adjustable via side guides and blast wheel positioning).
Web Height: 150–900mm (accommodated by the chamber’s internal height and vertical blast wheels).
Flange/Web Thickness: 6–50mm (the line’s blast intensity is adjustable to avoid damaging thin flanges while cleaning thick ones).
5.2 Blasting Performance Parameters
These parameters determine the line’s cleaning efficiency and surface quality:
Number of Blast Wheels: 6–12 wheels (4–6 horizontal, 2–4 vertical). More wheels (10–12) are used for heavy-duty lines processing thick H beams, while standard lines use 6–8 wheels.
Blast Wheel Power: 15–37kW per wheel. Vertical wheels (targeting inner corners) use 15–22kW motors, while horizontal wheels (targeting large flange surfaces) use 22–37kW motors.
Shot Size: 0.8–2.0mm steel shots. Smaller shots (0.8–1.2mm) are for thin H beams to prevent pitting, while larger shots (1.5–2.0mm) are for thick beams with heavy rust.
Shot Flow Rate: 100–300 kg/min. Heavy-duty lines use 200–300 kg/min for thick beams, while standard lines use 100–150 kg/min.
Cleanliness Level: Sa 2.5–Sa 3 (per ISO 8501-1). The line achieves Sa 2.5 at 1–2 m/min conveyor speed and Sa 3 at 0.5–1 m/min.
5.3 Conveyor and Throughput Parameters
These parameters impact the line’s production efficiency:
Conveyor Speed: 0.5–3 m/min (adjustable via variable-frequency motor). Slow speeds (0.5–1 m/min) for Sa 3 cleanliness, fast speeds (2–3 m/min) for Sa 2.5.
Throughput: 5–30 H beams per hour (depending on beam length and speed). A line processing 12m-long H beams at 1 m/min handles 5 beams per hour, while a line processing 6m beams at 3 m/min handles 30 beams per hour.
Conveyor Roller Specifications: Rollers have adiameter of 100–150mm and are made from high-carbon steel (45#) with a quenched-and-tempered surface (HRC 50–55) to resist wear from long-term contact with H beams. Roller spacing is 300–500mm, adjustable via a manual crank—narrower spacing (300mm) for lightweight H beams to prevent sagging, and wider spacing (500mm) for heavy beams to reduce friction during transport. The conveyor’s drive system uses a 7.5–15kW variable-frequency motor, providing smooth speed adjustment without sudden jolts that could shift the H beam.
5.4 Dust Collection System Parameters
These parameters ensure the line complies with environmental standards and maintains a clean working environment:
Air Volume: 10,000–30,000 m³/h. Light-duty lines (processing small H beams) use 10,000–15,000 m³/h, while heavy-duty lines (high shot flow rates, large beams) require 20,000–30,000 m³/h to capture excessive dust. The air volume is matched to the line’s throughput—higher volume for faster conveyor speeds (3 m/min) to avoid dust buildup.
Filtration Efficiency: ≥ 99.97% for particles ≥ 0.3μm, achieved by the dual-stage cyclone + HEPA filter system. This meets strict standards such as the EU’s EN 15038 (limit of 20 mg/m³ for particulate emissions) and the US EPA’s NESHAP (National Emission Standards for Hazardous Air Pollutants) for steel manufacturing.
Dust Collection Capacity: 80–200 kg/h. Light-duty lines collect 80–120 kg/h (mostly fine mill scale), while heavy-duty lines collect 150–200 kg/h (rust + scale from thick beams). The dust bins have a volume of 1–3 m³, allowing 8–12 hours of continuous operation before emptying—critical for 24/7 production in steel fabricators.
5.5 Power Consumption and Overall Dimensions
These parameters impact operational costs and installation requirements:
Total Installed Power: 100–300 kW. Light-duty lines (6 blast wheels, small conveyor) use 100–150 kW (blast wheels: 6×15kW = 90kW; conveyor: 10kW; dust fan: 15kW). Heavy-duty lines (12 blast wheels, large conveyor) use 250–300 kW (blast wheels: 12×22kW = 264kW; conveyor: 15kW; dust fan: 45kW). The line includes energy-saving features: blast wheels shut down automatically if no H beam is detected for 5+ minutes, reducing idle power consumption by 40%.
Overall Dimensions:
Length: 20–50m. Light-duty lines (short infeed/outfeed) are 20–30m long (infeed: 5m + chamber: 4m + recovery: 6m + outfeed: 5m). Heavy-duty lines (long infeed for 30m beams) are 40–50m long (infeed: 10m + chamber: 8m + recovery: 12m + outfeed: 10m).
Width: 3–6m. Determined by the blast chamber width (1.5–3m) and the dust collection system (1.5–3m). Heavy-duty lines with wider chambers (3m for 600mm flange beams) have a total width of 5–6m.
Height: 4–7m. Includes the blast chamber height (2–4m) and the shot hopper/recovery system (2–3m). Heavy-duty lines with taller chambers (4m for 900mm web beams) have a height of 6–7m.
Installation Requirements: The line requires a concrete foundation with a load-bearing capacity of 10–20 kN/m² (to support the heavy conveyor and chamber). For outdoor installation (common in bridge construction yards), the line is equipped with a weatherproof cover to protect electrical components from rain and dust.
These basic parameters ensure the H Beam Shot Blasting Pretreatment Line can be tailored to diverse industry needs—from small-scale steel fabricators processing 5 beams per hour to large infrastructure projects handling 30 beams per hour. By adjusting parameters such as conveyor speed, blast wheel power, and air volume, operators can balance cleaning quality, throughput, and operational costs, making the line a flexible solution for H beam pretreatment.
