- Jul 29, 2025
- Case Studies
15‑Ton QDX Double Girder Overhead Crane for Steel Mill Shop
Discover the power of our 15-ton QDX double girder overhead crane, perfect for steel mill shops in Pakistan. Boost your productivity and efficiency today!
A steel mill shop in Pakistan manufactures steel pipes for oil, gas, and construction companies. The shop's furnace area creates bundles of hot-rolled steel pipes that need handling during the finishing process. Steel pipes come in bundles weighing up to 15 tons, with individual lengths exceeding six meters. Workers must transport these bundles from the furnace bay to the straightening station, then the cutting line, and finally to the inspection platforms. The shop required a crane capable of lifting complete 15-ton pipe bundles, properly positioning them for straightening rolls, quick changeover to handle lower loads, and clearing a 7-m hook height under a 12-m ceiling. Existing lifting technologies, such as forklifts and mobile gantries, were incapable of properly handling complete bundles and lacked the precision needed for alignment. The customer's plant addition needed a strong overhead crane to handle 60 bundles every shift and assure operator safety.
Challenges Before Using QDX Double Girder Overhead Crane Product
Before installing the 15-ton QDX double girder crane, the shop used forklifts and manual slinging to handle steel pipe bundles. Forklift forks could not properly extract bundles from the tops of pallets, resulting in dropped pipes and product damage. Each bundle lift required many attachments and cribbing, taking up to 15 minutes every move.The shop recorded five safety issues in three months, including minor injuries caused by slings shifting during manual guiding. Material flow problems caused the cutting line to idle while staff manually staged bundles.Handling lesser loads, such as bundles of smaller-diameter pipes weighing 2-5 tons, necessitated shifting hoists on improvised gantry systems, resulting in an additional 10 minutes per changeover.Overall, material handling delays lengthened production cycles by 25%, increasing labor costs and endangering delivery deadlines.
15‑Ton QDX Double Girder Overhead Crane Product Design and Specifications
To meet the customer's needs, Yuantai engineered a QDX series double girder overhead travelling crane with a 15 ton capacity and a 5 ton auxiliary hook. Key design features include:
1. Double Girder Bridge Structure
The crane uses two parallel box‑section steel girders fabricated from Q345B steel. The box girder design provides high bending stiffness and low deflection under full load. Finite element analysis optimized web plate and flange thickness so the bridge can handle up to 50 lifts per day (FEM 2m service class) without fatigue. End trucks feature four forged steel wheels per side, heat‑treated to HRC 58 for wear resistance and running on U50 kg rails. Web‑to‑flange welds are continuous CJP (complete joint penetration) welds to ensure full strength.
2. Dual‑Hook Hoist Mechanism
The crane carries two independent hoists on a common trolley. The main hoist is rated for 15 ton, with dual‑speed motor control (4 m/min and 0.4 m/min) for fast lifts and precise lowering. An auxiliary 5 ton hoist with 8 m/min and 0.8 m/min speeds handles lighter pipe bundles and accessories. Each hoist drum uses wire rope sized to its load (32 mm for the main, 18 mm for the auxiliary), wound in six grooves for even seating. Brakes are spring‑applied, electric‑released disc brakes that engage upon power loss. Operators switch between hooks via an electrical selector on the pendant, eliminating manual re‑reeving and reducing changeover time to under one minute.
3. Travel and Control Systems
Bridge and trolley motions are driven by ABB ACS355 variable‑frequency drives. Soft‑start/stop ramps prevent jolts and load swing. Maximum bridge speed is 20 m/min and trolley speed is 15 m/min in high‑speed mode; low‑speed modes cut those speeds to 4 m/min and 3 m/min for precise positioning. The pendant control uses a dead‑man switch and proportional pushbuttons to allow fine control. A wireless remote option gives operators clear line‑of‑sight when guiding pipes into straighteners. Conductor bars supply 415 V, 50 Hz power and are enclosed to IP 65 standards to prevent dust ingress.
4. Safety and Monitoring Features
Design follows CMAA guidelines and OSHA 1910.179 requirements. Electronic overload sensors cut power at 110% of rated capacity. Upper and lower limit switches prevent hook overtravel. An anti‑two‑block device stops the hoist if the hook block nears the drum. Emergency‑stop stations at each runway end and on the pendant enable instant shutdown. A load‑moment indicator displays real‑time lift weight to the operator. The entire crane is inspected and tested at full load by a third‑party certifier, with documentation provided to the customer.
Performance in Diverse and Challenging Tasks
After commissioning in February 2025, the 15 ton QDX double girder crane handled a range of tasks that demonstrated its versatility and reliability.
1. Lifting Full Steel Pipe Bundles
The furnace area produces hot‑rolled steel pipe bundles weighing up to 15 ton. The main hook picks these bundles directly from the furnace conveyor pallet. In fast‑lift mode, each load travels from furnace to straightening station in under 30 seconds. Operators then switch to low‑speed mode to lower the bundle accurately into the straightener jaws, achieving alignment within ±20 mm. This process had previously required 10 minutes of manual guiding and cribbing. The crane now processes 60 bundles per shift, matching the shop's design throughput.
2. Handling Lighter Accessory Loads
In addition to full bundles, the shop moves smaller loads—such as pipe end‑caps, spacers, and skids—ranging from 0.5 ton to 5 ton. Using the 5 ton auxiliary hoist, operators quickly lift these items out of order bins and position them on assembly tables. The high‑speed mode speeds material replenishment, while low‑speed allows careful placement. The crane's ability to switch hooks rapidly eliminated the need for separate chain hoists and gantry rigs. It reduced handling steps by 40% and cut material staging time by 60%.
3. Transferring Cut Pipe Sections
After straightening and cutting, pipe sections up to 6 m long must be moved to inspection benches. The main hook picks a bundle of cut pipes with a spreader attachment—two single‑point hooks mounted on a 3 m spreader beam. This configuration avoids pipe deformation and allows each bundle to hang level. The crane transports the load through three bays—straightening, cutting, inspection—without re‑rigging, saving 8 minutes per bundle. In all, the crane executes up to 80 moves per day without performance loss.
4. Loading Finished Products
Once inspected and marked, finished pipe bundles are moved to the shipping area. The crane lifts directly onto transport frames or truck beds over a 20 m span. The bridge's 20 m/min travel and trolley's smooth acceleration ensure quick transfers without jolts that could shift bundles. Loading now takes 5 minutes per truck, down from 20 minutes when relying on forklifts and chains. The crane loads four trucks per shift, reversing the previous bottleneck.
Advantages of the 15‑Ton QDX Double Girder Overhead Crane Product
The QDX crane solution delivered multiple benefits:
1. Increased Productivity and Throughput
Before installation, material handling steps averaged 12 minutes per bundle move. The crane reduced that to under 5 minutes for full bundles and under 3 minutes for small loads. As a result, the shop's throughput increased by over 30%, meeting production targets without adding shifts. The efficiency gains also freed operators for higher‑value tasks like quality inspection and machine setup.
2. Enhanced Safety and Ergonomics
Replacing forklifts and manual slinging lowered accident risk. The operator controls loads precisely from the pendant or remote, maintaining clearance from moving loads. Integrated safety devices prevent overloads and limit traveling outside safe zones. In six months of operation, the plant recorded zero crane‑related incidents, compared to four near misses the prior year.
3. Reduced Changeover and Downtime
Dual hoists on one trolley removed the need to swap chain hoists or call in mobile rigs. Hook changeover time dropped from 10 minutes to under one minute. Routine inspections take under two hours per week.
4. Long‑Term Cost Savings
Overhead cranes have expected lifespans of 20 years, outlasting forklifts and mobile cranes that require replacement after 5–15 years. The QDX crane's durable components and energy‑efficient motors lower operating costs. The crane recovers up to 8% of hoist energy through regenerative braking.
Yuantai Overhead Crane for Steel Mill Shop
Other Applications of Double Girder Overhead Crane
Although the 15-ton overhead crane was initially designed for a steel pipe workshop, its rugged construction, great lifting capability, and precise control features make it a versatile lifting option for a variety of industries. The crane's dual-girder layout improves stability and allows for longer hook travel, making it perfect for demanding activities requiring the accurate and safe movement of large, heavy, or irregular loads. The following are some industrial applications where this crane model provides significant benefits.
1. Heavy Cylinder and Tank Fabrication
In industries such as chemical processing, oil and gas, and boiler manufacturing, heavy cylindrical components like pressure vessels and storage tanks must be handled with care. The QDX crane supports dual-hoist configurations that allow simultaneous lifting of large shells and attached nozzles or end caps, simplifying assembly processes. Its precise speed control makes it possible to rotate or invert cylindrical components safely, supporting weld alignment and non-destructive testing without frequent re-rigging. This minimizes downtime and enhances production throughput in fabrication bays.
2. Precast Concrete Element Handling
Precast concrete manufacturers frequently deal with bulky structural elements such as wall panels, lintels, girders, and bridge beams. These components often weigh 10 to 15 tons and require exact placement to prevent damage or deformation. The QDX double girder crane, when paired with a custom spreader beam or clamp, provides the reach and control necessary for moving large panels from casting beds to curing stations or transport vehicles. Its long travel span and synchronized hoisting minimize sway and help maintain dimensional tolerances, which is critical in modular construction projects.
3. Maintenance Workshops in Power Plants
Power generation facilities—including coal-fired, hydroelectric, and gas turbine plants—depend on reliable overhead lifting for routine maintenance and part replacement. The QDX crane is ideal for lifting heavy components such as turbine rotors, generator stators, and condenser sections, which typically fall within the 5 to 15-ton range. Its high hook lift and robust hoisting mechanism align well with the spatial constraints of turbine halls and maintenance bays. Moreover, the crane's moderate duty classification matches the cyclical maintenance demands of these facilities, ensuring durability without over-specification.
4. Heavy Machinery Assembly
In sectors like mining equipment manufacturing, earth-moving vehicle production, and agricultural machinery assembly, oversized and heavy parts must be accurately positioned during build-up. The QDX double girder crane handles tasks such as lifting engine blocks, transmission housings, or crawler chassis with ease. Its dual-speed operation—both for trolley and hoist travel—enables gradual, precise movements that are essential when aligning dowel pins, flanges, or coupling interfaces. The crane's rugged structure also supports high-frequency operation, which is a common requirement in busy assembly lines.
5. Shipbuilding and Marine Repair
Shipyards and marine equipment repair facilities often use double girder cranes for manipulating propulsion systems, steel plates, and internal hull structures. The QDX crane's extended span and hook height make it suitable for lifting components like diesel engines, propeller shafts, rudder assemblies, and fabricated modules into confined ship compartments. Its dual-speed control allows safe load handling even in areas with limited visibility or tight clearances. Additionally, its compatibility with auxiliary lifting tools such as rotating hooks and engine slings adds versatility for diverse marine applications.
