- May 23, 2025
- Case Studies
25-Ton Heavy-Duty Double Girder Overhead Crane for Pakistan
Explore the 25-ton heavy-duty double girder overhead crane designed for Pakistan's industrial needs. Discover its strengths, limitations, and critical applications before making a purchase decision.
The customer operates a steel fabrication plant in Karachi, Pakistan. The facility produces structural steel beams, welded frames, and machined assemblies for construction and engineering projects. In recent years, the steel mill industry in Pakistan has grown and the production of crude steel has increased. The customer is from one of the steel mills in Pakistan and describes the need to safely and reliably lift heavy sections weighing up to 25 tons in the workshop. They had been using 15-ton single girder cranes and other handling tools, and these handling systems could not handle the heaviest beams or cover the entire shop. Operators spend a lot of time repositioning loads and switching between different lifting devices, adding to the time required for handling.
Customer Needs And Pre-Implementation Challenges
1. Load Capacity And Span Requirements
The plant required a lifting solution with a safe working load (SWL) of 25 tons. The crane needed to operate over an 18m span indoors in order to move heavy steel. Their existing single girder cranes, however, are insufficient to meet current lifting needs due to their limited loads and limited stability.
2. Handling Diverse And Challenging Tasks
The crane had to adapt to varied tasks: moving 12 m long I-beams, lifting 20 ton welded modular frames into paint booths.
3. Safety And Ergonomic Concerns
Manual handling and use of undersized cranes contributed to near-miss incidents. According to the U.S. Occupational Injury Census, 24% of crane-related fatalities occur in the manufacturing industry each year. Customers place great importance on crane safety and they seek cranes equipped with safety features such as overload protection, anti-sway control and alarm systems to prevent accidents.
4. Operational Downtime And Maintenance Issues
In addition to the above requirements, the customer stated that the overhead cranes they were responsible for the main handling of were experiencing problems with rail shifting every few months, resulting in frequent wheel replacements, re-alignment of the rails and costly repairs, which were causing delays in their production process.
Solution We Provided
1. Double Girder Main Beam And Runway System
After many communications, we identified all the needs of the client and confirmed with the client that there were no errors. Through the efforts of our engineers, we offer the following product designs: The selected model is a 25 ton double girder overhead travelling crane conforming to ISO 4301-5 duty class M6 (A6), designed for irregular intensive use up to 1×10⁶ operating cycles over its life. Two high-strength welded box girders span 18 m indoor and rest on end carriages that travel on 45 kg/m rails. For outdoor use, a second runway extends 30 m with weather-resistant rail supports embedded in concrete sleepers, requiring only minimal site work.
The double girder configuration reduces girder deflection under load to under L/600 (where L is span length), ensuring precise hook positioning even with 25 ton loads. The end carriages use sealed-for-life roller bearings to resist dust ingress in the outdoor yard.
2. Heavy-Duty Electric Hoist And Trolley
The crane employs an MH series wire rope hoist rated 25 tons, driven by a two-speed motor (4 m/min and 0.4 m/min lifting speed) to allow fast approach and precise lifting near loads. Four-fall reeving on the hoist drum provides smooth vertical travel. The trolley is motor-driven at 20 m/min travel speed with variable frequency drive (VFD) control for acceleration and deceleration profiles that reduce load swing. All major hoist components—drum, gearbox, motor—carry CE and TUV certification. The wire rope is galvanized 8×36 IWRC type, rated for 6×SWL ultimate breaking force, tested to 1.5×SWL static proof load in factory tests.
3. Control And Safety Features
- Overload Protection:Strain gauge sensors monitor lift tension and inhibit motor drive above 100 percent SWL, accompanied by audible and visual alarms.
- Anti-Sway Control:VFD-based hoist acceleration limits and trolley jerk reduction minimize load swing during starts and stops.
- Emergency Stop For All Axes:Pushbutton e-stop on pendant and optional cabin control halts hoist, trolley, and crane travel immediately.
- Limit Switches:Upper and lower hoist limits and end carriages' travel limits prevent over-travel.
- IP55 Protection:All electrical enclosures and motors are rated for dust and water jets, suitable for dusty yards and occasional rain.
- Electrical And Mechanical Protections:The crane's transformer and VFDs are housed in climate-controlled terminals with thermostatic fans. Motors carry class F insulation for ambient temperatures up to 50 °C. Mechanical couplings include slip-clutches sized to torque-limit hoist drum overload to 1.2×SWL. Rails are fitted with flange-guide rollers on the end carriages to prevent accidental derailment under side winds up to 12 m/s.
Implementation Process And Site Commissioning
1. Pre-Installation Survey
Our engineering team surveyed the workshop and yard. They verified roof truss load-bearing capacity and measured existing runway beam alignment. Soil tests confirmed concrete sleeper foundations for the outdoor rails. Detailed load paths and cable routes were documented to avoid existing utilities.
2. Installation And Load Testing
Installation took two weeks. Indoor rails were welded to existing beams, then the double girders were lifted into position using a mobile crane. Outdoor rails were cast into concrete sleepers. The hoist and trolley were mounted, then connected to power and control wiring. Static proof tests at 125 percent SWL (31.25 t) verified structural integrity. Dynamic tests moved 25 t loads through full travel at rated speeds while logging motor current and rope tension. Safety devices were tested to full compliance before handover.
3. On-Site Crane Training
The installation team conducted three days of on-site training. Operators learned safe crane operation, daily pre-shift inspections, emergency procedures, and basic troubleshooting. We provided a user manual, maintenance schedule, and load test certificates. A final commissioning report detailed all test results and compliance statements.
Operational Performance And Outcomes
After the installation was completed, the customer they performed several more tests, which all performed very well. After many days of use by customers, they feedback that the whole handling process time is reduced by about 40%. And due to the increase in handling loads, their handling efficiency has increased a lot. The crane is currently operating well without any problems.
