Single Girder Crane Main Beam End Crack Repair

Kiki

crane repair

Table of Contents

We analyzed a 12-year-old 5t 31.5m single girder crane whose main beam end developed cracks (blue box in the photo). Here's the cause analysis and repair recommendations for your reference.

Single Girder Crane Main Beam End Crack Repair Analysis

Crack Cause Analysis

1.Stress Concentration

The beam end often has a variable cross-section design to save material while meeting strength and stiffness requirements. Sharp transitions (such as the right-angle corner in the photo) can lead to stress concentration, making the area prone to cracking under prolonged loading.
Connection angles and abrupt geometry changes disrupt smooth load transfer, limit beam deformation, and increase stress accumulation, promoting cracks.

2.Welding Defects

Improper welding (e.g., porosity, slag inclusions, lack of fusion) can create stress points, becoming the starting point for cracks.
Areas with complex welds, like sharp corners at variable cross-sections, are particularly difficult to control.

3.Fatigue Load

Long-term operation under dynamic loads, combined with stress concentration at variable cross-sections, can lead to fatigue cracks.
Uneven trolley movement or large gaps at track joints can cause impact loads, accelerating crack propagation.

4.Eccentric Load & Trolley Mismatch

Frequent lifting near one side of the beam can cause trolley mismatch, introducing torsional loads concentrated at the beam end.
Misaligned travel or rail contact (track creeping/rail bite) further aggravates the situation.

Repair Recommendations

Grind and clean the welds at the cracked area.
Drill stop holes at the crack tips.
Clean and re-weld cracks beyond stop holes.
Install reinforcement plates on both side web plates, covering 200mm from the corner toward mid-span to the beam end.
Add plug weld holes on reinforcement plates and weld around edges; if possible, install braces at the junction of flange plates for extra stiffness.
Post-weld cleaning and painting.

Prevention Tips

Use smooth cross-section transitions in design to reduce stress concentration.
Strictly control welding quality.
Conduct regular inspections to detect early cracks.
Avoid overloading and follow proper operating procedures.

Conclusion

Proper analysis, timely repair, and preventive measures are key to extending the service life of cranes and ensuring safe operation. Regular inspections, quality welding, and careful handling can prevent cracks from developing and spreading, keeping your equipment reliable and efficient.

Zora Zhao

Expert in Overhead Crane/Gantry Crane/Jib Crane/Crane Parts Solutions

With 10+ years of experience in the Crane Overseas Export Industry, helped 10,000+ customers with their pre-sales questions and concerns, if you have any related needs, please feel free to contact me!

WhatsApp: +86 189 3735 0200

Email: zorazhao@dgcrane.com

Contact Details

DGCRANE is committed to providing the professional Overhead crane products and relavent service. Exported to Over 100 Countries, 5000+ Customers Choose Us, Worth to be Trusted.

sales@dgcrane.com

+86 373 387 6188

+86 189 3735 0200

Floor 30,Gongyuan INT'I Building, Jinsui Road, Xinxiang City, Henan Province, China

Get In Touch

Fill out your details and someone from our sales team will get back to you within 24 hours!