Frequently Asked Questions About Crane Girders

Frequently asked questions about crane girders

We know that the main girder is an important part of the crane, which determines how much the crane can bear, so what kind of damage will happen to the main girder of the crane, and what is the damage form?

Surface Corrosion:
Crane operating environment is harsh. It usually works in dust containing acid, alkali and corrosive gases. The impact and natural aging of the anti-rust coating peel off during use, making the appearance lose its protection.
If the maintenance work is not timely, local corrosion and oxidation will be formed, the surface will be corroded to different degrees, the strength of the main girder will be reduced, and the steel structure will be deformed for a long time. This is also a common failure of the main girder of the double girder crane.

Crack:
Practice has proved that although cracks do not necessarily lead to cracks, it is very important to find and deal with cracks in time.
Even if it is not repaired in time, long-term operation is often the initial stage of cracks, especially transitional and dangerous cracks.
Generally speaking, cracks mainly occur in welding parts and stress concentration parts.

Deformation:
Including local tortuosity, deformation and eccentricity.
According to the inspection requirements of metal structures, the straightness tolerance of steel bars along the longitudinal axis is 1/750.
In use, the deformation of the main chord is not greater than 3‰-5‰; the deformation of the web is not greater than 2-4mm; the error of the connecting bolt hole spacing does not exceed 1/2 of the installation gap; the roundness error of the screw hole does not exceed 1/ of the installation gap 2; When it exceeds the above scale, it should be regarded as deformation.

The reasons for the deformation of the main girder of the crane are as follows:
The local bending deformation of the main beam is caused by collision and impact.
Due to the loosening of the connecting bolts, the bolt holes are ground into ellipses, causing arm eccentricity and additional bending moments.
The accidental collision deformation of the main beam is caused by wrong actions.
If the operating mechanism breaks down, the boom cannot control the reverse rotation, and it will collide with the tower body to cause serious deformation.
Long-term overloading will cause deformation of the main girder.