Some of the most important parts of underwater flotation bags are the attachment points or patches with straps and shackles to which the object being lifted is secured. These must be strong enough and have reserve capacity, in compliance with the relevant IMCA safety factors.

Buitink Technology develops underwater flotation bags in-house and an important part of this involves performing strength tests on the welds, fittings and patches.

Not only do the attachment points or patches need to be of sufficient strength when factory installed, they must be designed in such a way that the patches can be repaired in the field.

To test the practical strength of a flotation bag and its attachment points on land (i.e. not underwater) it can be filled with water and suspended. This produces almost the same load but “upside-down” if we compare it to the situation in which a flotation bag is deployed underwater and filled with air. 

The video below shows how the strength of a repaired patch compares to that of the original patch that was applied in our factory. It demonstrates that a repaired patch has more than 70% of the original tensile strength!

The video below shows how to repair a flotation bag patch: