A bollard might have a 100-tonne SWL. Useful to know, obviously.
But what happens when the vessel is moored at an angle? When the load comes from a different direction? And what is actually happening between the bollard, its anchorages and the structure beneath it?
And how much can you establish without pulling the bollard out of service – or pulling it out of the ground?
Quite a lot, as it turns out.
What Conventional NDT Can Tell You
For many bollard assessments, our standard non-destructive testing provides exactly what you need.
Eddy current testing, ultrasonic testing and GPR can establish cracking, corrosion, section loss, voiding and deterioration, alongside assessment of the bollard, anchor bolts and surrounding structure. From that assessment, we can establish capacity and SWL where appropriate.
But sometimes you want more than a condition assessment and you want to understand how the asset behaves under load.
That’s where seismic testing adds another dimension.
Seeing the Load, Not Just the Asset
Seismic testing uses sound waves introduced into the marine bollard to assess the bollard and its connection to the supporting structure.
By testing across different axes we can identify issues such as stretched or loose fixings while also gathering detailed loading data.
Testing can assess different mooring angles and operational loading conditions. It can show how the bollard responds as a vessel applies load and how that response changes when the load comes from different directions.
That can be particularly useful when dealing with increasing vessel sizes and more challenging operational demands or when you need to understand the limits of an existing installation.
And because the testing is non-destructive, we can also test the bollard while the vessel remains moored, provided the sensor can be safely accessed.
Looking Beyond the Bollard
Marine infrastructure can look perfectly straightforward at a surface level while concealing problems below it.
A quay might combine newer steel sheet piles with much older masonry. There may be voids behind a wall, deterioration below the waterline, or piles and other structural elements that have become difficult to access. Fender piles, rubbing strips and other components can deteriorate too – all forming part of the working asset.
The technology we use originated in France for testing piles on structures including jetties and motorway bridges, and we’ve used the same principles across marine infrastructure.
That’s important because the bollard is only one part of the load path.
A 100-tonne bollard is of limited use if the structure supporting it cannot safely accommodate that load. We’ve seen this in practice. We have been asked to carry out testing of marine bollards and then find that quay wall behind it is actually moving or is at different heights, even though, with the naked eye, the surface looks entirely level. The bollard is healthy, but the infrastructure which surrounds it is showing signs of decay.
When Seismic Testing Can Add Value
This is where seismic testing excels. We use it to investigate piles and supporting structures, including difficult-to-access areas beneath the waterline. For quay and harbour walls, this can form part of a wider quay wall inspection and assessment of the structure and its supporting infrastructure.
We’ve seen tender projects in the past where it has specified the use of divers – and sometimes divers will indeed be the right answer.
But they don’t necessarily have to be the first answer. In some projects, seismic testing can simplify what would otherwise be a more convoluted investigation.
For many assets, conventional NDT will provide everything you need. However, where you want to understand loading behaviour, mooring angles, the performance of connections or what is happening within difficult-to-access supporting structures, seismic testing can give you a highly detailed picture.
It is fast, non-destructive and can provide data that a straightforward condition assessment simply cannot.
Sometimes the most useful inspection is the one that answers a question you hadn’t thought to ask.
If you have marine infrastructure where the original records are incomplete, berth loading requirements have changed, or you simply want to know more about what is happening beneath the surface, we’d be happy to talk through which inspection approach makes sense for your asset – whether that’s a quay wall inspection, conventional NDT or seismic assessment.