Added value of our certification


The durability of an TETRAPODE, ACCROPODE™, ACCROPODE™II, ECOPODE™, CORELOC™ or X-bloc® armour is defined by the designer. It is acquired when the design is respected and when particular care is taken in the construction of the armour and its underlayer, to correspond at least to the 3D reduced model. The criteria for accepting the armour must be met without exception.

They are defined by the technical specifications issued under the license agreement. By CLI for ACCROPODE™, ACCROPODE™II, ECOPODE™ and CORELOC™ blocks. By DMC for X-bloc®.
The means implemented to ensure that these criteria are met must enable non-compliances to be identified without exception.

Exception to this rule can lead to localized or significant disorders. Repairs often by sea will be very expensive.
In extreme cases, the design is not respected in order to increase the profit margin by saving on materials.

Installation of ACCROPODE™II without underlay, directly on the core. The toe and the first line left very quickly.


Companies can easily make false profiles by using a multibeam sounder whose data are easily modifiable:

Project with multibeams

Inspection on the profile approved using tolerances + or – 0,4 meter.


On another project the multibeam survey of the profile was perfect:


In reality we measure holes of 1.7 meters and more for a tolerance of + or - 0.3 meters.

The data produced by the multibeam can be easily distorted to present acceptable profiles in place of a completely out-of-tolerance underlayer.


Placing tools have limitations that salers do not indicate

On DAS ISLAND ECHOSCOPE® was used to place the X-bloc® and to approve the underwater work. Major disruptions that occurred after the approval led CLAS inspectors to put in place a certification procedure for the reconstruction of 5000 meters of X-bloc® armour.

On Puerto Moin, VAN OORD, a highly experienced and more cautious company, asked CLAS to evaluate the latest version of the ECOSCOPE® that was planned to approve the X-bloc® installation work. We conducted two evaluations: at the beginning of the project and after six months of use with the same operators. We made an inspection with good visibility on X.bloc® approved by ECHOSCOPE®.

The figure below summarizes the conclusions of our report after six months of training operators:

On the other hand, all the comparative tests carried out on the ECHOSCOPE® installation up to and including 2016 conclude that the system sometimes highlights non-conformities that do not exist and does not reveal non-conformities that exist. It is due to the mask effect that concerns the acoustic tools even the finest as the ARIS acoustic camera that we tested in 2016. At Puerto Moin we also brought the proofs that nonconformities highlighted by ECHOSCOPE® images did not exist in reality.

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At RAS LAFFAN 2008 with ACCROPODE™ 4 m3 and at KHALIFA in 2009 with ACCROPODE™ 0.8 m3, the system did not work.The tests concluded that the system should be stopped despite the increased assistance provided by MESURIS.

In BARAKAH in 2013 with CORELOC™ of 2 m3 the system was stopped by NMDC and KEPCO Korean company in charge of building the ABU DHABI nuclear power plant. The system did not work satisfactorily.

The system as we saw it in 2017 on ALFAW is improved compared to the previous experiences that we had, so far the precision limited to + or - 0.15 meter generates discrepancies between reality and computer image, in particular by signaling missing contacts while these contacts exist, which led to CORELOC™ breakages in trying to adjust the placement. The system also signals established contacts which in reality are not, causing undetectable contact faults on computer generated images or on acoustic tools fixed on a frame. Out of profiles and holes are not correctly identified and again nonconformities that do not exist are reported by the software. The production is limited to 3 or 4 units per hour and this pose has not been validated and required repairs.


Divers must also be checked and the procedures they apply validated by specialists in the armours inspection for ACCROPODE™, ACCROPODE™II, CORELOC™, ECOPODE™ and X.bloc®

On one project we found that the divers of the company who supervised the ACCROPODE™ installation used the video of an approved ACCROPODE™ panel to film it from different angles and present the single panel video as different panels, in order to mask major nonconformities. We put an end to it.

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CLAS puts in place a simple and effective procedure for assessing tools for shell approval TETRAPODE, ACCROPODE™, ACCROPODE™II, CORELOC™, ECOPODE™, and X-bloc®.

An TETRAPODE, ACCROPODE™, ACCROPODE™II, CORELOC™, ECOPODE™ and X.bloc® armour may be approved if the acceptance criteria are met.


Validation of inspection tools

The procedure for validating an inspection tool is to carry out inspection with this tool and an inspection conducted under good visibility by a CLAS inspector. Both inspections must show the same non-conformities.

The ARIS acoustic camera

The ARIS acoustic camera offers unmatched acoustic image quality. CLAS tested it with the Underwater Acoustics Laboratory of the University of Girona in May 2016. The images are of better quality than those obtained with the DIDSON camera in 2009 on the same project.


Large disturbances are clearly visible, not the imitated defects, out-profiles and holes are difficult to assess. The fixed frame was equipped with a rotator to vary the inclination but this was not enough to reduce the mask effect which limits the nature and the quality of the collected information and does not make it possible to use it to control the acceptance criteria of the armour. It cannot be used to validate a pose for a CLASS A breakwater armour. The ARIS camera is now available in a diver version, which should allow for dynamic inspection by highlighting all nonconformities even with zero visibility. We must test it.



Holes reported on this image do not exist.

In contrast, real nonconformities may not be identified.

X-bloc® broken and poorly imbricated unidentified on ECHOSCOPE®


Multibeam sonars

The quality of the image is very variable according to the models


In the best case we are faced with the same limits as with the ECOSCOPE®. These tools can be used to survey the outer profiles of the armour, not to make an approval confirming that acceptance criteria are in place. The diffraction of the acoustic signal due to the design of the TETRAPODE, ACCROPODE™, ACCROPODE™II, CORELOC™, ECOPODE™ and X.bloc® blocks is too important. The mask effect is too important.
In addition to the mask effect, the context of the project, the presence of waves, depth, size of the blocks used are all factors that influence the ability of a tool to deliver information.

These tools can be used to survey the outer envelope of the armour that will be attached to the "as built".
All these tools are evolving and the certification procedure put in place by the CLAS inspectors allows companies and customers to know what the real possibilities of each tool are in the context of their projects.


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Clas certification - 2018 - Tous droits réservés - Mentions légales - Design : Pygmalis - Intégration : Ingeitec