Vibration technology is very attractive option for offshore applications. A vibratory hammer’s handling and pile driving speed are awesome, up to 10 times faster than when working with an impact hammer. Dieseko Group has built an extensive track record offshore with the installation of Monopiles, Anchor piles and Pin piles. Dieseko Group has 45 years of experience with this technology, and backed by our innovative approach, we have already devised many smart solutions such as pile upending, whereby the vibratory hammer can tilt to pick up a horizontal tube and upright it to driving position.
Watch our 2021 offshore video here.
It is precisely at the project level where we are in constant dialogue with large contractors to jointly develop tailor-made solutions for the challenge of delivering reliably, safely and on time. The vibratory-driving method represents a suitable alternative installation technique. The execution reveals clear advantages comparing to the conventional impact hammering. Both, the noise emission and the installation time can be decreased.
We strive to work with out clients at project level, so that our engineers can work on a tailor-made solutions that meet the project requirements and that are delivered on time. A good example of this type of cooperative client-supplier relationship is the GIANT that was developed and built for Saipem. It offers 2000kgm of power! Our commitment was: safety first, eliminate risk, innovate yet offer a reliable solutions.
Certification & Staff
Our products, organization, and our trained offshore operators are all correctly certified.
Special features on our equipment, such as the up-ending mechanism, as well as the load bearing parts, were designed, tested and certified in accordance with DNV Lifting Appliances. The GIANT 2ooo has been certified to work with casings with a top diameter of 8000mm and a weight of 1600t.
A vibratory hammers is made up of a vibrating gear case connected by elastomers to the suppressor head. The top part of the hammer does not vibrate and can be safely hoisted by a crane.The vibratory hammer is a mechanical sine-wave oscillator with weights rotating eccentrically in opposite directions. The effect of the vibrations is an oscillating vertical force classified to frequency and amplitude. Vibratory hammers work by eliminating soil resistance acting on the pile.
Installing and decommissioning
A large rental fleet of different types of large vibratory hammers including certified staff is available for anchoring, extracting or decommissioning. In particular for this type of work the advantages of a vibrator are considerable. For example by using the vibro hammer as a lifting tool, and the possibility to deploy in submerged conditions, up to hundreds of meters underwater.
Installation speed compared
The vibratory-driving method represents a suitable alternative installation technique. The execution reveals clear advantages comparing to the conventional impact hammering. Both, the noise emission and the installation time can be decreased.
This video was made during a comparison test between an impact hammer and a PVE vibratory hammer in Cuxhaven. What you see is the actual piling speed.
Vibro driven pile bearing capacity
Onshore the foundation pile load is predominantly axial. In the onshore market vibrating is a well-established installation method for steel foundation piles. Offshore pile foundations receive both axial as well as radial loads. In some cases, the installation of the piles by vibration method may somewhat reduce the axial load bearing capacity of the pile. This effect is usually compensated for by impact–driving the pile for the last few meters.
Characteristics: Vibratory driving noise emissions
The noise emissions occurring during offshore pile driving is an important aspect of environmental care. The potential damage to sea life caused by these emissions is evident. The German authorities have set a threshold level on these emissions of SEL 160 dB re 1μPa2 and SPLpeak-peak 190 dB re 1μPa2 at a distance of 750m from the source. Acoustic measurements were conducted during the offshore decommissioning of 4 wind turbine foundations using a Dieseko PVE500MU vibratory unit.
The measured sound levels of both the Sound Exposure Level (SEL) and the peak-to-peak Sound Pressure Level (SPL peak-peak) were found to be substantially lower than the threshold levels set by the German authorities. The industry is rapidly developing models to assess the noise emission on projects based on the vibratory hammer capacity, pile geometry and soil response. More information is available on request.
The handling of monopiles offshore using vibratory equipment is a great benefit for installation contractors. Dieseko has developed an active upending tool with this in mind. There is no need to separate the upending and pile driving operations as required for impact hammers. The obvious benefits being a continuous process from stabbing the monopile, to up-ending it, and then vibrating the pile to the final penetration depth.
Dieseko is involved in a first offshore pilot for installation of a heavy-duty anchor pile.
The project is the final stage of a new and revolutionary methodology to deliver anchor piles with high holding power. This is to provide a solution for the fast market for floating wind foundations.
With its partners Dieseko will provide the expertise to drive the anchor piles at any location on the seabed.
Pin piles anchor structures to the seabed. They are usually longer than monopiles but with a smaller diameter. Dieseko is fully equipped to supply the right people, tools and the best equipment for installing PIN piles. With the same features, such as high installation speed, low noise emissions and up-ending capability, Dieseko equipment can be quickly mobilized for projects all over the world.
The removal of old structures on the seabed is increasingly required by law. Decommissioned substations, turbine foundations or oil platform riser pipes all have steel pipes that need to be removed and the vibratory is the ideal tool for extracting them. A vibratory hammer is easily adaptable to work underwater even at great depths, where monitoring with an ROV can be part of accurate control.
PVE 500M dismantles wind farm Lely in only three hours. This 500 kgm eccentric power Vibratory Hammer is also available with an Upending tool.
The deployment of Dieseko’s Vibratory tools in submerged conditions is absolutely no problem. All our vibratory hammers are designed for subsea usage. The hydrostatic overpressure is compensated during the lowering and recovery of the tool subsea. This way no real limitations exist to the operational water depth when being deployed.
- Short pile driving times
- Accurate positioning and possibility for correction during insertion
- Much lower noise levels
- Reduction of installation costs by deploying fewer and more economical tools
- Increase of design life of MP’s due to different energy impact
- MP designed with thinner Wall Thickness leading to significant material savings and handling costs
- Possibility to extract piles