Published: Korabel.ru Magazine – №2 (40) July 2018
The production of large-capacity offshore structures is developing in the Arkhangelsk region. In 2017-2018, the Severodvinsk Design Bureau “Proship” developed a project of a self-lifting modular collapsible platform, which will be built at the shipyard “New Optimist”.
The customer of the project is GT North, a Severodvinsk-based company (part of the GT Corporation holding) that specializes in the construction and repair of hydraulic structures. Employees of the company work all over the country, from the Black and Caspian seas to the Kola Bay, and to fulfill their orders they need a prefabricated floating platform, such that it can be delivered to the site in parts – by water, road or rail. The engineers of the Proship Design Bureau undertook to design the platform.
The platform will consist of 25 modules connected by means of wedge locks. This is a complex and rarely used solution that requires high precision of manufacturing and positioning of parts. The project is unique in a sense for Russia: the only similar platform in our country (named “Fedor Ushakov”) was built in 2011 at Kaliningrad Shipyard “Sudoremont-Baltika”.
However, in the world practice such design solutions are applied widely enough. Therefore, at the first stage of work the engineers of Design Bureau “Proship” studied and summarized the relevant experience of European shipyards, having paid special attention to the issues of manufacturing and installation of dovetail locks. As a basis for design solutions they took the experience of one of the Dutch companies.
After the preliminary design of the locks, computer simulations were performed to determine the strength and stiffness characteristics of the connecting elements under a combination of different loads. For example, one of the test scenarios assumed that the ground beneath two of the four platform legs is washed out by the current, and the structure is stable only on the two diagonal legs. Various variants of hull twisting were also considered. Engineers performed a static analysis of the lock using an elastic material model and an elastic-plastic model with bilinear hardening. All calculations were performed by the finite element method using the Salome-Meca software package. The results showed that the designed lock has a sufficient bearing capacity resource.
At the final stage, ten scale models of the lock were made. The products were tested in Severodvinsk at the test bench of the department of design of lifting-transport and technological equipment of the Institute of Shipbuilding and Marine Arctic Technology (former Sevmashvtuz). Tensile diagrams of the models were built with the help of a testing machine. The results of computer modeling and tests on the test bench completely coincided, confirming the correctness of the calculations.
The platform will be built at the Arkhangelsk plant New Optimist in 2019. As of today, three modules out of 25 have been fully assembled. Measuring 35 by 17 meters, the structure will have a lifting capacity of 485 tons, and up to 15 people will be able to work on board simultaneously. It is planned that the platform with the installed equipment will be used for drilling wells, geological exploration of the shelf, as well as for the repair of other offshore facilities (including oil and gas fields). The platform is not self-propelled, it will be delivered to the place of work by tugboats or transport on land (in parts). The dimensions of the modules correspond to the dimensions of 40-foot sea containers, which facilitates transportation.
The platform will be of R2-RSN (4.5) class of the Russian Maritime Registry of Shipping. It will be equipped with towing, mooring, anchoring, pylonage, salvage, mast equipment and drilling systems. The platform is designed to operate in both southern and northern seas.